WO2016185240A1

WO2016185240A1 - A method and a system for controlling a plant for producing water from atmospheric air

Info

Publication number: WO2016185240A1
Application number: PCT/IB2015/000713
Authority: WO
Inventors: Rinaldo BRAVO; Luca DAL CANTO
Original assignee: Seas Société De L'eau Aerienne Suisse Sa
Priority date: 2015-05-15
Filing date: 2015-05-15
Publication date: 2016-11-24

Abstract

The present description illustrates a method and a system for controlling functioning of a plant (10) for producing water from atmospheric air, wherein the plant comprises: a heat exchanger (24), means (23) for generating an atmospheric air flow from an inlet (241 ) towards an outlet (242) of the heat exchanger (24), and a refrigerating unit (30) provided with an evaporator (244) in which a refrigerating fluid evaporates for cooling the atmospheric air flow internally of the heat exchanger (24); and wherein the method includes steps of: monitoring a characteristic temperature of the air flow at the inlet (241) of the heat exchanger (24), regulating the air flow in the heat exchanger (24) as a function of the characteristic temperature.

Description

A METHOD AND A SYSTEM FOR CONTROLLING A PLANT FOR PRODUCING WATER FROM ATMOSPHERIC AIR

TECHNICAL FIELD

The present invention relates in general to a plant for producing water from atmospheric air and a method for controlling the functioning of the plant.

PRIOR ART

As is known, there exist some zones of the world in which the water, especially potable water, is a precious and scarce resource, so scarce as to constitute a problem.

The problem is present for example in all remote or poorly-developed localities which lack an efficient water supply infrastructure. In many of these localities, the dwellings are not connected to a water distribution grid and, even if they are, the water they receive is often not potable. The people living in these zones are for this reason forced to buy expensive bottled water, or fill jugs with water having a doubtful purity and taste coming from wells or local water stations. If there are no wells, many houses use rainwater which is collected from gutterings and stored in poorly-hygienic cisterns.

The problem arises also in places where the existing water infrastructures have not been efficiently maintained. In these places, the tubes conveying the water can exhibit faults and the storage cisterns can be cracked, so that large quantities of water are lost along the network, and are unusable.

The supply of potable water represents a particularly acute problem also in the majority of desert or semi-desert zones of the world, where drought prevents collection of water either from wells or atmospheric precipitation. On the other had, the effects of climate change have begun to modify meteorology in the word with respect to the usual models, and these changes, in combination with an ever-increasing human population, and therefore with an increase in the need for water for domestic, agricultural and industrial uses, might cause these arid zones to increase in size.

The problem of potable water is also present in the majority of contexts in which people live for a long time in maritime areas, for example on small islands, on floating oil excavation platforms, or even on merchant ships which remain for many days at sea before docking in a port. In all these cases, the potable water is stored in cisterns which are periodically refilled, with consequent problems connected with the hygiene of the cisterns but also with the risk of remaining without potable water each time a problem intervenes to prevent replenishing.

To mitigate this problem, in the past it has been proposed to use the plants producing water from atmospheric air. The atmospheric air contains a certain quantity of water in the form of moisture, the condensation of which in liquid form is as droplets, when the temperature of the air falls below the dew-point temperature.

By exploiting this principle, a typical plant for water production from the atmospheric air comprises a quantity of condensation which is crossed by a flow of filtered atmospheric air generated with the aid of special ventilators. The condensation unit generally comprises a heat exchanger in which the current of atmospheric air is in heat exchange relation with a cooling fluid. This cooling fluid circulates in a refrigerating unit, which also comprises a compressor, a condenser and an expansion valve, and uses the exchanger as an evaporator. The evaporation of the refrigerating fluid subtracts heat from the atmospheric air flow and cools it to below dew point, condensing the moisture therein. The condensate is collected, sterilised, possibly enriched with salts and lastly dispensed or stored in cisterns.

In order to function, this type of plant requires a large quantity of energy (for example electrical energy and/or fuel) to actuate the ventilators which generate the air flow and to actuate the compressor and the ventilators of the refrigerating machine condenser, to the point that the water production costs can at times be very high and not economically viable. One of the reasons or this collateral effect lies in the fact that many of the plants which at present product water from the atmospheric air operate often in poorly efficient conditions.

The efficiency of these plants depends in fact not only on constructional aspects but is also strongly influenced by the atmospheric conditions in which each single plant operates. One of the most relevant atmospheric conditions is represented by the moisture content of the atmospheric air, which depends on the relative humidity of the air in relation to the air temperature and with the pressure thereof. With the aim of producing a predetermined quantity of water, if the moisture content of the air is small, the plant consumes a quantity of energy that is greater than the quantity of energy which the plant would consume if the moisture content of the environmental air were greater.

Consequently once the plant for producing the water has been positioned in the final position thereof, there might be periods in which the meteorological conditions are favourable to the production of water, and other periods in which the climatic conditions are unfavourable, reducing the efficiency of the plant and therefore increasing production costs.

This dependence on the meteorological conditions is aggravated by the fact that the ventilators for generating the atmospheric air flow are normally operated at a constant velocity, thus absorbing a substantially equal quantity of energy in any condition, and in that each possible variation of the meteorological conditions is compensated for only by a greater or lesser absorption of energy by the compressor, obtaining an overall energy balance which is not always optimal.

An aim of the present invention is to disclose a plant for producing water from atmospheric air and a method for controlling the functioning of the plant, which enable improving the energy efficiency even in meteorological conditions different from conditions pondered at design stage.

A further aim is to attain the above-mentioned objective with a solution that is simple, rational and relatively inexpensive.

SUMMARY OF THE INVENTION

These and other aims are attained by the characteristics of the invention as reported in the independent claims. The dependent claims delineate preferred and/or particularly advantageous aspects of the invention.

In particular, an embodiment of the invention discloses a method for controlling functioning of a plant for producing water from atmospheric air,

wherein the plant comprises: - a heat exchanger,

- means for generating an atmospheric air flow from an inlet towards an outlet of the heat exchanger, and

- a refrigerating unit provided with an evaporator in which a refrigerating fluid evaporates for cooling the atmospheric air flow internally of the heat exchanger,

and wherein the method includes steps of:

- monitoring a characteristic temperature of the air flow at the inlet of the heat exchanger,

- regulating the airflow in the heat exchanger as a function of the characteristic temperature.

With this solution it is possible to vary the energy absorption of the means generating the atmospheric air flow, obtaining a better efficiency of the plant also following a variation of the environmental conditions.

In an aspect of the invention the airflow is increased in response to a reduction of the characteristic temperature of the air flow at the inlet of the heat exchanger, and reduced in response to an increase of the characteristic temperature.

In this way an optimum overall energy consumption can be obtained with a water production level that is still satisfactory.

In a further aspect of the invention, the air flow generating means comprise one or more ventilators and the air flow rate is regulated by adjusting the velocity of the ventilators.

In this way, by optimising the flow rate of the atmospheric production air, an excellent energy absorption of the ventilators is obtained.

In a further aspect of the invention, the characteristic temperature of the air flow at the inlet of the heat exchanger can be the dew point temperature. This solution enables a very effective and precise regulating of the plant for production of water.

In this regard, the dew point temperature can be determined by means of steps of:

- measuring the dry bulb temperature of the air flow at the inlet of the heat exchanger,

- measuring the moisture (typically the relative humidity) of the air flow at the inlet of the heat exchanger,

- establishing the dew point temperature on the basis of the temperature and humidity of the air flow at the inlet of the heat exchanger.

This aspect provides a valid solution for the determination of the dew point temperature.

In a further aspect of the invention, the characteristic temperature of the air flow at the inlet of the heat exchanger can be the dry bulb temperature.

With this solution there is no need for the presence of a moisture sensor, thus reducing the costs and complexity of the plant.

Alternatively, the use of the dry bulb temperature as the characteristic temperature might possibly represent a simplified control system which automatically enters into operation on the plant, should a fault or malfunctioning of the relative humidity probe(s), i.e. when it is not possible to obtain a certain determination of the dew point temperature of the air in inlet to the heat exchanger.

Irrespective of these considerations, in an aspect of the invention the regulation of the rate of the air flow comprises steps of:

- using the characteristic temperature of the air flow at the inlet of the heat exchanger so as to set a desired value of a characteristic temperature of the air flow at the outlet of the heat exchanger,

- regulating the air flow in the heat exchanger as a function of the desired value. This aspect provides a valid solution for obtaining the regulation of the air flow rate, taking account of the atmospheric conditions in which the plant operates and regulating in consequence.

In this case too, the characteristic temperature of the air flow at the outlet of the heat exchanger can be the dew point temperature or the dry bulb temperature.

Note that as internally of the heat exchanger there is a first condensation of the moisture contained in the air flow, the dry bulb temperature of the air flow at the outlet of the heat exchanger is substantially equal to the dew point temperature thereof.

In an aspect of the invention, the desired value of the characteristic temperature of the air flow at the outlet of the heat exchanger is increased in response to an increase of the characteristic temperature of the air flow at the inlet of the exchanger, and vice versa is reduced in response to a reduction of the characteristic temperature of the air flow at the inlet of the heat exchanger. This aspect of the invention also represents a valid solution for increasing the air flow rate in response to a reduction of the characteristic temperature of the air flow and in order to reduce the air flow in response to an increase of the characteristic temperature of the air flow in inlet.

In a variant of the invention, the method can comprise further steps of:

- monitoring the saturated vapour temperature of the refrigerating fluid internally of the refrigerating unit,

- regulating the air flow in the heat exchanger as a function of the characteristic temperature of the air flow at the inlet of the heat exchanger of the saturated vapour temperature of the refrigerating fluid.

With this solution it is possible to vary the energy absorption of the means generating the atmospheric air flow in a coordinated way with the energy absorption of the refrigerating unit.

In an aspect of this variant, the air flow rate is reduced in response to an increase of the saturated vapour temperature of the refrigerating fluid and increased in response to a reduction of the saturated vapour temperature. In this way, the ventilators will tendentially absorb greater energy when the refrigerating unit consumes less and, vice versa, the ventilators will tendentially absorb less energy when the refrigerating unit consumes more, always obtaining a satisfactory energy balance.

In a further aspect of this variant, the regulation of the rate of the air flow comprises steps of:

- using the characteristic temperature of the air flow at the inlet of the heat exchanger and the saturated vapour temperature of the refrigerating fluid so as to set a desired value of a characteristic temperature of the air flow at the outlet of the heat exchanger, - regulating the airflow in the heat exchanger as a function of the desired value. This aspect provides a valid solution for obtaining the regulation of the air flow rate, taking account of the atmospheric conditions in which the plant operates and the load of the refrigerating unit, and regulating in consequence.

In a further aspect of this variant the desired value of the characteristic temperature of the air flow at the outlet of the heat exchanger is reduced in response to an increase of the saturated vapour temperature of the refrigerating fluid (with the effect of maintaining an optimal level of energy efficiency of the compressor and reducing the electrical absorption of the ventilators) and for increasing it in response to a reduction of the saturated vapour temperature (with the effect of optimising the energy performance of the compressor, preventing the freezing of the condensate on the heat exchanger should the evaporation temperature be lower than 0°C and, given the power available to the compressor, obtaining an increase of the water production).

This aspect of the invention also represents a valid solution for reducing the air flow rate in response to an increase of the saturated vapour temperature of the refrigerating fluid and for increasing the air flow in response to a reduction of the saturated vapour temperature.

- monitoring the characteristic temperature of the air flow at the outlet of the heat exchanger (for example the dew point temperature or the dry bulb temperature),

- calculating a difference between the monitored value and the desired value of the characteristic temperature of the air flow at the outlet of the heat exchanger,

- regulating the airflow in the heat exchanger as a function of the difference. With this solution the air flow is regulated by means of a precise control in retraction of the characteristic temperature of the air flow at the outlet of the heat exchanger.

In a further aspect of the invention, the desired value of the characteristic temperature of the air flow at the outlet of the heat exchanger is obtained from a chart (for example a chart correlating the desired value to the characteristic temperature of the air flow at the inlet of the heat exchanger, or a chart which correlates the desired value to both the characteristic value of the air flow at the inlet of the heat exchanger and to the saturated vapour temperature of the refrigerating fluid).

This solution enables obtaining the desired value rapidly and with a reduced computational intervention.

In a further aspect of the invention, the chart is selected from a group of charts calibrated on a basis of different climatic characteristics.

In this way the control of the plant can be modified on the basis of the climate in the zones in which it is located to operate.

In a variant of all the above-described solutions, instead of being based on the characteristic temperature at the outlet of the heat exchanger, the control method and all aspects thereof can be based on a temperature leap (difference) between the characteristic temperature of the air flow at the inlet of the exchanger and the characteristic temperature of the air flow at the outlet of the exchanger.

With the same modalities as described in the foregoing, the method might therefore include setting, on the basis of the characteristic temperature of the air flow at the inlet of the heat exchanger and possibly also the saturated vapour temperature of the refrigerating fluid, a desired value of the temperature leap and regulating the rate of the air flow as a function of the desired value of the temperature leap, for example with a retroactive control including monitoring the temperature leap, calculating the difference between the monitored value and the desired value of the temperature leap, and regulating the air flow rate as a function of the difference.

This variant substantially represents a technical equivalent of the preceding solutions, since to a predetermined characteristic temperature of the air flow at the inlet of the exchanger and to a predetermined temperature leap corresponds uniquely a specific characteristic temperature of the air flow at the outlet of the exchanger, and vice versa.

It is stressed here that the variants described above of the control method might all be implemented on a same plant, so as to be able to be used in a selective way, for example on the basis of the actual climatic conditions or with a seasonal programming, or the like.

A further embodiment of the invention discloses a plant for obtaining water from atmospheric air, comprising:

- a heat exchanger,

- an electronic control system configured for:

This embodiment substantially obtains the same effects delineated in the foregoing, in particular the effect of enabling varying the energy absorption of the means generating the atmospheric air flow, obtaining a better efficiency of the plant also following a variation of the environmental conditions.

In an aspect of the invention, the electronic control system can be configured so as to increase the air flow in response to a reduction of the characteristic temperature of the air flow at the inlet of the heat exchanger, and reduced in response to an increase of the characteristic temperature.

In a further aspect of the invention, the air flow generating means comprise one or more ventilators, and the electronic control system is configured so as to regulate the air flow rate by adjusting the velocity of the ventilators.

In this regard, the electronic control system can be configured such as to determine the dew point temperature by means of steps of:

Irrespective of these considerations, in an aspect of the invention the electronic control system is configured to regulate the rate of the air flow, carrying out steps of:

- regulating the air flow in the heat exchanger as a function of the desired value. This aspect provides a valid solution for obtaining the regulation of the air flow rate, taking account of the atmospheric conditions in which the plant operates, and regulating in consequence.

In an aspect of the invention, the electronic control system can be configured so as to increase the desired value of the characteristic temperature of the air flow at the outlet of the heat exchanger in response to an increase of the characteristic temperature of the air flow at the inlet of the heat exchanger, and vice versa reduced in response to a reduction of the characteristic temperature of the air flow at the inlet of the heat exchanger.

This aspect of the invention also represents a valid solution for increasing the air flow rate in response to a reduction of the characteristic temperature of the air flow and in order to reduce the air flow in response to an increase of the characteristic temperature of the air flow in inlet.

In a variant of the invention, the electronic control system can be configured so as to carry out further steps of:

With this solution it is possible to vary the energy absorption of the means generating the atmospheric air flow in a coordinated way with the energy absorption of the refrigerating unit. In an aspect of this variant, the electronic control system can be configured so as to reduce the air flow rate in response to an increase of the saturated vapour temperature of the refrigerating fluid and to increase the air flow rate in response to a reduction of the saturated vapour temperature.

In this way, the ventilators will tendentially absorb greater energy when the refrigerating unit consumes less and, vice versa, the ventilators will tendentially absorb less energy when the refrigerating unit consumes more, always obtaining a satisfactory energy balance.

In a further aspect of this variant, the electronic control system can be configured to regulate the rate of the air flow, carrying out steps of:

- using the characteristic temperature of the air flow at the inlet of the heat exchanger and the saturated vapour temperature of the refrigerating fluid so as to set a desired value of a characteristic temperature of the air flow at the outlet of the heat exchanger,

- regulating the airflow in the heat exchanger as a function of the desired value. This aspect provides a valid solution for obtaining the regulation of the air flow rate, taking account of the atmospheric conditions in which the plant operates and the load of the refrigerating unit, and regulating in consequence.

In a further aspect of this variant the electronic control system can be configured so as to reduce the desired value of the characteristic temperature of the air flow at the outlet of the heat exchanger in response to an increase of the temperature of the saturated vapour of the refrigerating fluid with the effect of maintaining an optimal level of energy efficiency of the compressor and reducing the electrical absorption of the ventilators and for increasing it in response to a reduction of the saturated vapour temperature (with the effect of optimising the energy performance of the compressor, preventing the freezing of the condensate on the heat exchanger should the evaporation temperature be lower than 0°C and, given the power available to the compressor, obtaining an increase of the water production). This aspect of the invention also represents a valid solution for reducing the air flow rate in response to an increase of the saturated vapour temperature of the refrigerating fluid and for increasing the air flow in response to a reduction of the saturated vapour temperature.

In this way it is advantageously possible to maintain an excellent level of energy efficiency of the compressor and reduce the absorption of electricity of the ventilators, maximise the energy performance of the compressor obtained by raising the evaporation temperature, prevent freezing of the condensate on the batteries should the temperature be lower than 0°C and, given the power available to the compressor, obtain an increase in water production.

Irrespective of these considerations, in an aspect of the invention the electronic control system can be configured to regulate the rate of the air flow, carrying out steps of:

In a further aspect of the invention, the electronic control system is configured so as to obtain the desired value of the characteristic temperature of the air flow at the outlet of the heat exchanger from a chart (for example a chart correlating the desired value to the characteristic temperature of the air flow at the inlet of the heat exchanger, or a chart which correlates the desired value to both the characteristic value of the air flow at the inlet of the heat exchanger and to the saturated vapour temperature of the refrigerating fluid).

This solution enables obtaining the desired value rapidly and with a reduced computational intervention. In a further aspect of the invention, the electronic control system can be configured such as to select a chart from a group of charts calibrated on a basis of different climatic characteristics.

In a variant of all the above-described solutions, instead of being based on the characteristic temperature at the outlet of the heat exchanger, the electronic control system can be based on a temperature leap (difference) between the characteristic temperature of the air flow at the inlet of the exchanger and the characteristic temperature of the air flow at the outlet of the exchanger.

With the same modalities as described in the foregoing, the electronic control system might therefore be configured such as to set, on the basis of the characteristic temperature of the air flow at the inlet of the heat exchanger and possibly also the saturated vapour temperature of the refrigerating fluid, a desired value of the temperature leap and regulate the rate of the air flow as a function of the desired value of the temperature leap, for example with a retroactive control including monitoring the temperature leap, calculating the difference between the monitored value and the desired value of the temperature leap, and regulating the air flow rate as a function of the difference.

It is stressed here that the variants described above of the control system might all be implemented on a same plant, so as to be able to be used in a selective way, for example on the basis of the actual climatic conditions or with a seasonal programming, or the like.

Further characteristics and advantages of the invention will emerge from a reading of the following description, provided by way of non-limiting example with the aid of the figures illustrated in the appended tables of drawings. Figure 1 is a pesrpective elevation view of a plant for producing water according to an embodiment of the present invention.

Figure 2 is a plan view from above of the plant of figure 1.

Figure 3 is a view along section Ill-Ill of figure 2.

Figure 4 is a schematic frontal view of figure 3.

Figure 5 is section V-V of figure 3.

Figure 6 is section VI-VI of figure 3.

Figure 7 is section VII-VII of figure 3.

Figure 8a is a perspective view of the condensation unit of the plant of figure 1 , according to an embodiment.

Figure 8b is the view of figure 8 relating to a constructional variant of the condensation unit.

Figures 9, 10 and 11 are three plan views of a plant for producing water according to various constructional alternatives.

Figure 12 is the hydraulic layout of the plant of figure .

Figure 12b is a variant of the hydraulic layout of figure 12.

Figure 13 is the hydraulic layout of a variant of the plant of figure 1.

Figure 14 is the hydraulic layout of a second variant of the plant of figure 1.

Figure 15a is a block diagram illustrating a control logic of the plant of figure 1. Figure 15b is a block diagram illustrating a variant of the logic control of figure

15a.

Figure 16 is a diagram representing the variation of the air flow and therefore of the velocity of the ventilators on varying the saturated vapour temperature in the refrigerating unit.

The figures show a plant 10 for production of water, for example potable water, by condensing the moisture that is present in the atmospheric air.

The plant 10 schematically comprises a condensation unit 20 configured for dehumidifying an atmospheric air flow, condensating and collecting a part of the water present therein, a refrigerating unit 30 configured for generating the cold necessary for condensation of the air flow in the condensation unit 20, and a purification unit 40 configured for making condensation water and collected in the condensation unit 20 potable. Condensation unit

As illustrated in figure 3, the condensation unit 20 comprises an inlet opening 21 by which the moist air to be dehumidified enters, and an opposite outlet opening 22 from which the dehumidified air exits.

The condensation unit 20 comprises a heat exchanger 24, which is interposed between the inlet opening 21 and the outlet opening 22, so as to be crossed by the air flow.

The heat exchanger 24 comprises a first parallelepiped body 240 arranged with the main dimension vertical and provided with a front face 241 , with respect to the advancement direction of the air flow from the inlet opening 21 to the outlet opening 22, and an opposite rear face 242. The front face 241 and the rear face 242 can be for example rectangular with a vertical longitudinal axis.

Between the front face 241 and the rear face 242 the first parallelepiped body 240 defines a through-channel 243 (shown only schematically in figure 5) that is open at the faces 241 and 242. This through-channel 243 crosses the first parallelepiped body 240 in the direction imposed by the air flow entering from the inlet opening 21 , in the example in a perpendicular direction to the faces 241 and 242. The through-channel 243 is further closed in the transversal direction so that the air flow can be directed only in the longitudinal direction entering the first parallelepiped body 240 from the front face 241 and exiting therefrom only from the rear face 242.

The first parallelepiped body 240 is preferably crossed transversally, with respect to the crossing direction of the air flow, by a first tube bundle 244. This first tube bundle 244 is bent in a serpentine shape so as to cross the whole transversal section of the first parallelepiped body 240 several times, for example extending over the whole height and for the whole thickness thereof. In this way, the first tube bundle 244 is lapped by the air flow crossing the first heat exchanger 24.

The first parallelepiped body 240, and the first tube bundle 244, are preferably made of a metal material having high heat conductivity and being resistant to oxidation, such as for example stainless aluminium, of a type suitable for use with food.

The condensation unit 20 further comprises a pair of additional heat exchangers, denoted respectively by 25 and 26, which are interposed between the inlet opening 21 and the outlet opening 22 and are able to be crossed in series by the air flow which is forced by the ventilator 23.

In practice, with respect to the air flow direction, the condensation 20 comprises a second heat exchanger 25, located upstream of the main exchanger 24, and a third heat exchanger 26 located downstream of the main exchanger 24.

The second heat exchange plate 25 comprises a second parallelepiped body

250 arranged with the main dimension vertical which, with respect to the advancement direction of the air flow from the inlet opening 21 to the outlet opening 22, is provided with a respective front face 251 and an opposite rear face 252.

The front face 251 and the rear face 252, can be rectangular with the longitudinal axis vertical and having a like shape to the shape of the faces 241 and 242 of the first parallelepiped body 240.

Between the front face 251 and the rear face 252 the second parallelepiped body 250 defines a through-channel 253 (shown in figure 6), entirely alike to the through-channel of the first parallelepiped body 240 that is open at the faces 251 and 252. This through-channel 253 crosses the second parallelepiped body 250 in the direction imposed by the air flow entering from the inlet opening 21 , in the example in a perpendicular direction to the faces

251 and 252. The through-channel 253 is closed in the transversal direction so that the air flow can be directed only in the longitudinal direction entering the second parallelepiped body 250 from the front face 251 and exiting therefrom only from the rear face 252.

The second parallelepiped body 250 is preferably crossed transversally, with respect to the crossing direction of the air flow, by a second tube bundle 254. This second tube bundle 254 is bent in a serpentine shape so as to cross the whole transversal section of the second parallelepiped body 250 several times, for example extending over the whole height and for the whole thickness thereof. In this way, the second tube bundle 254 is lapped by the air flow crossing the second heat exchanger 25, before passing through the main exchanger 24.

The second parallelepiped body 250, and the second tube bundle 254, are preferably made of a metal material having high heat conductivity and being resistant to oxidation, such as for example stainless aluminium, of a type suitable for use with food.

Likewise, the heat exchange plate 26 comprises a third parallelepiped body 260 arranged with the main dimension vertical which, with respect to the advancement direction of the air flow from the inlet opening 21 to the outlet opening 22, is provided with a respective front face 261 and an opposite rear face 262.

The front face 261 and the rear face 262, can be rectangular with the longitudinal axis vertical and having a like shape to the shape of the faces 241 and 242 of the first parallelepiped body 240.

Between the front face 261 and the rear face 262 the third parallelepiped body

260 defines a through-channel 253 (shown in figure 7), entirely alike to the through-channel of the first parallelepiped body 240 that is open at the faces

261 and 262. This through-channel 263 crosses the first parallelepiped body 250 in the direction that the air flow entering from the inlet opening 21 , in the example in a perpendicular direction to the faces 261 , 262. The through- channel 263 is closed in the transversal direction so that the air flow can be directed only in the longitudinal direction entering the third parallelepiped body 260 from the front face 261 and exiting therefrom only from the rear face 262. The third parallelepiped body 260 is preferably crossed transversally, with respect to the crossing direction of the air flow, by a third tube bundle 264. The third tube bundle 264 is bent in a serpentine shape so as to cross the whole transversal section of the second parallelepiped body 260 several times and, for example, extending over the whole height and for the whole thickness thereof. In this way, the third tube bundle 264 is lapped by the air flow crossing the third heat exchanger 26, after having passed through the main exchanger 24. The third parallelepiped body 260, and the third tube bundle 264, are preferably made of a metal material having high heat conductivity and being resistant to oxidation, such as for example stainless aluminium, of a type suitable for use with food.

As illustrated in figure 12, the third tube bundle 264 is hydraulically connected with the second tube bundle 254 by means of a closed hydraulic circuit 255, which is provided with a recycling pump 256 able to recycle a heat exchange liquid, for example water or a mixture of water and glycol, between the second and third heat exchanger 25 and 26.

In particular, the hydraulic circuit 255 can comprise a first portion 257 which connects the inlet of the tube bundle 254 of the second exchanger 25 with the outlet of the tube bundle 264 of the third exchanger 26 and a second portion 258 which connects the outlet of the tube bundle 254 of the second exchanger 25 with the inlet of the second tube bundle 264 of the third exchanger 26. In this way, owing to the thrust exerted by the recycling pump 256, the heat exchange liquid circulating in the hydraulic circuit 255 crosses in succession the tube bundle 264 of the third exchanger 26, where it is cooled by the dehumidified and cold air flow which exits from the main exchanger 24, and then the tube bundle 254 of the second exchanger 25, where it heats up by subtracting heat from the moist and hot in inlet to the main exchanger 24.

As illustrated in the embodiment of figure 14, it is possible to use the heat of the cold heat exchange liquid circulating in the first portion 257, entirely or only in part (if in a quantity of lower than the total in circulation) for cooling a secondary liquid destined to serve a user, for example the water of a cooling plant or the like.

In this way, the hydraulic circuit 255 can comprise a first auxiliary branch 267 which branches from the first portion 257 and a second auxiliary branch 266 which joins the second portion 258.

A heat exchanger 268 can be included between the first branch 267 and the second branch 266, for example of a liquid-liquid type, in which the heat exchange liquid circulating in the circuit 255 is in heat exchange relationship with the secondary liquid to be cooled. Naturally the hydraulic circuit 255 is also provided with appropriate regulating valves (not illustrated) which regulate the quantity of heat exchange liquid crossing the exchanger 268.

Referring once more to figure 3, the main heat exchanger 24 and the auxiliary heat exchangers 25 and 26 are arranged in succession and aligned in a pack, so that the rear face 262 of the third parallelepiped body 260 defines the outlet opening 22 of the condensation unit 20, while the front face 251 of the second parallelepiped body 250 defines the inlet opening 21.

The main heat exchanger 24 is advantageously fixed by means of threaded organs to the pair of auxiliary heat exchangers 25 and 26, so as to define a compact sandwich structure. The threaded organs, for example, can be stud screws 28 having axes parallel to the advancement direction of the air flow from the inlet opening 21 to the outlet opening 22 (see figure 8a).

In practice, the stud screws 28 exhibit a length only slightly greater than the sum of the thicknesses of the heat exchangers 24, 25 and 26 and exhibit threaded opposite ends, able to project out of the sandwich structure.

Each stud screw 28 is insertable in a series of through-holes 26 (in the example four in number located at the vertices of the front faces 241 ,251 ,261 and of the rear faces 242,252,262) aligned with one another and realised in the three heat exchangers 24, 25 and 26 (see figures 5, 6 and 7) The threaded through-holes 280 can be singly finished by hollow tubular elements. The opposite ends of each of the stud screws 28 are screwed to lock nuts 281 able to block the sandwich pack structure constituted by three heat exchangers 24, 25 and 26. Alternatively or additionally, each parallelepiped body 245,250,260 can comprise a perimeter flange able to border each of the front faces 241 ,251 ,261 and of the rear faces 242,252,262, for example projecting externally of the respective parallelepiped body 240,250,260 (see figure 8b).

For example, the parallelepiped bodies 240,250,260 can be coupled to one another by means of the respective perimeter flanges, for example solidly (e.g. by welding).

Each parallelepiped body 240,250,260 can further comprise one or more inspection windows provided with openable and/or removable hatch doors for inspection and periodic cleaning of the parallelepiped bodies 240,250,260. In any case, the sandwich structure constituted by the first parallelepiped body 240 the second parallelepiped body 250 and the third parallelepiped body 260 defines a tunnel, closed in a lateral direction to the fluid crossing and open exclusively at the inlet opening 21 (i.e. the front face 251) and the outlet opening 22 (i.e. the rear face 262).

The condensation unit 20 further comprises a filter apparatus 27 which, located so as to intercept the inlet opening 21 and occupying all the air passage surface, is able to be crossed by the whole moist air flow which enters the inlet opening 20, i.e. in the front face 251 of the second parallelepiped body 250, so as to remove any solid particulate and/or any pollutant and/or any saline residues and/or other impurities.

In the illustrated example, the filter apparatus 27 comprises in particular one or more first filters 271 , for example of the anti-particulate type, downstream of which one or more second filters 272 can be present, for example of the rigid pocket type. Upstream of the first filters 271 , the filter unit 27 can also include the presence of a protection grid 273.

A chemical air treatment unit 275 can be included between the filter apparatus 27 and the condensation unit 20, as illustrated in figures 8a and 8b.

This chemical treatment unit 275 is useful as the ambient air can contain contaminants having variable composition both in terms of the natural climatic and biological alterations (organic putrefaction, volcanic eruptions etc.) and due to the anthropic presence deriving from civic and industrial activity such as extraction industries, petro plants, craft workshops and agricultural activities (animal husbandry or use of fertilisers, disinfectants, phytopharmaceutical products, herbicides, etc.) which cause diffusion of micro-pollutants which are dispersed in the air.

The micro-pollutants can belong to various categories, among which: Ammonia, Volatile Organic Compounds (hydrocarbons in various forms: Aliphatics, Aromatics, Halogenates, etc.) cations and anions in ionic form or saline form (Potassium, Hydrogen Sulphide, Nitrogen Oxide, etc) or Aerosols in general containing elements and dissolved molecules belonging to the above-indicated families of compounds.

The chemical treatment unit 275 reduces the concentration of the micro- pollutants before the air flow crosses the condensation unit 20, so that at the most a minimal quantity thereof is left in the water, thus facilitating the successive steps of purification and potabilisation. In practice, the chemical treatment unit 275 protects and prevents the contamination of the whole condensation unit.

The chemical treatment unit 275 can comprise, for example, an air-permeable membrane, which occludes the inlet 21 of the condensation unit 20 so as to intercept all the air flow directed internally and eliminate the concentration of micro-pollutants.

The permeable membrane can be for example crossed by only Zeolite (for example carbalite and/or phillipsite) so as to realise a step of zeolitic catalysis, or by only activated charcoal, so as to realise an adsorption step of the micro- pollutants.

Alternatively, the permeable membrane might be made from a mixture of Zeolite and activated charcoal, so as to carry out both steps and obtain a better elimination of the airborne micro-pollutants. Should the presence of contaminants be particularly high, it is possible to include installation in series of one or more permeable membranes made of Zeolite, activated charcoal or mixtures thereof according to the treatments to be made.

In practice, the treatment unit 275 might comprise a container or a series of containers, in box or cylinder form, containing the above-mentioned permeable membranes, which can be arranged parallel to one another in order to be crossed in series by the air flow, and each of which can be composed of or will contain the suitable materials for the treatment to be carried out, i.e. Zeolite, activated charcoal or a mixture thereof. These containers are preferably structured in such a way as to be easily removed from the structure, so that a replacement of the porous membranes can be made with fresh or regenerated ones.

The condensation unit 20 comprises at least a ventilator 23, which can be located at the outlet opening 22, and is configured so as to force an air flow to enter through the inlet opening 21 and exit from the outlet opening 22.

In the illustrated example, the heat exchange plate 20 comprises a plurality of ventilators 23 located posteriorly of the rear face 262 of the second heat exchanger 26, with respect to the advancement direction of the air flow from the inlet opening 21 to the outlet opening 22, are located downstream of the rear face 262 of the third exchanger 26.

The ventilators 23 are such as to occupy the whole passage surface of the air on the rear face 262 of the third exchanger 26, in practice being uniformly distributed with respect to the surface of the rear face itself.

In the example, the ventilators 23 are flanked and aligned to one another along a vertical direction, i.e. along the prevalent extension direction of the outlet opening 22 and of the main exchanger 24.

The ventilators 23 can be actuated by one or more electric motors (not illustrated) which are able to operate them at different velocities to which different air flow rates crossing the condensation unit 20 apply. In general terms, the greater the air flow rate and therefore the rotation velocity of the ventilators 23 is, the greater is the absorbed electrical power of the actuating motors, also caused by the increase in the load losses and the consequent need for greater head developed by the ventilators 23.

As illustrated in figure 8a downstream of the ventilators 23 an accelerator element of the dehumidified air flow can be fixed, which exits from the outlet opening 22.

For example, the accelerator element can comprise a converging nozzle 230, i.e. a converging connection provided with a broadened end associated to the downstream end of the ventilator 23 and a free tapered end located downstream of the advancement direction of the air flow, imposed by the same ventilator 23.

The condensation unit 20 further comprises at least a collecting tub 291 located inferiorly thereof main exchanger 24 for collecting the condensation water separating from the air flow which crosses the exchanger

In the example the condensation unit 20 also comprises also a second collecting tub 292 located inferiorly of the second exchanger 25 and a third collecting tub 293 located interiorly of the third exchanger 26.

Each collecting tub 291 ,292,293 is slidably associated to the respective parallelepiped body 240,250,260 with respect to a horizontal sliding direction perpendicular to the advancement direction of the air flow along the condensation unit 20.

As illustrated for example in figure 8b, the connection between the parallelepiped body 240,250,260 and the respective collecting tub 291 ,292,293 can be made substantially sealed or in any case isolated from outside by means of removable and/or openable padding.

The bottom of each collecting tub 291 , 292 and 293 is advantageously inclined with respect to a horizontal plane, so as to make the water converge towards a lowered collection point.

As illustrated in figure 12, the water is sent from the collecting tubs 291 , 292 and 293 to the purification unit 40 through a conveying tubing 43 on which at least a sourcing pump 41 is located.

However, the water that collects in the tubs 291 , 292 and 293 is normally at a lower temperature than a temperature requested for consumption. Therefore, before being sent to the purification unit 40, the cold water can be circulated in a special heat exchanger 46, located in series with and upstream of the main heat exchanger 24, so as to further pre-cool the air flow in inlet. This heat exchanger 46 can be realised for example as an autonomous element similar to the exchangers 24, 25 and 26, or can be made in the form of a tube bundle which is added internally of the second exchanger 25.

Refrigerating unit

The refrigerating unit 30 can be based on any known cooling technology, though in the majority of applications a conventional refrigerating compressing cycle of steam will be the sturdiest and most versatile system. For this reason, the refrigerating unit 30 generally comprises a refrigerating circuit 31 in which a refrigerating fluid circulates, for example R-134a, through a compressor 310, a condenser 312, an expansion valve 319 and an evaporator.

The compressor 310 is configured to increase the pressure of the refrigerating fluid to the state of vapour coming from the evaporator. The compressor 310 can be a rotary screw compressor or a compressor of any other type. The compressor 310 is moved by a motor 31 1 , for example by an electric motor connected to an electric distribution grid or a generator. The compressor 310 might also be of type normally called "semi-hermetic", i.e. having an electric motor inserted in the compressor body. It is however possible for the motor 31 1 to be an internal combustion engine, for example a diesel engine.

The condenser 312 is configured such as to cause condensation of the high- pressure refrigerating fluid coming from the compressor 310, losing heat to the external environment. The condenser 312 can be a tube and/or fin condenser, and can be provided with one or more fans 314 able to create a forced-air flow through the condenser 312, facilitating dissipation of the heat produced by the condensation of refrigerating fluid.

The expansion valve 319 is configured so as to lower the pressure of the refrigerating fluid coming from the condenser 312. The expansion valve 319 can be a fixed-geometry valve or a variable-geometry valve, for example having an electro-mechanical activation. In particular, the expansion valve 319 can be a regulatable valve, for example a thermostatic valve.

The evaporator is configured to cause evaporation of the lower-pressure refrigerating fluid coming from the expansion valve 319, subtracting heat from the surrounding atmosphere.

In the example the evaporator of the refrigerating unit 30 is defined by the main heat exchanger 24 of the condensation unit 20, i.e. by the tube bundle 244, so that the evaporation of the refrigerating fluid can directly cool the environmental air flow to be dehumidified.

In other words, the first tube bundle 244 defines a branch of the refrigerating circuit 31 which receives the refrigerating fluid in the liquid state and at low pressure in outlet from the expansion valve 319 and sends it to the vapour state towards the compressor 310. As it evaporates internally of the first tube bundle 244, the refrigerating fluid cools the air flow which, as it crosses the condensation unit 20, laps the external surface of the tube bundle 244.

It is however possible that in other embodiments the evaporator of the refrigerating unit 30 is separated from the main exchanger 24 of the condensation unit. For example, the evaporator of the refrigerating unit 30 can be used to cool an intermediate vector fluid, for example a mixture of water and glycol, which is circulated by a further pump in an auxiliary hydraulic circuit connected with the main exchanger 24. In this way, in the main exchanger 24, the air flow is cooled by the vector fluid and not directly by the refrigerating fluid, avoiding contamination of the condensation water in a case of small faults in the heat exchanger 24.

In some embodiments, the refrigerating unit 30 can comprise also a second evaporator 315 in arrival from a second expansion valve 3 8.

The second evaporator 315 can be connected to the refrigerating circuit 31 so as to be arranged in parallel with respect to the heat exchanger 24, i.e. so that the refrigerating fluid circulating in the second evaporator 315 does not circulate in the heat exchanger 24 and vice versa.

In practice, the second evaporator 315 can comprise an inlet for the refrigerating fluid, which is hydraulically connected by means of a branch conduit 316 to a portion of the refrigerating circuit 31 comprised between the outlet of the compressor 312 and the inlet of the first condenser 319 and an outlet for the refrigerating fluid, which is hydraulically connected by means of a delivery conduit 317 to a portion of the refrigerating circuit 31 comprised between the outlet of the heat exchanger 24 and the inlet of the compressor 310.

The second pressure valve 3 8 is located in the branch conduit 316 so as to lower the pressure of the refrigerating fluid coming from the condenser 312. The expansion valve 318 can be a fixed-geometry valve or a variable- geometry valve, for example having an electro-mechanical activation. In particular, the expansion valve 3 8 can be a regulatable valve, for example a second thermostatic valve.

In the second evaporator 315 the refrigerating fluid is in heat exchange relation with a secondary vector fluid, separate and distinct from the flow of atmospheric air that crosses the condensation unit 20, which circulates in an auxiliary circuit 320 activated by a pump or by any other known system (not illustrated). According to the uses for which it is destined, the secondary vector fluid can be a second air flow to be cooled for different aims with respect to the production of water, or might be water or a mixture of water, for example a mixture of water and glycol.

Consequently the second evaporator 315 could be a liquid/gas exchanger or a liquid/liquid exchanger. In an embodiment, not illustrated, the second evaporator 3 5 could comprise a tube bundle able to contain the refrigerating fluid and located internally of a tank able to contain the secondary vector fluid. In any case the condensation of the refrigerating fluid internally of the second condenser 315 removes heat from the vector fluid, which therefore cools down. This low-temperature secondary vector fluid can therefore be advantageously used for many purposes.

For example, the secondary vector fluid might be used in a conditioning/cooling plant for a roof of a building or any other type of structure (e.g. a ship, oil platform or the like) or device. In general, by room is meant any chamber or compartment that is to be occupied by people and/or objects, and the internal temperature of which must be conditioned/cooled, such as for example a refrigerate compartment for conserving perishable products, a room of a building or a cabin of a ship.

In this context, the second evaporator could be used so as to cool an intermediate secondary vector fluid, which in turn can be successively used to cool a flow of air directed to the environment to be conditioned/cooled.

For this purpose, the auxiliary circuit 320 could therefore comprise at least a further heat exchanger (not illustrated) in which the secondary vector fluid is in a heat exchange relation with air destined for the room.

Alternatively, the second evaporator 315 might be used so as to directly cool a flow of air internally of the above-mentioned room, i.e. so that there is a direct heat exchange between the air flow and the refrigerating fluid flowing in the second evaporator, such that the air flow in the room to be conditioned/cooled would also represent the secondary vector fluid.

The system, set up in this way, enables directly regulating the desired temperature of the heat vector fluids of any type used or the direct regulating of the environmental conditions or the desired treatment.

In other embodiments, the refrigerating unit 30 can also comprise a further evaporator for cooling an air flow internally of a second condensation unit 20 for production of water, as schematically illustrated in figure 12b.

In practice, this further evaporator is the heat exchanger 24 of a second condensation unit 20 substantially identical to the one described in the foregoing.

The two heat exchangers 24 of this embodiment can be connected to the refrigerating circuit 31 so as to be arranged reciprocally in parallel with respect to the heat exchanger 24, i.e. so that the refrigerating fluid circulating in a heat exchanger 24 does not circulate in the other and vice versa.

The pressure of the refrigerating fluid flowing in the further heat exchanger 24 is regulated by a further expansion valve 319 located at the inlet of the heat exchanger 24 of the second condensation unit 20, for example a further thermostatic valve.

This embodiment can be particularly useful in all cases in which the climatic conditions or production needs can require a lower refrigerating power in order to obtain the condensation of the water present in the air. In this case, the second condensation unit 20 can be set in function on reaching an under- exploiting condition of the power the compressor 310 can develop.

In some embodiments, the refrigerating unit 30 can also comprise a second condenser 321 configured so as to enable condensation of the refrigerating fluid coming from the compressor 310. The second condenser 321 can be connected to the refrigerating circuit 31 so as to be arranged in parallel with respect to the first condenser 312, i.e. so that the refrigerating fluid circulating in the second condenser 321 does not circulate in the first condenser 312 and vice versa.

In practice, the second condenser 321 can comprise an inlet for the refrigerating fluid, which is hydraulically connected by means of a branch conduit 322 to a portion of the refrigerating circuit 31 comprised between the outlet of the compressor 310 and the inlet of the first condenser 312 and an outlet for the refrigerating fluid, which is hydraulically connected by means of a delivery conduit 323 to a portion of the refrigerating circuit 31 comprised between the outlet of the first condenser 3 2 and the inlet of the expansion valve/s 319 and 318.

The flow of refrigerating fluid flowing at the inlet of the second condenser 321 is regulated by an intercept valve 324 located in the branch conduit 322. A further intercept valve 325 can also be positioned in the portion of the refrigerating circuit 31 comprised between the attachment point of the branch conduit 322 and the inlet of the first condenser 312. Each of the intercept valves 324 and 325 can be an electrical actuating valve. Alternatively the two valves 324 and 325 might be replaced by a single valve of the three-way type which performs the exchange with a single activation.

In the second condenser 321 the refrigerating fluid is in heat exchange relation with a further vector fluid, for example water or a mixture of water and glycol, which circulates in an auxiliary circuit 326 activated by a pump 327. In the illustrated example, the second condenser 321 is configured as an exchanger (of any type) in which the refrigerating fluid is able to exchange heat with the vector fluid, with no direct contact. In other embodiments, the second condenser 320 might however be configured as a tube bundle immersed directly in the storage tank containing the vector fluid. In other embodiments, the second condenser 320 might be an exchanger in which the refrigerating fluid exchanges heat directly with the air used as a heat vector fluid destined to other uses or to a room to be heated.

In any case the condensation of the refrigerating fluid internally of the second condenser 320 supplies heat to the vector fluid, which therefore heats up. This high-temperature vector fluid can therefore be advantageously used for many purposes, for example internally of a heating plant for rooms or as hot sanitary water.

As illustrated in figure 3, a further aim can be one of realising a defrosting system enabling thawing the ice which in determined functioning conditions can form in the main heat exchanger 24 of the condensation unit 20, and also in the second and third heat exchanger 25 and 26.

For this purpose, the auxiliary circuit 326 can comprise a storage tank 328 of the hot vector fluid produced in the second condenser 321 , a delivery conduit 329 which connects an outlet of the storage tank 328 with the inlet of a heating element 330 and a return conduit 331 which connects an outlet of the heating element 330 with an inlet of the storage tank 328, newly passing through the pump 327 and the second condenser 321.

The heating element 330 can be made in the form of a tube bundle which is predisposed internally of the first parallelepiped body 240 of the main exchanger 24. In this way, the hot vector fluid in arrival from the storage tank 328 can heat the stacks of the first tube bundle 244, thus thawing the ice that might have formed thereon.

To extend the defrosting system also to the second and third heat exchangers 25 and 26, the auxiliary circuit 326 can be hydraulically connected to the hydraulic circuit 255, in such a way that the hot fluid coming from the storage tank 328 can selectively circulate also internally of each of the second and third tube bundles 254 and 264. It is however possible that in other embodiments, the second and the third exchanger 25 and 26 can each comprise a further tube bundle connected to the auxiliary circuit 326 independently of the hydraulic circuit 255, in a substantially like way to what is described for the heat exchange plate 24.

Purification unit

As mentioned in the foregoing, the purification unit 40 comprises a sourcing pump 41 which, through the conveyor tube 42, is able to collect the condensation water collected on the bottom of the collecting tub 29 , 292 and 293 and send it to a purifier 43 (see figure 4).

The purifier 43 can be provided with one or more filters, of which for example an anti-particulate filter, an anti-bacterial filter and/or a filter for removing the organic substance that might be present in the water, an activated charcoal filter.

Further, the purifier 43 can comprise a steriliser, for example functioning with UV or ozone lamps.

Further, the purifier 43 can comprise a mineraliser, for example located downstream of the filters and suitable for adding mineral salts and other elements or other organoleptic elements.

The purifier 43 can lastly comprise a tank 44 in which the water purified by the purifier 43 is stored, which tank 44 comprises an emptying stopcock 45.

Plant layout

As illustrated in figures 1 and 2, the condensation unit 20 can be arranged internally of a first parallelepiped module 200 defined by a tubular frame, which comprises two rectangular portals 201 parallel to one another and joined by at least four longitudinal cross-members 202 parallel to the advancement direction of the air flow imposed by the ventilator 23.

The portals 201 exhibit a vertical longitudinal axis and have a slightly greater dimension with respect to the faces 241 ,251 ,261 ; 242,252,262 of the parallelepiped bodies 240,250,260.

The two portals 201 are for example parallel to the faces 241 ,251 ,261 ; 242,252,262 of the parallelepiped bodies 240, 250, 260 and, respectively, externally border the front face 251 , which defines the inlet opening 21 , and the rear face 262 which defines the outlet opening 22.

In practice the rear portal 201 , i.e. the one which borders the rear face 262 of the second exchanger 262 and is proximal thereto, defines an interconnecting face of the first module 200, the opposite face to the interconnecting face of the first module 200 is defined by the front portal 201 i.e. the one bordering the front face 251 and each contiguous face (for example four in number, of which two lateral, one upper and one lower) to the interconnecting face of the first module 200 is defined by a pair of cross-members 202 parallel to one another. The interconnecting face and the respective opposite face are provided with filler sheets able to fill any interspace between the portal 201 and respectively the inlet opening 21 and the outlet opening 22, so that the air flow forced by the ventilator 23 is totally conveyed along the tunnel defined by the sandwich structure of the heat exchangers 24 and the heat exchange plate 24, 25 and 26.

Each contiguous face to the interconnecting face can be provided with filler sheets, for example fixed sheets or mobile sheets, for example of a hatch or door type. At least one of the filler sheets closing a contiguous lateral face is advantageously openable for removal of the collecting tubs 291 ,292,293 along the sliding direction and/or for removing, along the sliding direction, one or more of the parallelepiped bodies 240,250,260 for cleaning or replacing them. The portals 201 exhibit a width (horizontal), defining the width of the first module 200, the extension of which is W/2, in which W is for example a maximum width of the internal compartment of a container of standard dimensions (for example 234 cm), for example transportable by sea.

The refrigerating unit 30 (with the exception of the evaporator, i.e. the heat exchange plate 24) can in turn be arranged internally of a second parallelepiped module 300 defined by a tubular frame, which comprises two rectangular portals 301 parallel to one another and joined by four longitudinal cross-members 302 parallel to the advancement direction of the air flow imposed by the ventilator 23. For example the cross members 302 are able to join the vertices of the portals 301.

The portals 301 exhibit a vertical longitudinal axis and lie on parallel planes to the faces 241 ,251 ,261 ; 242,252,262 of the parallelepiped bodies 240,250,260 of the condensation unit 20.

In practice, each portal 301 delimits an interconnecting face of the second module 300, able to interconnect, as will be more fully described in the following, at least with the interconnecting face of a first module 200.

Each contiguous face to the interconnecting face (for example four in number of which two lateral, one upper and one lower) of the second module 300 can be provided with filler sheets, for example fixed sheets or mobile sheets, for example of a hatch or door type. At least one of the lateral filler sheets is advantageously openable for aspirating, by the fans 314, air from the environment surrounding the second module.

The portals 301 exhibit a horizontal side, defining the width of the second module 300, the extension of which is substantially W, in which W is for example a maximum width of the internal compartment of a container of standard dimensions (for example 234 cm), for example transportable by sea. In the example W is a little smaller than the maximum width of the internal compartment of a container of standard dimensions and preferably is substantially 220 cm.

In practice, the second module 300 exhibits a width W (in the transversal direction to the crossing direction of the first module 200 by the air flow) that is twice the width W/2 of the first module 200.

The length L of the first module 200, in the parallel direction to the advancement direction of the air flow along it, can be smaller than the width W.

The second module 300 and the first module 200 exhibit a same height, for example a maximum length of the internal compartment of a container of standard dimensions, for example transportable by sea.

The first module 200 and the second module 300 are joined to one another and reciprocally fixed by means of a respective interconnecting face, which are able to match substantially parallel to one another.

In practice, the interconnecting face of the first module 200 occupies a half of the surface of one of the interconnecting faces of the second module 300 to which it is fixed.

The interconnecting faces can be fixed to one another by bolts or another threaded organ and/or by means of appropriate weld seams which interconnect the longitudinal members defining the portals 201 of the first module 200 and the portals 301 of the second module 300.

The dissipating fans 314 of the condenser 312 of the refrigerating unit 30 are, for example, located on an upper contiguous face of the second module 300. One or both the lateral contiguous faces of the second module 300 can exhibit an access opening (closable at least partially by an openable hatch) from which the ambient air drawn from the fans 314 enters).

The width of the access opening, the rotation velocity and the overall flow rate of the ventilators 23, the rotation velocity and the overall flow rate of the dissipating fan 214 are configured so as to define an air mixture substantially comprising 2/3 of ambient air entering the second module 300 from the access opening and 1/3 of dehumidified air entering the second module 300 by means of the ventilator 23 and exiting from the first module 200.

The condensation unit 40 can be arranged internally of a third parallelepiped module 400 defined by a tubular frame, which comprises two rectangular portals 401 parallel to one another and joined by at least four longitudinal cross-members 402 parallel to the advancement direction of the air flow imposed by the ventilator 23. For example the cross members 402 are able to join the vertices of the portals 401.

The portals 401 exhibit a vertical longitudinal axis and lie on parallel planes to the faces 241 ,251 ,261 ; 242,252,262 of the parallelepiped bodies 240,250,260 of the condensation unit 20.

In practice, each portal 401 delimits an interconnecting face of the second module 400, able to interconnect, as will be more fully described in the following, at least with the interconnecting face of the second module 300. Each contiguous face to the interconnecting face (for example four in number of which two lateral, one upper and one lower) of the third module 400 can be provided with filler sheets, for example fixed sheets or mobile sheets, for example of a hatch or door type.

For example, the emptying stopcock 45 is accessible from one of the above- mentioned contiguous faces, from externally of the third module 400, for example lateral.

In a first realisation, shown in figures 2 and 9, the portals 401 of the third module 400 exhibit a horizontal side, defining the width of the third module 400, which exhibit an extension W/2, in which W is for example a maximum width of the internal compartment of a container of standard dimensions (for example 234 cm), for example transportable by sea.

As mentioned, in the example W is a little smaller than the maximum width of the internal compartment of a container of standard dimensions and preferably is substantially 220 cm.

In practice, in the first embodiment, the third module 400 exhibits a width W/2 (in the transversal direction to the crossing direction of the first module 200 by the air flow) that is equal to the width W/2 of the first module 200 and half the width W of the second module 300.

The length L of the third module 400, in the parallel direction to the advancement direction of the air flow along the first module 200, in the first embodiment, is equal to the length L of the first module 200.

The third module 400 and the first module 200 exhibit a same height, for example a maximum length of the internal compartment of a container of standard dimensions, for example transportable by sea.

In practice, in this embodiment, the first module 200 and the third module 300 exhibit a same external dimension and a same external shape.

The third module 400 and the second module 300 are joined to one another and reciprocally fixed by means of a respective interconnecting face, which are able to match substantially parallel to one another.

The interconnecting faces can be fixed to one another by bolts or another threaded organ and/or by means of appropriate weld seams which interconnect the longitudinal members defining the portals 301 of the second module 300 and the portals 401 of the third module 400.

In practice, the interconnecting face of the third module 400 occupies a half

(that is, in the first embodiment, the half left free by the first module 200) of the surface of one of the interconnecting faces of the second module 300 to which the first module 200 is fixed.

A contiguous lateral face of the third module 400 is, also, fixed to a contiguous lateral face of the first module 200.

The above-mentioned contiguous lateral faces can be fixed to one another by bolts or another threaded organ and/or by means of appropriate weld seams which interconnect the cross members 202 and 402 defining the contiguous lateral faces, respectively of the first module 200 and the third module 400. In practice, in the first embodiment, the apparatus 10 is constituted by one first module 200, one second module 300, one third module 400, fixed to one another as described above.

In a second embodiment shown in figure 10, in which the above-described water flow and the power of the apparatus 10 are substantially double with respect to the apparatus 10 of the first embodiment, the portals 401 of the third module 400 exhibit a horizontal side defining the width of the third module 400, the extension of which is W, in which W is for example a maximum width of the internal compartment of a container of standard dimensions (for example 234 cm), for example transportable by sea.

In the example W is a little smaller than the maximum width of the internal compartment of a container of standard dimensions and preferably is substantially 220 cm.

In practice, in the third embodiment, the third module 400 exhibits a width W (in the transversal direction to the crossing direction of the first module 200 by the air flow) that is equal to the width W of the second module 300 and double the width W of the first module 200.

The length L of the third module 400, in the parallel direction to the advancement direction of the air flow along the first module 200, in the second embodiment can be less than the above-mentioned dimension W and, for example substantially equal to the length L of the second module 300.

The third module 400, the second module 300 and the first module 200 exhibit a same height, for example a maximum height of the internal compartment of a container of standard dimensions, for example transportable by sea.

In practice, in the second embodiment, the apparatus 10 is constituted by two first modules 200, two second modules 300, one (or two) third modules 400, fixed to one another.

One of the second modules 300 exhibits one of the fixed interconnecting faces (as described above for the first embodiment) to the interconnecting face of each of the two first modules 200.

In practice, each interconnecting ace of a first module 200 occupies (and is fixed) to half the surface of the interconnecting face of one of the second modules 300.

The first modules 200 are fixed to one another by a respective contiguous lateral face, for example they can be fixed to one another by bolts or another threaded organ and/or by means of appropriate weld seams which interconnect the cross members 202 defining the contiguous lateral faces. The further interconnecting face of the second module 300 opposite the face fixed to the first modules 200, is fixed to the interconnecting face of the further second module 300. The interconnecting faces of the two second modules 300 can be fixed to one another by bolts or another threaded organ and/or by means of appropriate weld seams which interconnect the longitudinal members defining the portals 301 of the second modules 300

The further interconnecting face of the second module 300 opposite the face fixed to the second module 300, is fixed to the interconnecting face of the third module 400.

The interconnecting faces of the third module 400 and the second module 300 can be fixed to one another by bolts or another threaded organ and/or by means of appropriate weld seams which interconnect the longitudinal members defining the portals 301 of the further second module 300 and the portals 401 of the third module 400.

Each refrigerating unit 30 of each second module 300 is connected, as described in the foregoing, to each heat exchange plate 24 of one of the two condensation units 20.

In the second embodiment, a converging nozzle 230 is connected to each ventilator 23 of the condensation unit 20 more distant from the respective refrigerating unit 30 (and respective second module 300), so that the dehumidified air exiting from the first module 200 is accelerated and sent on towards the more distant second module 300.

Obviously the purification plant 40 will receive the water to be purified from each collecting tub 291 ,292,293 of each condensation unit 20.

In a third embodiment shown in figure 11 , in which the above-described water flow and the power of the apparatus 10 are substantially double with respect to the apparatus 10 of the second embodiment, the portals 401 exhibit, as in the above-described second embodiment, a horizontal side defining the width of the third module 400, the extension of which is W, in which W is for example a maximum width of the internal compartment of a container of standard dimensions (for example 234 cm, in the example 220 cm), for example transportable by sea. In practice, in the third embodiment, the third module 400 exhibits a width W (in the transversal direction to the crossing direction of the first module 200 by the air flow) that is equal to the width W of the second module 300 and double the width W of the first module 200.

In practice, in the third embodiment, the apparatus 10 is constituted by four first modules 200, four second modules 300, and at least one, in the example two third modules 400.

In this embodiment, two third modules 400 are fixed to one another by means of a respective interconnecting face, for example by bolts or another threaded organ and/or by means of appropriate weld seams which interconnect the longitudinal members defining the portals 401 of the third modules.

As described above in relation to the second embodiment, two respective second modules 300 are joined and fixed to both interconnecting free faces of the third modules 400 (opposite the interconnecting face joining the third modules) to faxes of which free interconnecting faces further interconnecting faces of two further second modules 300 are respectively fixed.

As described above in relation to the second embodiment, two interconnecting faces of two first modules 200 are respectively fixed to each free interconnecting surface of the second modules 300, which two interconnecting faces are fixed to one another by two contiguous lateral faces, as described in the foregoing for the second embodiment.

In practice, in the third embodiment, the apparatus 10 exhibits a symmetrical distribution of the first and second modules 200,300 with respect to a perpendicular plane to the air flow advancement direction, along the first modules 200 and passing through the median line of the third module 400. In this case too, each refrigerating unit 30 of each second module 300 is connected, as described in the foregoing for the second embodiment, to each heat exchange plate 24 of one of the two condensation units 20.

Obviously each purification plant 40 arranged in the respective third module 400 will receive the water to be purified from each collecting tub 291 ,292,293 of each closest condensation unit 20.

For example, the first, second and third module 200, 300, 400, once fixed reciprocally as described in the foregoing define a substantially single-block apparatus having a width W of slightly less than the maximum width of the internal compartment of a container of standard dimensions (for example 220 cm), for example transportable by sea; a height of slightly less than the maximum height of the internal compartment of a container of standard dimensions (for example 263 cm), for example transportable by sea, and having a variable length as a function of the flow rate and/or power requested, which is substantially 495 cm for the first embodiment, 905 cm for the second embodiment and 18 0 cm for the third embodiment, so as to be able to be inserted in a standard container for transportation thereof.

Control system

As illustrated in figure 12, the plant 10 further comprises an electronic control and monitoring system 60, which can coordinate and control the functioning of the various components of the plant 10, acting on the basis of a series of control data which are measured by appropriate sensors distributed in the various parts of the plant 10.

The electronic control and monitoring system 60 substantially automates the production of the water and supplies an interface through which it is possible to start up/stop the plant 10, configure it and control the functioning state thereof. These control and monitoring operations can occur locally, with the supervision of an operator in direct contact with the water production plant 10, or remotely via a central control unit which is geographically distance from the water production plant.

For this reason the electronic control and monitoring system 60 can comprise two main parts: an electronic central control unit 605 situated on-board the plant 10 and an electronic remote management unit 610 situated in the central control unit. Both the central management unit 605 and the remote management unit 610 can comprise hardware and software components. The central control unit 605 can also be connected to the sensors and other parts of the electronic control and monitoring system 60 via a data acquisition module 615 and appropriate connections. For reasons of reliability and security, a redundancy electronic module 620 can be present to replace the control unit 605 in case of malfunctioning. Both data acquisition module 615 and the redundancy module 620 can be arranged on-board the plant for atmospheric water production 10, for example situated internally of the module 400, together with the central control unit 605.

The central control unit 605 can also include a central digital processing unit (CPU), for example based on one or more microprocessors, which can be in communication with a storage system and an interface bus. The CPU is configured for carrying out memorised instructions in the form of programs (software) in the memory system, and for sending and receiving signals to/from the interface bus. The memory system can include various memorisation types comprising optical memorisation systems, magnetic memorisation systems, solid-state memories, and other types of non-volatile memory. The interface bus can be configured so as to send and modulate the analog and/or digital signals to/from various sensors and control devices. In this way, the central control unit 605 is connected to all the sub-systems which make up the production plant of the atmospheric water 10, with the aim of sending the commands necessary for correct functioning thereof and for acquiring the functioning status. The above programs can then incorporate the control methods of the plant functioning 10 which will be described in the following, enabling the CPU to carry out the steps of the methods and therefore control the production plant of the atmospheric water 10. The central control unit 605 can also include a user interface device, such as for example a display and/or a touch screen display, through which an operator can start/stop the atmospheric water production plant 10, configure the plant 10 and control the functioning status thereof.

In particular, the central control unit 605 can be made as an industrial computer, which implements the control logic of the plant 10 and supplies, via the interface device, the main commands for functioning thereof. The industrial computers are in fact particularly resistant to factors such as vibrations, electromagnetic interferences, working temperatures and others besides. Further, industrial computers have a great flexibility of programming and are relatively economical. In other embodiments, the central control unit 605 can however be realised as a PLC (Programmable Logic Controller), which can be made up of inlet/outlet calculation modules, which is programmed to actuate the logic control of the plant.

The redundancy module 620 can be an electronic microprocessor control unit arranged on-board the production plant of the atmospheric air 10 and connected to the central control unit 605.The redundancy module 620 is configured so as to implement the basic functioning of the control and communication for the plant 10 in a case of a malfunctioning of the central control unit 605. The redundancy module 620 bears and maintains the water production plant in a state of safe and stable functioning up to replacement of the central control unit 605.

The central control unit 605 communicates with the remote management unit 610 by means of a remote transmission data system 625 which can comprise a geo-localisation module. The remote data transmission system 625 can enable communication between the central control unit 605 and the remote management unit 610 via Ethernet cable, GPRD (standard mobile network), satellite or other technologies. Independently of the communication technology thereof, the connection between the on-board central control unit 605 and the remote management unit 610 can be verified regarding the Internet using for example the TCP/IP or UDP/IP protocol according to needs. The communication can be ciphered so as to prevent undesired access to the communication channel. The level of cryptography can depend on the type of communication channel used, as the cryptography has an impact on the quantity of data to be transmitted. The geo-localisation system can be based on GPS technology and can be used to verify the movements and the present geographical position of the production plant 10 of the atmospheric air. The position sensors can be sent to the remote management unit 610, where they can be consulted at any moment.

The monitoring and control system 60 can further comprise a plurality of measuring stations which can be installed on-board the plant 10, each of which generally comprises a certain number of sensors and apparatus which measure the flow conditions of the atmospheric air which is treated internally of the condensation unit 200, such as to supply useful information for the functioning of the plant 10. The measurements taken by each measuring station include some characteristic parameters of air, such as the temperature of the air and the humidity of the air (for example, the relative humidity). Therefore, each measuring station can generally include a thermometer for measuring the temperature of the air and a hygrometer for measuring the humidity thereof. The data supplied by the measuring stations can be sent to the central control unit 605 by means of the data acquisition module 615, and the remote management unit 610 by means of the remote transmission data system 625.

In particular, the control and monitoring apparatus 60 might possibly comprise also a first measuring station 635 for measuring the temperature and humidity of the air flow at the inlet to the main heat exchanger 24, for example between the exchanger 24 and the exchanger 25, and a second measuring station 640 for measuring the temperature and the humidity of the air flow at the outlet of the main exchanger 24, for example between the exchanger 24 and the exchanger 26. The control and monitoring apparatus might possibly comprise also a third measuring station 645 for measuring the temperature and humidity of the air flow upstream of the exchanger 25, for example between the filtering system 27 and the exchanger 25, and a fourth measuring station 650 for measuring the temperature and the humidity of the air flow downstream of the exchanger 26, for example between the exchanger 26 and the row of ventilators 23.

The control and monitoring system 60 can further comprise a temperature sensor 655 arranged in the refrigerating circuit 31 in the downstream portion of the main exchanger 24 and the second evaporator 315 (if present) so as to be able to measure the saturated vapour temperature of the refrigerating fluid in the gaseous state which enters the compressor 310.

The control and monitoring system 60 can naturally comprise also many other sensors able to measure parameters which are important for the management of the plant 10 functioning, which are not described herein as they are beyond the scope of the present description.

Plant operation

In the normal functioning of the plant 10, the ventilators 23 are set in operation so as to generate a continuous air flow that crosses the condensation unit 20, in particular the main exchanger 24 and the auxiliary exchangers 25 and 26. At the same time, the compressor 310 and the condenser 312 of the refrigerating unit 30 are also set in operation, so that the evaporation of the refrigerating unit in the main exchanger 24 is able to cool the air flow to a lower temperature than the dew point temperature, thus causing condensation of the vapour in the air flow, which vapour accumulates in the form of water in the collecting tub 291 and is then sent on to the purification unit 40.

At the same time the recycling pump 256 is also set in operation, so as to cause the heat exchange liquid to flow internally of the closed hydraulic circuit 255 connecting the heat exchangers 25 and 26. In this way, the cold and dehumidified air flow exiting the main exchanger 24 cools the heat exchange liquid which is in the second exchanger 26. This cold liquid is sent upstream of the heat exchanger 25 where it is heated by the air flow in inlet before returning back to the exchanger 26. In this way, the air flow crossing the first exchanger 25 is pre-cooled before reaching the main heat exchanger 24. Owing to this pre-cooling, the air flow can be brought to a temperature equal to or near to the dew point, without using energy directly produced by the refrigerating unit 30, but simply by recuperating a part of the heat energy which otherwise would be lost in the air.

Note here that the vapour in the air flow can condense not only in the main exchanger 24 but also in part in the first heat exchanger 25. The water produced in the first heat exchanger 25 accumulates in the relative collecting tub 292 and is thence also sent on to the purification unit 40.

The cold and dehumidified air flow that exits the condensation unit 20, downstream of the ventilators 23, can be conveyed into the refrigerating unit 30, so as to pass it through the condenser 312, where it can cool the refrigerating fluid in the gaseous state by means of the heat exchange plate 24, causing condensation thereof.

Alternatively, the cold and dehumidified cold air flow from the condensation unit 20, or a part thereof, can be deviated and conveyed towards other users. For example, the air flow can be used for supplying other air treatment plants and/or for supply conditioning/cooling plants of buildings or other structures. In these and other cases, the condenser 312 of the refrigerating unit 30 can be supplied wholly or in part by a second flow of ambient air coming directly from outside the plant 10, for example entering by the access opening of the second module 300. As mentioned in the foregoing, it is preferable for a mixture of air substantially comprising 2/3 of ambient air and 1/3 of cold and dehumidified air coming from the condensation unit 20 to be made to cross the condenser 312.

With the aim of making this functioning effective, all the active components of the plant 10, such as for example the compressor 3 0, the condenser 312 and the expansion valves 319 and 318 of the refrigerating unit 30, as well as the heat exchanger 24, 25 and 26 and the ventilators 23 of the condensation unit 20, are generally dimensioned so as to obtain a certain water production in determined standard environmental conditions. For example, the plant 10 can be dimensioned so as to obtain about 100 litres of water per hour, in standard atmospheric conditions, i.e. with ambient air at temperatures of about 30°C and relative humidity at about 70%.

In order to obtain these performances in standard atmospheric conditions, the refrigerating unit 30 can be made to function so that the saturated vapour temperature of the refrigerating fluid is about 5.5°C (at the compressor 310 inlet), while the ventilators 23 of the condensation unit 20 can be made to function at a predefined velocity able to generate an air flow of about 8000 m3/h. This standard functioning condition is represented in the diagram of figure 16.

In this functioning condition, the measuring station 645 located upstream of the heat exchanger 25 will therefore detect the standard conditions, i.e. an air flow temperature of 30°C with a relative humidity of 70%, to which corresponds an air dew point temperature of about 23.9°C. With the effect of the exchanger 25, the measuring station 635 located at the inlet of the main exchanger 24 can measure a temperature of the air flow of about 21.5°C with a relative humidity of 100°C (to which naturally corresponds an air dew point temperature of 21 .5°C). The measuring station 640 located between the heat exchanger 24 and the exchanger 26 can measure an air flow temperature of about 9°C with a relative humidity of about 99%. The heat leap of the air flow between downstream of the main exchanger 24 is therefore about 12.5°C. Lastly, the measuring station 650 located between the heat exchanger 26 and the exchanger 23 can measure an air flow temperature of about 24.2°C with a relative humidity of about 37%. At the same time, the temperature of the heat exchange liquid exiting from the exchanger 26 and enters the exchanger 25 can be about 15.3°C, while the temperature of the heat exchange liquid exiting from the exchanger 25 and returns into the exchange 26 can be about 27.5°C. As mentioned in the foregoing, the components of the plant 10 are selected and dimensioned so that in these standard functioning conditions, the energy consumption of the compressor 310 and the ventilators 23 is optimal, i.e. the ratio between the energy expended and the quantity of water produced in the time unit is as small as possible.

However, during prolonged operation, the atmospheric conditions, in particular the temperature and the relative humidity of the ambient air can change, so that the plant 10 might be operating in conditions of reduced performance. To cope with this possibility and seek to maintain an optimal ratio between energy consumption and production of water, the control unit 605 can be configured so as to implement an appropriate control cycle, a first embodiment of which is described in the following with the aid of the block diagram of figure 15a.

This control cycle includes primarily determining a characteristic temperature T_a of the air flow at the inlet of the main heat exchanger 24, i.e. between the main exchanger 24 and the exchanger 25 (block S100).

The characteristic temperature T_a can be for example the dew point temperature of the air flow at inlet of the main heat exchanger 24. This dew point temperature can be determined on the basis of the dry bulb temperature and the relative humidity of the air flow at the inlet of the main heat exchanger 24, which can be measured by the measuring station 635. In particular, the dew point temperature can be calculated as a function of the dry bulb temperature and the relative humidity, or it can be obtained by an appropriate chart or table which correlates each pair of values of the temperature and the relative humidity at a corresponding value of the dew point temperature.

Alternatively, the characteristic temperature T_a can be for example the dry bulb temperature of the air flow at inlet of the main heat exchanger 24. In this case the dry bulb temperature can be simply measured with the temperature sensor of the measuring station 635, which might be therefore not equipped with the relative humidity sensor, thus simplifying and reducing the cost of the electronic control and monitoring system 60.

The use of the dry bulb temperature as the characteristic temperature might possibly represent a simplified control system which automatically enters into operation should a fault or malfunctioning of the relative humidity probe(s), i.e. when it is not possible to obtain a certain determination of the dew point temperature of the air at the heat exchanger.

In this regard, note that as the passage through the heat exchanger 25 already normally causes a first condensation of the moisture contained in the air flow, the dry bulb temperature of the air flow at the inlet of the main heat exchanger

24 is substantially equal to the dew point temperature thereof.

In any case, the characteristic temperature T_a of the air flow in inlet to the exchanger 24 is used by central control unit 605 for determining a desired value Ts (set-point) of a characteristic temperature of the air flow at the outlet of the main exchanger 24 (block S105), i.e. between the main exchanger 24 and the successive exchanger 26.

In this case too, the characteristic temperature of the air flow at the outlet of the main exchanger 24 can be the dew point temperature or the dry bulb temperature.

In this regard too, note further that as the passage through the heat exchanger 24 causes a first condensation of the moisture contained in the air flow, the dry bulb temperature of the air flow at the inlet of the main heat exchanger 24 is substantially equal to the dew point temperature thereof.

The desired value T_s can be obtained from an appropriate calibration chart or table which correlates the value of the characteristic temperature T_a of the temperature of the air flow in inlet to the exchanger 24 to a corresponding desired value T_s of the characteristic temperature of the air flow in outlet from the exchanger 24. The calibration chart or table can be determined by means of purely theoretical considerations and/or by means of experimental activities that are then stored in the central control unit 605.

At the same time, the control cycle includes the central control unit 605 also measuring the real value Tb of the characteristic temperature of the air flow at the outlet of the exchanger 24 (block S1 10).

In a case where the characteristic temperature of the air flow at the outlet of the main heat exchanger 24 is the dew point temperature, the real value Tb can simply be determined on the basis of the dry bulb temperature and the relative humidity of the air flow at the outlet of the main heat exchanger 24 as measured by the measuring station 640.

In a case where the characteristic temperature of the air flow at the outlet of the main heat exchanger 24 is the dry bulb temperature, the real value Tb can simply be measured with the temperature sensor of the measuring station 640, which might therefore be without the relative humidity sensor.

At this point, the control cycle includes the control centre 605 regulating the velocity of the ventilators 23, and therefore the rate of the air flow which crosses the condensation unit 20, so that the measured value Tb of the characteristic temperature of the air flow downstream of the exchanger 24 coincides with the desired value T_s.

To obtain this effect, the central control unit 605 can be configured so as to calculate and error D (that is a difference) between the measured value Tb and the desired value T_s (block S115) and to regulate the velocity of the ventilators 23 so as to minimise the error D.

For example, the error D can be used as an input of a controller (block S120), for example a PI controller (proportional-integrative) or a PID controller (proportional-integrative-derivative), the output U is used to command the velocity of the ventilators 23 (block S125).

The above-delineated control cycle is continually repeated during plant 10 functioning, thus obtaining a continuous regulating of the velocity of the ventilators 23 based on a retroactive control of the characteristic temperature of the air flow between the exchanger 24 and the exchanger 26, aimed at obtaining a predetermined desired value T_s of the temperature, which can vary cycle after cycle on the basis of the characteristic temperature T_a of the air flow in inlet to the exchanger 24 as predicted by the calibration chart or table used. In this regard, this calibration chart or table is structured so that following an increase of the characteristic temperature T_a of the air flow at the inlet of the exchanger 24, the desired value T_s of the characteristic temperature of the air flow at the outlet of the exchanger 24 is increased, causing a reduction of the velocity of the ventilators 23 and therefore of the air flow rate, and so that following a reduction of the characteristic temperature T_a of the air flow at the inlet of the exchanger 24, the desired value T_s of the characteristic temperature of the air flow at the outlet of the exchanger 24 is reduced, causing an increase in the velocity 23 and therefore of the air flow rate.

A variant of the control cycle is described in the following with the aid of the block diagram of figure 5b.

As in the preceding case, this control cycle too includes primarily determining a characteristic temperature T_a of the air flow at the inlet of the main heat exchanger 24, i.e. between the main exchanger 24 and the exchanger 25 (block S200).

Alternatively, the characteristic temperature T_a can be the dew point or dry bulb temperature of the air flow at inlet of the main heat exchanger 24.

At the same time the control cycle further includes measuring the saturate vapour temperature T_e of the refrigerating fluid which enters the compressor 310 coming from the heat exchanger 24 (block S205). This measurement can be made for example by means of the temperature sensor 655.

The characteristic temperature T_a of the air flow at the inlet of the heat exchanger 24 and the saturated vapour temperature T_e of the refrigerating fluid and thus used by the central control unit 605 for determining a desired value Ts (set-point) of a characteristic temperature of the air flow at the outlet of the main exchanger 24 (block S210), i.e. between the main exchanger 24 and the successive exchanger 26.

This desired value T_s can be obtained with a suitable calibration chart or table which correlates each pair of values of the characteristic temperature T_a at the inlet of the exchanger 24 and the saturated vapour temperature Te to a corresponding desired value T_s of the characteristic of the temperature of the air flow in outlet from the exchanger 24. The calibration chart or table can be determined by means of purely theoretical considerations and/or by means of experimental activities that are then stored in the central control unit 605. At the same time, the control cycle includes the central control unit 605 also measuring the real value Tb of the characteristic temperature of the air flow at the outlet of the exchanger 24 (block S215).

To obtain this effect, the central control unit 605 can be configured so as to calculate and error D (that is a difference) between the measured value Tb and the desired value T_s (block S220) and to regulate the velocity of the ventilators 23 so as to minimise the error D.

For example, the error D can be used as an input of a controller (block S225), for example a PI controller (proportional-integrative) or a PID controller (proportional-integrative-derivative), the output U is used to command the velocity of the ventilators 23 (block S230).

The above-delineated control cycle is continually repeated during plant 10 functioning, thus obtaining a continuous regulating of the velocity of the ventilators 23 based on a retroactive control of the characteristic temperature of the air flow between the exchanger 24 and the exchanger 26, aimed at obtaining a predetermined desired value T_s of the temperature, which can vary cycle after cycle on the basis of the characteristic temperature T_a of the air flow in inlet to the exchanger 24 and the saturated vapour temperature T_e of the refrigerating fluid in inlet to the compressor 310, as predicted by the calibration chart or table used.

In this regard, this calibration chart or table is structured so that following an increase of the temperature of the saturated vapour value Te of the refrigerating fluid, due for example to an increase in the characteristic temperature T_a of the air flow at the inlet of the exchanger 24, the desired value Ts of the characteristic temperature of the air flow downstream of the exchanger 24 is reduced, causing a reduction in the velocity of the ventilators 23 and therefore of the air flow; and so that, following a reduction in the saturated vapour temperature T_e of the refrigerating fluid, for example following a reduction of the characteristic temperature T_a of the air flow in inlet to the exchanger 24, the desired value T_s of the temperature of the air flow downstream of the exchanger 24 is increased, causing an increase in the velocity of the ventilators 23 and therefore of the air flow rate.

With this type of regulation, the plant 10 is able to produce a satisfactory quantity of water in many climatic conditions, while always guaranteeing the best ratio between the working conditions of the compressor 310 and the energy absorption of the ventilators 23.

This type of regulation is visually represented in the diagram of figure 16, which shows how the volumetric rate V of the air flow generated by the ventilators (y axis) varies as a function of the characteristic temperature Ta at the inlet of the exchanger 24 and the saturated vapour temperature Te of the refrigerating fluid (broken line).

In this diagram it is therefore possible to appreciate how a reduction of the characteristic temperature T_a corresponds generally to a reduction of the saturated vapour temperature Te of the refrigerating fluid to which corresponds an increase (not represented) of the desired value T_s of the characteristic temperature of the air flow downstream of the exchanger 24 and a corresponding increase of the volumetric flow rate of the air flow generated by the ventilators 23. Differently, to an increase of the characteristic temperature Ta corresponds, generally, an increase of the saturated vapour temperature T_e of the refrigerating fluid, to which corresponds a reduction (not illustrated) of the desired value T_s of the characteristic temperature of the air flow downstream of the exchanger 24 and a corresponding reduction of the volumetric rate of the air flow.

As can be seen in this graph, the gradient with which the volumetric rate of the air flow varies in response to a variation of the saturated vapour temperature Te of the refrigerating fluid is not constant, but depends on the value of the saturated vapour temperature T_e (in fact the curve representing this correlation is not a straight line, but is broken with portions in different inclinations). The number and slope of these portions, which is reflected in the values memorised in the calibration chart, can be established on the basis of a study of the monthly and daily climatic seasonal characteristics of the place in which the plant 10 is installed. For different locations of the plant 10, the number and slope of these portion can therefore vary, requiring a corresponding variation of the vales contained in the calibration chart.

For these and other reasons, the in the control and monitoring system 60 numerous calibration charts can be stored, specific for the climatic characteristics of various places in which the plant 10 can be installed, among which the central control unit 605 can select the one most indicated by the present location of the plant 10.

Although the control logics described above are based on the characteristic temperature at the outlet of the heat exchanger, they could be based on a temperature leap (difference) between the characteristic temperature of the air flow at the inlet of the exchanger and the characteristic temperature of the air flow at the outlet of the exchanger.

With the same modalities as described in the foregoing, the central control unit 605 might therefore be configured such as to set, on the basis of the characteristic temperature T_a of the air flow at the inlet of the heat exchanger 24 and possibly also the saturated vapour temperature T_e of the refrigerating fluid, a desired value of the temperature leap and regulate the rate of the air flow as a function of the desired value of the temperature leap, for example with a retroactive control including monitoring the temperature leap, calculating the difference between the monitored value and the desired value of the temperature leap, and regulating the air flow rate as a function of the difference.

It is stressed here that the variants described above of the control method might all be implemented in a same central control unit 605, so as to be able to be used in a selective way, for example on the basis of the actual climatic conditions or with a seasonal programming, or the like.

With reference to the plant of figure 12b, the plant 10 can be made to function by placing in operation both condensation units 20. The air flow generated by the ventilators 23 of the two condensation units 20 can be regulated in the same way, or the two air flows can be regulated independently, by performing a dedicated control for each condensation unit.

Apart from being used for the production of water from the atmospheric air, the plant 10 can also be used to cool the vector fluid which circulates in the auxiliary circuit 320, which (as mentioned) can in turn be used internally of a conditioning/cooling as mentioned in the foregoing.

In this case, the central control unit 605 is configured such as to actuate the expansion valve 318, so that the refrigerating fluid at low temperature coming from the condenser 312 can flow into the second evaporator 315. In particular, the refrigerating fluid can be entirely deviated into the second evaporator 315, completely bypassing the exchanger 24, or can be only partly deviated, so that a first part of the refrigerating fluid circulates in the second evaporator 315 and a second part continues circulating in the exchanger 24. In the first case the plant 0 will stop producing water and will only function to cool the vector fluid of the auxiliary circuit 320, while in the second case the plant 0 will function for both aims.

In a case where the plant functions for both aims, the central control unit 605 will continue managing the functioning of the ventilators 23 according to the modalities described in the foregoing, automatically reacting to any variations in the temperature of the saturated vapour T_e due to the deviation of a part of the refrigerating fluid internally of the second evaporator 315. Thus for example, if the use includes a reduction of the vaporisation temperature T_e, the central control unit 605 will automatically increase the velocity of the ventilators 23 and therefore the air flow which crosses the condensation unit 20, so as to guarantee a heat load to the compressor 310 with both uses.

During the above-described functioning, the plant 10 can also be used to heat the vector fluid which circulates in the auxiliary circuit 326, which (as mentioned) can in turn be used internally of a heating plant or as hot sanitary water.

In this case, the central control unit 605 is configured such as to regulate the intercept valve 324 and possibly the intercept valve 325, so that the refrigerating fluid at high temperature coming from the compressor 310 can flow into the second condenser 322. In particular the refrigerating fluid can be entirely deviated into the second condenser 322, completely bypassing the condenser 312. In this way, a total recuperation of the condensation heat generated by the preceding compression of the refrigerating fluid is obtained in the second condenser, which heats the vector fluid of the auxiliary circuit 326.

As mentioned in the foregoing, the hot vector fluid obtained in the second condenser 322 might be used for defrosting the heat exchangers 24, 25 and 26. This need can be manifested when the plant 10 is used for production of water starting from air having a dew point temperature of less than 0°C. In these climatic conditions, as the air condensation point is lower than the water freezing point, ice can be directly obtained which progressively acumulates on the tubes of the tube bundle 244 of the exchanger 24. In these cases, while the plant 0 functions to produce water/ice, the refrigerating fluid coming from the condenser 310 is deviated into the second condenser 322, so as to heat the vector fluid into the storage tank 328. By opening appropriate valves in the auxiliary circuit 326, the vector fluid accumulated can then be cyclically sent to the tube bundle 330 which is internal of the heat exchanger 24, obtaining thawing of the ice and therefore the production of water. In particular, the frequency with which the hot vector fluid is sent to the tube bundle 330 can be regulated by the central control unit 605 on the basis of the temperature of the air flow in outlet from the condensation unit 20.

As with the reduction of the air temperature it is progressively more difficult to thaw the ice, this operation can be accelerated and made more efficient, enabling the hot vector fluid of the storage tank 328 to circulate also in the hydraulic circuit 255, so that the heat exchangers 25 and 26 in fact become heating elements that effectively aid the thawing of the ice.

Obviously a technical expert in the sector might make numerous modifications of a technical-applicational nature to the above-described plant 10 without forsaking the scope of the invention as claimed in the following.

Claims

1. A method for controlling functioning of a plant (10) for producing water from atmospheric air,

wherein the plant comprises:

- a heat exchanger (24),

- means (23) for generating an atmospheric air flow from an inlet (241) towards an outlet (242) of the heat exchanger (24), and

- a refrigerating unit (30) provided with an evaporator (244) in which a refrigerating fluid evaporates for cooling the atmospheric air flow internally of the heat exchanger (24),

and wherein the method includes steps of:

- monitoring a characteristic temperature of the air flow at the inlet (241) of the heat exchanger (24),

- regulating the air flow in the heat exchanger (24) as a function of the characteristic temperature.

2. The method of claim 1 , wherein the air flow is increased in response to a reduction of the characteristic temperature of the air flow at the inlet (241) of the heat exchanger (24) and reduced in response to an increase of the characteristic temperature.

3. The method according to any one of the preceding claims, wherein the air flow generating means comprise one or more ventilators (23) and the air flow rate is regulated by adjusting the velocity of the ventilators (23).

4. The method of any one of the preceding claims, wherein the characteristic temperature of the air flow at the inlet (241) of the heat exchanger (24) is the dew point temperature.

5. The method of claim 4, wherein the dew point temperature is determined by steps of:

- measuring the dry bulb temperature of the air flow at the inlet (241) of the heat exchanger (24),

- measuring the moisture of the air flow at the inlet (241) of the heat exchanger (24),

- establishing the dew point temperature on the basis of the dry bulb temperature and the humidity of the air flow at the inlet (241) of the heat exchanger (24).

6. The method of any one claims from 1 to 3, wherein the characteristic temperature of the air flow at the inlet (241) of the heat exchanger (24) is the dry bulb temperature.

7. The method of any one of the preceding claims, wherein the regulating of the air flow rate comprises steps of:

- using the characteristic temperature of the air flow at the inlet (241 ) of the heat exchanger (24) for setting a desired value of a characteristic temperature of the air flow at the outlet (242) of the heat exchanger (24),

- regulating the airflow in the heat exchanger (24) as a function of the desired value.

8. The method of claim 7, wherein the desired value of the characteristic temperature of the air flow at the outlet (242) of the heat exchanger (24) is increased in response to an increase of the characteristic temperature of the air flow at the inlet (241 ) of the heat exchanger (242) and is reduced in response to a reduction of the characteristic temperature of the air flow at the inlet (241 ) of the heat exchanger (24).

9. The method of any one of the preceding claims, comprising further steps of:

- monitoring the saturated vapour temperature of the refrigerating fluid internally of the refrigerating unit (30),

- regulating the air flow in the heat exchanger as a function of the characteristic temperature of the air flow at the inlet of the heat exchanger (24) and of the saturated vapour temperature of the refrigerating fluid.

10. The method of claim 9, wherein the air flow rate is reduced in response to an increase of the saturated vapour temperature of the refrigerating fluid in response to a reduction of the saturated vapour temperature.

11. The method of claim 9 or 10, wherein the regulating of the air flow rate comprises steps of:

- using the characteristic temperature of the air flow at the inlet (241) of the heat exchanger (24) and the saturated vapour temperature of the refrigerating fluid so as to set a desired value of a characteristic temperature of the air flow at the outlet (242) of the heat exchanger (24),

12. The method of claim 1 1 , wherein the desired value of the characteristic temperature of the air flow at the outlet (242) of the heat exchanger (24) is reduced in response to an increase of the saturated vapour temperature of the refrigerating fluid and increased in response to a reduction of the saturated vapour temperature.

13. The method of any one of claims 7 or 11 , wherein the regulating of the air flow rate comprises steps of:

- monitoring the characteristic temperature of the air flow at the outlet (242) of the heat exchanger (24),

- calculating a difference between the monitored value and the desired value of the characteristic temperature of the air flow at the outlet (242) of the heat exchanger (24),

- regulating the air flow in the heat exchanger (24) as a function of the difference.

14. The method of claim 7 or 1 , wherein the desired value of the temperature of the air flow at the outlet (242) of the heat exchanger (24) is obtained from a chart.

15. The method of claim 14, wherein the chart is selected from a group of charts calibrated on a basis of different climatic characteristics.

16. A plant (10) for obtaining water from atmospheric air, comprising:

- a heat exchanger (24),

- means (239) for generating an atmospheric air flow from an inlet (241 ) towards an outlet (242) of the heat exchanger (24), and

- an electronic control system (60) configured for:

- monitoring a characteristic temperature of the air flow at the inlet (241 ) of the heat exchanger (24),

17. The plant (10) of claim 17, wherein the electronic control system (60) is configured such as to increase the air flow in response to a reduction of the characteristic temperature of the air flow at the inlet (241) of the heat exchanger (24) and to reduce the air flow in response to an increase of the characteristic temperature.

18. The plant (10) of claim 16 or 17, wherein the air flow generating means comprise one or more ventilators (23), and wherein the electronic control system (60) is configured so as to regulate the air flow rate by adjusting the velocity of the ventilators (23).

19. The plant (10) of any one of claims from 16 to 18, wherein the characteristic temperature of the air flow at the inlet (241) of the heat exchanger (24) is the dew point temperature.

20. The plant (10) of claim 19, wherein the electronic control system (60) can be configured such as to determine the dew point temperature by means of steps of:

- measuring the humidity of the air flow at the inlet (241 ) of the heat exchanger (24),

21. The plant (10) of any one of claims from 16 to 18, wherein the characteristic temperature of the air flow at the inlet (241) of the heat exchanger (24) is the dry bulb temperature.

22. The plant (10) of any one of claims from 16 to 21 , wherein the electronic control system (60) is configured such as to regulate the air flow rate by performing steps of:

- using the characteristic temperature of the air flow at the inlet (241) of the heat exchanger (24) so as to set a desired value of a characteristic temperature of the air flow at the outlet (242) of the heat exchanger (24),

23. The plant of claim 22, wherein the electronic control system (60) is configured so as to increase the desired value of the characteristic temperature of the air flow at the outlet (242) of the heat exchanger (24) in response to an increase of the characteristic temperature of the air flow at the inlet (241) of the heat exchanger (242) and to reduce the desired value of the characteristic temperature of the air flow at the inlet (241 ) of the heat exchanger.

24. The plant (10) of any one of claims from 16 to 23, wherein the electronic control system (60) is further configured for:

- regulating the air flow in the heat exchanger (24) as a function of the characteristic temperature of the air flow at the inlet (241) of the heat exchanger (24) of the saturated vapour temperature of the refrigerating fluid.

25. The plant (10) of claim 24, wherein the electronic control system (60) is configured so as to reduce the air flow in response to an increase of the saturated vapour temperature of the refrigerating fluid and to increase the desired value of the characteristic temperature of the air flow in response to a reduction of the saturated vapour temperature.

26. The plant (10) of claim 23 or 24, wherein the electronic control system (60) is configured such as to regulate the air flow rate by performing steps of:

- using the characteristic temperature of the air flow at the inlet (241 ) of the heat exchanger (24) and the saturated vapour temperature of the refrigerating fluid so as to set a desired value of a characteristic temperature of the air flow at the outlet (242) of the heat exchanger (24),

27. The plant of claim 26, wherein the electronic control system (60) is configured so as to reduce the desired value of the characteristic temperature of the air flow at the outlet (242) of the heat exchanger (24) in response to an increase of the saturated vapour temperature of the refrigerating fluid and to increase the desired value of the characteristic temperature of the air flow in response to a reduction of the saturated vapour temperature.

28. The plant (10) of claim 22 or 26, wherein the electronic control system (60) is configured so as to regulate the air flow rate by performing steps of:

- regulating the air flow in the heat exchanger as a function of the difference.

29. The plant (10) of claim 22 or 26, wherein the electronic control system (60) is configured so as to obtain the desired value of the characteristic temperature of the air flow at the outlet (242) of the heat exchanger (24) from a chart.

30. The plant (10) of claim 29, wherein the electronic control system (60) can be configured such as to select a chart from a group of charts calibrated on a basis of different climatic characteristics.