GB2526657A - A hydrothermal system for residential units - Google Patents

Abstract

A heating system comprises a central hot water generator 10 which circulates hot or cold water through primary pipes 14 to residential units 16, the primary pipes 14 comprising delivery pipe 18 and return pipe 20. The residential units 16 comprise a plurality of utilities 22 including a thermal utility 24. Secondary pipes 14 are in fluid communication with primary pipes 14 with secondary delivery pipe 18 supplying utilities 22 and secondary return pipe 20 conveying water from thermal utility 24 to primary return pipe 20. A hydraulic interface unit 30 is in fluid communication with secondary pipes 14 and comprises electronic control unit 34. The electronic control unit 34 controls motor-operated modulating valve 36 according to signals from ambient temperature detector 29 and flow measurement means 38 which measures flow in either the secondary delivery 18 or return 20 pipes. There may be at least one primary pipe for cold water 19 in fluid communication with at least one secondary cold water pipe 19 and an external water supply network or a domestic utility.

Description

A hydrothermal system for residential units

Technical field

The present invention relates, in general, to the field of hydraulic plant design fcr civil use; in particular, the in-vention relates to a hydrothermal plant for residential units equipped with a system for balancing the flow rates.

Background art

Balancing a variety of needs, including having an energy-efficient, flexible, balanced, economical system as regards to running costs and equity in the usage distribution, is re- quired to central heating hydraulic systems used in residen- tial buildings, both from the point of view of the user and -in an increasingly important manner -from the regulatory point of view.

The highest efficiency in terms of energy consumption and thermal efficiency is obtained, in the case of a plant that will serve a plurality of residential units, by providing a single station for producing hot water (also referred to as "technical water", with reference to the heated fluid which directly supplies the thermal utilities and exchanges heat with the water destined to domestic or sanitary utilities) as a single heat generator allows to reach higher efficien-cies compared to the case where the same heat power were achieved using a plurality of lower size generators.

This solution, used in systems of the centralized type, how- ever involves a number of problems in the correct distribu- tion of the heated flow by the generator to the various resi- dential units; in fact, different units (for size, arrange- ment and environment volumes, distance from the central gen-erator) normally have different needs, both in terms of flow rate of technical hot water destined to thermal utilities (with the meaning of radiators, heaters, radiant panels etc.), and domestic utilities (which must generally be pro-vided with a dual supply system of hot and cold water) These systems are negatively affected (in terms of wasteful-ness and heat losses) by a non-optimal hydraulic balancing of the flows. It is apparent that not all the loads, connected to the distribution network, are to have the same flow rate (which should be the project one for all of them) ; this con-dition is mainly due to the different head loss values the various draw points of each unit are subject to. Moreover, this condition is not stable but undergoes constant varia-tions depending on how many users are active at any given time.

Moreover, it's well known that the user, whom the supply of technical hot water is addressed to, prefers to pay what ac-tually consumed by his home, rather than having to pay out a lump sum that, under certain circumstances, may not be com- mensurate with the benefited service. Finally, the units dis- location at different distances with respect to the central-ized hot water generator entails to design the system so that each unit can receive the needed flow of hot water, regard-less of the number and length of the branches that lead to other units from the central water supply circuit.

In the prior art, to allow proper adjustment of the hydraulic system (in the sense of serving a plurality of units provid- ing them with a hot water flow sufficient to their require- ments) , the available differential pressure is increased (in-creasing the circulators size) , which is a condition that leads to higher involuntary thermal losses and greater con- sumption of electrical energy; these factors inter alia con- tribute to downgrade the efficiency classification of build-ings.

More specifically, in the known art an accounting and manage- ment hydraulic interface unit (also called "satellite mod-ule"), able to operate such an adjustment, is applied to each branch, which leads to the single residential unit from the centralized adduction plant. Generally, the satellite module includes a series of valve devices and electronic devices, with which the flow rates to the addressed thermal and sani- tary utilities of the relative residential units are adjust-ed.

The present invention primarily relates, although not exclu- sively, to the management and adjustment of technical hot wa-ter flows intended to serve thermal utilities; currently, this adjustment is obtained by throttling or inhibiting the water passage inside a closed-circuit pipe, comprising a de-livery branch of the hot water flow to the thermal utilities, and a return branch of the chilled water to the central heat generator.

The adjustment techniques are of the electronic-mechanical type, where the electronics controls, on the basis of the signal from one or more thermostats, a motor-operated ON/OFF valve for the supply of the apartment heating circuit.

Nowadays, the flow balance, which Is implemented internally to the satellite modules, is operated with mechanical sys-tems, which can be divided into three types, depending on the corresponding flow management strategy.

A first strategy is to inhibit the flow circulation in the circuit that serves the thermal utilities by means of a stat-ic balance valve (which introduces a fixed head loss) it is a manually operable valve, which allows to balance the flow rates until the target values, necessary for the proper func-tioning of the system, are reached. This solution, however, is affected by a high imprecision, linked to the arbitrari- ness in the flow management, which introduces sensitive oper-ational failures in the plant operation. This also depends on the fact that this solution reguires an initial calibration difficult to modify at a later time, and is therefore opera-tively very rigid and inefficient.

Another strategy is to ensure the flow management through one or more so-called dynamic balance valves, which allow to maintain a constant flow to a predetermined value, automati-cally and without having to act from the outside. The dynamic balance valves are of the cartridge type, with a generally metallic body inside which a shutter for generating of a pressure drop (in the form of an elastic body against which the pressure of the flow rate acts) is housed; generally, the shutter causes the passage section to decrease when the con-trast pressure by the flow increases.

In the prior art there is an additional mechanical solution, which contemplates the use of a pressure differential control valve. The pressure differential control valves are suitable for circuits with variable flow, in particular with radiators with thermostatic valves, in which a pressure regulation is recommended. From the functional point of view, the valve is generally constituted by a shutter acting on the return branch of the hydrothermal circuit, which shutter is actuated on the basis of a pressure signal, taken from the delivery branch of the hot water flow and acting on a membrane, or an- other mechanical contrast member. This contrast member re-guires an initial calibration that can be hardly changed in a second time, in this way allowing little flexibility to the differential control valve.

Furthermore, given the complexity of the device, this solu-tion proves decidedly expensive with remaining profiles of imprecision in adjusting the flows, compromising the correct heat input to the residential unit served by the device.

Also, the currently known systems do not allow to set multi-ple flow rate values, as it would be necessary to apply many balancing devices how many are the values to check. This would be much more disadvantageous when, for example, both the function of producing domestic hot water and the heating function were present in the accounting hydraulic interface, in which case the hydraulic interface unit would have to man-age even very different flows (depending from the different needs of the heating circuit and the domestic utilities sup-ply circuit) . In the prior art only one mechanical device is always applied, which is calibrated to the higher flow rate of the two considered, a condition which implies an implicit imbalance in the distribution network.

Summary of the invention

An object of the present invention is to overcome the above mentioned disadvantages, by proposing a solution that at the same time has characteristics of economy and precision, in adjusting the hydrothermal plant, higher than in the prior art -This aim is achieved by implementing in the satellite module a system that applies a variable head loss (dynamic) as a function of the instantaneous pressure conditions. The disad- vantaged satellite modules (supposedly more distant from cir-culators) will apply a pressure drop either null or minimum, while the progressively more favored (nearer) modules will apply an increasing pressure drop in order to "ensure" an equal head at the inlet to each unit. An egual head corre-sponds to an egual available flow.

The system comprises an electronic management system that op-erates by comparing one or more set-point values (settable flow values) with a value read from a flowmeter, and acts through one or more modulating motor-operated valves by ap-plying a given head loss. The electronic reads, compares and acts on a regular basis with a settable time.

More specifically, the new electronic control system replaces the mechanical adjustment valve present in the devices ac-cording to the prior art, and interfaces with the measuring means of the flow flowing in the hot water delivery branch or in the return branch. The flowmeter conveniently send a sig- nal to an electronic control unit, in which a signal is di-rected from one or more ambient temperature detecting means (thermostats) , placed inside the apartment.

When the ambient temperature deviates from the temperature the thermostat is set on, the iatter sends a digital signal to the electronic control device. The electronic control unit accordingly actuates a motor-operated valve, by throttling the passage section of the delivery branch so as ic vary the head loss amount on the supply circuit of the thermal utili- ties and modulate the hot water flow at the inlet to the res-idential unit. The head loss variation induced on the circuit was operated, in the prior art, by the mechanicai balancing valve, with the disadvantages listed above, and the motor-operated valve was only of the On/Off type, having solely the function of intercepting the fluid on the basis of the digi-tal signal coming from the room thermostat.

Otherwise, the modulating motor-operated valve according to the invention adds a function for adjusting the flow during the active heating condition.

In this mode, the valve will not solely remain fully open or fully closed, as in the prior art, but will modulate with electronic control according to a flow rate signal sent to the control unit by measuring means (flowmeter) of the flow flowing through one of the delivery branch to, or return branch from, thermal utilities, and compares this value with a preset value.

The flowneter sends a feedback to the electronic control unit, by means of a flow-indicative signal, and the electron-ic control device, on the basis of the acquired signals, emits a control signal for the modulating motor-operated valve, by which the adjustment of the heat system is operat-ed.

The command signal issued by the electronic unit is received by the valve motor.

The balancing system according to the invention allows to set one or more flow rate values, and the motor-operated valve possibly present on the sanitary circuit (to serve domestic utilities such as showers, taps etc.) not only will operate depending from the dispensing temperature but may have an up-per opening limit even depending from the maximum preset flow rate. The motor-operated valve will conveniently become modu- lating in order to impose a pressure drop that does not ex-ceed the designed flow rate.

An accounting and management module according to the present invention is much more accurate than traditional systems, since it is fully electronic (and preferably adjusted with a PIP logic) . The operating range is normally much wider if compared with mechanical systems. On satellite modules with already integrated electronics, the system is more economical than using even only one mechanical dynamic balance device.

The system is always balanced even varying the accivation of various units (thermal and/or domestic) . This condition al-lows to set circulators with reduced heads (reduction in electrical energy consumption) , reduction of the involved flows (lower heat losses on the distribution network because the diameters are smaller) and noise reduction, because re-duced differential pressures are required.

Among other advantages, a system structured according tc the present invention benefits from the ability to adjust, ac- cording to convenience, the system flow rate control parame-ters, regardless for example of any pre-calibration of the mechanical valves. This gives the hydrothermal implant, ac- cording to the invention, inexpensiveness, simplicity of pro-duction, and flexibility.

The above and other objects and advantages are achieved, ac-cording to one aspect of the invention, by a system having the features defined in claim 1. Preferred embodiments of the invention are defined in the dependent claims.

Brief description of the drawings

The functional and structural features of some preferred em-bodiments of a hydrothermal system according to the invention are described below. Reference is made to the accompanying drawings, in which: -Figure 1 shows a hydraulic scheme of a hydrothermal system for residential units, according to one embodi-ment of the invention; -Figures 2A and 2B are hydraulic circuit diagrams of a hydraulic interface unit, comprised in the system in Figure 1, according to the prior art and one embodiment of the invention, respectively; -Figures 3A and 3B are schematic views of a hydraulic interface unit, designed so as to comprise a component according to the prior art and realized according to an embodiment of the invention, respectively; and -Figures 4A and 43 represent hydraulic diagrams of a hydraulic interface unit, according to two different em-bodiments of the invention.

Detailed description

Before an embodiment of the invention is explained in detail, it is to be understood that the invention is not limited in its application to the details of construction and the ar- rangement of the components set forth in the following de-scription or illustrated in the drawings. The invention is capable of other embodiments and of being practiced or being carried out in various ways. Also, it is to be understood that the phraseology and terminology used herein are for the purpose of description and should not be regarded as limit-ing. The use of "including" and "comprising" and variations thereof is meant to encompass the items listed thereafter and equivalents thereof as well as additional items and equiva-lents thereof.

Referring initially to Figure 1, a hydrothermal system for residential units 9, according to the invention, comprises at least one centralized hot water generator 10. Said central generator, known per se, can be a type of boiler with natllral gas, oil or any other device adapted to generate a flow of heated water.

One or more pumping means 12, possibly located at different heights of the plant, circulate the water (the hot water ex-iting from the centralized generator and, optionally, the cold water coming from an external supply network) within a plurality of pipes 14, here referred to as "primary".

The primary pipes 14 have the purpose of serving units 16 -10 - (usually two or more), possibly placed to different heights and distances with respect to the centralized generator 10.

The primary pipes 14 comprise at least two primary pipes ex-iting from, and in fluid communication with, the centralized generator 10, respectively, a primary delivery pipe 18 of the hot water which supplies the different units 16 from the cen-tralized generator 10, and at least one primary return pipe of the water from the residential units 16 to the central-ized generator 10.

Each unit 16 has a plurality of utilities 22 that may include one or more thermal utilities 24, and/or one or more domestic utilities 26.

Through a series of branches 28, a plurality of pipes 14T, here referred to as "secondary", branches off from the plu-rality of primary pipes 14, for each residential unit 16, such secondary pipes supplying the utilities 22 with a frac-tion of the flows conveyed by the primary pipes 14.

The plurality of secondary pipes 14T must include at least one secondary delivery pipe 18' of the hot water (intercepted by the communicating and corresponding primary delivery pipe 18), and at least one secondary return pipe 20' of water from the thermal utilities of the residential unit (that is poured into the coirimunicating and corresponding primary return pipe 20).

At least one ambient temperature detection means 29 (prefera-bly a thermostat with a digital output) is placed inside of each residential unit 16; conveniently, a temperature detec-

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tion means 29 is present in each room of the residential unit. However, it is possible that only part of the residen- tial unit is subject to temperature measurement by the detec-tion means 29, or rather a single detection means 29 serves the whole house.

At least one accounting and management hydraulic interface unit 30 (otherwise called "satellite module") is placed in fluid communication with the plurality of secondary pipes 14', and is located in the proximity of the brarches 28 of the secondary pipes 14' from the primary pipes 14 (i.e., in a position substantially upstream with respect to the secondary pipes that supply the utilities of the single residential unit) The hydraulic interface unit 30 is connected to both the sec- ondary delivery pipe 18' of hot water and the secondary re- turn pipe 20' of water from the thermal utilities to the cen-tralized generator 10.

it is possible to place, upstream and downstream of the sat-ellite module 30, shut-off valves 32 of the flow passing within the secondary delivery and return pipes 18', 20' (as shown in Figures 2A, 2B, 4A and 4B) . The expression "up-stream" indicates, with respect to the satellite module 30, the proximal end of the satellite module 30 with respect to the branches 28 of the secondary pipes 14' from the primary pipes 14; the expression "downstream" refers to the distal end of the satellite module 30 with respect to said branches.

The satellite module 30 comprises an electronic control de-vice 34, capable of processing a plurality of signals from -12 -other devioes comprised in the hydrothermal system, as will be better appreciated in the following description.

The satellite module 30 comprises a modulating motor-operated valve 36, continuously adjustable and placed, in this exam-ple, on the secondary delivery pipe 1ST, so that the valve can throttle the passage section of such delivery pipe 18', conseguently adjusting the flow rate of hot water. In a dif-ferent embodiment, not shown, the modulating motor-operated valve 36 can be applied on the secondary return pipe 20' At least one water flow measurement means 38 is associated with the secondary delivery pipe 18! or the secondary return pipe 20'. In the example shown here, a single flow measure-ment means 38 is placed on the secondary return pipe 20', although other solutions are not excluded, such as that of placing a larger number of flow measurement means simultane- ously on both secondary delivery and return pipes. In a sat-ellite module according to the present invention, only one of said flow measurement means 38 will generally be sufficient, for example upstream of a flow drawn from the secondary de-livery pipe 18' and intended for a heat exchanger internal to the satellite module, for producing domestic hot water (ac-cording to one embodiment shown below) Comparing Figure 2A, which schematically represents a solu-tion known in the prior art, with Figure 2B, illustrative of an embodiment according to the invention, the skilled in the art will appreciate that a traditional balancing valve 40 (for example of the static, dynamic, or differential pressure control type in general) , is replaced by the flowmeter 38, said balancing valve not being electronically connected to -13 -the electronic control device 34.

The ambient temperature measuring means 29, the motor-operated valve 36 and the modulating flow measuring means 38 are connected to the electronic control device 34 by means of respective connections 29'', 36'', 38T -For clarity of expo-sition, with the single superscript T'TT' are indicated, in the examples illustrated here, connections of the hydraulic type, while with the double superscript " " are indicated connec- tions capable of establishing an electronic communication be-tween two devices. These connections 29'', 36'', 38'' allow the electronic control device 34 to receive/emit signals from and/or to the devices the electronic control unit 34 is con-nected with.

In particular, the electronic control device 34 receives a digital signal from the ambient temperature detection means 29 (one or more) , if the room temperature deviates from the desired one; said control device also receives a flow rate value from the flow measurement means 38, in the form of one or more signals. Preset flow rate values are preferably stored in the electronic control device 34, depending on the thermal conditions that are supposed to be reached within the residential units. Alternatively, the electronic control de- vice 34 may operate the adjustment on the basis of an algo-rithm implemented in the control logic thereof.

The electronic control device 34 is set to elaborate, on the basis of these data, a given variation in the flow the modu-lating motor-operated valve must be provided with, and to emit a corresponding command signal that throttles the pas-sage section, by modulating the motor-operated valve 36, and -14 -modulates the hot water flow in the secondary delivery pipe 18'.

In one embodiment, a filter 42 is arranged on the return branch 20' of the water from thermal utilities 24 to the pri-mary pipes 14.

In a preferred embodiment, an energy accounting means 44 is associated to the secondary delivery and return pipes 18', 20', said accounting means, known per se, being adapted to provide an energy consumption data as a difference between the energy supplied to the residential unit through the sec- ondary delivery pipe 18T and the energy reentering the prima- ry pipes 14, through the secondary return pipe 20', after be-ing transited in the thermal utilities 24 of the residential unit. Conveniently, the accounting means 44 may exchange sig- nals with the electronic control device 34, by means of a re-spective connection 44! Normally, but not necessarily, domestic utilities 26 may be present among the utilities 22 within the various residential units 16, in addition to utilities of the thermal type 24, such domestic utilities being not uniquely designed to re-lease heat to the rooms of the residential unit, but rather to provide hot or cold domestic water.

To supply such domestic utilities 26, a hydrothermal system, according to one embodiment of the present invention, may comprise at least one or two additional primary pipes 19, 21, with respect to the primary delivery and return pipes 18, 20 intended to supply the thermal utilities of residential units.

-15 -Such additional primary pipes are at least a first primary pipe for cold water 19, in fluid communication upstream with an external water supply network, and optionally a second primary pipe for cold water 21, which can be in fluid corumu- nication upstream with the external water supply network, ac-cording to the example illustrated here. A water softener for domestic water 46 and/or an auxiliary heating system, for ex-ampLe a system that exploits solar energy (not shown) , may be associated to the second primary pipe for cold water 2L Said first and second primary pipes for cold water 19, 21 are placed in fluid communication with corresponding first and second secondary pipes for cold water 19', 21', associated to each residential unit 16 by branches 28. According to a mode not shown, the second secondary pipe for cold water 21! can be a branch from the first secondary pipe for cold water 19T When the water softener 46 is present, a further energy ac-counting means 44 will conveniently be associated with the second secondary pipe for cold water 21', in a manner not shown.

The second secondary pipe 21' can be, in a manner not shown, a branch of the first secondary pipe for cold water 19'.

The first secondary pipe for cold water 19T supplies domestic utilities 26 with cold water; the second secondary pipe 21' can supply directly the domestic utilities 26 with hot water, if such hot water is produced by the centralized generator 10 (in a manner not shown) , or it can be arranged in fluid com-munication downstream with a third secondary pipe 21'a, which -16 - deliveries hot water to domestic utilities 26 of the residen-tial unit. In the latter case, between the second secondary pipe for cold water 21! and the third secondary pipe 2l'a for hot water is fluidically interposed a heat exchanger 48 lo-cated within the satellite module 30 (as shown in Figures 3A, 3B, 4A and 4B) In one embodiment of the invention, a certain technical water flow (i.e., heated by the centralized hot water generator 10) is drawn from the secondary delivery pipe 18' and returned to the secondary return pipe 20', said flow being drawn and fed back through corresponding secondary branches 18'a, 20'a. In this way, a heat exchange between the secondary delivery and return pipes 18', 20' and the heat exchanger 48 is provided.

The water circulation, within the heat exchanger 48, causes the hot technical water flow, drawn from the secondary deliv-ery pipe 18!, to release some of its heat to the cold water flow coming from the second secondary pipe of cold water 21' and directed to the third secondary pipe of hot water 21!a, before returning to the secondary return pipe 20'. In this way, the domestic cold water entering the exchanger can be heated by technical hot water produced by the centralized generator.

A second motor-operated valve 37 can be associated, in addi-tion or in alternative to the first motor-operated valve 36, to the secondary delivery branch 18!a, and can be electroni-cally connected to the electronic control device 34, by means of a respective connection 37'', so as to adjust the flow drawn from the secondary delivery pipe 18! and directed to the heat exchanger 48.

-17 -In the embodiment according to which the heat exchanger 48 is integrated in the satellite module 30, the heating function and domestic hot water production will self-exclude (that is, when thermal utilities are supplied, domestic hot water pro-duction is inhibited, and vice-versa) , the first and second motor-operated valves 36, 37 working independently of each other.

A further embodiment of the invention, with particular refer-ence to the configuration of the accounting and management hydraillic interface unit 30, is illustrated in figure 4B. In the configuration illustrated here, the satellite module 30 illustrated in figure 4A is eguipped with: a punping means 12, possibly used as an alternative to the modulating motor- operated valve 36 (wherein the pumping means 12 were a boost- er pump, in particular of the electronic type, able to opera-tively replace the motor-operated valve) , said pumping means being preferably associated with the secondary delivery pipe 18' and electronically connected to the electronic control device 34 through a respective connection 12' ; a second flow measurement means 39, preferably associated with the second secondary pipe of cold water 21' and electronically connected to the electronic control device 34, by means of a respective connection 39'', so as to electronically communicate, to the control unit 34, a signal relating to the flow rate of cold water entering the heat exchanger 48; a temperature sensor 21' a between the third secondary pipe 21'a and the electron-ic control device 34, for producing domestic hot water; a static flow limiter 50; a volumetric meter of domestic water 52, preferably associated with the first secondary pipe of cold water 19 and/or the second secondary pipe of cold water -18 - 21', and electronically connected to the electronic control device 34, by means of a respective connection 52'', so as to communicate consumption data to the electronic control unit.

From the functional point of view, the thermal adjustment be-tween the needs of single units 16 and general hydrothermal system 9, is carried on as follows; further in the present description, reference will be made to a single unit, alt-hough the described process is applicable to all the units served by the general hydrothermal plant 9.

The ambient temperature within a residential unit is detected by the temperature measurement means 29 (thermostat) , which transmits a corresponding digital signal to the electronic control device 34 placed in the satellite module 30, by means of respective electrical connection 29''.

The flow data detected by flow measurement means 38 also en- ters the electronic control device 34, and such data is com-pared with a preset flow data for the specific residential unit, suitable to provide a heat contribution to the residen- tial unit such as to achieve/maintain a set temperature lev-el. On the basis of these parameters, the electronic control device 34 processes a data indicative of a variation in the flow of hot water, suitably adjusted according to the set nominal flow, which has to be supplied to thermal utilities of the residential unit 24 for achieving/maintaining the set temperature. Finally, the electronic control device 34 sends a control signal, corresponding to the processed flow data, to the motor-operated valve 36 through connection 36'', con-sequently varying the flow rate of incoming hot water to thermal utilities 24.

-19 -The achieved advantage is to have a system which is extremely flexible, being possible to set reference values several times without difficulty, economical, thanks to the exclusion of expensive mechanical valve components, precise, and sim-ple, since it is not necessary to provide already existing satellite modules with complex components (is sufficient only the flow meter) , but rather lightening the system from a ma-jar part of its mechanics.

Various aspects and embodiments of a hydrothermal system ac- cording to the invention have been described. It is under- stood that each embodiment may be combined with any other em- bodiment. The invention also is not limited to the embodi-ments described but may be varied within the scope defined by the appended claims.

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