GB1558563A

GB1558563A - Heat recovery from a compression refrigeration machine to heat water

Info

Publication number: GB1558563A
Application number: GB26284/75A
Authority: GB
Original assignee: Individual
Current assignee: Individual
Priority date: 1976-09-14
Filing date: 1976-09-14
Publication date: 1980-01-03

Description

(54) HEAT RECOVERY FROM A COMPRESSION REFRIGERATION MACHINE TO HEAT WATER (71) I, JOHN ALAN HAMMOND, a British Subject, of 67 Halton Road, Sutton Coldfield, West Midlands, B73 6NR, do hereby declare the invention for which I pray that a Patent may be granted to me, and the method by which it is to be performed, to be particularly described in and by the following statement: This invention relates to a system for the heating of water by means of the recovery of heat produced by compression refrigeration machines of the kind having an evaporator.

a compressor, a condenser and an expansion valve, through all of which refrigerant circulates, and in which heat is extracted from one zone of the machine to evaporate liquid refrigerant by means of the evaporator. and is recoverable from another zone of the machine, where the refrigerant. vaporized by the evaporator, is condensed by the condenser.

There are known at present systems in which a building is heated by means of heat recovered from compression refrigeration machines. However, since the building does not normally require any significant heating in the summer months, any heat recovered during the summer is largely wasted by rejection to the atmosphere. The heat recovered during the summer months is not, at present therefore, fully utilised and could usefully be used for other heating purposes.

The object of the present invention is to provide a system for heating water by means of heat recovered from a compression refrigeration machine, in an efficient and convenient manner.

According to the present invention a system for heating water by means of heat recovered from a compression refrigeration machine of the kind specified, comprises a heat storage circuit for storing water which, in use, is directly or indirectly heated by heat recovered, in use, from said another zone of the machine, said heat storage circuit comprising said condenser of the machine, a storage vessel, an outlet from said storage vessel for water, heated directly or indirectly by heat recovered in use, from said another zone of the machine, to be removed from the system, a reservoir having a line therefrom to supply water to the storage vessel, and means for replenishing said reservoir. the system further comprising a heat dissipation circuit for dissipating from the system heat which is recovered, in use. from said machine and which is in excess of that required for heating water, said heat dissipation circuit being separate from said heat storage circuit and including a further condenser connected in the refrigerant circulation circuit of said compression refrigeration machine in series with said condenser in said heat storage circuit and downstream thereof. so that heat which is recovered, in use. from said machine and which is in excess of that required for heating water is dissipated either directly or indirectly from said further condenser.

The invention will now be described by way of example with reference to the accompanying drawings in which: Figure 1 shows a diagrammatic layout of one system for recovering heat from a series of compression refrigeration machines in which the heat recovered is used to heat water for washing. the system being constructed in accordance with the present invention, Figure 2is a fragmentary diagrammatic layout of a modified form of the arrangement of Figure 1.

Figure 1 shows three separate compression refrigeration units having respective series-connected evaporators, 10, 11, 12, which are, for example, direct expansion water coolers. The refrigeration units further include respective compressors 13, 14, 15 and series-connected water cooled condensers 16. 17, 18.

With each unit, refrigerant flows from the evaporator to the compressor and then to one or, as will be described, several condensers, before passing through an expansion valve (not shown), which controls the refrigerant flow rate, and returning to the evaporator.

Auxiliary condensers 19, 20 have their refrigerant circuits connected in series with the condensers 16, 17 respectively whilst further auxiliary condensers 21. 22 are similarly connected.

In Figure 1, the three condensers 19, 16 and 21 are shown connected in that particular sequence from the compressor 13 for the sake of clarity, so that the circuits associated with the condensers can be clearly shown.

However, in use, the condenser 21 would be connected to the compressor 13 immediately downstream thereof, followed by the condenser 19 and then the condenser 16.

Similarly condenser 22 would be connected directly to the compressor 14, followed by the condenser 20 and then the condenser 17.

The evaporators 10, 11, 12 are connected in a return line 23, the direction of flow through the evaporators being from the evaporator 10 to the evaporator 11 and then the evaporator 12. A cold water tank 24 in the flow circuit containing the evaporators allows for expansion and contraction of the water in the circuit. A pump 25 in said line 23 pumps water through the evaporators.

Although not shown as such, the flow line 23 is continuous. there being cooled water circuits in the line 23, downstream of the evaporators. The cooled water is circulated through a main cooling coil of an air conditioning apparatus with which the system of the present invention is intended to be used. Alternativelv the cooled water can be used in other types of processes where cooling is required. A main supply fan blows air through the coil thereby to supply cool air to the building. Each separate refrigeration unit can be brought into operation by a thermostat 26 in the line 23. The thermostat operates successive compressors through a controller 27.

A flow line 30 taken from the line 23 at a position upstream of the evaporator 10 by-passes the evaporators 10, 11 and 12 and rejoins the line 23 downstream of the evaporator 12. Between the evaporators 10 and 11, and between the evaporators 11 and 12 are respective flow lines connected between the lines 23 and 30.

Connected to the line 23 at a position downstream of the position where the line 30 joins it. is a flow line 31 from a heat reservoir vessel 32. A further heat reservoir vessel 33 is disposed alongside the vessel 32 and the two vessels are connected by a flow line 34. The purpose of these vessels will be explained later.

From the vessel 33 is an outlet flow line 35 which is connected through a valve 36 to the line 23 at a position upstream of the pump 25.

The condensers 16, 17, 18 are connected in series in a flow line 37 from a cooling tower arrangement comprising a pair of cooling towers 38, 39 respectively and an associated storage tank 40. The line 37 is connected to a flow line 41 to which respective flow lines 42, 43 to the cooling towers 38, 39 are connected. The cooling towers have respective sumps and these sumps are connected by respective short lines to a flow line 44 to the storage tank 40.

The tank 40 is, in use, mounted lower than the sumps so that they are self-draining. The tank 40 but not the towers 38, 39 are disposed within the building in which the heat recovery system of the invention is installed. From the bottom of the tank 40 is a flow line 45 which is connected to the condenser 18. A pump 46 is provided in the line 45 upstream of the condenser 18 to pump water through the condensers 16, 17 and 18. Flow of water through these condensers is in the opposite direction to that through the evaporators 10 11 and 12. A flow line 47 connected to the line 37 at a position between the condensers 17 and 18 by-passes the condensers 16 and 17 and rejoins the line 37 upstream of the condenser 16. A short flow line 48 from the line 47 joins the line 37 at a position between the condensers 16 and 17.

The ends of the line 41 are connected to a flow line 49 which joins the line 45 just below the tank 40. The cooling towers 38,39 have associated fans 50, 51 respectively to cool the water therein. The operation of the fans is controlled through a controller 52 by a thermostat 53 in the line 37 to the cooling towers. Also controlled through the controller 52 by thermostats 54. 55 are respective valves 56. 57 in the line 41. Further valves 58, 59 are positioned in the respective flow lines 42, 43 and these are controlled through the controller 52 by respective thermostats 60. 61.

The tank 40 has an associated chemical storage tank (not shown) for treating the water in the tank 40 and also means for topping up the tank 40 (also not shown).

The condensers 19 and 20 are connected in series in a flow line 62 along which colder water is circulated by a pump 63. A by-pass line 64 from the line 62 at a position downstream of the condenser 20 is provided around the condensers 19 and 20 in a similar manner to the line 47 around the condenser 16 and 17. The flow through the condensers 19. 20 is in the same direction as through the condensers 16. 17.

At a position downstream of the condenser 19, is a bank of immersion heaters or a heat exchanger 65 with a by-pass flow line 66 around it. From the line 62, at a position between the condenser 19 and the heat exchanger 65, is a flow line 67 which leads to the further heat reservoir vessel 33 and also connects with the flow line 35. A flow line 68 from the line 31 at a position between the heat reservoir vessel 32 and the condenser 12, joins the line 62 at a position upstream of the pump 63. A water tank 69 connected to the line 62 at a position upstream of the pump 63 allows contraction and expansion of the water in the line 62. Pipe lines 70, 71 lead from the top of the tank 69 into the tops of the heat reservoir vessels 32, 33 respectively to allow for expansion and contraction of the water in the reservoirs 32,33 also.

Although not shown as such, the flow line 62 is continuous. Water heated by the condensers 20 and 19 is used in two ways to heat the building in which the heat recovery system is installed. Firstly, it is led to various heaters and fan convectors around the perimeter of the building and secondly it is led to a main heating coil of the air conditioning system fitted in the building. A main supply fan blows air through the coil thereby supplying heated air to the building.

In the line 62 at a position downstream of the heat exchanger 65 is a thermostat 88 which is controlled through a controller 89, which is the main heat balance controller for the system. The controller 89 controls operation of the heat exchanger 65 and also of the pump 46 in the flow line 45. Furthermore, the controller 89 controls free cooling fresh air dampers 90 in the air conditioning system.

The auxiliary condensers 22. 21 are connected in series in a flow line 72 from a pump 73. A by-pass flow line 74 is connected around the condensers in a similar manner to the other by-pass lines 30, 47 and 64, and is connected at a portion upstream of the condensor 21 to a regulating valve 95 in the line 72. The flow line 72 leads from the valve 95 to an inlet adjacent the top of a storage vessel 75 and from the bottom of the vessel 75 is an outlet flow line 76 to the pump 73. A supply line 77 from a main cold water storage tank 78 is connected to a further inlet of the vessel 75 at the same distance from the bottom of the storage vessel as the outlet line 76. From an outlet at the top of the vessel there is an open vent line 80 to the tank 78 and also a supply line 79 from which connections for showers 81.

water taps and other appliances (not shown) requiring hot water can be taken. A return flow line 82 returns water from the appliances and the line 79. by means of a secondary pump 83 to a central inlet 84 of the vessel 75. A by-pass flow line 85 extends from a flow line between the pump 83 and the inlet 84, to join the outlet flow line 76 downstream of the vessel 75. There is provided a valve 86 in th, line 85 and a further valve 87 in the line 76 upstream of where the lines 85 and 76 join.

The connections of the lines 72, 77 and the line to the inlet 84 are all made tangentially in order to minimise mixing of the water within the vessel and thus define zones therein. It is, however, possible to provide a number of baffle plates within the vessel to accomplish these objectives. Such baffle plates would be arranged to divide the vessel lengthwise.

In operation, water is circulated in series through the evaporators 10, 11 and 12 by the pump 25, expansion and contraction of the water being accommodated by the tank 24.

The thermostat 26 has its set point and throttling range adjusted so that it starts the compressors 13, 14, 15, progressively as it senses the need for more cooling of the water flowing in the line 23. The thermostat 26 is adjusted so that in winter the temperature of the chilled water circulated to the chilled water circuits is a maximum, for example 50"F and in summer, it is for example 40"F. The refrigeration unit having the compressor 13 as the lead unit can produce chilled water at approximately 50"F. summer or winter provided that the flow and return design conditions are 54"F and 40"F respectively.Such an arrangement keeps the refrigeration machine work load fairly constant, the power need to compress the refrigerant from its evaporating to condensing pressures being kept to a minimum particularly in winter. This arrangement also ensures that the system adjusts itself in accordance with temperature changes. Provision may be made for governing the system temperature in accordance with humidity conditions.

In the normal condenser water circuit, that is, the heat dissipation circuit containing the condensers 16, 17 and 18, water is circulated by the pump 46 through firstly the condenser 18 and then successively through the other condensers in the line 37. Water leaving the condensers, after being heated thereby reaches the line 41. The temperature of the water is sensed by the thermostats 54 and 55 and if the water is too cool, the thermostats operate to maintain the valves 58, 59 closed so that the water by-passes the cooling towers 38, 39 and flows through the line 49 into the line 45 thereby conserving heat. As the temperature of water in the line 41 increases, the valves 58. 59 open and water flows to the cooling towers 38, 39. When more than 5% of the water reaching the line 41 is flowing in the cooling towers 38, 39, the fans 50, 51 operate.However when less than 5% of the water reaching line 41 is flowing into the cooling towers, the fans 50 and 51 are automatically switched off by the control of the thermostat 53 and controller 52. This prevents over Voling of the tower. This method of preventing the water temperature becoming too low in the open cooling tower circuit is only required if low water temperatures are critical to the refrigeration compressors. If this is not critical the control circuit incorporating the controller 52 can be eliminated, and the control of the cooling tower circuit left very coarse merely by controlling the cooling tower fans 50 and 51 and pump 46, directly from a further controller whenever heat is needed to be rejected. Water cooled in the cooling towers flows via the line 44 to the tank 40.

Rejection of heat from the condensers 16, 17 and 18, into the normal condenser water circuit can be controlled by measuring the refrigerant head pressure. This measurement can be carried out by the use of pressure sensors (not shown). A selector (not shown) associated with the sensors transmits the higher of the two signals it receives from the sensors through a controller which controls a valve which operates to govern flow between the by-pass line 47 and the condensers 16 and 17. If it is required to conserve heat in the circuit, flow is taken through the line 47, whereas if it is required to reject heat into the circuit then flow is through the condensers 16, 17.

As stated, the controller 89 controls the position of the free cooling fresh air dampers 90 which provide free cooling during suitable outside weather conditions, that is, with an outside temperature of less than approximately 58"F. As heat is rejected into the normal condenser water circuit. the pump 46 circulates this higher temperature water to the cooling towers and the thermostat 53 controls the rejection of heat to the atmosphere by regulating the valves 56 to 59 either to reject heat through the cooling towers 38 and 39 or to conserve heat through the line 49 to the return line 45 and pump 46.

The circuit containing the auxiliary condensers 19. 20 provides for the circulation of hot water around a building and associated areas which are to be heated. Water is circulated firstly through the auxiliary condenser 20 and then the auxiliary condenser 19 by the pump 63, any expansion or contraction of the water being accommodated by the tank 69. Water leaving the condensers 19, 20 after being heated thereby has its temperature sensed by the thermostat 88. If the condensers are producing insufficient heat to meet the requirements for heating the building the thermostat 88 senses that the temperature of the water is not high enough and consequently the controller 89 operates the heat exchanger or immersion heater bank 65. This produces water at a higher temperature than that produced by the refrigeration machine.

Heat can therefore be added to the water for heating the building through the heat exchanger or immersion heater 65. Heat can also be added to the building heating circuit from the heat reservoir vessels 32, 33. The reservoirs 32, 33 store surplus heat produced during the day in the building circuit.

When the air-conditioning plant is switched off at night, the building structure may cool to, for example, 50"F. However the temperature must be raised to, for example, 65"F by the time the building is occupied. Conventionally, to raise the temperature to the required value, either the boiler of the system has to be started up five or six hours in advance of the time of occupation of the building or the boiler plant may be made oversized to shorten the "pre-heat" time, that is, the time taken to raise the temperature to the required value.

However with the heat reservoir vessels 32, 33, the surplus heat stored is used to reduce the pre-heat time to between one third and one quarter of the normal.

Heat can also be added to the cooled water circuit from the vessels 32, 33 if required. The heating water is used to heat the building through, for example, water to air heater exchangers controlled by valves and localised thermostats (not shown).

The circuit containing the condensers 21 and 22 is to provide hot water for washing.

Water is pumped through the condensers 22 and 21 by the pump 73. expansion and contraction of the water being accommodated in the main cold feed water tank 78.

The temperature of water flowing in the line 72 can be controlled by a thermostat and associated controller (not shown). The controller regulates the valve 95 in the line 72 by mixing hot water from the auxiliary condensers 21. 22 with return water from the pump 73 through the by-pass line 74.

The temperature of the hot water is produced by way of the condensers 21, 22 can be as high as 1300F (54"C) or as flow as 77"F (250C).

Cold water is drawn from the bottom zone of the storage vessel 75 along the line 76 to the pump 73 which pumps it through the condensers 22 and 21 where the water is heated. Also flowing in the line 76 is the water returned by the pump 83 along the line 85. The hot water then flows along the return line 72 into the top zone of the storage vessel 75 through an inlet which is of increased diameter as compared to the line 72 in order to reduce the velocity of the water entering the top of the vessel. The inlet for water from the line 72 is disposed tangentially to the side of the vessel in order to dissipate the water movement by a horizontal circular mixing motion, rather than by a vertical mixing motion.

Hot water for washing can be drawn off from the top zone of the vessel 75 through the supply line 79. In order that hot water is constantly available at various draw off positions, such as the showers 81, the secondary pump 83 returns some cooler return water to a central zone of the storage vessel 75 along the return line 82 and oversized inlet 84.

The hot water drawn off from the top of the vessel is replaced by cold water from the main cold feed water tank 78 through the supply line 77. Thus the cold water is supplied to the lowest zone of the vessel 75.

The open vent line 80 allows any air bubbles entrained in the water to be released. Means (not shown) are provided for replenishing the tank 78.

The purpose of the vessel 75 is to act as a buffer between the constantly varying hot water load for washing and the varying heat production of the refrigeration units. Thus an interface between the hot and cold water in the vessel, moves up and down within the vessel as the amount of hot water drawn off varies. The size of the vessel 75 is designed to meet maximum peak demands and an allowance is made for intermixing.

As already pointed out, flow through the condensers in the washing water circuit, the building heating circuit and the normal condensor circuit is in the same direction, left to right as shown in Figure 1. This is in the opposite direction to the flow through the evaporators in the cooled water circuit.

This arrangement enables the refrigerant pressure differentials. which reflect the energy input required, to be kept low. The refrigerant pressures are related to the evaporating and condensing temperatures, and by reducing these, the absorbed horse power is much reduced.

This produces, for example, a refrigerant temperature differential of 76.5"F for the refrigeration machine comprising the compressor 13, 71.6"F for the machine comprising the compressor 14. and 66.6"F for the machine comprising the compressor 15.

Conventional plants operate at temperature differentials of from 75"F to 800F, and most heat recovery plants have differentials of from 85"F to 95"F.

In the circuit of Figure 1, no direct control is provided for the hot water washing circuit and its temperature can thus rise as high as the refrigerant condensing temperature of 123"F. However, even at this temperature the water cannot scald.

If the main heat balance controller 89 were to malfunction. the refrigerant machines would automatically stop on the high refrigerant pressure control set at 1300F. Since this is the maximum temperature the hot water can reach. plastic pipework can be used.

If a guaranteed hot water temperature is required, for example in a hairdressing installation, a control can be provided.

Means, such as a heat exchanger or immersion heater bank, would be provided in the hot water circuit to the vessel 75 for adding heat to the circuit.

In some conventional systems, far too hot water at 1400F to 1500F is mixed with cold water to achieve an optimum of about llO"F. However, with the system shown in Figure 1, the water is supplied at only slightly hotter than the optimum, to allow for pipe heat loses, and the cold water system is eliminated.

Where a control is provided, for example, in a hairdressing installation, water at a temperature of 1200F may be required for hand washing. Whilst water at 105"F may be required elsewhere in the installation. In such a case, a cold water system would be required.

The temperature of the water can be controlled in several ways. Firstly the refrigerant condensing pressure can be sensed. The refrigerant pressure is easier to measure than the refrigerant temperature, because of superheating of the refrigerant.

Secondly. the temperature of the hot water flowing to the vessel 75 can be sensed bv a thermostat linked to a controller. The controller can operate a heat exchanger to add heat to the water. The controller also controls the valve 95 in the line 72. If heat is required in the circuit. the valve is operated so that water flows through the condensers 21, 22. If the temperature is too high, the valve is operated so that water flows in the line 74. thereby by-passing the condensers.

Other methods of control include sensing the water temperature in the normal condenser circuit and sensing the temperature of water in the building heating circuit.

In Figure 1. the control is achieved by sensing the temperature in the building heating circuit.

Controlled free cooling, by means of the dampers 90, enables the refrigeration load to be exactly matched to the heating requirements. With a building having a constant outside air temperature of for example 50"F. the structure will in the early morning be initiallv cold. Heat will thus need to be drawn from the heat reservoir. At about 11 o'clock the building will be in a neutral position and at about 2 o'clock the reservoir may be storing heat. During all this time the free cooling damper will be closed. Howev er, once the heat reservoir vessels are fully charged. the building would have a surplus of heat. At this point the dampers are automatically opened by the control, thus reducing the internal heat load until ultimately the outside air could do all the cooling.Before this happens. the control senses this and exactly matches the surplus heat with the heating requirement (including the hot water for washing) of the building.

It will be appreciated that very many different modifications of the arrangement of condensers and pipework shown in Figure 1 is possible. Several of these will now be described.

Firstly the number of auxiliary condensers in the hot water circuits for washing. the normal condenser circuit and the building heating circuit can be varied to suit the average hot water loads. It is desirable though not essential to have at least one complete stand-by auxiliary condenser on a separate refrigeration unit, thus having a minimum of two auxiliary condensers in total. The auxiliary condensers can be installed on new or existing refrigeration systems, having any number of units or stages.

The auxiliary condensers do not have to match the total heat output of their respective refrigeration units. With centrifugal or screw compression refrigeration units the auxiliary condensers may be quite small.

However, they must be capable of operating with at least 75 per cent of the hot water load without causing damage to their associated compressor.

Secondly it is of course possible to omit the building heating circuit. In this case. the only auxiliary condensers provided are those in the hot water circuits for the washing water.

A further modification which is possible is the removal from the building heating circuit of the auxiliarv condensers therein. To provide heat for th;t building heating circuit.

some hot water from the circuit for hot washing water is led to a heat exchanger in the building heating circuit. Means can also be provided, in this case. in the building heating circuit for adding further heat thereto. Such means could be an immersion heater bank or a heat exchanger connected to a boiler circuit.

In all modified arrangements the connection of the pipework to and from the storage vessel 75 can be as shown in Figure 1. It is however possible to dispense with the return line 82. pump 83 and inlet 84. thereby eliminating the feedback of hot water from the showers. taps. or other similar appliances to the storage vessel 75.

Figure 2 shows part of a modified form of the arrangement shown in Figure 1. In this modified form. the heat dissipating circuit.

including the water cooled condensers 16.

17, 18 and the cooling towers 38. 39 are omitted. In place of each of the water cooled condensers 16 to 18. there is pro vided an air cooled condenser 91. This allows direct heat dissipation from each condenser to atmosphere. Figure 2 shows the arrangement for the lead refrigeration machine only. but the same arrangement would be used for the other refrigeration machines also. The air cooled condenser 91 is connected in the refrigerant flow line 92, at a position downstream of the condenser 19 in the building heating circuit. In the arrangement shown, the condenser 21 in the hot water washing circuit is connected first from the refrigeration machine and flow in the lines 61,72 is in opposite directions.

A fan 93 is provided to blow cool air over the finned condenser, thereby dissipating the heat surplus in the refrigerant into the air. The speed of the fan is controlled from the pressure sensor 28 through controller 27 and a thyristor 94. This arrangement obviates the need for the cooling towers 38, 39 and tank 40.

In an alternative embodiment, water in the line 72 flows to a heat exchanger disposed within the storage vessel 75. The storage vessel, reservoir and water draw off positions such as showers and taps. form a closed circuit. The heat exchanger extracts heat from the water in the line 72, which water is then returned from the heat exchanger to the condensers 21. 22 by the pump 73.

The extracted heat raises the temperature of the water in the vessel 75 to a temperature high enough for washing. Such an arrangement would normallv be used on a system where the hot water load for washing is less than 10arc of the total heat output of the refrigeration machine. The remainder of the system can take any of the forms illustrated and/or described.

In a further alternative arrangement. a heat exchanger or immersion heater is arranged in the storage vessel to add heat to the water therein, the hot water flowing to the vessel 75 from the line 72 raising the water to its final required high temperature.

The remainder of the system can be as illustrated in Figures 1 or 2 or take any of the alternative forms described.

In all the embodiments described it is possible to use other fluids than water to absorb heat from the condensers and auxili ary condensers of the compression refrigeration machines. The fluid absorbing the heat would subsequentlv flow to a heat exchanger where it would give up its heat to the water actually in or flowing into the storage vessel. Thus it can be seen that the hot water provided for washing purposes can be heated either directly or indirectly by the heat recovered from the refrigeration machines.

Thus as described in the alternative embodiments. the water in the storage vessel can be heated indirectly bv provision of a heat exchanger in the vessel. The heated fluid flowing to the heat exchanger can be water or, for example, oil, since such fluid is out of contact with the water used for washing.

Alternately, the water for washing could be heated by passing it through a heat exchanger outside the storage vessel. The water for washing would flow from the vessel as cold water and then receive the heat recovered from the machine at the heat exchanger, before flowing back to the storage vessel.

Again, the fluid which receives the heat from the machine and flows to the heat exchanger could be other than water, for example, oil.

It is to be understood that the present invention for the recovery of heat from compression refrigeration machines to heat water for washing, can be used in conjunction with any known heat recovery system in which the heat recovered is used to heat buildings. Alternatively it can be applied to compression refrigeration machines not normally suited to heat recovery for heated buildings, or to domestic compression refrigeration units or to industrial or commercial process compression refrigeration plants.

WHAT WE CLAIM IS: 1. A system for heating water by means of heat recovered from a compression refrigeration machine of the kind specified.

comprising a heat storage circuit for storing water which, in use, is directly or indirectly heated by heat recovered, in use. from said another zone of the machine, said heat storage circuit comprising said condenser of the machine, a storage vessel, an outlet from said storage vessel for water. heated directly or indirectly by heat recovered in use, from said another zone of the machine, to be removed from the system. a reservoir having a line therefrom to supply water to the storage vessel. and means for replenishing said reservoir, the system further comprising a heat dissipation circuit for dissipating from the system heat which is recovered, in use. from said machine and which is in excess of that required for heating water, said heat dissipation circuit being separate from said heat storage circuit and including a further condenser connected in the refrigerant circulation circuit of said compression refrigeration machine in series with said condenser in said heat storage circuit and downstream thereof, so that heat which is recovered, in use. from said machine and which is in excess of that required for heating water is dissipated either directly or indirectly from said further condenser.

2. A system as claimed in Claim 1. in which the storage vessel has an inlet and an additional outlet for flow of water to and from the vessel. water heated bv the heat recovered by the refrigeration machine flowing into the vessel through said inlet and water to be heated by said heat recovered flowing from the vessel through said additional outlet.

3. A system as claimed in Claim 2, in which water heated directly by the heat recovered from the refrigeration machine flows into the vessel.

4. A system as claimed in anyone of the preceding Claims in which said heat dissipation circuit is a water heating circuit for indirectly dissipating excess heat from said further condenser.

5. A system as claimed in Claim 4 in which the refrigeration machine has a still further condenser connected to its refrigerant circuit, said still further condenser being connected in a water heating circuit for heating a building with which the system is associated, in use. the temperature of heated water flowing in said building heating circuit being lower than the temperature of the heated water flowing to said storage vessel.

6. A system as claimed in Claim 5 in which a further refrigeration machine is provided, the further refrigeration machine having three condensers connected in its refrigerant circuit, each condenser of the further machine being connected either in series with a respective one of the condensers of said refrigeration machine, or in parallel therewith.

7. A system as claimed in Claim 6 in which a still further refrigeration machine is provided which has a single condenser connected in series or in parallel with the pair of condensers provided in the heat dissipation circuit for dissipating excess heat from the system.

8. A system as claimed in Claim 6 in which the respective evaporators of the two refrigeration machines are connected in series or in parallel in a cooling water circuit.

9. A system as claimed in Claim 7 in which the respective evaporators of the three refrigeration machines are connected in series or in parallel or in a combination of both in a cooling water circuit.

10. A system as claimed in any one of Claims 6 to 9 in which a by-pass line is provided around the pair of series connected condensers in the hot water circuit to the storage vessel to allow water to flow to the storage vessel without passing through one or both of these condensers.

11. A system as claimed in any one of claims 3 to 10 in which a heat exchanger or immersion is provided in the system to add heat to the water flowing to the storage vessel.

12. A system as claimed in any one of claims 3 to 11 in which a feedback line is provided to return to the storage vessel and/or to the hot water circuit at a position

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. or, for example, oil, since such fluid is out of contact with the water used for washing. Alternately, the water for washing could be heated by passing it through a heat exchanger outside the storage vessel. The water for washing would flow from the vessel as cold water and then receive the heat recovered from the machine at the heat exchanger, before flowing back to the storage vessel. Again, the fluid which receives the heat from the machine and flows to the heat exchanger could be other than water, for example, oil. It is to be understood that the present invention for the recovery of heat from compression refrigeration machines to heat water for washing, can be used in conjunction with any known heat recovery system in which the heat recovered is used to heat buildings. Alternatively it can be applied to compression refrigeration machines not normally suited to heat recovery for heated buildings, or to domestic compression refrigeration units or to industrial or commercial process compression refrigeration plants. WHAT WE CLAIM IS:

1. A system for heating water by means of heat recovered from a compression refrigeration machine of the kind specified.

upstream of the condensers therein, heated water which flows from said vessel at said outlet.

13. A system as claimed in Claim 12in which a pump is provided in said hot water circuit to pump water through the conde nsers in the circuit and a further pump is provided in said feedback line to return water to the storage vessel and/or the hot water circuit.

14. A system as claimed in Claim 12 in which the heated water flowing to the storage vessel flows to a top zone thereof, the water flowing from the storage vessel to be heated flows from a lower zone thereof, to which lower zone said line to supply water to the storage vessel is connected, and the feedback line to return heated water to the storage vessel leads to a central zone thereof.

15. A system as claimed in Claim 14 in which the heated water flows into the storage vessel through an inlet which is disposed tangentially to the storage vessel.

16. A system as claimed in any one of Claims 4 to 8 in which said heat dissipation includes a cooling tower to which water heated in the circuit, can be taken.

17. A system as claimed in Claim 16 in which said heat dissipation circuit includes a by-pass line to enable water to by-pass said cooling tower when the temperature of the water in the circuit is below a required value.

18. A system as claimed in claim 17 in which a thermostat is provided in said heat dissipation circuit to sense the temperature of water flowing from the condenser or condensers therein, said thermostat being controlled by a controller which also con trols the operation of valves to divert water along said by pass line or to the cooling tower as required.

19. A system as claimed in Claim 18 in which said controller controls a fan associ ated with said cooling tower. the fan operat ing when heat is required to be dissipated.

20. A system as claimed in Claim 16 in which the cooling tower has a sump dis posed above a storage tank for the heat dissipation circuit, so that the sump is self draining.

21. A system as claimed in Claim 6 in which a controller is provided to bring the refrigeration machines successivelv into operation by the operation of respective compressors of the machines.

22. A system as claimed in Claim 5 in which said building heating circuit includes a heat exchanger or immersion heater for adding heat to the water flowing in said circuit.

23. A system as claimed in Claim 22 in which a controller is provided to control operation of the heat exchanger in response to a thermostat in a flow line from said condenser in the building heating circuit and also to control free cooling dampers which control dissipation of heat from the building.

24. A system as claimed in Claim 8 or one of Claims 21 and 22 including a heat reservoir vessel which can store any surplus heat produced in the building heating circuit for addition thereto when extra heat is required therein.

25. A system as claimed in Claim 24 in which heat stored in the heat reservoir vessel can be added to the cooling water circuit.

26. A system as claimed in Claim 8 in which the flow of water through the pairs of condensers in the building heating circuit, the heat dissipation circuit and the circuit for producing the heated water which flows to the storage vessel is in the same direction and opposite to the direction of flow through the evaporators in the cooling water circuits.

27. A system as claimed in any one of claims 1 to 4 in which the water flowing to the storage vessel flows in a circuit which includes a heat exchanger for extracting heat from the heated water to heat fluid flowing in a circuit for heating a building with which the system is associated. in use.

28. A system as claimed in any one of claims 1 to 3 in which said further condenser is an air cooled condenser which has an associated fan directly to dissipate heat from the further condenser. the fan being controlled through a controller, by a refrigerant pressure sensor connected in the refrigerant circuit of the refrigeration machine.

29. A system as claimed in any one of Claims 2, 4 to 9, 12. 14, 15 or 21 to 26, in which water heated indirectly by the heat recovered from the refrigeration machine flows into the vessel. said water passing through a heat exchanger outside the vessel, to which heat exchanger fluid heated by the heat recovered from the refrigeration machine flows.

30. A system as claimed in Claim 29, in which said heat dissipation circuit includes a cooling tower to which water heated in the circuit, can be taken.

31. A system as claimed in Claim 30, in which said heat dissipation circuit includes a by-pass line to enable water to by-pass said cooling tower when the temperature of the water in the heat dissipation circuit is below a required value.

32. A system as claimed in Claim 31, in which a thermostat is provided in said heat dissipation circuit to sense the temperature of water flowing from the condenser or condensers therein, said thermostat being controlled bv a controller which also controls the operation of valves to divert water along said by-pass line or to the cooling tower as required.

33. A system as claimed in Claim 32, in which said controller controls a fan associated with said cooling tower, the fan operating when heat is required to be dissipated.

34. A system as claimed in any one of Claims 29 to 33 in which the fluid heated by the heat recovered from the machine flows in a circuit which includes a heat exchanger for extracting heat from said heated fluid to heat water flowing in a circuit for heating a building with which the system is associated, in use.

35. A system as claimed in Claim 1, in which a heat exchanger is disposed within said storage vessel, fluid flowing, in use, through said heat exchanger having been heated by the heat recovered from said refrigeration machine, whereby water in said storage vessel is heated indirectly by said heat recovered.

36. A system as claimed in Claim 35. in which the heat dissipation circuit is a water heating circuit for indirectly dissipating excess heat from the system.

37. A system as claimed in Claim 36. in which the refrigeration machine has a still further condenser connected in its refrigerant circuit, said still further condenser being connected in a fluid heating circuit for heating a building with which the system is associated in use, the temperature of heated fluid flowing in said building heating circuit being lower than the temperature the water in the storage vessel is heated.

38. A system as claimed in Claim 37. in which a further refrigeration machine is provided, the further refrigeration machine having three condensers connected in its refrigerant circuit. each condenser of the further machine being connected either in series with a respective one of the condensers of said refrigeration machine, or in parallel therewith.

39. A system as claimed in Claim 38. in which a still further refrigeration machine is provided which has a single condenser connected in series or in parallel with the pair of condensers provided in the heat dissipation circuit for dissipating excess heat from the system.

40. A system as claimed in Claim 38. in which the respective evaporators of the two refrigeration machines are connected in series or in parallel in a cooling water circuit.

41. A system as claimed in Claim 39. in which the respective evaporators of the three refrigeration machines are connected in series or in parallel or in a combination of both in a cooling water circuit.

42. A system as claimed in any of Claims 1, and 35 to 41 in which means are provided in the storage vessel for adding heat to the water therein, said heat being other than said heat recovered from said compression refrigeration machine.

43. A system as claimed in Claim 42, in which said means is a heat exchanger or immersion heater.

44. A system as claimed in any one of Claims 1 and 35 to 43 in which a feedback line is provided to return to the storage vessel heated water which flows from said vessel at said outlet.

45. A system as claimed in any one of Claims 35 to 44, in which the fluid flowing through the heat exchanger flows in a circuit which includes a heat exchanger for extracting heat from the fluid to heat water flowing in a circuit for heating a building with which the system is associated, in use.

46. A system as claimed in any one of Claims 35 to 45 in which said further condenser is an air cooled condenser which has an associated fan directly to dissipate heat from the further condenser, the fan being controlled through a controller, by a refrigerant pressure sensor connected in the refrigerant circuit of the refrigeration machine.

47. A system as claimed in Claim 3 or Claim 29, in which the heated water flowing to the storage vessel flows to one zone thereof and the water which flows from the storage vessel to be heated flowing to a different zone thereof. said outlet being from said one zone.

48. A system as claimed in any one of the preceding Claims, in which means are provided for controlling the temperature of said heated water.

49. A system for heating water by means of heat recovered from a compression refrigeration machine of the kind specified substantiallv as hereinbefore described with reference to and as shown in Figure 1 of the accompanying drawings.

50. A system for heating water by means of heat recovered from a compression refrigeration machine of the kind specified substantiallv as hereinbefore described with reference to and as shown in Figure 2 of the accompanying drawings.