GB1587057A

GB1587057A - Heat recovery system

Info

Publication number: GB1587057A
Application number: GB1743876A
Authority: GB
Original assignee: CONSERVE RECYCLING Ltd
Current assignee: CONSERVE RECYCLING Ltd
Priority date: 1977-07-29
Filing date: 1977-07-29
Publication date: 1981-03-25

Description

(54) HEAT RECOVERY SYSTEM (71) We, CONSERVE (RECYCLING) LIMITED, a British Company of 84 Middle Street, Yeovil, Somerset, 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 heat recovery system applicable to refrigeration plants which incorporate air cooled refrigeration units. At the present moment most units of this kind serve to extract the heat from the refrigerant and dispose of the heat into the atmosphere by means of a heat exchanger.

The total effect of this represents an extremely large wastage of usable heat.

An object of the invention is to provide a system by which heat may be recovered from a refrigeration plant in a simple manner. More especially it is an object of the invention to provide a system which incorporates existing components of refrigeration plant.

According to the invention I provide a method of adapting the refrigeration circuit of a refrigerator having a compressor, an air cooled condensor, an expansion valve and an expansion chamber, to incorporate a heat recovery system said method comprising providing a calorifier condensor between the compressor and the air cooled condensor and providing a relief valve between the air cooled condensor and the expansion valve. said relief valve serving to control the condensation of refrigerant whereby the bulk of the heat loss from the refrigerant takes place in the calorifier. Hot water produced in the calorifier may be used in a varietv of wavs.

Further according to the invention provide a refrigerator unit incorporating heat recovery system comprising an expansion valve. an expansion chamber for receiving the expanded refrigerant. a compressor connected to the outlet of the expansion chamber, a calorifier having its primary coil connected to the outlet of the compressor, an air cooled condenser connected to the output of the primary coil of the calorifier, a relief valve connected to the output of the air cooled condenser, and means coupling the relief valve outlet with the expansion valve, said relief valve being so selected that in operation the bulk of the heat loss from the refrigerant takes place in the calorifier.

An embodiment of the invention will now be described by way of example with reference to the accompanying drawing which shows a schematic diagram of a refrigeration system adapted in accordance with the invention. Whilst a system can be provided incorporating a combination of a heat recovery unit and a refrigerator, the invention will be described as an adaptation of an existing refrigerator. The latter comprises a thermostatically controlled expansion valve 10, an expansion chamber 11 or coil located in proximity to the storage space of the refrigerator, a motor driven compressor 12, a condenser 13 cooled by a fan 14, and a reservoir 15 for the liquid refrigerant coupled to complete the circuit to the expansion valve 10.

In order to recover the heat normally lost at the air cooled condenser in accordance with the present invention, a calorificrcondenser 16 is connected by means of its primary coil 17 in the line between the compressor and the condenser 13. The calorifier jacket may be connected to a hot water tank or may be directly couplcd to the point of demand. Between the condenser 13 and the reservoir 15 is connected a relief valve 18 which in this example is designed to open at 150 p.s.i. After start up of the system with the valve closed, the hot superheated gas from compressor passcs through the primary coil 17 where it is condensed to a liquid by the water in the jacket of the calorifier, thus effecting useful exchange of the superheat and latent heat. The liquid flows into the condenser 13 which fills up whereby cooling by means of the fan 14 is rendered substantially ineffective.

Since the relief valve is closed, pressure builds up in the condenser system. At 150 p.s.i. the relief valve opens slightly which allows the level in the condensers 16, 13 to fall so that the fan gradually commences additionally to condense further refrigerant gas within the condenser 13. Pressure would then build up again as more gas is liquified.

When the temperature in the jacket of the calorifier exceeds a predetermined level (e.g. about 35"C) the condensing effect of the heated water will reduce whereby less gas will liquify .and the pressure increases, resulting in a fall of the level of the liquid in the condenser 13 by greater opening of the relief valve. The more the level falls, the more gas enters the condenser 13 which will be cooled by the air fan. Thus the liquid within the condenser 13. provides a liquid trap which rises and falls to effect a greater or teaser degree of condensing within the air cooled section as determined by external conditions of ambient and water temperature in the calorifier.

When the gas is cooled in the condenser 13, the pressure will drop causing the relief valve to close. The pressure will build up and the valve will once again open. Thus the valve modulates and the liquid level in the condenser 13 will rise and fall resulting in a self regulator of the . condensation effect.

Thus, after start up (say 1 l/2 to 2 hours) the condenser 13 which is rendered inoperative on start up by the relief valve has returned to its normaL duty.

For cold weather application, the system may be modified by inclusion of a bypass valve 20. in, a line connected between the interconnection of the compressor 12 and calorifier 16 and. the interconnection between: the relief valve 18 and the reservoir 15. The bypass valve 20 is designed to open when the pressure on the compressor side is about 20 p.s.i. greater than on the relief valve side. The purpose of this bypass valve is to ensure start up at low temperatures especially where the refsigerator is operated with low ambient temperatures and where the water to the calorifier is also at a low temperature, by preventing the relief valve 18 acting as an expansion valve and "freezing" the storage reservoir.

At start up, the system is in a state of balance (say 50 p.s.i.). The compressor will build.up pressure until at a certain level (70 p.s.i.) the bypass valve 20 opens so that the portion of the circuit including the calorifier 16, the condenser 13 and the relief-valve 18 is-bypassed.- Liquid.will also build up in the two condensers, prior to operation of relief valve 18. The hot gas/vapour mixture causes a build up of pressure because of the restriction at the expansion valve 10.

At a pressure of 150 p.s.i., the relief valve will open, which brings into operation the primary coil 17 of the calorifier, the condenser being substantially ineffective as it is full of liquid. The bypass valve shuts when the.difference at the inlet and outlet sides thereof falls below 20 p.s.i.

WHAT I CLAIM IS: 1. A method of adapting the refrigeration circuit of a refrigerator having a compressor, an air cooled condensor, an expansion valve and an expansion chamber, to incorporate a heat recovery system said method comprising providing a calorifier condensor between the compressor and the air cooled condensor and providing a relief valve between the air cooled condensor and the expansion valve, said relief valve serving to control the condensation of refrigerant whereby the bulk of the heat loss from the refrigerant takes place in the calorifier.

2. A method as claimed in claim 1, wherein a bypass valve is provided between.

downstream of the compressor and the downstream side of the relief valve, the - bypass valve opening in response to a pressure difference across it above a predetermined liinit between the downstream side of the compressor and the downstream sideof the relief valve.

3. A refrigerator incorporating a heat recovery system comprising an expansion valve, an expansion chamber for receiving expanded refrigerant from the expansion valve, a compressor connected to the outlet of the expansion chamber, a cal'orifier having its primary coil connected to the outlet of the compressor to condense compressed refrigerant from the compressor, an air cooled condensor connected to the output of the primary coil of the calorifier, a relief valve connected between the .output of the air cooled condensor and the expansion valve, said relief valve being so selected-that in operation the bulk of the heat loss from the refrigerant takes place in the calorifier.

4. A refrigerator as claimed in claim 3, wherein a bypass valve is provided'between downstream of the compressor ànd the downstream side of the relief valve, the bypass valve opening in response to a pressure difference across it above a predetermined limit between the downstream side of the compressor and the downstream side of the relief valve.

5. A method as claimed in claim 1, substantially as hereinbefore described with reference to the accompanying drawing.

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

Claims

**WARNING** start of CLMS field may overlap end of DESC **. calorifier, thus effecting useful exchange of the superheat and latent heat. The liquid flows into the condenser 13 which fills up whereby cooling by means of the fan 14 is rendered substantially ineffective. Since the relief valve is closed, pressure builds up in the condenser system. At 150 p.s.i. the relief valve opens slightly which allows the level in the condensers 16, 13 to fall so that the fan gradually commences additionally to condense further refrigerant gas within the condenser 13. Pressure would then build up again as more gas is liquified. When the temperature in the jacket of the calorifier exceeds a predetermined level (e.g. about 35"C) the condensing effect of the heated water will reduce whereby less gas will liquify .and the pressure increases, resulting in a fall of the level of the liquid in the condenser 13 by greater opening of the relief valve. The more the level falls, the more gas enters the condenser 13 which will be cooled by the air fan. Thus the liquid within the condenser 13. provides a liquid trap which rises and falls to effect a greater or teaser degree of condensing within the air cooled section as determined by external conditions of ambient and water temperature in the calorifier. When the gas is cooled in the condenser 13, the pressure will drop causing the relief valve to close. The pressure will build up and the valve will once again open. Thus the valve modulates and the liquid level in the condenser 13 will rise and fall resulting in a self regulator of the . condensation effect. Thus, after start up (say 1 l/2 to 2 hours) the condenser 13 which is rendered inoperative on start up by the relief valve has returned to its normaL duty. For cold weather application, the system may be modified by inclusion of a bypass valve 20. in, a line connected between the interconnection of the compressor 12 and calorifier 16 and. the interconnection between: the relief valve 18 and the reservoir 15. The bypass valve 20 is designed to open when the pressure on the compressor side is about 20 p.s.i. greater than on the relief valve side. The purpose of this bypass valve is to ensure start up at low temperatures especially where the refsigerator is operated with low ambient temperatures and where the water to the calorifier is also at a low temperature, by preventing the relief valve 18 acting as an expansion valve and "freezing" the storage reservoir. At start up, the system is in a state of balance (say 50 p.s.i.). The compressor will build.up pressure until at a certain level (70 p.s.i.) the bypass valve 20 opens so that the portion of the circuit including the calorifier 16, the condenser 13 and the relief-valve 18 is-bypassed.- Liquid.will also build up in the two condensers, prior to operation of relief valve 18. The hot gas/vapour mixture causes a build up of pressure because of the restriction at the expansion valve 10. At a pressure of 150 p.s.i., the relief valve will open, which brings into operation the primary coil 17 of the calorifier, the condenser being substantially ineffective as it is full of liquid. The bypass valve shuts when the.difference at the inlet and outlet sides thereof falls below 20 p.s.i. WHAT I CLAIM IS:

1. A method of adapting the refrigeration circuit of a refrigerator having a compressor, an air cooled condensor, an expansion valve and an expansion chamber, to incorporate a heat recovery system said method comprising providing a calorifier condensor between the compressor and the air cooled condensor and providing a relief valve between the air cooled condensor and the expansion valve, said relief valve serving to control the condensation of refrigerant whereby the bulk of the heat loss from the refrigerant takes place in the calorifier.

2. A method as claimed in claim 1, wherein a bypass valve is provided between.

6. A refrigerator as claimed in claim 3,

substantially as hereinbefore described with reference to the accompanying drawing.