GB1584323A

GB1584323A - Reversible cycle heat pump

Info

Publication number: GB1584323A
Application number: GB267378A
Authority: GB
Original assignee: TERMOMECCANICA ITALIANA SpA
Current assignee: TERMOMECCANICA ITALIANA SpA
Priority date: 1977-02-01
Filing date: 1978-01-23
Publication date: 1981-02-11
Also published as: IT1072386B; FR2379036A1; ES466490A1; DE2739658A1

Description

(54) REVERSIBLE CYCLE HEAT PUMP (71) We, TERMOMECCANICA ITALIANA S.pA. an Italian Company of Via del Molo 1, Le Spezia, Italy, do hereby declare the invention, for which we pray that a patent may be granted to us, 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 reversible cycle heat pump.

It is known that a heat pump plant has the task of heating a primary fluid at the expense of a natural or artificial heat source, which thus gives heat to the primary fluid.

It is further known that a cooling plant has the task of cooling a primary fluid at the expense of a natural or artificial coolth source, which thus absorbs heat from the primary fluid.

Usually, these two types of plant are different and it was not possible according to the known prior art to use a single plant as both a heat pump and a refrigerator, without excessively complicating the circuit and increasing the number of heat exchangers, thereby leading to unacceptably high costs.

Reversible heat pumps are known, for example of the type described and claimed in British Patent No. 1 101 268, in which however the secondary fluid is always air, both in the first and second heat exchangers.

In addition, such reversible heat pumps make use of thermostatic valves which can be used only at very low power, for instance up to 50,000 refrigeration units/ hour. For industrial plants the potential of which is much higher than that of such domestic plants, thermoplastic valves cannot be used.

The present invention provides a reversible cycle heat pump, comprising first and second heat exchangers each adapted to operate as a condenser or as an evaporator for a circulating refrigerant or primary fluid, a separator for liquid and vapour phases of the refrigerant or primary fluid, a compressor for drawing the vapour phase from the separator to compress and heat it and pass it to one of the heat exchangers for condensation of the refrigerant or primary fluid and to heat a secondary fluid, an expansion valve placed between the heat exchanger where the refrigerant or primary fluid condenses and the said separator, a circulation pump for drawing the liquid phase of the refrigerant or primary fluid from the separator and to pass it to the other heat exchanger to be evaporated and to cool a secondary fluid, and an arrangement of valves operable so that either of the heat exchangers may be used as the condenser while the other is used as the evaporator.

The invention thus allows the use of the same heat exchangers as both evaporators or condensers.

The invention will be further described, by way of example only, with reference to the accompanying drawings, which show diagrammatically a preferred embodiment of the invention in the different modes of operation thereof, in which: Figure 1 is a diagram of an apparatus according to the invention wherein the conduits shown by heavy lines are those used when the apparatus operates as a heat pump, while the conduits shown by thin lines are those not in use in that mode of operation; Figure 2 shows diagrammatically the cycle followed by the primary fluid when the apparatus works as a heat pump; Figure 3 is a diagram similar to Figure 1, but wherein the conduits shown by heavy lines are those used when the apparatus operates as a cooling device, while the conduits shown by thin lines are those not in use in that mode of operation; and Figure 4 shows diagrammatically the cycle followed by the primary fluid when the apparatus works as a cooling device.

The apparatus shown in the drawings, performing the Carnot cycle, consists essentially of the following components: a) a compressor 1 coupled in a known manner, direct or indirectly, to a motor (not shown in the drawings); b) a separator 2 c) a circulation pump 3; d) a first heat exchanger 4 using as secondary fluid air taken from and given back to the atmosphere; e) a second heat exchanger 5 using a secondary fluid in the form of liquid in a heating or cooling circuit; f) a receiver 6 for the condensed cooling fluid; g) an expansion valve 7; h) three-way two-position distribution valves 81, 82, 83, 84, 85.

The valves 81 and 82 are symmetrically arranged so that each will selectively connect either the output from the compressor 1 or the output from the pump 3 to the inlet to the heat exchanger 4 while connecting the other to the heat exchanger 5.

Similarly, the valves 83 and 84 ar symmetrically arranged so as to connect the output of the heat exchanger 4 or 5 acting as condenser to the collector 6 and the output of the heat exchanger acting as evaporator to the vapour side of the separator 2.

From the receiver 6, the condensed liquid passes via the expansion valve 7 to the liquid side of the separator 2, while any uncondensed primary fluid or refrigerant is passed back via the valve 85 to the heat exchanger which is acting as condenser.

It is to be noted that the heat exchangers 4 and 5 are both fed from above and are each arranged at a higher level than the separator 2 and the collector 6.

The apparatus operates as follows: - Operation as heat pur?zp The high temperature thermal source is the second heat exchanger 5.

The low temperature thermal source is the first heat exchanger 4.

The compressor 1 draws from the separator 2 the primary fluid or refrigerant, compresses it and increases its temperature, and then conveys the same to the high temperature thermal source 5 where the secodary liquid absorbs heat from the primary fluid as the latter condenses.

The condensed primary fluid is conveyed, through suitable operation of the valves 81 to 85, to the collector 6, and then through the expansion valve 7 to the separator 2. From the seperator 2, the primary fluid in the liquid phase is conveyed through the circulation pump 3 to the low temperature thermal source 4, where it evaporates and cools down a further secondary fluid, this time consisting of air from the atmosphere, and from here the primary fluid goes back to the separator 2; in this case, therefore, the heat exchanger 4 represents the source giving heat to the primary fluid.

Operation as cooling device The high temperature thermal source is the first heat exchanger 4.

The low temperature thermal source is the second heat exchanger 5.

The compressor 1 sucks from the separator 2 the primary fluid, compresses it and increases its temperature, and then conveys the same to the high temperature thermal source 4 which absorbs heat from the primary fluid as the latter condenses, by means of a secondary fluid consisting of air from the atmosphere.

The condensed primary fluid is conveyed, through suitable operation of the distribution valves, to the collector 6, then through the expansion valve 7 to the separator 2, and from there, through the pump 3, in the liquid phase to the low temperature thermal source 5, where it evaporates and finally to the separator 2.

The low temperature heat is absorbed by a secondary fluid which is subsequently used.

According to a particular embodiment of the invention, the primary fluid or refrigerant consists of Freon 12 or Freon 22; "Freon" is a Registered Trade Mark. The secondary fluid passing through the first heat exchanger 4 consists of air taken from the atmosphere. The air is then given back to the atmosphere at a higher temperature when the apparatus works as a cooling device; and at a lower temperature when the apparatus works as a heat pump.

The secondary fluid passing through the second heat exchanger consists of water circulating in a closed circuit, the water being cooled when apparatus works as a cooling device and heated when the apparatus works as a heat pump.

Figures 1 and 3 show the inlet and outlet temperatures of the air and water for the first and second exchangers relating to the particular manner of use of the apparatus.

Further, Figures 1 and 3 show, adjacent the rectangles representing the two heat exchangers 4 and 5, the refrigerant temperatures when the two exchangers work as an evaporator and a condenser and as a condenser and an evaporator respectively.

The corresponding pressures are the balance pressures between the liquid phase and the vapour phase.

Figures 2 and 4 shows diagrammatically the Carnot cycles obtained in the two cases.

The abscissae represent the entropies S of the primary fluid, while the ordinates represents the absolute temperatures T thereof.

The reversible cycle heat pump may be used with a reciprocating compressor and also with a centrifugal or screw compressor of high delivery for air conditioning, heating and cooling plants.

The reversible cycle heat pump may be used with a cooling compressor actuated by a petrol engine or a Diesel engine, or by a gas turbine.

The reversible cycle heat pump may be designed to operate in a completely automatic way, including, where required, cycle reversal and defrosting.

It will be appreciated that the valves 83 and 84 which are provided downstream of the outlets of the heat exchangers 4 and 5 put, through a pair of conduits, the outlet of one heat exchanger selectively in communication with the vapour zone and the liquid zone of the separator 2 and the outlet of the other heat exchanger selectively in communication with the liquid zone and the vapour zone of the separator.

Conduits for the refrigerant or primary fluid within either of the heat exchangers may suitably comprise inclined descending pipes so as to allow a quick discharge of the refrigerant or primary fluid contained in these pipes, when each of the heat exchangers changes operation from absorbing heat to giving heat.

WHAT WE CLAIM IS: 1. A reversible cycle heat pump, comprising first and second heat exchangers each adapted to operate as a condenser or as an evaporator for a circulating refrigerant or primary fluid, a separator for liquid and vapour phases of the refrigerant or primary fluid, a compressor for drawing the vapour phase from the separator to compress and heat it and pass it to one of the heat exchangers for condensation of the refrigerant or primary fluid and to heat a secondary fluid, an expansion valve placed between the heat exchanger where the refrigerant or primary fluid condenses and the said separator, a circulation pump for drawing the liquid phase of the refrigerant or primary fluid from the separator and to pass it to the other heat exchanger to be evaporated and to cool a secondary fluid, and an arrangement of valves operable so that either of the heat exchangers may be used as the condenser while the other is used as the evaporator.

2. A reversible cycle heat pump as claimed in Claim 1, wherein one of the heat exchangers uses air as a secondary fluid, while the other uses water in a heating or cooling circuit.

3. A reversible cycle heat pump as claimed in Claim 1 or 2, wherein the delivery of the compressor and that of the circulation pump feed alternatively the inlets of the two heat exchangers through a pair of three-way two-position valves, the first of which puts the inlet of the relevant heat exchanger selectively in communication with the compressor delivery or the circulation pump delivery respectively, while the second of which puts the inlet of the relevant heat exchanger selectively in communication with the circulation pump delivery or the compressor delivery respectively.

4. A reversible cycle heat pump as claimed in Claim 3, wherein a second pair of three-way two-position valves are provided downstream of the outlets of the said heat exchangers so as to put, through a pair of conduits, the outlet of the first heat exchanger selectively in communication with the vapour zone and the liquid zone of the said separator and the outlet of the second heat exchanger selectively in communication with the liquid zone and the vapour zone of the separator respectively, and wherein the conduit connecting the outlet of the first or second heat exchanger with the liquid zone of the separator is provided with a collector for the refrigerant or primary fluid coming from the heat exchanger or condenser, the said expansion valve being located in the conduit connecting the said collector with the liquid zone of the separator.

5. A reversible cycye heat pump as claimed in Claim 4, wherein the upper part of the collector is connected, through a fifth three-way two-position valve, with the inlet of the heat exchanger acting as a condenser.

6. A reversible cycle heat pump as claimed in Claim 4 or 5, wherein the said heat exchangers are both fed from above and are each arranged at a higher level than the said separator and the said collector.

7. A reversible cycle heat pump as claimed in Claim 6, wherein conduits for the refrigerant or primary fluid within either the first or second heat exchanger comprise inclined descending pipes so as to allow a quick discharge of the refrigerant or primary fluid contained in the said pipes, when each of the said heat exchangers changes operation from absorbing heat to giving heat.

8. A reversible cycle heat pump substanially as herein described with reference to, and as shown in, the accompanying drawings.

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

Claims

**WARNING** start of CLMS field may overlap end of DESC **. a petrol engine or a Diesel engine, or by a gas turbine. The reversible cycle heat pump may be designed to operate in a completely automatic way, including, where required, cycle reversal and defrosting. It will be appreciated that the valves 83 and 84 which are provided downstream of the outlets of the heat exchangers 4 and 5 put, through a pair of conduits, the outlet of one heat exchanger selectively in communication with the vapour zone and the liquid zone of the separator 2 and the outlet of the other heat exchanger selectively in communication with the liquid zone and the vapour zone of the separator. Conduits for the refrigerant or primary fluid within either of the heat exchangers may suitably comprise inclined descending pipes so as to allow a quick discharge of the refrigerant or primary fluid contained in these pipes, when each of the heat exchangers changes operation from absorbing heat to giving heat. WHAT WE CLAIM IS:

1. A reversible cycle heat pump, comprising first and second heat exchangers each adapted to operate as a condenser or as an evaporator for a circulating refrigerant or primary fluid, a separator for liquid and vapour phases of the refrigerant or primary fluid, a compressor for drawing the vapour phase from the separator to compress and heat it and pass it to one of the heat exchangers for condensation of the refrigerant or primary fluid and to heat a secondary fluid, an expansion valve placed between the heat exchanger where the refrigerant or primary fluid condenses and the said separator, a circulation pump for drawing the liquid phase of the refrigerant or primary fluid from the separator and to pass it to the other heat exchanger to be evaporated and to cool a secondary fluid, and an arrangement of valves operable so that either of the heat exchangers may be used as the condenser while the other is used as the evaporator.