EP1420218A2

EP1420218A2 - Heat-save cooler

Info

Publication number: EP1420218A2
Application number: EP03025862A
Authority: EP
Inventors: Vito Simi
Original assignee: Rhoss SpA
Current assignee: Rhoss SpA
Priority date: 2002-11-13
Filing date: 2003-11-11
Publication date: 2004-05-19
Anticipated expiration: 2023-11-11
Also published as: ATE408103T1; EP1420218A3; DE60323443D1; ES2312712T3; EP1420218B1; ITTO20020982A1

Abstract

A single- or reversible-cycle heat-save cooler (1) having a first heat exchanger (2) where a cooling fluid exchanges heat with the outside environment; a second heat exchanger (3) where the cooling fluid exchanges heat with a first liquid; a cooling fluid compressor unit (5) where the cooling fluid is compressed to increase its pressure; and a third heat exchanger (4) where the cooling fluid exchanges heat with a second liquid; the third heat exchanger (4) being located immediately downstream from the compressor unit (5); and the cooler (1) also having a liquid-gas separating unit (17) located immediately downstream from the third heat exchanger (4) to retain all or part of the liquid cooling fluid issuing from the third heat exchanger (4).

Description

The present invention relates to a heat-save cooler.
More specifically, the present invention relates to a single- or reversible-cycle cooler for centralized air conditioning systems, to which the following description refers purely by way of example.
As is known, centralized air conditioning systems normally comprise a cooler for cooling the liquid circulating in the fan convectors (fan coils) forming part of the system, so as to enable the fan convectors to withdraw heat from the surrounding environment and so cool the air in the rooms of the building in which they are installed.
In centralized air conditioning systems, the cooler (or coolers) normally operates on the heat pump principle, and is therefore capable of both cooling and heating the liquid circulating in the hydraulic circuit of the air conditioning system, so that the fan convectors of the air conditioning system can selectively withdraw or yield heat to or from the surrounding environment, depending on the time of year, with no need for a boiler.
Over the past few years, given the enormous amount of heat produced by the coolers in normal operating conditions, various manufacturers, to make better use of available resources, have opted to recover all or part of this heat and use it for producing hot water for domestic or other purposes, a function which hitherto has always been performed by boilers external to the air conditioning system.
The addition of this extra function, however, has seriously complicated design of the coolers, which must now be able to heat or cool the liquid circulating in the air conditioning system as a function of environmental conditions, while at the same time ensuring enough heat is produced for use, on request, in producing hot water for domestic or other purposes.
More specifically, addition of the "heat-save" function has also called for the addition of an auxiliary heat exchanger, immediately downstream from the delivery side of the compressor, where the high-pressure cooling fluid from the compressor exchanges heat with an external liquid eventually used for purposes not necessarily related to temperature control of the building, such as the production of hot water for domestic purposes.
The presence of an auxiliary heat exchanger also calls for an auxiliary storage tank for storing additional liquid cooling fluid, by which to compensate, when necessary, for variations in the volume of the cooling fluid on passing to the liquid state in the auxiliary heat exchanger.
Early passage to the liquid state of part of the high-pressure cooling fluid from the compressor, in fact, drastically reduces the total volume of the gaseous cooling fluid in the cooler, thus compromising operation of the cooler unless additional cooling fluid is fed immediately into the circuit.
It should be pointed out that early passage to the liquid state of part of the high-pressure cooling fluid from the compressor only occurs when the "heat-save" function is active, i.e. when the external liquid is circulated in the auxiliary heat exchanger to absorb heat from the cooling fluid, so that various devices are required to connect the auxiliary cooling fluid storage tank, on command, to the cooler circuit.
The increase in the complexity of the coolers has brought about a serious reduction in reliability as a whole, and hence high running cost, which accounts for their not being used on a wide scale.
It is an object of the present invention to provide a single- or reversible-cycle heat-save cooler designed to eliminate the aforementioned drawbacks.
According to the present invention, there is provided a heat-save cooler comprising a first heat exchanger where a cooling fluid exchanges heat with the outside environment; a second heat exchanger where said cooling fluid exchanges heat with a first liquid; a cooling fluid compressor unit where said cooling fluid is compressed to increase its pressure; and a third heat exchanger where said cooling fluid exchanges heat with a second liquid; said third heat exchanger being located immediately downstream from said compressor unit; and the cooler being characterized by also comprising a liquid-gas separating unit located immediately downstream from said third heat exchanger to retain the liquid cooling fluid issuing from said third heat exchanger.
A non-limiting embodiment of the present invention will be described by way of example with reference to the accompanying drawings, in which:
Figure 1 shows, schematically, a heat-save cooler in accordance with the teachings of the present invention;
Figure 2 shows a section, with parts removed for clarity, of a component part of the Figure 1 cooler.
Number 1 in Figure 1 indicates as a whole a heat-save cooler, which may be used to advantage in centralized air conditioning systems of buildings; which systems normally comprise a number of fan convectors appropriately distributed within the building being temperature controlled, and at least one cooler for heating or cooling the heat-carrying liquid (normally water) conducted to the various fan convectors via the hydraulic circuit of the air conditioning system.
In the following description, specific reference is made purely by way of example to a reversible-cycle heat-save cooler, and this is no way to be inferred as excluding single-cycle coolers. i.e. for simply cooling the heat-carrying liquid conducted to the fan convectors.
Cooler 1 operates on the heat pump principle, by which heat is transferred from one environment to another by subjecting a gaseous cooling fluid to a closed thermodynamic cycle, such as the Carnot cycle. The thermodynamic principles on which the heat pump is based are widely known and therefore not described in detail.
Cooler 1 comprises a first heat exchanger 2 where the cooling fluid exchanges heat with the outside environment; a second heat exchanger 3 where the cooling fluid exchanges heat with the heat-carrying liquid conducted to the fan convectors via the hydraulic circuit of the air conditioning system; and a third heat exchanger 4 where the cooling fluid exchanges heat with a second liquid eventually used for other purposes not necessarily related to temperature control of the building, e.g. producing hot water for domestic use.
Cooler 1 also comprises a cooling fluid compressor unit 5 where the cooling fluid is subjected to compression (e.g. adiabatic compression) so that the pressure of the cooling fluid leaving compressor unit 5 is greater than the pressure of the cooling fluid entering the compressor unit; and a cooling fluid distributor 6 for selectively and appropriately connecting, on command, the delivery side 5a and intake side 5b of compressor unit 5 to heat exchangers 2 and 3.
More specifically, distributor 6 selectively connects delivery side 5a and intake side 5b of compressor unit 5 to heat exchangers 2 and 3 to enable cooler 1 to selectively:

cool the heat-carrying liquid circulating in the hydraulic circuit of the air conditioning system, so as to transfer heat to the outside environment;
cool the heat-carrying liquid circulating in the hydraulic circuit of the air conditioning system, so as to transfer heat to the outside environment and/or to the liquid eventually used for other purposes not directly related to temperature control of the building;
heat the heat-carrying liquid circulating in the hydraulic circuit of the air conditioning system, so as to withdraw heat from the outside environment; or
heat the heat-carrying liquid circulating in the hydraulic circuit of the air conditioning system and the liquid eventually used for other purposes not necessarily related to temperature control of the building, so as to again withdraw heat from the outside environment.

In the following description, specific reference is made, for the sake of simplicity, to the production of hot water for domestic use, though this in no way excludes use of the second liquid for other purposes.
Heat exchangers 2, 3, 4 and compressor unit 5 are devices widely used in the sector, and are therefore not described in detail.
With reference to Figure 1, heat exchanger 2 permits heat exchange between the cooling fluid and outside environment, so as to produce condensation or evaporation of the cooling fluid, depending on the difference in temperature between the cooling fluid and outside environment.
More specifically, when the temperature of the cooling fluid entering heat exchanger 2 is higher than that of the outside environment, heat exchanger 2 allows the cooling fluid flowing through it to cool gradually and yield heat to the outside environment, while the noncondensed part of the fluid passes from the gaseous to the liquid state. Conversely, when the temperature of the cooling fluid entering heat exchanger 2 is lower than that of the outside environment, heat exchanger 2 allows the cooling fluid flowing through it to heat gradually and absorb heat from the outside environment, while passing from the liquid to the gaseous state.
In the example shown, heat exchanger 2 has two inlets and two outlets for the cooling fluid, which are appropriately connected to each other to define, in heat exchanger 2, a cooling path, along which the high-temperature cooling fluid is gradually cooled and yields heat to the outside environment, while passing from the gaseous to the liquid state; and a heating path, along which the low-temperature cooling fluid is gradually heated and absorbs heat from the outside environment, while passing from the liquid to the gaseous state.
More specifically, in the example shown, heat exchanger 2 is defined by a known, forced-air, external heat exchanger, which has an inlet 2a for high-temperature gaseous cooling fluid, an outlet 2b for medium-temperature liquid cooling fluid, an inlet 2c for medium-temperature liquid cooling fluid, and an outlet 2d for low-temperature gaseous cooling fluid, and which coincides with inlet 2a.
Inlet 2a and outlet 2b of heat exchanger 2 define the ends of the cooling path; inlet 2a is connected directly to distributor 6 by a first connecting pipe 7; and outlet 2b is connected directly to heat exchanger 3 by a second connecting pipe 8, along which are fitted a known non-return valve 9 and a known dehydration filter 10. Non-return valve 9 is so oriented as to only allow cooling fluid to flow from heat exchanger 2 to dehydration filter 10.
Inlet 2c and outlet 2d of heat exchanger 2, on the other hand, define the ends of the heating path; inlet 2c is connected directly to heat exchanger 3 by a connecting pipe 11 connected to pipe 8 immediately downstream from dehydration filter 10; and outlet 2d is connected directly to distributor 6 by pipe 7.
With reference to Figure 1, heat exchanger 3 permits heat exchange between the cooling fluid and the heat-carrying liquid supplied to the fan convectors, so as to increase or reduce the temperature of the cooling fluid by withdrawing or yielding heat from or to the heat-carrying liquid circulating in the air conditioning system.
More specifically, when the temperature of the cooling fluid entering heat exchanger 3 is higher than that of the heat-carrying liquid, heat exchanger 3 allows the cooling fluid flowing through it to cool gradually and yield heat to, and so heat, the heat-carrying liquid. Conversely, when the temperature of the cooling fluid entering heat exchanger 3 is lower than that of the heat-carrying liquid, heat exchanger 3 allows the cooling fluid flowing through it to heat gradually and absorb heat from, and so cool, the heat-carrying liquid.
Heat exchanger 3 has a primary circuit, along which flows the heat-carrying liquid conducted to the fan convectors of the air conditioning system; and a secondary circuit, along which the cooling fluid flows.
The inlet and outlet of the primary circuit - hereinafter indicated 3a and 3b - are connected to the hydraulic circuit of the air conditioning system; and the inlet and outlet of the secondary circuit - hereinafter indicated 3c and 3d - are connected, one directly to heat exchanger 2, and the other to distributor 6.
More specifically, inlet 3c of heat exchanger 3 is connected directly to pipe 8 with the interposition of a controlled on-off valve 12 located immediately downstream from the junction of pipes 11 and 8 to intercept cooling fluid flow to and from dehydration filter 10; and outlet 3d of heat exchanger 3 is connected directly to distributor 6 by a connecting pipe 13.
Heat exchanger 4 permits heat exchange between the cooling fluid and water for domestic use, so that the cooling fluid is cooled by yielding heat to, and so heating, the domestic water.
In this case, the temperature of the cooling fluid entering heat exchanger 4 is always higher than that of the domestic water, so that the cooling fluid flowing through heat exchanger 4 is cooled gradually and yields heat to the domestic water, but not vice versa.
Like heat exchanger 3, heat exchanger 4 has a primary circuit, along which flows the domestic water to be heated; and a secondary circuit, along which the cooling fluid flows.
The inlet and outlet of the primary circuit - hereinafter indicated 4a and 4b - are obviously connected to the hydraulic circuit of the building; and the inlet and outlet of the secondary circuit - hereinafter indicted 4c and 4d - are connected, one to the delivery side 5a of compressor unit 5, and the other to distributor 6, so as to connect heat exchanger 4 immediately downstream from compressor unit 5.
More specifically, inlet 4c of heat exchanger 4 is connected by a pipe 14 directly to delivery side 5a of compressor unit 5; and outlet 4d of heat exchanger 4 is connected to distributor 6 by a connecting pipe 15, which is fitted with a non-return valve 16 oriented to only permit cooling fluid flow from heat exchanger 4 to distributor 6.
With reference to Figures 1 and 2, along pipe 15, cooler 1 also comprises a liquid-gas separating unit 17 for retaining the liquid cooling fluid issuing from heat exchanger 4, so as to prevent the liquid cooling fluid from flowing along pipe 15 to distributor 6. The separating unit is substantially defined by a liquid-gas separating tank 18 located along pipe 15, immediately downstream from heat exchanger 4 (i.e. upstream from non-return valve 16), to continually separate the liquid cooling fluid from the gaseous cooling fluid, and to retain inside it all the liquid cooling fluid issuing from heat exchanger 4.
Liquid-gas separating tank 18 is widely used in this sector for other applications, and is therefore not described in detail, except to state that it has a drain outlet 18a at the bottom by which to draw off liquid cooling fluid accumulated inside the tank.
In addition, liquid-gas separating unit 17 also comprises : a connecting pipe 19 which, by means of an end fork, connects drain outlet 18a of the tank to both inlet 2c of heat exchanger 2 and inlet 3c of heat exchanger 3; a controlled on-off valve 20 located along pipe 19, immediately downstream from drain outlet 18a, to control liquid cooling fluid flow from the liquid-gas separating tank; and an expansion valve 21 for rapidly expanding the cooling fluid flowing along pipe 19.
More specifically, expansion valve 21 is located downstream from on-off valve 20, and rapidly expands the cooling fluid flowing along pipe 19 so that the pressure of the cooling fluid issuing from expansion valve 21 is lower than the pressure of the cooling fluid entering the valve.
With reference to Figures 1 and 2, liquid-gas separating unit 17 preferably, though not necessarily, also comprises a level switch 22 housed inside liquid-gas separating tank 18 to open on-off valve 20 when the liquid level inside liquid-gas separating tank 18 exceeds a predetermined threshold value; and two non-return valves 23 and 24, the first of which is located along the end portion of pipe 19 connected to inlet 3c of heat exchanger 3 to only permit cooling fluid flow to inlet 3c of heat exchanger 3, and the second of which is located along the end portion of pipe 19 connected to inlet 2c of heat exchanger 2 to only permit cooling fluid flow to inlet 2c of heat exchanger 2.
With reference to Figure 1, cooling fluid compressor unit 5 is, as stated, known, and comprises a conventional screw or piston compressor 25 for gaseous fluids (or similar); and a liquid-gas separating tank 26 located upstream from the intake side of compressor 25 to prevent the liquid cooling fluid from reaching the intake side of, and so irreparably damaging, compressor 25. Cooling fluid compressor unit 5 preferably, though not necessarily, also comprises a non-return valve (not shown) located immediately downstream from delivery side 5a of compressor 25 and so oriented as to only permit gaseous cooling fluid flow to heat exchanger 4.
With reference to Figure 1, in the example shown, distributor 6 of cooler 1 is defined by a conventional, electrically controlled, four-way valve 27, which is driven by an electronic central control unit (not shown) of the cooler, together with on-off valve 12 and possibly on-off valve 20.
More specifically, four-way valve 27 is a slide valve, which has four inlets selectively connectable directly with one another in pairs, and which can alternatively assume two distinct operating configurations enabling two of the four inlets of the valve to selectively and alternatively communicate directly with either one of the other two inlets of the valve.
In other words, four-way valve 27 has two primary inlets and two secondary inlets; and the primary inlets can be connected selectively and alternatively to either one of the two secondary inlets of the valve, but can never communicate directly with each other.
More specifically, four-way valve 27 has four inlets 27a, 27b, 27c, 27d, and can assume two distinct operating configurations : in a first operating configuration, inlet 27a communicates directly with inlet 27b, while inlet 27c communicates directly with inlet 27d; in a second operating configuration, inlet 27a communicates directly with inlet 27d, while inlet 27c communicates directly with inlet 27b.
As for connection of four-way valve 27 to the other components of cooler 1, inlet 27a of four-way valve 27 is connected directly by pipe 15 to liquid-gas separating unit 17; inlet 27b is connected directly to pipe 7; inlet 27c is connected directly by a pipe 29 to liquid-gas separating tank 26 and intake side 5b of compressor unit 5; and inlet 27d of four-way valve 27 is connected directly to pipe 13 from heat exchanger 3.
As will be clear, inlets 27a and 27c define the primary inlets, and inlets 27b and 27d the secondary inlets of four-way valve 27.
With reference to Figure 1, cooler 1 also has at least one expansion valve 28 for rapidly expanding the cooling fluid, so as to complete the closed thermodynamic cycle in opposition to compressor unit 5, which rapidly compresses the cooling fluid.
More specifically, expansion valve 28 rapidly expands the in-transit cooling fluid, so that the pressure of the cooling fluid issuing from expansion valve 28 is lower than the pressure of the cooling fluid entering the valve, and is obviously located along the pipe connecting the heat exchanger in which the cooling fluid is cooled to the heat exchanger in which the cooling fluid is heated before returning to compressor unit 5.
More specifically, in the example shown, cooler 1 comprises three expansion valves 28 : a first expansion valve 28 is located along pipe 8, between inlet 3c of heat exchanger 3 and on-off valve 12; and a second and third expansion valve 28 are located along pipe 11, at inlet 2c of heat exchanger 2.
With reference to Figure 1, in the example shown, cooler 1 also comprises a bypass circuit 31, by which the cooling fluid from inlet 3c of heat exchanger 3 bypasses the expansion valve 28 along pipe 8. Bypass circuit 31 comprises a connecting pipe 32 having a first end branch connected to pipe 8, between inlet 3c of heat exchanger 3 and expansion valve 28, and a second end branch connected to pipe 8, between non-return valve 9 and dehydration filter 10; a cooling fluid storage tank 33 located along pipe 32; and a non-return valve 34 located along pipe 32, between storage tank 33 and pipe 8. The non-return valve 34 is so oriented as to only allow cooling fluid flow from storage tank 33 to dehydration filter 10, but not vice versa.
Operation of cooler 1 will now be described, assuming it is initially in the summer configuration, i.e. in the operating mode in which it withdraws heat from the heat-carrying liquid at heat exchanger 3, and yields heat to the outside environment at heat exchanger 2.
In this operating mode, on-off valve 12 is in the open position, and four-way valve 27 is in the first operating position wherein inlet 27a communicates directly with inlet 27b, and inlet 27c communicates directly with inlet 27d.
With reference to Figure 1, the cooling fluid from compressor 25 flows successively through pipe 14, heat exchanger 4, pipe 15, liquid-gas separating tank 18, and non-return valve 16 to inlet 27a of four-way valve 27 of distributor 6. On reaching inlet 27a, the cooling fluid flows through four-way valve 27, out through inlet 27b, and along pipe 7 to inlet 2a of heat exchanger 2, where it yields heat to the outside environment and is cooled.
The cooling fluid flows out of heat exchanger 2 through outlet 2b and successively, along pipe 8, through non-return valve 9, dehydration filter 10, on-off valve 12 and, finally, expansion valve 28, where it is expanded rapidly before flowing through inlet 3c of heat exchanger 3.
Inside heat exchanger 3, the cooling fluid absorbs heat from the heat-carrying liquid circulating in the hydraulic circuit of the air conditioning system, then flows along pipe 13 to distributor 6, and from there back to compressor 25 via liquid-gas separating tank 26.
More specifically, the cooling fluid from heat exchanger 3 flows along pipe 13 to inlet 27d of four-way valve 27, out through inlet 27c of the valve, and along pipe 29 to liquid-gas separating tank 26 communicating directly with the intake side of compressor 25.
It should be pointed out that, in this operating mode, outlet 3d of heat exchanger 3 communicates directly with intake side 5b of compressor unit 5, which is therefore able to draw in by suction not only the cooling fluid from pipe 8, but also all the cooling fluid in bypass circuit 31, i.e. in pipe 32 and storage tank 33. Given the orientation of non-return valve 34, emptying bypass circuit 31 obviously has no effect on normal cooling fluid flow from heat exchanger 2 along pipe 8.
To heat the heat-carrying liquid circulating in the hydraulic circuit of the air conditioning system, i.e. to switch from the summer to the winter configuration, the electronic central control unit (not shown) governing operation of cooler 1 closes on-off valve 12 and sets four-way valve 27 to the second operating position.
In which case, the cooling fluid from compressor 25 flows successively through pipe 14, heat exchanger 4, pipe 15, liquid-gas separating tank 18, and non-return valve 16 to inlet 27a of four-way valve 27 of distributor 6, where it flows out through inlet 27d of four-way valve 27 and along pipe 13 into heat exchanger 3 through outlet 3d.
After yielding heat to the heat-carrying liquid circulating in heat exchanger 3, the cooling fluid flows out through inlet 3c of heat exchanger 3; flows along an initial portion of pipe 8 and is side-tracked into bypass circuit 31 before reaching expansion valve 28 in pipe 8; flows along pipe 32 and successively through storage tank 33 and non-return valve 34; and eventually flows back to pipe 8 upstream from dehydration filter 10. Expansion valve 28, in fact, prevents the cooling fluid from flowing along pipe 8 directly to on-off valve 12.
On reaching pipe 8 once more, the cooling fluid flows through dehydration filter 10, and is then side-tracked along pipe 11, along which it flows through expansion valves 28 before reaching inlet 2c of heat exchanger 2. As in the previous cases, on flowing through expansion valves 28, the cooling fluid is subjected to rapid (e.g. isoenthalpic) expansion, thus bringing about a rapid fall in temperature.
Inside heat exchanger 2, the cooling fluid is heated by absorbing heat from the outside environment, and flows out of the exchanger through inlet 2d and along pipe 7 to inlet 27b of four-way valve 27.
Inside four-way valve 27, the cooling fluid is directed to inlet 27c of the valve, from which it flows along pipe 29 to liquid-gas separating tank 26 communicating directly with the intake side of compressor 25.
As regards liquid-gas separating unit 17, the liquid-gas separating tank 18 retains all the liquid cooling fluid issuing from heat exchanger 4, regardless of whether all or part of the cooling fluid flowing through heat exchanger 4 condenses and yields heat.
On detecting a liquid cooling fluid level in liquid-gas separating tank 18 over and above a predetermined threshold, level switch 22 inside liquid-gas separating tank 18 opens on-off valve 20 to allow the liquid cooling fluid to flow along pipe 19 to expansion valve 21.
At this point, the liquid cooling fluid is subjected to rapid (e.g. isoenthalpic) expansion, thus bringing about a rapid fall in pressure and temperature.
Because of the two non-return valves 23 and 24 along the two end portions of pipe 19, and the difference in pressure at the ends of the two end portions of pipe 19, the cooling fluid issuing from expansion valve 21 is forced towards inlet 2c/3c of the heat exchanger 2/3 currently operating as an evaporator, i.e. towards the inlet of the heat exchanger in which the cooling fluid is able to absorb heat to increase its own temperature and pass entirely to the gaseous state.
The advantages of cooler 1 are obvious: liquid-gas separating unit 17 immediately downstream from heat exchanger 4 provides for disassociating the quantity of cooling fluid in cooler 1 from operation with or without heat saving by means of heat exchanger 4, so that cooler 1 can be loaded with the amount of cooling fluid actually required for correct operation, as in the absence of heat exchanger 4.
That is, liquid-gas separating unit 17 provides for eliminating the auxiliary liquid cooling fluid storage tank and everything connected to it, thus greatly improving reliability of the cooler as a whole.
Clearly, changes may be made to cooler 1 as described and illustrated herein without, however, departing from the scope of the present invention.
In particular, as stated, heat-save cooler 1 may be a single- as opposed to a reversible-cycle type, and therefore have no distributor 6 or any other summer-to-winter switching components, i.e. four-way valve 27, bypass circuit 31, etc. In which case, pipe 15 is connected directly to pipe 7, and pipe 13 is connected directly to pipe 29.

Claims

A heat-save cooler (1) comprising a first heat exchanger (2) where a cooling fluid exchanges heat with the outside environment; a second heat exchanger (3) where said cooling fluid exchanges heat with a first liquid; a cooling fluid compressor unit (5) where said cooling fluid is compressed to increase its pressure; and a third heat exchanger (4) where said cooling fluid exchanges heat with a second liquid; said third heat exchanger (4) being located immediately downstream from said compressor unit (5); and the cooler (1) being characterized by also comprising a liquid-gas separating unit (17) located immediately downstream from said third heat exchanger (4) to retain the liquid cooling fluid issuing from said third heat exchanger (4).
A cooler as claimed in Claim 1, characterized by also comprising a cooling fluid distributor (6) for appropriately connecting said third heat exchanger (4) and said compressor unit (5) to said first (2) and said second (3) heat exchanger.
A cooler as claimed in Claim 1 or 2, characterized in that said liquid-gas separating unit (17) comprises a liquid-gas separating tank (18) located immediately downstream from said third heat exchanger (4) and for continually separating liquid cooling fluid from gaseous cooling fluid, and retaining inside it all the liquid cooling fluid issuing from said third heat exchanger (4).
A cooler as claimed in Claim 3, characterized in that said liquid-gas separating tank (18) has a drain outlet (18a) by which to draw off liquid cooling fluid accumulated in the tank.
A cooler as claimed in Claim 4, characterized in that said liquid-gas separating unit (17) also comprises a connecting pipe (19) for connecting said drain outlet (18a) of the liquid-gas separating tank (18) to both the inlet (2c) of said first heat exchanger (2) and the inlet (3c) of said second heat exchanger (3); a controlled on-off valve (20) located along the connecting pipe (19), downstream from said drain outlet (18a), to control liquid cooling fluid flow from said liquid-gas separating tank (18); and an expansion valve (21) for rapidly expanding the cooling fluid flowing along said connecting pipe (19).
A cooler as claimed in Claim 5, characterized in that said liquid-gas separating unit (17) also comprises a level switch (22) for opening the on-off valve (20) when the liquid level in said liquid-gas separating tank (18) exceeds a predetermined threshold value.
A cooler as claimed in Claim 5 or 6, characterized in that said liquid-gas separating unit (17) also comprises a first non-return valve (23) located along the end portion of the connecting pipe (19) communicating with the inlet (3c) of said second heat exchanger (3), so as to only permit cooling fluid flow to the inlet (3c) of the second heat exchanger (3); and a second non-return valve (24) located along the end portion of said connecting pipe (19) communicating with the inlet (2c) of said first heat exchanger (2), so as to only permit cooling fluid flow to the inlet (2c) of the first heat exchanger (2).
A cooler as claimed in any one of Claims 2 to 7, characterized in that said cooling fluid distributor (6) comprises a four-way valve (27) having four inlets (27a, 27b, 27c, 27d) selectively connectable directly in pairs.