Thermal conditioning system

Abstract

The invention relates to a refrigerant circuit (10) comprising: - a first main loop (A1) comprising, in succession, in the direction of circulation of the refrigerant: -- a first compressor (7), -- a first heat exchanger (1) thermally coupled with a first air flow (Fe1) external to a passenger compartment of a motor vehicle, -- a first expansion valve (31), -- a second heat exchanger (2), - a second main loop (A2) comprising, in succession, in the direction of circulation of the refrigerant: -- a second compressor (8), -- a third heat exchanger (3) thermally coupled with a second air flow (Fe2) external to the passenger compartment of the vehicle, -- a second expansion valve (32), -- a fourth heat exchanger (4) thermally coupled with an air flow (Fi) internal to the passenger compartment of the motor vehicle, - a fifth heat exchanger (5) arranged jointly on the first main loop (A1) and on the second main loop (A2).

Description

[0001] Description

[0002] Title: Thermal Conditioning System

[0003] technical field

[0004] [1] The present invention relates to the field of thermal conditioning systems. Such systems can, for example, be fitted to motor vehicles. These systems ensure thermal regulation of various vehicle components, such as the passenger compartment or an electrical energy storage battery, when the vehicle is electrically powered. Heat exchange is managed primarily by the compression and expansion of a refrigerant circulating in a circuit containing several heat exchangers. A compressor forces the refrigerant into a high-pressure state and allows its circulation within the circuit.

[0005] Previous technique

[0006] [2] Chemical refrigerants generally have a high global warming potential (GWP), which is a disadvantage. Carbon dioxide, which by definition has a global warming potential of one, can be used as a refrigerant. To optimize energy efficiency, it is useful to have multiple operating modes available to make the best use of the various available heat sources.

[0007] [3] The cooling capacity provided by the climate control system is distributed between the passenger compartment and other vehicle components, such as the batteries. In certain applications, such as rapid battery charging, the required cooling capacity may necessitate a refrigerant flow rate exceeding the maximum capacity of a single compressor. To provide sufficient cooling capacity, some climate control systems may therefore include two separate compressors arranged in parallel on the same refrigerant circuit. Depending on the operating mode and the required cooling capacity, both compressors may operate simultaneously, or only one of the two compressors may be activated.

[0008] [4] Controlling such a circuit can be tricky. In particular, it can be difficult to ensure that the oil contained in the refrigerant returns satisfactorily to each of the compressors.

[0009] [5] There is therefore a need for an improved thermal conditioning system that can provide increased cooling power while being simple to control.

[0010] Summary

[0011] [6] To this end, a thermal conditioning system for motor vehicles is proposed, comprising a refrigerant circuit configured to circulate a refrigerant, the refrigerant circuit comprising: a first main loop comprising successively, according to the direction of refrigerant flow:

[0012] -- a first compressor comprising a refrigerant inlet and a refrigerant outlet,

[0013] -- a first heat exchanger thermally coupled with a first flow of outside air to the passenger compartment of a motor vehicle,

[0014] -- a first regulator,

[0015] -- a second heat exchanger, a second main loop comprising successively, according to the direction of refrigerant flow:

[0016] -- a second compressor,

[0017] -- a third heat exchanger thermally coupled with a second flow of outside air into the vehicle's passenger compartment,

[0018] -- a second regulator,

[0019] -- a fourth heat exchanger thermally coupled with an airflow from inside the passenger compartment of the motor vehicle, a fifth heat exchanger jointly arranged on the first main loop and on the second main loop and configured to allow heat exchange between: -- the refrigerant circulating in the first main loop between the first expansion valve and the inlet of the first compressor, and

[0020] -- the refrigerant circulating in the second main loop between the third heat exchanger and the second expansion valve.

[0021] [7] The two refrigerant loops can operate jointly in a coupled manner and provide a particularly high maximum cooling capacity, for example, greater than 25 kW. In addition, the cooling capacity supplied can be easily controlled.

[0022] [8] The features listed in the following paragraphs can be implemented independently of each other or in any technically possible combination:

[0023] [9] The second main loop is decoupled from the first main loop.

[0024]

[0010] The second main loop and the first main loop are thermally coupled via the fifth exchanger.

[0025]

[0011] The first exchanger is configured to operate as a refrigerant fluid condenser, or as a gas cooler in the case of a supercritical fluid such as R744.

[0026]

[0012] According to one embodiment, the first heat exchanger is configured to exchange heat with the first outside airflow to the vehicle's passenger compartment.

[0027]

[0013] According to one embodiment, the first heat exchanger is configured to exchange heat with a heat transfer fluid circulating in a closed heat transfer fluid circuit, the heat transfer fluid circuit comprising a heat exchanger configured to exchange heat with the first outside airflow to the vehicle's passenger compartment.

[0028]

[0014] The second exchanger is configured to operate as a refrigerant fluid evaporator.

[0029]

[0015] The third heat exchanger is configured to operate as a refrigerant condenser, or as a gas cooler in the case of a supercritical fluid such as R744.

[0016] The fourth heat exchanger is configured to operate as a refrigerant evaporator.

[0030]

[0017] The fourth heat exchanger can cool the airflow inside the passenger compartment, so as to cool the passenger compartment and ensure the thermal comfort of the passengers.

[0031]

[0018] According to one embodiment, the fourth heat exchanger is configured to exchange heat with the airflow inside the vehicle's passenger compartment.

[0032]

[0019] According to one embodiment, the fourth heat exchanger is configured to exchange heat with a heat transfer fluid circulating in a closed heat transfer fluid circuit, the heat transfer fluid circuit comprising a heat exchanger configured to exchange heat with the airflow inside the vehicle's passenger compartment.

[0033]

[0020] The first main loop includes a first refrigerant fluid accumulator located downstream of the second exchanger and upstream of the inlet of the first compressor.

[0034]

[0021] The second compressor includes a refrigerant inlet and a refrigerant outlet.

[0035]

[0022] The second main loop includes a second refrigerant accumulator located downstream of the fourth exchanger and upstream of an inlet of the second compressor.

[0036]

[0023] According to one embodiment of the thermal conditioning system, the second heat exchanger is thermally coupled with a first element of an electric traction chain of a motor vehicle.

[0037]

[0024] The second heat exchanger allows the first element of the vehicle's electric powertrain to be cooled, or the heat losses of this powertrain element to be recovered.

[0038]

[0025] According to one embodiment, the first element of the vehicle's electric powertrain comprises an electrical energy storage battery.

[0026] Alternatively or complementaryly, the first element of the vehicle's electric powertrain comprises an electric traction motor.

[0039]

[0027] Alternatively or in addition, the first element of the vehicle's electric traction chain includes an electronic control unit for the vehicle's electric traction motor.

[0040]

[0028] According to one embodiment, the third heat exchanger is thermally coupled with the element of the electric traction chain via a heat transfer fluid circulating in a heat transfer fluid circuit.

[0041]

[0029] According to one embodiment of the thermal conditioning system, the fifth heat exchanger is arranged on the first main loop downstream of the first expansion valve and upstream of the second exchanger.

[0042]

[0030] In this case, the fifth heat exchanger is configured to allow heat exchange between:

[0043] - the refrigerant circulating in the first main loop downstream of the first expansion valve and upstream of the second heat exchanger, and

[0044] - the refrigerant circulating in the second main loop downstream of the third heat exchanger and upstream of the second expansion valve.

[0045]

[0031] According to this embodiment, the first main loop may include a fourth expansion valve disposed downstream of the fifth heat exchanger and upstream of the second heat exchanger.

[0046]

[0032] The fourth expansion valve allows the efficiency of the heat exchange in the fifth exchanger to be adjusted.

[0047]

[0033] According to another embodiment of the thermal conditioning system, the fifth heat exchanger is disposed on the first main loop downstream of the second exchanger and upstream of the first accumulator.

[0048]

[0034] In this case, the fifth heat exchanger is configured to allow heat exchange between:

[0049] - the refrigerant circulating in the first main loop downstream of the second exchanger and upstream of the first accumulator, and - the refrigerant circulating in the second main loop downstream of the third heat exchanger and upstream of the second expansion valve.

[0050]

[0035] In this case, the first main loop is devoid of a fourth regulator.

[0051]

[0036] The fifth heat exchanger comprises a first heat exchange section disposed on the first main loop and a second heat exchange section disposed on the second main loop.

[0052]

[0037] The fifth heat exchanger is configured to allow heat exchange between the refrigerant in the first heat exchange section and the refrigerant in the second heat exchange section.

[0053]

[0038] According to one embodiment, the first heat exchange section is arranged on the first main loop downstream of the first regulator and upstream of the fourth regulator.

[0054]

[0039] According to another embodiment, the first heat exchange section is arranged on the first main loop downstream of the second exchanger and upstream of the first accumulator.

[0055]

[0040] According to one embodiment, the thermal conditioning system includes a branch connecting a first connection point located on the second main loop downstream of the fifth exchanger and upstream of the second expansion valve to a second connection point located on the second main loop downstream of the fourth heat exchanger and upstream of the inlet of the second compressor, the branch successively comprising a third expansion valve and a sixth heat exchanger.

[0056]

[0041] The sixth exchanger is configured to operate as a refrigerant fluid evaporator.

[0057]

[0042] According to one embodiment of the thermal conditioning system, the sixth heat exchanger is thermally coupled with a second element of an electric powertrain of a motor vehicle.

[0043] The sixth heat exchanger allows the second element of the vehicle's electric powertrain to be cooled, or the heat losses of this powertrain element to be recovered.

[0058]

[0044] According to one embodiment, the second element of the vehicle's electric drive chain comprises an electrical energy storage battery.

[0059]

[0045] Alternatively or in addition, the second element of the vehicle's electric drive chain comprises an electric vehicle traction motor.

[0060]

[0046] Alternatively or in a complementary manner, the second element of the vehicle's electric traction chain comprises an electronic control unit for the vehicle's electric traction motor.

[0061]

[0047] According to one embodiment, the third heat exchanger is thermally coupled with the second element of the electric traction chain via a heat transfer fluid circulating in a heat transfer fluid circuit.

[0062]

[0048] According to one embodiment of the thermal conditioning system, the first main loop of the refrigerant circuit includes a first internal heat exchanger configured to allow heat exchange between:

[0063] - the refrigerant circulating downstream of the first heat exchanger and upstream of the first expansion valve, and

[0064] - the refrigerant fluid circulating downstream of the first accumulation device and upstream of the inlet of the first compressor.

[0065]

[0049] The first internal exchanger makes it possible to increase the enthalpy variation of the refrigerant during the thermodynamic cycle of the first main loop, and therefore to increase the thermal power that the thermal conditioning system can provide.

[0066]

[0050] The first internal heat exchanger includes a first heat exchange section located on the first main loop between the first heat exchanger and the first expansion valve.

[0051] The first internal heat exchanger includes a second heat exchange section located on the first main loop downstream of the first accumulator and upstream of the inlet of the first compressor.

[0067]

[0052] The first internal exchanger is configured to allow heat exchange between the refrigerant in the first heat exchange section and the refrigerant in the second heat exchange section.

[0068]

[0053] According to one embodiment of the thermal conditioning system, the second main loop of the refrigerant circuit includes a second internal heat exchanger configured to allow heat exchange between:

[0069] - the refrigerant circulating downstream of the fifth heat exchanger and upstream of the second expansion valve, and

[0070] - the refrigerant fluid circulating downstream of the second accumulation device and upstream of an inlet of the second compressor.

[0071]

[0054] The second internal exchanger makes it possible to increase the enthalpy variation of the refrigerant during the thermodynamic cycle of the second main loop, and therefore to increase the thermal power that the thermal conditioning system can provide.

[0072]

[0055] The second internal exchanger includes a first heat exchange section arranged on the second main loop downstream of the fifth exchanger and upstream of the second expansion valve.

[0073]

[0056] The second internal exchanger includes a second heat exchange section arranged on the second main loop downstream of the second accumulator and upstream of the inlet of the second compressor.

[0074]

[0057] The second internal exchanger is configured to allow heat exchange between the refrigerant in the first heat exchange section and the refrigerant in the second heat exchange section.

[0075]

[0058] When the bypass branch is present, the first heat exchange section is located on the second main loop between the fifth heat exchanger and the first connection point.

[0059] According to one embodiment of the thermal conditioning system, the second main loop of the refrigerant circuit includes a seventh heat exchanger thermally coupled with the second outside air flow, the seventh heat exchanger being located upstream of the fifth heat exchanger.

[0076]

[0060] According to one embodiment, the seventh heat exchanger is arranged upstream of the third exchanger.

[0077]

[0061] According to one embodiment, the seventh heat exchanger is located downstream of the third exchanger and upstream of the fifth exchanger.

[0078]

[0062] The seventh heat exchanger is configured to exchange heat with a heat transfer fluid circulating in a closed heat transfer fluid circuit, the heat transfer fluid circuit comprising a heat exchanger configured to exchange heat with the second outside airflow to the vehicle's passenger compartment.

[0079]

[0063] The invention also relates to a method of operating a thermal conditioning system as described above, in a so-called passenger compartment cooling mode in which:

[0080] - a first flow of refrigerant circulates in the first compressor where it reaches a first high pressure, and circulates in the first main loop, successively in the first heat exchanger where it releases heat, in the first expansion valve where it undergoes expansion and reaches a first low pressure lower than the first high pressure, in the fifth heat exchanger where it receives heat, in the second heat exchanger without exchanging heat, and returns to the first compressor,

[0081] - a second flow in the second compressor where it passes to a second high pressure, and circulates in the second main loop, successively in the third exchanger where it gives off heat, in the fifth exchanger where it gives off heat, in the second expansion valve where it undergoes expansion and passes to a second low pressure lower than the second high pressure, in the fourth exchanger where it receives heat, and returns to the second compressor.

[0082]

[0064] In this operating mode:

[0083] - The refrigerant flows through the fourth expansion valve without undergoing any expansion. - The refrigerant flow rate in the bypass branch is zero.

[0084] - The flow rate of heat transfer fluid in the circuit is zero.

[0085] - The first high pressure is greater than the second high pressure.

[0086] - The first low pressure is higher than the second low pressure.

[0087]

[0065] The first exchanger dissipates the heat from the high-pressure, high-temperature refrigerant fluid from the first compressor into the first outside air stream.

[0088] The third heat exchanger dissipates the heat from the high-pressure, high-temperature refrigerant from the second compressor into the second stream of outside air. This cools the refrigerant from the second compressor.

[0089] At the first heat exchange section of the fifth heat exchanger, the low-pressure refrigerant from the first expansion valve evaporates, with the heat of vaporization supplied by the high-pressure refrigerant from the third heat exchanger. The high-pressure refrigerant from the third heat exchanger is thus cooled.

[0090] The fourth heat exchanger evaporates the refrigerant from the second heat exchange section of the fifth heat exchanger, with the heat of vaporization supplied by the interior airflow. This cools the interior airflow, thus cooling the passenger compartment.

[0091] The sixth exchanger is not traversed by refrigerant fluid and is thermally inactive, that is to say there is no heat exchange between the refrigerant fluid and the heat transfer fluid of the circuit.

[0092] The second exchanger is thermally inactive, as there is no circulation of heat transfer fluid in the circuit.

[0093] The first internal exchanger and the second internal exchanger are both active.

[0094]

[0066] In this operating mode, the indoor airflow is cooled at the fourth heat exchanger. The heat extracted from the indoor airflow is partly dissipated in the second outdoor airflow at the third heat exchanger, and partly transferred to the refrigerant of the first main loop at the fifth heat exchanger. The heat received by the refrigerant of the first main loop at the fifth heat exchanger is dissipated in the first outdoor airflow at the first heat exchanger.

[0095] The first main loop cools the refrigerant in the second main loop, without cooling the first element of the traction chain.

[0096]

[0067] The invention also relates to a method of operating a thermal conditioning system as described above, in a so-called first mode of passenger compartment cooling and battery cooling in which:

[0097] - a first flow of refrigerant circulates in the first compressor where it reaches a first high pressure, and circulates in the first main loop, successively in the first heat exchanger where it releases heat, in the first expansion valve where it undergoes expansion and reaches a first low pressure lower than the first high pressure, in the fifth heat exchanger where it receives heat, in the second heat exchanger where it receives heat, and returns to the first compressor,

[0098] - a second flow in the second compressor where it passes to a second high pressure, and circulates in the second main loop, successively in the third exchanger where it releases heat, in the fifth exchanger where it releases heat, and divides into:

[0099] -- a third flow circulating in the second main loop, successively in the second expansion valve where it undergoes expansion and passes to a second low pressure lower than the second high pressure, in the fourth exchanger where it receives heat, and

[0100] -- a fourth flow circulating in the bypass branch, successively in the third expansion valve where it undergoes expansion and passes to the second low pressure, in the sixth exchanger where it receives heat, and joins the refrigerant from the fourth exchanger, the total flow formed returns to the second compressor.

[0101]

[0068] In this operating mode:

[0102] - The heat transfer fluid circulates in the circuit of the second heat exchanger.

[0103] - The heat transfer fluid circulates in the circuit of the sixth heat exchanger. - The first high pressure is greater than the second high pressure.

[0104] - The first low pressure is higher than the second low pressure.

[0105]

[0069] This mode of operation differs from the previous one in that the refrigerant fluid discharged by the second compressor circulates in parallel in the sixth exchanger and in the fourth exchanger, and in that the second exchanger is thermally active.

[0106] The first element is cooled at the second exchanger, and the second element is cooled at the sixth exchanger.

[0107] The indoor airflow is cooled at the fourth exchanger.

[0108]

[0070] In this mode of operation, the heat taken from the indoor airflow and that taken from the second element are partly dissipated in the second outdoor airflow at the level of the third exchanger, and is partly transferred to the refrigerant of the first main loop at the level of the fifth exchanger.

[0109] The heat received by the refrigerant from the first main loop at the fifth exchanger and the heat received from the first element at the second exchanger are dissipated in the first outside airflow at the first exchanger.

[0110]

[0071] The invention also relates to a method of operating a thermal conditioning system as described above, in a so-called second mode of passenger compartment cooling and battery cooling in which:

[0111] - the refrigerant flow rate in the first main loop is zero,

[0112] - a flow of refrigerant circulates in the second compressor where it is subjected to high pressure, and circulates in the second main loop, successively in the third heat exchanger where it releases heat, in the fifth heat exchanger, and divides into:

[0113] -- a second flow circulating in the second main loop, successively in the second expansion valve where it undergoes expansion and passes to a low pressure lower than the high pressure, in the fourth exchanger where it receives heat, and

[0114] -- a third flow circulating in the bypass branch, successively in the third expansion valve where it undergoes expansion and passes to low pressure, in the sixth exchanger where it receives heat, and joins the refrigerant fluid from the fourth exchanger, the total flow formed returns to the second compressor.

[0115]

[0072] In this operating mode:

[0116] - The first compressor is inactive.

[0117] - The second compressor is active.

[0118] - The heat transfer fluid circulates in the circuit of the sixth heat exchanger.

[0119]

[0073] The second element is cooled at the level of the sixth exchanger.

[0120] The indoor airflow is cooled at the fourth exchanger.

[0121] The heat taken from the indoor airflow and the second element is dissipated in the second outdoor airflow at the third exchanger.

[0122] The fifth exchanger is inactive. Similarly, the first exchanger is inactive. The same is true for the second exchanger.

[0123]

[0074] The invention also relates to a method of operating a thermal conditioning system as described above, in a so-called accelerated passenger compartment cooling mode in which:

[0124] - a first flow of refrigerant circulates in the first compressor where it reaches a first high pressure, and circulates in the first main loop, successively in the first heat exchanger where it releases heat, in the first expansion valve where it undergoes expansion and reaches a first low pressure lower than the first high pressure, in the fifth heat exchanger where it receives heat, in the second heat exchanger without exchanging heat, and returns to the first compressor,

[0125] - a second flow in the second compressor where it passes to a second high pressure, and circulates in the second main loop, successively in the third exchanger where it gives off heat, in the fifth exchanger where it gives off heat, in the second expansion valve where it undergoes expansion and passes to a second low pressure lower than the second high pressure, in the fourth exchanger where it receives heat, and returns to the second compressor.

[0126]

[0075] This mode of operation differs from the first mode of operation by an increase in the first flow rate of refrigerant discharged by the first compressor, by an increase in the second flow rate of refrigerant discharged by the second compressor and by an increase in the expansion ratio ensured by the first expansion valve.

[0127] In other words, the rotational speed of the first compressor and the rotational speed of the second compressor are increased. The expansion ratio achieved by the first expansion valve is increased; that is, in this operating mode, the first low pressure is lower than the value of the first low pressure in the first operating mode.

[0128]

[0076] In this operating mode:

[0129] - The refrigerant flows through the fourth expansion valve without undergoing any expansion.

[0130] - The flow rate of refrigerant in the bypass branch is zero.

[0131] - The flow rate of heat transfer fluid in the circuit is zero.

[0132] - The first high pressure is greater than the second high pressure.

[0133] - The first low pressure is higher than the second low pressure.

[0134]

[0077] The first exchanger dissipates the heat from the high-pressure, high-temperature refrigerant fluid from the first compressor into the first outside air stream.

[0135] The third heat exchanger dissipates the heat from the high-pressure, high-temperature refrigerant from the second compressor into the second stream of outside air. This cools the refrigerant from the second compressor.

[0136] At the first heat exchange section of the fifth heat exchanger, the low-pressure refrigerant from the first expansion valve evaporates, with the heat of vaporization supplied by the high-pressure refrigerant from the third heat exchanger. This cools the high-pressure refrigerant in the second main loop.

[0137] The fourth heat exchanger evaporates the refrigerant from the second heat exchange section of the fifth heat exchanger, with the heat of vaporization supplied by the interior airflow. This cools the interior airflow, thus cooling the passenger compartment.

[0138] The sixth exchanger is not traversed by refrigerant fluid and is thermally inactive, that is to say there is no heat exchange between the refrigerant fluid and the heat transfer fluid of the circuit.

[0139] The second exchanger is thermally inactive, as there is no circulation of heat transfer fluid in the circuit.

[0140] The first internal exchanger and the second internal exchanger are both active.

[0141]

[0078] In this operating mode, the indoor airflow is cooled at the fourth heat exchanger. The heat extracted from the indoor airflow is partly dissipated in the second outdoor airflow at the third heat exchanger, and partly transferred to the refrigerant of the first main loop at the fifth heat exchanger.

[0142] The heat received by the refrigerant from the first main loop at the fifth exchanger is dissipated in the first outside airflow at the first exchanger.

[0143] This operating mode allows for rapid cooling of the passenger compartment, with all the cooling power being used to cool the interior airflow at the level of the fourth exchanger.

[0144] Brief description of the drawings

[0145]

[0079] Other features, details and advantages will become apparent upon reading the detailed description below, and upon analysis of the accompanying drawings, on which:

[0146]

[0080] [Fig. 1] is a schematic view of a thermal conditioning system according to a first embodiment of the invention,

[0147]

[0081] [Fig. 2] is a schematic view of a thermal conditioning system according to a second embodiment of the invention,

[0148]

[0082] [Fig. 3] is a schematic view of a thermal conditioning system according to a first variant of the second embodiment,

[0149]

[0083] [Fig. 4] is a schematic view of a thermal conditioning system according to a second variant of the second embodiment,

[0150]

[0084] [Fig. 5] is a schematic view of a thermal conditioning system according to a third embodiment of the invention,

[0085] [Fig. 6] is a schematic view of the thermal conditioning system of Figure 2, operating according to a first mode of operation, called passenger compartment cooling mode,

[0151]

[0086] [Fig. 7] is a schematic view of the thermal conditioning system of Figure 2, operating according to a second mode of operation, called the first mode of passenger compartment cooling and battery cooling,

[0152]

[0087] [Fig. 8] is a schematic view of the thermal conditioning system of Figure 2, operating according to a third mode of operation, called the second mode of passenger compartment cooling and battery cooling,

[0153]

[0088] [Fig. 9] is a schematic view of the thermal conditioning system of Figure 2, operating according to a fourth operating mode, called accelerated passenger compartment cooling mode,

[0154]

[0089] [Fig. 10] is a diagram illustrating the operation of the proposed thermal conditioning system.

[0155] Description of the implementation methods

[0156]

[0090] To facilitate reading the figures, the various elements are not necessarily drawn to scale. In these figures, identical elements bear the same reference numerals. Certain elements or parameters may be indexed, that is, designated, for example, as first element or second element, or first parameter and second parameter, etc. This indexing aims to differentiate similar, but not identical, elements or parameters. This indexing does not imply a priority of one element or parameter over another, and the designations may be interchanged.

[0157]

[0091] In the following description, the expression "a first element upstream of a second element" means that the first element is placed before the second element with respect to the direction of flow, or path, of a fluid. Similarly, the term "a first element downstream of a second element" means that the first element is placed after the second element with respect to the direction of flow, or path, of the fluid in question. In the case of the refrigerant circuit, the term "a first element is upstream of a second element" means that the refrigerant flows successively through the first element, then the second element, without passing through the compression device. In other words, the refrigerant exits the compression device, possibly passes through one or more elements, then passes through the first element, then the second element, and then returns to the compression device, possibly after passing through other elements.

[0158]

[0092] The expression "a second element is placed between a first element and a third element" means that the shortest path to go from the first element to the third element or from the third element to the first element passes through the second element.

[0159]

[0093] When it is specified that a subsystem includes a given element, this does not exclude the presence of other elements in that subsystem.

[0160]

[0094] The thermal conditioning system 100, which will be described below, comprises an electronic control unit 60 that receives information from various sensors measuring, in particular, the characteristics of the refrigerant at various points in the circuit. The electronic control unit 60 also receives instructions from the vehicle occupants, such as the desired temperature inside the passenger compartment. The electronic control unit 60 can also receive instructions from other electronic subsystems, such as the electrical energy storage battery management system. The electronic control unit 60 implements control laws to operate the various actuators, in order to control the thermal conditioning system 100 and ensure compliance with the received instructions.

[0161]

[0095] A first compression device 7 allows a refrigerant to circulate in a first main loop A1 of a refrigerant circulation circuit 10. A second compression device 8 allows a refrigerant to circulate in a second main loop A2 of the refrigerant circulation circuit 10. Each compression device 7, 8 can be an electric compressor, that is, a compressor whose moving parts are driven by an electric motor. The compression devices 7, 8 each have a low-pressure refrigerant intake side, also referred to respectively as the inlet 7a, 8a of the compression device, and a high-pressure refrigerant discharge side, also referred to respectively as the outlet 7b, 8b. The internal moving parts of the compressor 7 cause the refrigerant to pass from a first low pressure at the inlet 7a to a first high pressure at the outlet 7b.After expansion in one or more expansion devices and circulation in the first main loop A1 of circuit 10, the refrigerant returns to the inlet 7a of compressor 7 and begins a new thermodynamic cycle.

[0162] Similarly, the internal moving parts of the compressor 8 cause the refrigerant to pass from a low pressure on the inlet side 8a to a high pressure on the outlet side 8b. After expansion in one or more expansion chambers and circulation in at least one part of the second main loop A2 of the circuit 10, the refrigerant returns to the inlet 8a of the compressor 8 and begins a new thermodynamic cycle.

[0163]

[0096] The first main loop A1 of the refrigerant fluid circuit 10 forms the first closed circuit in which a first refrigerant fluid can circulate.

[0164] The second main loop A2 of the refrigerant fluid circuit 10 forms a second closed circuit in which a second refrigerant fluid can circulate.

[0165] The refrigerant circuit 10 is leak-proof when it is in its nominal operating condition, i.e., without any faults or leaks. Each connection point of the circuit 10 allows the refrigerant to flow into one of the circuit sections that converge at that connection point. The distribution of the refrigerant between the circuit sections converging at a connection point is achieved by opening or closing the shut-off valves, check valves, or expansion devices located on each of these sections. In other words, each connection point is a means of redirecting the refrigerant arriving at that connection point. Various shut-off valves and check valves thus allow the refrigerant to be selectively directed into the different branches of the refrigerant circuit, in order to ensure different operating modes, as will be described later.

[0166]

[0097] The refrigerant used by the refrigerant circuit 10 is a natural refrigerant, such as R744. R290 can also be used. It is also possible to use a chemical refrigerant, such as R1234yf or R134a.

[0167]

[0098] Each refrigerant expansion device, also called an expansion valve, can be an electronic expansion valve. In an electronic expansion valve, the passage area through which the refrigerant passes can be continuously adjusted between a closed position and a maximum open position. To achieve this, an electronic control module for the expansion valve drives an electric motor that moves a movable shutter, thus controlling the passage area available to the refrigerant.

[0168]

[0099] Interior airflow refers to the flow of air directed towards the passenger compartment of a motor vehicle. Interior airflow may circulate within a heating, ventilation, and / or air conditioning (HVAC) system. A vehicle may be equipped with several HVAC systems. For example, one system may manage the front area of ​​the passenger compartment, and a second system may manage the rear area.

[0169] These installations have not been shown in the various figures. One or more motor-fan units, not shown, are installed in each heating, ventilation and / or air conditioning system in order to increase, if necessary, the flow rate of the indoor air supplied by that system.

[0170]

[0100] The term "external airflow Fe" refers to an airflow that is not directed towards the vehicle's passenger compartment. In other words, this airflow Fe remains outside the vehicle's passenger compartment. Another motor-fan assembly, also not shown, can be activated to increase the flow rate of the external airflow Fe if necessary.

[0171]

[0101] The airflow provided by each of the motor-fan groups can be adjusted in real time according to the heat exchange requirements, for example by the electronic control unit of the thermal conditioning system 100.

[0172]

[0102] The term "first exchanger" is equivalent to the term "first heat exchanger". Similarly, the term "internal exchanger" is equivalent to the term "internal heat exchanger". The term "storage device" is equivalent to the term "refrigerant storage device".

[0173]

[0103] The heat transfer fluid circuit(s) also form one or more closed and sealed circuits in which a heat transfer fluid can circulate.

[0104] Figure 1 shows a first embodiment of a thermal conditioning system 100 for a motor vehicle.

[0174] The thermal conditioning system 100 includes a refrigerant fluid circuit 10 configured to circulate a refrigerant fluid.

[0175] The refrigerant circuit 10 comprises a first main loop A1 consisting successively, according to the direction of refrigerant flow:

[0176] - a first compressor 7 comprising a refrigerant inlet 7a and a refrigerant outlet 7b,

[0177] - a first heat exchanger 1 thermally coupled with a first external airflow Fe1 to the passenger compartment of a motor vehicle,

[0178] - a first regulator 31,

[0179] - a second heat exchanger 2.

[0180] The refrigerant circuit 10 comprises a second main loop A2 consisting successively, according to the direction of refrigerant flow:

[0181] - a second compressor 8,

[0182] - a third heat exchanger 3 thermally coupled with a second external airflow Fe2 to the vehicle's passenger compartment,

[0183] - a second regulator 32,

[0184] - a fourth heat exchanger 4 thermally coupled with an internal airflow Fi to the passenger compartment of the motor vehicle.

[0185] The refrigerant circuit 10 includes a fifth heat exchanger 5 arranged jointly on the first main loop A1 and on the second main loop A2 and configured to allow heat exchange between:

[0186] - the refrigerant circulating in the first main loop A1 between the first expansion valve 31 and the inlet 7a of the first compressor 7, and

[0187] - the refrigerant circulating in the second main loop A2 between the third heat exchanger 3 and the second expansion valve 32.

[0188]

[0105] The two refrigerant loops can operate jointly in a coupled manner and provide a particularly high maximum cooling capacity, for example, greater than 25 kW. Furthermore, the cooling capacity supplied can be easily controlled.

[0106] The second main loop A2 is separate from the first main loop A1.

[0189] In other words, the refrigerant circulating in the second main loop A2 does not circulate in the first main loop A1.

[0190] The chemical nature of the refrigerant contained in the second main loop A2 may be different from that of the refrigerant contained in the first main loop A1.

[0191]

[0107] The pressure level in the second main loop A2 is independent of the pressure level in the first main loop A1.

[0192] The first compressor 7 and the second compressor 8 can be activated simultaneously, i.e. refrigerant fluid circulates in the two main loops A1, A2 simultaneously.

[0193] The first compressor 7 can also be activated while the second compressor 8 is deactivated. In this case, refrigerant circulates only in the first main loop A1.

[0194] Conversely, the second compressor 8 can be activated while the first compressor 7 is deactivated. In this case, refrigerant circulates only in the second main loop A2.

[0195]

[0108] The second main loop A2 and the first main loop A1 are thermally coupled via the fifth exchanger 5.

[0196]

[0109] The first exchanger 1 is configured to operate as a refrigerant fluid condenser, or as a gas cooler in the case of a supercritical fluid such as R744.

[0197] Indeed, the first exchanger 1 can receive high-pressure, high-temperature refrigerant fluid from the first compressor 7. This refrigerant fluid is thus in a gaseous state at high pressure and high temperature.

[0198]

[0110] The thermal coupling between the first exchanger 1 and the first outside air flow Fe1 can be achieved in different ways.

[0199]

[0111] According to the embodiments illustrated in particular in Figures 1 to 3 and in Figure 5, the first heat exchanger 1 is configured to exchange heat with the first outside airflow Fe1 to the vehicle's passenger compartment. The thermal coupling between the first heat exchanger 1 and the first outside airflow Fe1 is then of the so-called direct type.

[0200]

[0112] The first exchanger 1 can be installed in a first wheel arch of the vehicle, for example a front wheel arch.

[0201] According to one variant, the first interchange 1 can be installed in the front of the vehicle, just behind the grille.

[0202]

[0113] According to a variant illustrated in Figure 4, the first heat exchanger 1 is configured to exchange heat with a heat transfer fluid circulating in a closed heat transfer fluid circuit 50. The heat transfer fluid circuit 50 includes a heat exchanger 1A configured to exchange heat with the first outside airflow Fe1 to the vehicle's passenger compartment.

[0203] The thermal coupling between the first heat exchanger 1 and the first outside air flow Fe1 is then of the so-called indirect type, since it is achieved via a heat transfer fluid.

[0204]

[0114] The heat transfer fluid can be, for example, a mixture of water and glycol. Circuit 50 includes a circulation pump, not shown, for circulating the heat transfer fluid in circuit 50. The pump is, for example, an electric pump. The pump can be selectively activated to circulate the heat transfer fluid, or deactivated to interrupt the circulation of the heat transfer fluid.

[0205]

[0115] The second exchanger 2 is configured to operate as a refrigerant fluid evaporator.

[0206] Indeed, the second exchanger 2 can receive two-phase refrigerant fluid in a predominantly liquid state, and in a low-pressure state.

[0207]

[0116] The third exchanger 3 is configured to operate as a refrigerant fluid condenser, or as a gas cooler in the case of a supercritical fluid such as R744.

[0208] Indeed, the third exchanger 3 can receive gaseous refrigerant fluid, at high pressure and high temperature, from the second compressor 8.

[0209]

[0117] The third heat exchanger 3 can be located in a second wheel arch of the vehicle.

[0118] Alternatively, the first heat exchanger 1 and the third heat exchanger 3 can both be located at the front of the vehicle, for example behind the vehicle's grille.

[0210] In this case, the first outside airflow Fe1 is the same as the second outside airflow Fe2.

[0211] The first interchange 1 and the third interchange 3 can, for example, be arranged side by side, parallel to the vehicle's transverse axis. The first interchange 1 and the third interchange 3 can also be arranged one above the other, that is, offset along a vertical axis.

[0212] Alternatively, the first exchanger 1 can be arranged upstream of the third exchanger 3 according to the direction of flow of the outside air flow Fe.

[0213]

[0119] The fourth heat exchanger 4 is configured to operate as a refrigerant fluid evaporator.

[0214]

[0120] Indeed, the fourth exchanger 4 can receive two-phase refrigerant fluid in a predominantly liquid state and in a low-pressure state, after expansion in the second expansion valve 32.

[0215]

[0121] The fourth heat exchanger 4 can cool the interior airflow Fi to the passenger compartment, so as to cool the passenger compartment and ensure the thermal comfort of the passengers.

[0216]

[0122] As with the first exchanger 1, the thermal coupling between the fourth exchanger 4 and the internal airflow Fi can be achieved in different ways.

[0217]

[0123] According to the embodiments illustrated in particular in Figures 1 to 3 and in Figure 5, the fourth heat exchanger 4 is configured to exchange heat with the internal airflow Fi to the passenger compartment of the vehicle.

[0218] The thermal coupling between the fourth heat exchanger 4 and the internal airflow Fi is then said to be direct.

[0219]

[0124] According to an alternative embodiment, illustrated in Figure 4, the fourth heat exchanger 4 is configured to exchange heat with a heat transfer fluid circulating in a closed heat transfer fluid circuit 40. The heat transfer fluid circuit 40 includes a heat exchanger 4A configured to exchange heat with the interior airflow Fi to the vehicle's passenger compartment.

[0220]

[0125] The thermal coupling between the fourth heat exchanger 4 and the internal airflow Fi is then said to be indirect, since it is achieved through a heat transfer fluid.

[0221] The heat transfer fluid can be, for example, a mixture of water and glycol.

[0222]

[0126] Circuit 40 includes a circulation pump, not shown, for circulating the heat transfer fluid. The circulation pump may be an electric pump.

[0223]

[0127] In the case of direct thermal coupling, the fourth heat exchanger 4, called the passenger compartment evaporator, is located in the vehicle's heating, ventilation and / or air conditioning system.

[0224] In the case of indirect thermal coupling, the 4A exchanger, known as the passenger compartment cooling radiator, is located in the heating, ventilation and / or air conditioning system.

[0225]

[0128] The fifth heat exchanger 5 comprises a first heat exchange section 5a arranged on the first main loop A1 and a second heat exchange section 5b arranged on the second main loop A2.

[0226]

[0129] The fifth heat exchanger 5 is configured to allow heat exchange between the refrigerant in the first heat exchange section 5a and the refrigerant in the second heat exchange section 5b.

[0227] The first heat exchange section 5a and the second heat exchange section 5b can exchange heat but cannot exchange matter. The refrigerant circulating in the first heat exchange section 5a and the refrigerant circulating in the second heat exchange section 5b cannot mix and remain separate.

[0228] The fifth heat exchanger 5 is, for example, a plate heat exchanger.

[0130] According to the illustrated example, the first main loop A1 includes a first refrigerant accumulator 11 located downstream of the second heat exchanger 2 and upstream of the inlet 7a of the first compressor 7.

[0229]

[0131] The second compressor 8 includes a refrigerant inlet 8a and a refrigerant outlet 8b. The second main loop A2 includes a second refrigerant accumulator 12 located downstream of the fourth heat exchanger 4 and upstream of an inlet 8a of the second compressor 8.

[0230]

[0132] The first accumulator 11 makes it possible to compensate for variations in the quantity of refrigerant circulating in the first main loop A1, depending on the operating conditions.

[0231] Similarly, the second accumulator 12 makes it possible to compensate for variations in the quantity of refrigerant circulating in the second main loop A2.

[0232]

[0133] According to an unrepresented variant, the first main loop A1 may include an accumulation device disposed downstream of the first exchanger 1 and upstream of the first expansion valve 31.

[0233]

[0134] According to the illustrated example, the second heat exchanger 2 is thermally coupled with a first element 25 of an electric drive chain of a motor vehicle.

[0234]

[0135] The second heat exchanger 2 allows the first element 25 of the vehicle's electric powertrain to be cooled, or the heat losses generated by the operation of this element 25 of the powertrain to be recovered.

[0235]

[0136] According to one embodiment, the first element 25 of the vehicle's electric drive chain comprises an electrical energy storage battery.

[0236] Alternatively or in addition, the first element 25 of the vehicle's electric drive chain includes an electric vehicle traction motor.

[0237] Alternatively or in addition, the first element 25 of the vehicle's electric drive chain includes an electronic control unit for the vehicle's electric traction motor.

[0238]

[0137] According to the illustrated example, the third heat exchanger 3 is thermally coupled with the element 25 of the electric traction chain via a heat transfer fluid circulating in a heat transfer fluid circuit 30A.

[0239]

[0138] The 30A circuit includes a circulation pump, not shown, which can be selectively switched on or off.

[0240]

[0139] According to the first embodiment, illustrated in Figure 1, as well as in the second embodiment and its variants, illustrated in Figures 2 to 4, the fifth heat exchanger 5 is arranged on the first main loop A1 downstream of the first expansion valve 31 and upstream of the second exchanger 2.

[0241]

[0140] In this case, the fifth heat exchanger 5 is configured to allow heat exchange between:

[0242] - the refrigerant circulating in the first main loop A1 downstream of the first expansion valve 31 and upstream of the second heat exchanger 2, and

[0243] - the refrigerant circulating in the second main loop A2 downstream of the third heat exchanger 3 and upstream of the second expansion valve 32.

[0244]

[0141] In the second embodiment and its variants, illustrated in Figures 2 to 4, the first main loop A1 may include a fourth expansion valve 34 disposed downstream of the fifth heat exchanger 5 and upstream of the second heat exchanger 2.

[0245] The fourth expansion valve 4 allows the efficiency of the heat exchange in the fifth exchanger 5 to be adjusted.

[0246]

[0142] According to the third embodiment of the thermal conditioning system 100, illustrated in Figure 5, the fifth heat exchanger 5 is arranged on the first main loop A1 downstream of the second exchanger 2 and upstream of the first accumulator 11.

[0247]

[0143] In this case, the fifth heat exchanger 5 is configured to allow heat exchange between:

[0248] - the refrigerant circulating in the first main loop A1 downstream of the second heat exchanger 2 and upstream of the first accumulator 11, and

[0249] - the refrigerant circulating in the second main loop A2 downstream of the third heat exchanger 3 and upstream of the second expansion valve 32.

[0250]

[0144] In this case, the first main loop A1 is devoid of a fourth regulator 34.

[0251] The refrigerant fluid exiting the first heat exchange section 5a joins the first accumulator 11 without passing through any other heat exchanger or expansion valve.

[0252]

[0145] According to the second embodiment and its variants, illustrated in figures 2 to 4, the first heat exchange section 5a is arranged on the first main loop A1 downstream of the first regulator 31 and upstream of the fourth regulator 34.

[0253]

[0146] According to the third embodiment, corresponding to Figure 5, the first heat exchange section 5a is arranged on the first main loop A1 downstream of the second exchanger 2 and upstream of the first accumulator 11.

[0254]

[0147] Only the arrangement of the first heat exchange section 5a varies between the second and third embodiments. The arrangement of the second heat exchange section 5b remains unchanged.

[0255]

[0148] According to the second embodiment and its variants, as well as according to the third embodiment, illustrated in figures 2 to 5, the thermal conditioning system 100 comprises a branch branch B2 connecting a first connection point R1 to a second connection point R2.

[0256] The first connection point R1 is located on the second main loop A2 downstream of the fifth exchanger 5 and upstream of the second expansion valve 32.

[0257] The second connection point R2 is located on the second main loop A2 downstream of the fourth heat exchanger 4 and upstream of the inlet 8a of the second compressor 8. The branch branch B2 includes successively a third expansion valve 33 and a sixth heat exchanger 6.

[0258]

[0149] The sixth heat exchanger 6 is thus configured to operate as a refrigerant evaporator.

[0150] The second accumulator 12 is arranged downstream of the second connection point R2.

[0259]

[0151] According to the illustrated example of the thermal conditioning system 100, the sixth heat exchanger 6 is thermally coupled with a second element 26 of an electric drive chain of a motor vehicle.

[0260] The sixth heat exchanger 6 allows, depending on the selected operating mode, either the cooling of the second element 26 of the vehicle's electric powertrain, or the recovery of heat losses from this element 26 of the powertrain.

[0261]

[0152] The second element 26 of the vehicle's electric drive chain may include an electrical energy storage battery.

[0262] Alternatively or in addition, the second element 26 of the vehicle's electric drive chain may include an electric vehicle traction motor.

[0263] Alternatively or in addition, the second element 26 of the vehicle's electric drive chain may include an electronic control unit for the vehicle's electric traction motor.

[0264]

[0153] According to the illustrated example, the third heat exchanger 3 is thermally coupled with the second element 26 of the electric traction chain via a heat transfer fluid circulating in a heat transfer fluid circuit 30B.

[0265] Circuit 30B includes a circulation pump, not shown, which can be selectively activated or deactivated depending on the selected operating mode.

[0266]

[0154] The second embodiment and its variants, as well as the third embodiment, differ from the first embodiment in particular by the presence of internal exchangers.

[0267]

[0155] In these embodiments, the first main loop A1 of the refrigerant circuit 10 includes a first internal heat exchanger 13 configured to allow heat exchange between:

[0268] - the refrigerant circulating downstream of the first heat exchanger 1 and upstream of the first expansion valve 31, and

[0269] - the refrigerant fluid circulating downstream of the first accumulation device 11 and upstream of the inlet 7a of the first compressor 7.

[0270]

[0156] The first internal exchanger 13 makes it possible to increase the enthalpy variation of the refrigerant fluid during the thermodynamic cycle of the first main loop A1, and therefore to increase the thermal power that the thermal conditioning system 100 can provide.

[0271]

[0157] The first internal exchanger 13 has a first heat exchange section 13a arranged on the first main loop A1 between the first exchanger 1 and the first expansion valve 31.

[0272] The first heat exchange section 13a receives the high-pressure refrigerant fluid from the first exchanger 1.

[0273]

[0158] The first internal exchanger 13 includes a second heat exchange section 13b arranged on the first main loop A1 downstream of the first accumulator 11 and upstream of the inlet 7a of the first compressor 7.

[0274] The second heat exchange section 13b receives the low-pressure refrigerant fluid from the first accumulator 11.

[0275]

[0159] The first internal exchanger 13 is configured to allow heat exchange between the refrigerant in the first heat exchange section 13a and the refrigerant in the second heat exchange section 13b.

[0276]

[0160] Similarly, the second main loop A2 of the refrigerant circuit 10 includes a second internal heat exchanger 14 configured to allow heat exchange between:

[0277] - the refrigerant circulating downstream of the fifth heat exchanger 5 and upstream of the second expansion valve 32, and

[0278] - the refrigerant fluid circulating downstream of the second accumulation device 12 and upstream of an inlet 8a of the second compressor 8.

[0279]

[0161] The second internal exchanger 14 makes it possible to increase the enthalpy variation of the refrigerant during the thermodynamic cycle of the second main loop A2, and therefore to increase the thermal power that the thermal conditioning system 100 can provide.

[0162] The second internal exchanger 14 has a first heat exchange section 14a arranged on the second main loop A2 downstream of the fifth exchanger 5 and upstream of the second expansion valve 32.

[0280]

[0163] The second internal exchanger 14 has a second heat exchange section 14b arranged on the second main loop A2 downstream of the second accumulator 12 and upstream of the inlet 8a of the second compressor s.

[0281]

[0164] The second internal exchanger 14 is configured to allow heat exchange between the refrigerant in the first heat exchange section 14a and the refrigerant in the second heat exchange section 14b.

[0282]

[0165] When the branch branch B2 is present, the first heat exchange section 14a is arranged on the second main loop A2 between the fifth exchanger 5 and the first connection point R1.

[0283]

[0166] The presence of the internal heat exchangers 13 and 14 is independent of the presence of the branch branch B2. Thus, according to variants not shown, the circuit 10 may include the internal heat exchangers 13 and 14 but not a branch branch B2.

[0284]

[0167] According to variants of the second embodiment, illustrated in Figures 3 and 4, as well as according to the third embodiment, illustrated in Figure 5, the second main loop A2 includes an additional heat exchanger.

[0285]

[0168] The second main loop A2 of the refrigerant circuit 10 thus includes a seventh heat exchanger 9 thermally coupled with the second outside air flow Fe2. The seventh heat exchanger 9 is located upstream of the fifth heat exchanger 5.

[0286]

[0169] As shown in particular in Figures 3 to 5, the seventh heat exchanger 9 is arranged upstream of the third exchanger 3.

[0287]

[0170] According to an unrepresented variant, the seventh heat exchanger 9 can be arranged downstream of the third exchanger 3 and upstream of the fifth exchanger 5.

[0288]

[0171] The seventh heat exchanger 9 is configured to exchange heat with a heat transfer fluid circulating in a closed heat transfer fluid circuit 51, the heat transfer fluid circuit 51 comprising a heat exchanger 9A configured to exchange heat with the second outside airflow Fe2 to the vehicle's passenger compartment.

[0289]

[0172] Like the third exchanger 3, the seventh exchanger 9 helps to cool the high-pressure, high-temperature refrigerant fluid discharged by the second compressor 8.

[0290]

[0173] The thermal conditioning system circuit 100 proposed herein can operate in various modes. Some of these modes will now be described and illustrated in Figures 6 to 9.

[0291]

[0174] In these figures, the portions of the circuit 10 in which a flow of refrigerant fluid circulates are shown in thick solid lines, while the portions in which the refrigerant fluid does not circulate are shown in thin dashed lines.

[0292] Different arrows indicate the direction of refrigerant flow in the different portions of circuit 10 which are traversed by a flow of refrigerant.

[0293]

[0175] In steady state, the time variation of the mass of refrigerant in a heat exchanger is zero. The flow rate of refrigerant downstream of a heat exchanger is therefore equal to the flow rate of refrigerant upstream of that heat exchanger.

[0294] Similarly, there is no accumulation of refrigerant in an expansion valve, and the flow rate of refrigerant downstream of an expansion valve is equal to the flow rate upstream of that expansion valve.

[0295]

[0176] Figure 6 schematically illustrates a method of operation of the thermal conditioning system 100 of Figure 2, in a so-called passenger compartment cooling mode.

[0296] In this operating mode:

[0297] - a first flow Qr1 of refrigerant fluid circulates in the first compressor 7 where it passes to a first high pressure HP1, and circulates in the first main loop A1, successively in the first exchanger 1 where it gives up heat, in the first expansion valve 31 where it undergoes expansion and passes to a first low pressure BP1 lower than the first high pressure HP1, in the fifth exchanger 5 where it receives heat, in the second exchanger 2 without exchanging heat, and returns to the first compressor 7.

[0298] - a second flow Qr2 in the second compressor 8 where it passes to a second high pressure HP2, and circulates in the second main loop A2, successively in the third exchanger 3 where it gives off heat, in the fifth exchanger 5 where it gives off heat, in the second expansion valve 32 where it undergoes expansion and passes to a second low pressure BP2 lower than the second high pressure HP2, in the fourth exchanger 4 where it receives heat, and returns to the second compressor 8.

[0299]

[0177] This mode of operation is used when only cooling of the passenger compartment is desired, and it is not necessary to cool the first element 25 or the second element 26 of the vehicle's drive chain.

[0300]

[0178] In this mode of operation, the refrigerant circulates in the fourth expansion valve 34 without undergoing expansion.

[0301]

[0179] In this operating mode:

[0302] - The refrigerant flow rate in the bypass branch B2 is zero.

[0303] The third regulator 33 is indeed in the closed position.

[0304] - The flow rate of heat transfer fluid in circuit 30A is zero.

[0305] The circulation pump for circuit 30A is inactive.

[0306] - The first high pressure HP1 is greater than the second high pressure HP2.

[0307] - The first low pressure BP1 is higher than the second low pressure BP2.

[0308]

[0180] The first exchanger 1 dissipates in the first outside air stream Fe1 the heat from the high-pressure, high-temperature refrigerant fluid coming from the first compressor 7.

[0309] The third exchanger 3 dissipates the heat from the high-pressure, high-temperature refrigerant fluid from the second compressor 8 into the second outside air stream Fe2. The refrigerant fluid from the second compressor 8 is thus cooled.

[0310] At the first heat exchange section 5a of the fifth heat exchanger 5, the refrigerant at the first low pressure BP1, coming from the first expansion valve 31, evaporates. The heat of vaporization is supplied by the refrigerant at the second high pressure HP2, coming from the third heat exchanger 3. The refrigerant at the second high pressure HP2 from the third heat exchanger 3 is thus cooled.

[0311] The fourth heat exchanger 4 evaporates the refrigerant from the second heat exchange section 5b of the fifth heat exchanger 5. The heat of vaporization is supplied by the interior airflow Fi. The interior airflow Fi is thus cooled, which helps to cool the passenger compartment.

[0312] The sixth exchanger 6 is not traversed by refrigerant fluid and is thermally inactive, that is to say there is no heat exchange between the refrigerant fluid and the heat transfer fluid of circuit 30B.

[0313] The second exchanger 2 is thermally inactive, because there is no circulation of heat transfer fluid in circuit 30A.

[0314] The first internal exchanger 13 and the second internal exchanger 14 are both active.

[0315]

[0181] The refrigerant fluid from the second exchanger 2 circulates in the first accumulator 11, then in the first heat exchange section 13b of the first internal exchanger 13, and joins the inlet 7a of the first compressor 7.

[0316] Similarly, the refrigerant from the fourth exchanger 4 circulates in the second accumulator 12, then in the first heat exchange section 14b of the second internal exchanger 14, and joins the inlet 8a of the second compressor 8.

[0317]

[0182] In this operating mode, the indoor airflow Fi is cooled at the fourth exchanger 4. The heat taken from the indoor airflow Fi is partly dissipated in the second outdoor airflow Fe2 at the third exchanger 3, and partly transferred to the refrigerant of the first main loop A1 at the fifth exchanger 5.

[0318] The heat received by the refrigerant fluid from the first main loop A1 at the fifth exchanger 5 is dissipated in the first outside air flow Fe1 at the first exchanger 1.

[0319] The first main loop A1 cools the refrigerant of the second main loop A2, without cooling the first element 25 of the traction chain.

[0320] The role of the first main loop A1 here is to cool the refrigerant fluid of the second main loop A2.

[0321]

[0183] Figure 7 schematically illustrates a method of operation of the thermal conditioning system 100 of Figure 2, in a mode called first mode of passenger compartment cooling and battery cooling.

[0322] In this operating mode:

[0323] - a first flow Qr1 of refrigerant circulates in the first compressor 7 where it passes to a first high pressure HP1, and circulates in the first main loop A1, successively in the first exchanger 1 where it releases heat, in the first expansion valve 31 where it undergoes expansion and passes to a first low pressure BP1 lower than the first high pressure HP1, in the fifth exchanger 5 where it receives heat, in the second exchanger 2 where it receives heat, and returns to the first compressor 7,

[0324] - a second flow Qr2 in the second compressor 8 where it passes to a second high pressure HP2, and circulates in the second main loop A2, successively in the third exchanger 3 where it releases heat, in the fifth exchanger 5 where it releases heat, and divides into:

[0325] -- a third flow Qr3 circulating in the second main loop A2, successively in the second expansion valve 32 where it undergoes expansion and passes to a second low pressure BP2 lower than the second high pressure HP2, in the fourth exchanger 4 where it receives heat, and

[0326] -- a fourth flow Qr4 circulating in the bypass branch B2, successively in the third expansion valve 33 where it undergoes expansion and passes to the second low pressure BP2, in the sixth exchanger 6 where it receives heat, and joins the refrigerant fluid from the fourth exchanger 4.

[0327] The total flow formed Qr2 returns to the second compressor 8.

[0328]

[0184] This operating mode is used when joint cooling of the passenger compartment, the first element 25 and the second element 26 is desired.

[0329]

[0185] In this operating mode:

[0330] - The heat transfer fluid circulates in circuit 30A of the second exchanger 2.

[0331] The circulation pump for circuit 30A is activated. - The heat transfer fluid circulates in circuit 30B of the sixth heat exchanger 6.

[0332] - The first high pressure HP1 is greater than the second high pressure HP2.

[0333] - The first low pressure BP1 is higher than the second low pressure BP2.

[0334]

[0186] This mode of operation differs from the previous one in that the refrigerant fluid discharged by the second compressor 8 circulates in parallel in the sixth exchanger 6 and in the fourth exchanger 4, and in that the second exchanger 2 is thermally active.

[0335] The first element 25 is cooled at the level of the second exchanger 2, and the second element 26 is cooled at the level of the sixth exchanger 6.

[0336] The internal airflow Fi is cooled at the level of the fourth exchanger 4.

[0337]

[0187] In this mode of operation, the heat taken from the indoor airflow Fi and that taken from the second element 26 are partly dissipated in the second outdoor airflow Fe2 at the level of the third exchanger 3, and is partly transferred to the refrigerant of the first main loop A1 at the level of the fifth exchanger 5.

[0338] The heat received by the refrigerant from the first main loop A1 at the fifth exchanger 5 and the heat received from the first element 25 at the second exchanger 2 are dissipated in the first outside air flow Fe1 at the first exchanger 1.

[0339]

[0188] Figure 10 schematically represents the thermodynamic cycle of the refrigerant fluid of the first main loop A1, in solid lines, and the thermodynamic cycle of the refrigerant fluid of the second main loop A2, in dashed lines.

[0340] The horizontal axis represents the enthalpy of the refrigerant and the vertical axis represents its pressure. The curve s represents the saturation curve of the refrigerant, which in this example is R744.

[0341]

[0189] In Figure 10, point E_7a schematically represents the state of the refrigerant at the inlet of the first compressor 7. Point E_7b schematically represents the state of the refrigerant at the outlet of the first compressor 7, i.e., at high temperature and at the first high pressure HP1. Point E_1 corresponds to the state at the outlet of the first heat exchanger 1. Point E_13a corresponds to the state at the outlet of the first heat exchange section 13a of the first internal heat exchanger 13. In the illustrated example, the refrigerant is R744 for the first main loop A1 and for the second main loop A2. The high-pressure refrigerant is thus in a supercritical state.

[0342] Point E_31 corresponds to the outlet state of the first expansion valve 31, and therefore to the first low-pressure BP1. This point also corresponds to the inlet state of the first heat exchange section 5a of the fifth heat exchanger 5. The symbol E_5a corresponds to the outlet state of the first heat exchange section 5a of the fifth heat exchanger 5. The symbol E_11 is the characteristic point of the outlet state of the first accumulator 11. The symbol E_13b corresponds to the outlet state of the second heat exchange section 13b of the first internal heat exchanger 13. This point coincides with point A_7a, characteristic of the inlet of the first compressor 7.

[0343]

[0190] Point E_8a schematically represents the state of the refrigerant at the inlet of the second compressor 8. Point E_8b schematically represents the state of the refrigerant at the outlet of the second compressor 8, i.e., at high temperature and the second high pressure HP2. Point E_3 corresponds to the state at the outlet of the third heat exchanger 3. Point E_5b corresponds to the state at the outlet of the second heat exchange section 5b of the fifth internal heat exchanger 5.

[0344] Point E_14a corresponds to the outlet state of the first heat exchange section 14a of the second internal exchanger 14.

[0345] Point E_32 corresponds to the outlet state of the second expansion valve 32, therefore to the second low-pressure BP2. Point E_12 is the characteristic point of the outlet state of the second accumulator 12. Point E_14b corresponds to the outlet state of the second heat exchange section 14b of the second internal heat exchanger 14. This point coincides with point A_8a, characteristic of the inlet of the second compressor 8.

[0346]

[0191] In Figure 10, the symbol Q5b, the enthalpy difference between point E_3 and point E_5b, represents the amount of heat released at the fifth heat exchanger 5 by the refrigerant circulating in the second main loop A2. The symbol Q5a corresponds to the amount of heat received at the fifth heat exchanger 5 by the refrigerant circulating in the first main loop A1. The symbol Q5a corresponds to the enthalpy difference between point E_31 and point E_5a.

[0347] The symbol Q2 represents the amount of heat received at the level of the second exchanger 2 by the refrigerant circulating in the first main loop A1, and corresponding to the cooling of the first element 25.

[0348] The distribution between the quantity of heat Q5a and the quantity of heat Q2 can be achieved by adjusting the flow rate of the heat transfer fluid in the circuit 30A. In the case of the previous operating mode, illustrated in Figure 6, the quantity of heat Q2 is zero, and the entire cooling capacity of the first main loop A1 is used to cool the refrigerant of the second main loop A2.

[0349]

[0192] Figure 8 schematically illustrates a method of operation of the thermal conditioning system 100 of Figure 2, in a mode called second mode of passenger compartment cooling and battery cooling.

[0350] In this operating mode:

[0351] - the refrigerant flow rate in the first main loop A1 is zero,

[0352] - a flow Qr of refrigerant fluid circulates in the second compressor 8 where it is increased to a high pressure HP2, and circulates in the second main loop A2, successively in the third heat exchanger 3 where it releases heat, in the fifth heat exchanger 5, and is divided into:

[0353] -- a second flow Qr2 circulating in the second main loop A2, successively in the second expansion valve 32 where it undergoes expansion and passes to a low pressure BP2 lower than the high pressure HP2, in the fourth exchanger 4 where it receives heat, and

[0354] -- a third flow Qr3 circulating in the bypass branch B2, successively in the third expansion valve 33 where it undergoes expansion and passes to the low pressure BP2, in the sixth exchanger 6 where it receives heat, and joins the refrigerant fluid coming from the fourth exchanger 4.

[0355] The total flow formed Qr returns to the second compressor 8.

[0356]

[0193] This operating mode is used when moderate cooling of the passenger compartment and the second element 26 is desired. In other words, the cooling power supplied is lower than in the previous mode.

[0357]

[0194] In this operating mode:

[0358] - The first compressor 7 is inactive. - The second compressor 8 is active.

[0359] - The heat transfer fluid circulates in circuit 30B of the sixth exchanger 6.

[0360] - The heat transfer fluid does not circulate in the 30A circuit of the second exchanger 2.

[0361]

[0195] The second element 26 is cooled at the level of the sixth exchanger 6.

[0362] The internal airflow Fi is cooled at the level of the fourth exchanger 4.

[0363] The heat taken from the indoor airflow Fi and the second element 26 is dissipated in the second outdoor airflow Fe2 at the level of the third exchanger 3.

[0364] The fifth exchanger, 5, is inactive. Similarly, the first exchanger, 1, is inactive. The same applies to the second exchanger, 2.

[0365]

[0196] Figure 9 schematically illustrates a method of operation of the thermal conditioning system 100 of Figure 2, in a so-called accelerated cooling mode of the passenger compartment.

[0366] In this operating mode:

[0367] - a first flow Qr1 of refrigerant circulates in the first compressor 7 where it passes to a first high pressure HP1, and circulates in the first main loop A1, successively in the first exchanger 1 where it releases heat, in the first expansion valve 31 where it undergoes expansion and passes to a first low pressure BP1 lower than the first high pressure HP1, in the fifth exchanger 5 where it receives heat, in the second exchanger 2 without exchanging heat, and returns to the first compressor 7,

[0368] - a second flow Qr2 in the second compressor 8 where it passes to a second high pressure HP2, and circulates in the second main loop A2, successively in the third exchanger 3 where it gives off heat, in the fifth exchanger 5 where it gives off heat, in the second expansion valve 32 where it undergoes expansion and passes to a second low pressure BP2 lower than the second high pressure HP2, in the fourth exchanger 4 where it receives heat, and returns to the second compressor 8.

[0369]

[0197] This operating mode is used when rapid cooling of the passenger compartment is desired, and it is not necessary to cool the first element 25 or the second element 26 of the vehicle's powertrain. The circulation of the refrigerant is the same as in the first operating mode.

[0370]

[0198] This mode of operation differs from the first mode of operation by an increase in the first flow rate Qr1 of refrigerant discharged by the first compressor 7, by an increase in the second flow rate Qr2 of refrigerant discharged by the second compressor 8 and by an increase in the expansion ratio ensured by the first expansion valve 31.

[0371] In other words, the rotational speed of the first compressor 7 and the rotational speed of the second compressor 8 are increased. The expansion ratio achieved by the first expansion valve 31 is increased; that is, in this operating mode, the first low pressure BP1 is lower than the value of the first low pressure in the first operating mode.

[0372]

[0199] In this operating mode:

[0373] - The refrigerant flows through the fourth expansion valve 34 without undergoing expansion.

[0374] - The refrigerant flow rate in the bypass branch B2 is zero.

[0375] - The flow rate of heat transfer fluid in circuit 30A is zero.

[0376] - The first high pressure HP1 is greater than the second high pressure HP2.

[0377] - The first low pressure BP1 is higher than the second low pressure BP2.

[0378]

[0200] The first exchanger 1 dissipates in the first outside air stream Fe1 the heat from the high-pressure, high-temperature refrigerant fluid coming from the first compressor 7.

[0379] The third exchanger 3 dissipates the heat from the high-pressure, high-temperature refrigerant fluid from the second compressor 8 into the second outside air stream Fe2. The refrigerant fluid from the second compressor 8 is thus cooled.

[0380] At the level of the first heat exchange section 5a of the fifth exchanger 5, the low-pressure refrigerant from the first expansion valve 31 evaporates, the heat of vaporization being supplied by the high-pressure refrigerant from the third exchanger 3. The high-pressure refrigerant of the second main loop A2 is thus cooled.

[0381] The fourth heat exchanger 4 evaporates the refrigerant from the second heat exchange section 5b of the fifth heat exchanger 5, the heat of vaporization being supplied by the interior airflow Fi. The interior airflow Fi is thus cooled, which cools the passenger compartment.

[0382] The sixth exchanger 6 is not traversed by refrigerant fluid and is thermally inactive, that is to say there is no heat exchange between the refrigerant fluid and the heat transfer fluid of circuit 30B.

[0383] The second exchanger 6 is thermally inactive, because there is no circulation of heat transfer fluid in circuit 30B.

[0384] The first internal exchanger 13 and the second internal exchanger 14 are both active.

[0385]

[0201] In this operating mode, the indoor airflow Fi is cooled at the fourth exchanger 4. The heat taken from the indoor airflow Fi is partly dissipated in the second outdoor airflow Fe2 at the third exchanger 3, and partly transferred to the refrigerant of the first main loop A1 at the fifth exchanger 5.

[0386] The heat received by the refrigerant fluid from the first main loop A1 at the fifth exchanger 5 is dissipated in the first outside air flow Fe1 at the first exchanger 1.

[0387] This operating mode allows for rapid cooling of the passenger compartment, with all the cooling power being used to cool the interior airflow Fi at the level of the fourth exchanger 4.

[0388]

[0202] Other modes of operation, not described, may also be achieved.

Claims

Demands

1. Thermal conditioning system (100) for a motor vehicle, comprising a refrigerant circuit (10) configured to circulate a refrigerant, the refrigerant circuit (10) comprising: a first main loop (A1) comprising successively, according to the direction of refrigerant flow: -- a first compressor (7), -- a first heat exchanger (1) thermally coupled with a first outside airflow (Fe1) to a passenger compartment of a motor vehicle, -- a first expansion valve (31), -- a second heat exchanger (2), a second main loop (A2) comprising successively, according to the direction of refrigerant flow: -- a second compressor (8), -- a third heat exchanger (3) thermally coupled with a second external airflow (Fe2) to the vehicle's passenger compartment, -- a second expansion valve (32), -- a fourth heat exchanger (4) thermally coupled with an interior airflow (Fi) to the passenger compartment of the motor vehicle, a fifth heat exchanger (5) jointly arranged on the first main loop (A1) and on the second main loop (A2) and configured to allow heat exchange between: -- the refrigerant circulating in the first main loop (A1) between the first expansion valve (31) and the inlet (7a) of the first compressor (7), and -- the refrigerant circulating in the second main loop (A2) between the third heat exchanger (3) and the second expansion valve (32).

2. Thermal conditioning system (100) according to claim 1, wherein the second heat exchanger (2) is thermally coupled with a first element (25) of an electric drive chain of a motor vehicle.

3. Thermal conditioning system (100) according to claim 1 or 2, wherein the fifth heat exchanger (5) is arranged on the first main loop (A1) downstream of the first regulator (31) and upstream of the second exchanger (2).

4. Thermal conditioning system (100) according to the preceding claim, wherein the first main loop (A1) comprises a fourth expansion valve (34) disposed downstream of the fifth heat exchanger (5) and upstream of the second interchange (2).

5. Thermal conditioning system (100) according to any one of the preceding claims, wherein: the first main loop (A1) comprises a first accumulation device (11) of refrigerant fluid disposed downstream of the second heat exchanger (2) and upstream of the inlet (7a) of the first compressor (7), the second compressor (8) includes a refrigerant inlet (8a) and a refrigerant outlet (8b), and the second main loop (A2) includes a second accumulation device (12) of refrigerant fluid disposed downstream of the fourth exchanger (4) and upstream of the inlet (8a) of the second compressor (8).

6. Thermal conditioning system (100) according to claim 1 or 2 in combination with claim 5, wherein the fifth heat exchanger (5) is disposed on the first main loop (A1) downstream of the second exchanger (2) and upstream of the first storage device (11).

7. Thermal conditioning system (100) according to claim 5 or 6, comprising a branch (B2) connecting a first connection point (R1) located on the second main loop (A2) downstream of the fifth heat exchanger (5) and upstream of the second expansion valve (32) to a second connection point (R2) located on the second main loop (A2) downstream of the fourth heat exchanger (4) and upstream of the second storage device (12), the branch (B2) successively comprising a third expansion valve (33) and a sixth heat exchanger (6).

8. Thermal conditioning system (100) according to the preceding claim, wherein the sixth heat exchanger (6) is thermally coupled with a second element (26) of an electric drivetrain of a motor vehicle.

9. Thermal conditioning system (100) according to any one of claims 5 to 8, wherein the first main loop (A1) of the refrigerant circuit (10) comprises a first internal heat exchanger (13) configured to permit heat exchange between: - the refrigerant circulating downstream of the first heat exchanger (1) and upstream of the first expansion valve (31), and - the refrigerant fluid circulating downstream of the first accumulation device (11) and upstream of the inlet (7a) of the first compressor (7).

10. Thermal conditioning system (100) according to any one of claims 5 to 9, wherein the second main loop (A2) of the refrigerant circuit (10) comprises a second internal heat exchanger (14) configured to permit heat exchange between: - the refrigerant circulating downstream of the fifth heat exchanger (5) and upstream of the second expansion valve (32), and - the refrigerant fluid circulating downstream of the second accumulation device (12) and upstream of an inlet (8a) of the second compressor (8).

11. Thermal conditioning system (100) according to any one of the preceding claims, wherein the second main loop (A2) of the refrigerant circuit (10) includes a seventh heat exchanger (9) thermally coupled with the second outside airflow (Fe2), the seventh heat exchanger (9) being disposed upstream of the fifth exchanger (5).

12. A method of operating a thermal conditioning system (100) according to any one of claims 1 to 11, in a so-called passenger compartment cooling mode in which: - a first flow (Qr1) of refrigerant circulates in the first compressor (7) where it passes through a first high pressure (HP1), and circulates in the first main loop (A1), successively in the first heat exchanger (1) where it releases heat, in the first expansion valve (31) where it undergoes expansion and passes through a first low pressure (BP1) lower than the first high pressure (HP1), in the fifth exchanger (5) where it receives heat, in the second exchanger (2) without exchanging heat, and returns to the first compressor (7), - a second flow (Qr2) in the second compressor (8) where it passes to a second high pressure (HP2), and circulates in the second main loop (A2), successively in the third exchanger (3) where it gives up heat, in the fifth exchanger (5) where it gives up heat, in the second expansion valve (32) where it undergoes expansion and passes to a second low pressure (BP2) lower than the second high pressure (HP2), in the fourth exchanger (4) where it receives heat, and returns to the second compressor (8).

13. A method of operating a thermal conditioning system (100) according to any one of claims 1 to 11 in combination with claim 7, in a mode referred to as the first mode of passenger compartment cooling and battery cooling in which: - a first flow (Qr1) of refrigerant circulates in the first compressor (7) where it passes to a first high pressure (HP1), and circulates in the first main loop (A1), successively in the first exchanger (1) where it gives up heat, in the first expansion valve (31) where it undergoes expansion and passes to a first low pressure (BP1) lower than the first high pressure (HP1), in the fifth exchanger (5) where it receives heat, in the second exchanger (2) where it receives heat, and returns to the first compressor (7), - a second flow (Qr2) in the second compressor (8) where it passes to a second high pressure (HP2), and circulates in the second main loop (A2), successively in the third exchanger (3) where it releases heat, in the fifth exchanger (5) where it releases heat, and divides into: -- a third flow circulating in the second main loop (A2), successively in the second expansion valve (32) where it undergoes expansion and passes to a second low pressure (BP2) lower than the second high pressure (HP2), in the fourth exchanger (4) where it receives heat, and -- a fourth flow circulating in the bypass branch (B2), successively in the third regulator (33) where it undergoes expansion and passes to the second low pressure (BP2), in the sixth exchanger (6) where it receives heat, and joins the refrigerant from the fourth exchanger (4), the total flow formed returns to the second compressor (8).

14. A method of operating a thermal conditioning system (100) according to any one of claims 1 to 11 in combination with claim 7, in a so-called second mode of passenger compartment cooling and battery cooling in which: - the refrigerant flow rate in the first main loop (A1) is zero, - a flow (Qr) of refrigerant circulates in the second compressor (8) where it is increased to a high pressure (HP2), and circulates in the second main loop (A2), successively in the third heat exchanger (3) where it releases heat, in the fifth heat exchanger (5), and is divided into: -- a second flow (Qr2) circulating in the second main loop (A2), successively in the second expansion valve (32) where it undergoes expansion and passes to a low pressure (BP2) lower than the high pressure (HP2), in the fourth exchanger (4) where it receives heat, and -- a third flow (Qr3) circulating in the bypass branch (B2), successively in the third expansion valve (33) where it undergoes expansion and passes to the low pressure (BP2), in the sixth exchanger (6) where it receives heat, and joins the refrigerant fluid from the fourth exchanger (4), the total flow formed returns to the second compressor (8).

15. A method of operating a thermal conditioning system (100) according to any one of claims 1 to 11, in a so-called accelerated passenger compartment cooling mode in which: - a first flow (Qr1) of refrigerant circulates in the first compressor (7) where it passes to a first high pressure (HP1), and circulates in the first main loop (A1), successively in the first exchanger (1) where it gives up heat, in the first expansion valve (31) where it undergoes expansion and passes to a first low pressure (BP1) lower than the first high pressure (HP1), in the fifth exchanger (5) where it receives heat, in the second exchanger (2) without exchanging heat, and returns to the first compressor (7), - a second flow (Qr2) in the second compressor (8) where it passes to a second high pressure (HP2), and circulates in the second main loop (A2), successively in the third exchanger (3) where it gives up heat, in the fifth exchanger (5) where it gives up heat, in the second expansion valve (32) where it undergoes expansion and passes to a second low pressure (BP2) lower than the second high pressure (HP2), in the fourth exchanger (4) where it receives heat, and returns to the second compressor (8).

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