THERMAL MANAGEMENT SYSTEM

CROSS-REFERENCES TO RELATED APPLICATIONS

[0001] This application claims the benefit of US Provisional Application 63/381 ,784, filed November 1 , 2022, and 63/491 ,138, filed March 20, 2023, the contents of both of which are incorporated herein by reference in their entirety.

FIELD OF THE DISCLOSURE

[0002] This disclosure relates generally to the field of heat exchangers and more particularly to a coolant-refrigerant heat exchanger and associated thermal management system for use in an electric vehicle.

BACKGROUND

[0003] Thermal management systems in electric vehicles (EVs) are known to employ coolant heaters for the purpose of heating coolant that is ultimately circulated through components of the EV that require heating for performance reasons, such as the vehicle’s traction battery. Additionally, refrigerant heaters are known in EV’s for serving certain specific purposes. However, each of the existing thermal management systems suffers from certain deficiencies. It is of continued interest to improve the performance and efficiency of EV thermal management systems.

SUMMARY

[0004] In an aspect, a coolant-refrigerant heat exchanger is provided for a thermal management system for an electric vehicle. The coolant-refrigerant heat exchanger includes a plurality of flow plates and a secondary heater. The plurality of flow plates each have a plurality of faces and a peripheral edge. The plurality of flow plates are sealingly joined together to define a coolant flow path through the coolant- refrigerant heat exchanger and a refrigerant flow path through the coolant-refrigerant heat exchanger. The coolant flow path and the refrigerant flow path are positioned in order to transfer heat from one of the coolant and the refrigerant to the other of the coolant and the refrigerant. The flow plates are made from a material that is electrically conductive. The secondary heater is positioned to heat both the refrigerant and the coolant in the coolant-refrigerant heat exchanger. The secondary heater includes an induction coil that is positioned proximate to the flow plates and is energizable to heat the flow plates by induction.

[0005] Other aspects of the present disclosure may also be patentable.

BRIEF DESCRIPTION OF THE DRAWINGS

[0006] The foregoing and other aspects of the invention will be better appreciated with reference to the attached drawings, as follows:

[0007] Figure 1 is a schematic view of a basic vehicular air conditioning system using refrigerant, in accordance with the prior art.

[0008] Figure 2 is a pressure-enthalpy chart for the refrigerant in the air conditioning system shown in Figure 1.

[0009] Figure 3A is a schematic view of a basic vehicular heat pump system, in accordance with the prior art, in a cooling mode.

[0010] Figure 3B is a schematic view of the heat pump system shown in Figure 3A, in a heating mode.

[0011] Figure 4 is a pressure-enthalpy chart for the refrigerant in the air conditioning system shown in Figure 1.

[0012] Figure 5 is a schematic view of a vehicular thermal management system that incorporates a coolant system and a refrigerant system, in accordance with an embodiment of the present disclosure.

[0013] Figure 6 is a perspective view of a coolant-refrigerant heat exchanger, in accordance with an embodiment of the present disclosure, which includes a secondary heater. [0014] Figures 7a and 7b together are a perspective exploded view of the coolant-refrigerant heat exchanger shown in Figure 6.

[0015] Figure 8 is a magnified perspective view of a portion of the coolantrefrigerant heat exchanger shown in Figure 6.

[0016] Figure 9 is a perspective sectional view of the coolant-refrigerant heat exchanger shown in Figure 6.

[0017] Figure 10 is a perspective, partially-exploded view of a portion of the coolant-refrigerant heat exchanger shown in Figure 10, illustrating the flow of coolant and refrigerant therethrough.

[0018] Figure 11 is a schematic illustration showing the flow of coolant and refrigerant through the coolant-refrigerant heat exchanger shown in Figure 6.

[0019] Figure 12 is a schematic illustration showing an alternative flow path for coolant and refrigerant through an alternative embodiment of the coolant-refrigerant heat exchanger shown in Figure 6.

[0020] Figure 13 is a schematic illustration of a thermal management system in accordance with an embodiment of the present disclosure, incorporating the coolantrefrigerant heat exchanger shown in Figure 6, in a cabin heating mode using the secondary heater.

[0021] Figure 14 is a side elevation view of an electric vehicle incorporating the thermal management system shown in Figure 13.

[0022] Figure 15 is a pressure-enthalpy chart for the refrigerant in the thermal management system shown in Figure 13.

[0023] Figure 16 is a flow diagram of a method of controlling the secondary heater shown in Figure 7b, when the thermal management system is operated in the mode shown in Figure 13.

[0024] Figure 17 is a sectional side view of a portion of a plurality of flow plates that are part of the coolant-refrigerant heat exchanger shown in Figures 6-10, in an intermediate stage of manufacture of the coolant-refrigerant heat exchanger. [0025] Figure 18 is a perspective view of flow plate assembly formed that is used as part of a coolant-refrigerant heat exchanger in accordance with another embodiment.

[0026] Figure 19 is a coolant-refrigerant heat exchanger in accordance with another embodiment of the present disclosure in which an induction coil is wrapped around a flow plate assembly.

[0027] Figure 20 is an elevation view of the coolant-refrigerant heat exchanger shown in Figure 19.

[0028] Figure 21 is an elevation view of a coolant-refrigerant heat exchanger in accordance with another embodiment of the present disclosure, which is similar to the embodiment shown in Figure 19, but which includes an inner thermal insulation layer.

[0029] Figure 22 is an elevation view of a coolant-refrigerant heat exchanger in accordance with another embodiment of the present disclosure, which is similar to the embodiment shown in Figure 21 , but which includes an outer thermal insulation layer.

[0030] Figure 23 is a perspective view of a coolant-refrigerant heat exchanger in accordance with another embodiment of the present disclosure, which includes a carrier that includes at least one groove for holding an induction coil.

[0031] Figure 24 is an elevation view of a coolant-refrigerant heat exchanger in accordance with another embodiment of the present disclosure, which includes at least one susceptor.

[0032] Figure 25 is a perspective view of the coolant-refrigerant heat exchanger shown in Figure 24.

[0033] Figure 26 is an elevation view of a coolant-refrigerant heat exchanger in accordance with another embodiment of the present disclosure, which is similar to the embodiment shown in Figure 24, but which includes an inner thermal insulation layer between the at least one susceptor and the induction coil.

[0034] Figure 27 is an elevation view of a coolant-refrigerant heat exchanger in accordance with another embodiment of the present disclosure, which is similar to the embodiment shown in Figure 24, but in which the at least one susceptor only partially surrounds the flow plate assembly. [0035] Figure 28 is an elevation view of a coolant-refrigerant heat exchanger in accordance with another embodiment of the present disclosure, which is similar to the embodiment shown in Figure 24, but which includes a carrier that includes at least one groove for holding an induction coil.

[0036] Figure 29 is an elevation view of a coolant-refrigerant heat exchanger in accordance with another embodiment of the present disclosure, which includes a plurality of C-shaped susceptors.

[0037] Figure 30 is an elevation view of a coolant-refrigerant heat exchanger in accordance with another embodiment of the present disclosure, which includes a plurality of C-shaped susceptors with at least one groove.

[0038] Figure 31 is a magnified sectional view of a portion of the coolantrefrigerant heat exchanger shown in Figure 30.

[0039] Figure 32 is an elevation view of a coolant-refrigerant heat exchanger in accordance with another embodiment of the present disclosure, which includes at least one susceptor that is inserted within the body of the flow plate assembly.

[0040] Figure 33 is a magnified sectional view of a portion of the coolantrefrigerant heat exchanger shown in Figure 32.

[0041] Figure 34 is a perspective exploded view of a coolant-refrigerant heat exchanger in accordance with another embodiment of the present disclosure, which includes at least one susceptor that is inserted within the body of the flow plate assembly and in which there is at least one induction coil inside each of the at least one susceptor.

[0042] Figure 35 is a sectional perspective view of the coolant-refrigerant heat exchanger shown in Figure 34.

DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS

[0043] For simplicity and clarity of illustration, where considered appropriate, reference numerals may be repeated among the figures to indicate corresponding or analogous elements. In addition, numerous specific details are set forth in order to provide a thorough understanding of the embodiment or embodiments described herein. However, it will be understood by those of ordinary skill in the art that the embodiments described herein may be practiced without these specific details. In other instances, well-known methods, procedures and components have not been described in detail so as not to obscure the embodiments described herein. It should be understood at the outset that, although exemplary embodiments are illustrated in the figures and described below, the principles of the present disclosure may be implemented using any number of techniques, whether currently known or not. The present disclosure should in no way be limited to the exemplary implementations and techniques illustrated in the drawings and described below.

[0044] Various terms used throughout the present description may be read and understood as follows, unless the context indicates otherwise: “or” as used throughout is inclusive, as though written “and/or”; singular articles and pronouns as used throughout include their plural forms, and vice versa; similarly, gendered pronouns include their counterpart pronouns so that pronouns should not be understood as limiting anything described herein to use, implementation, performance, etc. by a single gender; “exemplary” should be understood as “illustrative” or “exemplifying” and not necessarily as “preferred” over other embodiments. Further definitions for terms may be set out herein; these may apply to prior and subsequent instances of those terms, as will be understood from a reading of the present description.

[0045] Modifications, additions, or omissions may be made to the systems, apparatuses, and methods described herein without departing from the scope of the disclosure. For example, the components of the systems and apparatuses may be integrated or separated. Moreover, the operations of the systems and apparatuses disclosed herein may be performed by more, fewer, or other components and the methods described may include more, fewer, or other steps. Additionally, steps may be performed in any suitable order. As used in this document, “each” refers to each member of a set or each member of a subset of a set.

[0046] The indefinite article “a” is not intended to be limited to mean “one” of an element. It is intended to mean “one or more” of an element, where applicable, (i.e. unless in the context it would be obvious that only one of the element would be suitable). [0047] Any reference to upper, lower, top, bottom or the like are intended to refer to an orientation of a particular element during use of the claimed subject matter and not necessarily to its orientation during shipping or manufacture. The upper surface of an element, for example, can still be considered its upper surface even when the element is lying on its side.

[0048] DESCRIPTION OF BASIC AIR CONDITIONING SYSTEM

[0049] Reference is made to Figure 1 , which shows schematic diagram of a typical vehicular air conditioning system 10, in accordance with the prior art. It will be noted that the air conditioning system 10 shown in Figure 1 has been simplified in the sense that several components that are typically present, have been omitted here for simplicity.

[0050] The air conditioning system 10 shown in Figure 1 circulates a refrigerant through various components in order to cool a vehicle’s passenger cabin (shown schematically at 12). The air conditioning system 10 employs a compressor 14, a condenser 16, an expansion valve 18, and an evaporator 20.

[0051] The refrigerant enters the compressor 14 at a relatively low pressure, such as, for example, about 140 kPa, and a relatively low temperature such as, for example, -25 degrees Celsius. The compressor 14 compresses the refrigerant, to bring the refrigerant to a high pressure, such as, for example, about 1200 kPa. The compression of the refrigerant raises its temperature to, for example, about 110 degrees Celsius. As a result, the refrigerant is a high pressure, high temperature gas when leaving the compressor. The refrigerant then passes to the condenser 16. The condenser 16 is used to condense the refrigerant, by carrying out heat transfer from the refrigerant flowing therethrough to the air that surrounds the condenser 16. The condenser 16 is positioned outside the passenger cabin 12, such as in the engine compartment, shown at 21 , in embodiments in which the vehicle includes an engine. As a result of its placement, the condenser 16 is exposed to outside air, shown at 22, (which is air from outside the passenger cabin 12), as distinguished from interior air, shown at 24, (which is air from inside the passenger cabin 12). An outside fan 26 is provided to enhance the flow of the outside air 22 over the condenser 16. The temperature of the outside air 22 is lower than that of the refrigerant, and so the refrigerant condenses in the condenser 16, and leaves the condenser 16 as a liquid. [0052] The refrigerant then passes through the expansion valve 18, so as to reduce the pressure of the refrigerant. Some of the refrigerant may evaporate due to the reduction in pressure, however, a significant portion of the refrigerant remains liquid. The reduction in pressure of the refrigerant cools the refrigerant. Thus, the refrigerant leaves the expansion valve 18 as a low pressure, low temperature liquid or liquid/gas mix. The refrigerant then passes through the evaporator 20, which transfers heat from the interior air 24 to the refrigerant, in order to raise the temperature of the refrigerant so as to drive the evaporation of the refrigerant. An interior fan 28 may be provided to encourage the flow of interior air 24 over the evaporator 20. The evaporator 20 is positioned inside the passenger cabin 12 in the sense that the evaporator 20 may be positioned aft of the firewall in the vehicle, which separates the engine compartment 21 from the passenger cabin 12, and, more importantly, is exposed to a flow of the interior air 24. For greater clarity, the interior air 24 is air that is directed into the passenger cabin 12. Raising the temperature of the refrigerant in the evaporator 20 correspondingly cools the interior air 24, thereby cooling the interior air 24.

[0053] The refrigerant then leaves the evaporator 20 and returns to the inlet of the compressor 14, where it is compressed again and sent again to the condenser 16 in a continuous cycle.

[0054] DESCRIPTION OF BASIC PRESSURE-ENTHALPY CHART

[0055] Figure 2 is a pressure-enthalpy chart that shows the refrigeration cycle that the refrigerant undergoes, in a graphical format. As will be understood by one skilled in the art, the inverted U-shaped line represents the gas/liquid transition properties for the refrigerant. The dot-dash curve shown at 30 represents the changes in the properties of the refrigerant as it passes through the refrigeration cycle shown in Figure 1 . Point 32 represents the properties of the refrigerant immediately upstream of the compressor 14. Curve segment 30a is representative of the change in the properties of the refrigerant due to operation of the compressor 14. Point 34 is representative of the properties of the refrigerant downstream of the compressor 14 and upstream from the condenser 16. As can be seen, the pressure and the temperature of the refrigerant increase between point 32 and point 34. [0056] Curve segment 30b is representative of the change in the properties of the refrigerant due to operation of the condenser 16. Point 36 is representative of the properties of the refrigerant immediately downstream of the condenser 16 (and therefore upstream from the expansion valve 18). As can be seen, the temperature of the refrigerant decreases and then remains constant during the phase change that occurs in the condenser 16..

[0057] Curve segment 30c is representative of the change in the properties of the refrigerant due to the expansion valve 18. Point 38 is representative of the properties of the refrigerant immediately downstream of the expansion valve 18 and therefore upstream from the evaporator 20). As can be seen, the pressure and temperature of the refrigerant decrease as a result of passing through the expansion valve.

[0058] Curve segment 30d is representative of the change in the properties of the refrigerant due to passage through the evaporator 20. After passing through the evaporator 20, the refrigerant returns to point 32, which is representative of the properties of the refrigerant immediately downstream of the evaporator 20 (and therefore of the properties of the refrigerant immediately upstream of the compressor 14). As can be seen, the pressure and the temperature remain substantially constant in the evaporator 20. This is because the heat being transferred to the refrigerant is being used to drive the phase change (i.e. the evaporation) of the refrigerant, which occurs at a constant temperature, as will be understood by one skilled in the art. Optionally, the evaporator 20 may be sized to transfer to the refrigerant a bit more than the minimum amount of heat that is needed to evaporate all of the refrigerant, so as to drive an increase in temperature of the refrigerant once all of it has evaporated. This ensures that all of the refrigerant leaves the evaporator as a gas, with no fraction thereof remaining as a liquid. It is advantageous for all of the refrigerant to be in gaseous form when reaching the inlet of the compressor 14 so as to avoid damaging the compressor 14.

[0059] DESCRIPTION OF BASIC HEAT PUMP SYSTEM

[0060] Figures 3A and 3B show a thermal management system that is more sophisticated than the air conditioning system shown in Figure 1. The thermal management system may be referred to as a heat pump system and is shown at 40. The heat pump system 40 is similar to the air conditioning system 10 and includes the compressor 14 and the expansion valve 18, but also includes some different components. For example, the heat pump system 40 includes an outside heat exchanger 42 and an interior heat exchanger 44 instead of the condenser 16 and evaporator 20 shown in Figure 1 , respectively. The heat pump system 40 further includes a reversing valve 46, which is explained further below. The heat pump system 40 is capable of cooling the passenger cabin 12 in similar manner to the air conditioning system 10, but is also capable of heating the passenger cabin 12, using little extra equipment.

[0061] The outside heat exchanger 42 may be similar to the condenser 16 in the sense that the outside heat exchanger 42 is usable to carry out heat transfer from the refrigerant flowing therethrough to the air that surrounds the outside heat exchanger 42, in order to condense the refrigerant, but is also capable of receiving a flow of refrigerant liquid in the opposite direction therethrough in order to carry out heat transfer thereto from the air that surrounds the outside heat exchanger 42, in order to evaporate the refrigerant.

[0062] The interior heat exchanger 44 may be similar to the evaporator 20 in the sense that the interior heat exchanger 44 is inside the passenger cabin 12 and is usable to carry out heat transfer to the refrigerant flowing therethrough from the air that surrounds the interior heat exchanger 44, in order to evaporate the refrigerant, but is also capable of receiving a flow of refrigerant gas in the opposite direction therethrough in order to carry out heat transfer from the refrigerant to the air that surrounds the interior heat exchanger 44, in order to condense the refrigerant.

[0063] The reversing valve 46 is positionable in a plurality of positions, including a first position (Figure 3A) in which the reversing valve 46 transfers refrigerant flow from the compressor 14 to the outside heat exchanger 42 and from the interior heat exchanger 44 to the compressor 14, and a second position in which the reversing valve 46 transfers refrigerant flow to the interior heat exchanger 44 from the compressor 14 and to the compressor 14 from the outside heat exchanger 42.

[0064] The heat pump system 40 is operable in a first mode (Figure 3A), in which the reversing valve 46 is in the first position, used for cooling the passenger cabin 12, and a second mode (Figure 3B), in which the reversing valve 46 is in the second position, used for heating the passenger cabin 12.

[0065] The first mode (Figure 3A) is described as follows: The refrigerant enters the compressor 12 at a relatively low pressure, and a relatively low temperature. The compressor 12 compresses the refrigerant, to bring the refrigerant to a high pressure, which raises its temperature. As a result, the refrigerant is a high pressure, high temperature gas when leaving the compressor. The refrigerant then passes to the outside heat exchanger 42. The outside heat exchanger 42 acts as a condenser and is used to condense the refrigerant, by carrying out heat transfer from the refrigerant flowing therethrough to the outside air 22 that surrounds the outside heat exchanger 42. Optionally the outside fan 26 is provided to enhance air flow across the outside heat exchanger 42, and therefore enhances heat transfer from the outside heat exchanger 42. The refrigerant then passes through the expansion valve 18, so as to reduce the pressure of the refrigerant. Some of the refrigerant may evaporate due to the reduction in pressure, however, a significant portion of the refrigerant remains liquid. The reduction in pressure of the refrigerant cools the refrigerant. Thus, the refrigerant leaves the expansion valve 18 as a low pressure, low temperature liquid or liquid/gas mix. The refrigerant then passes through the interior heat exchanger 44, which acts as an evaporator and which transfers heat from the interior air 24 to the refrigerant (thereby cooling the interior air 24), in order to raise the temperature of the refrigerant so as to drive the evaporation of the refrigerant. Optionally the interior fan 28 is provided and is used to enhance air flow across the interior heat exchanger 44, and therefore enhances heat transfer from the interior air 24 to the refrigerant. The cooled interior air 24 cools the passenger cabin 12. The refrigerant then passes to the inlet of the compressor 14, where it is compressed again and sent again to the reversing valve 46 in a continuous cycle.

[0066] The second mode (Figure 3B) is described as follows: The refrigerant enters the compressor 12 at a relatively low pressure, and a relatively low temperature. The compressor 12 compresses the refrigerant, to bring the refrigerant to a high pressure, which raises its temperature. As a result, the refrigerant is a high pressure, high temperature gas when leaving the compressor 14. The refrigerant then passes to the interior heat exchanger 44, which acts as a condenser and is used to condense the refrigerant, by carrying out heat transfer from the refrigerant flowing therethrough to the interior air 24 that surrounds the interior heat exchanger 44 (thereby heating the interior air 24). Optionally the interior fan 28 is provided to enhance air flow across the interior heat exchanger 44, and therefore enhances heat transfer from the refrigerant to the interior air 24. The heated interior air 24 heats the passenger cabin 12. The refrigerant then passes through the expansion valve 18, so as to reduce the pressure of the refrigerant. Some of the refrigerant may evaporate due to the reduction in pressure, however, a significant portion of the refrigerant remains liquid. The reduction in pressure of the refrigerant cools the refrigerant. Thus, the refrigerant leaves the expansion valve 18 as a low pressure, low temperature liquid or liquid/gas mix. The refrigerant then passes through the outside heat exchanger 42, which acts as an evaporator and which transfers heat from the outside air 22 to the refrigerant, in order to raise the temperature of the refrigerant so as to drive the evaporation of the refrigerant. Optionally the outside fan 28 is provided and is used to enhance air flow across the outside heat exchanger 42, and therefore enhances heat transfer from the outside air 22. The refrigerant then passes to the inlet of the compressor 14, where it is compressed again and sent again to the reversing valve 46 in a continuous cycle.

[0067] Thus, by moving the reversing valve 46 between the first and second positions, the heat pump system 40 can be used to either heat or cool the passenger cabin, as desired.

[0068] Figure 4 is a pressure-enthalpy diagram illustrating the property changes that the refrigerant undergoes during operation of the heat pump system 40 shown in Figures 3A and 3B. As can be seen the general shape of the curve 30 in Figure 4 is similar to the shape of the curve 30 in Figure 2.

[0069] It will be noted that in a heat pump system such as the heat pump system 40, the refrigerant properties undergo the same cycle of compression, condensation, reduction in pressure, and evaporation, regardless of whether the heat pump system 40 is operating in the first mode or the second mode. Referring to Figure 4, point 32 corresponds to the properties of the refrigerant immediately upstream of the compressor, as before. Point 34 corresponds to the properties of the refrigerant downstream from the compressor 14 and upstream from the outside heat exchanger 42 when operating in the first mode, and downstream from the compressor and upstream from the interior heat exchanger 44 when operating in the second mode. Point 36 corresponds to the properties of the refrigerant downstream from the outside heat exchanger 42 and upstream from the expansion valve 18 when operating in the first mode, and downstream from the interior heat exchanger 44 and upstream from the expansion valve 18 when operating in the second mode. Point 38 corresponds to the properties of the refrigerant downstream from the expansion valve 18 and upstream from the interior heat exchanger 44 when operating in the first mode, and downstream from the expansion valve 18 and upstream from the outside heat exchanger 42 when operating in the second mode.

[0070] DESCRIPTION OF THERMAL MANAGEMENT SYSTEM WITH COOLANT-REFRIGERANT HEAT EXCHANGER

[0071] Figure 5 shows a thermal management system 50 that is more sophisticated than the heat pump system 40 shown in Figures 3A and 3B. The thermal management system 50 shown in Figure 5 includes a refrigerant system 52 and a coolant system 54. In Figure 5, a solid line represents a coolant conduit, and a dashed line represents a refrigerant conduit. The refrigerant system 52 includes a compressor 56, a plurality of control valves shown at V1 , V2, V3, and V4, a plurality of refrigerant check valves shown at CV1 , CV2, CV3 and CV4, a plurality of expansion valves shown at EXV1 , EXV2, and EXV3, an outside heat exchanger 58, an interior evaporator 60, and an interior condenser 62. The control valves V1 , V2, V3 and V4 may be simple on-off valves (e.g. solenoid valves). The outside heat exchanger 58 may be similar to the outside heat exchanger 16 shown in Figures 3A and 3B. The evaporator 60 and the interior condenser 62 may be provided instead of the interior heat exchanger 20 of Figures 3A and 3B, in order to enable enhanced functionality (e.g. both heating and defogging simultaneously), or for other reasons.

[0072] The coolant system 54 includes a first pump 64, a second pump 66, a plurality of control valves shown at 68a and 68b, a coolant check valve shown at 70, a high voltage heater 71 , and a radiator 72. Thermal loads may be present. In the case where the vehicle is an EV, the thermal loads may include, for example, a traction battery 74, and a traction motor 76 (including associated power electronics). A coolant-refrigerant heat exchanger 78 is provided, for heat exchange between the coolant in the coolant system 54 and the refrigerant in the refrigerant system 52. The coolant-refrigerant heat exchanger 78 has a coolant flow path 78a therethrough, and a refrigerant flow path 78b therethrough.

[0073] The operation of the thermal management system 50 is described as follows: The refrigerant system 52 is operable in a greater number of modes than the heat pump system 40 shown in Figures 3A and 3B. Such modes include a first mode, to heat the passenger cabin 12 using heat from the coolant in the coolant system 54 via the coolant-refrigerant heat exchanger 78, a second mode, to heat the passenger cabin 12 using heat from the coolant in the coolant system 54, and also using the outside heat exchanger 58 as an evaporator, and a third mode, to cool the passenger cabin 12, using the outside heat exchanger 58 as a condenser.

[0074] In the first mode, the control valves V1 , V2, V3 and V4 are controlled so as to direct refrigerant flow from the compressor 56, through the control valve V2, and through the interior condenser 62, where the refrigerant condenses and transfers heat to the interior air shown at 24, in order to heat the passenger cabin 12. From the interior condenser 62, the refrigerant passes through the check valve CV1. Downstream from the check valve CV1 , the refrigerant flow may be directed through a first refrigerant flow path 80a through an optional refrigerant-refrigerant heat exchanger 80, through the expansion valve EXV3, through the coolant-refrigerant heat exchanger 78, back through a second refrigerant flow path 80b through the refrigerantrefrigerant heat exchanger 80, and back to the inlet of the compressor 56. In the refrigerant-refrigerant heat exchanger 80, some heat is scavenged from the refrigerant in the first refrigerant flow path 80a to add heat to the refrigerant in the second refrigerant flow path 80b so as to further superheat the refrigerant in the second refrigerant flow path 80b to reduce the chance of any liquid refrigerant being present in that flow that could damage the compressor 56 that is downstream from it.

[0075] In the coolant-refrigerant heat exchanger 78, the refrigerant receives heat from the coolant flowing therethrough, thereby driving evaporation of the refrigerant, which is at low pressure as a result of passing through the third expansion valve EXV3. The coolant may be heated by one or more of several sources. This includes the traction battery 74, and/or the traction motor 76 (and the associated power electronics), and/or the high voltage heater 71 . More specifically, during discharging, and during charging, of the traction battery 74, heat is generated, which is transmitted to the coolant. Additionally the traction motor 76 and the associated power electronics generate heat during operation of the traction motor 76. In some situations however, such as upon vehicle startup when it is very cold outside, the traction battery 74 and the traction motor 76 may not be warm enough to provide sufficient heat to the coolant for heating the refrigerant in the coolant-refrigerant heat exchanger 78. In such situations, the high voltage heater 71 may be operated to heat the coolant, in order to heat the refrigerant in the coolant-refrigerant heat exchanger 78 sufficiently to evaporate the refrigerant. The refrigerant then passes from the coolant-refrigerant heat exchanger 78 to the second refrigerant flow path 80b in the refrigerant-refrigerant heat exchanger 80, and from there to the inlet of the compressor 56.

[0076] Optionally, a receiver/dryer 97 is provided to remove contaminants from the refrigerant, such as oils, water, dirt and debris as these contaminants can damage components such as the compressor 56.

[0077] In the first mode described above, all of the refrigerant flow passes through the coolant-refrigerant heat exchanger 78. In the second mode of operation, only a first portion of the refrigerant passes through the coolant-refrigerant heat exchanger 78 as described above, and a second portion of the refrigerant passes to the first expansion valve EXV1 , where its pressure will be reduced. From there, the second portion of the refrigerant travels to the outside heat exchanger 58, which will act as an evaporator, in order to evaporate the second portion of the refrigerant. The evaporated refrigerant passes from the outside heat exchanger 58 through the control valve V3, through the check valve CV3, and through the second refrigerant flow path 80b in the refrigerant-refrigerant heat exchanger 80 along with the first portion of the refrigerant, and from there to the inlet of the compressor 56.

[0078] In the third mode of operation for the thermal management system 50, the control valves V1 , V2, V3 and V4 are controlled so as to direct refrigerant flow from the compressor 56, through the control valve V1 , through the outside heat exchanger 58, which acts as a condenser, through the check valve CV2, through the first refrigerant flow path 80a through the refrigerant-refrigerant heat exchanger 80, through the second expansion valve EXV2, where the pressure of the refrigerant is reduced, and then through the interior evaporator 60 where the refrigerant is evaporated, thereby cooling the interior air 24, so as to cool the passenger cabin 12. From the interior evaporator 60, the refrigerant passes through the second refrigerant flow path 80b of the refrigerant-refrigerant heat exchanger 80, and from there to the inlet of the compressor 56.

[0079] The thermal management system 50 is advantageous over the heat pump system 40 shown in Figures 3A and 3B, in that the coolant-refrigerant heat exchanger 78 permits heat from the coolant to be used to help heat the refrigerant in situations where such heat is available and/or beneficial.

[0080] DESCRIPTION OF STRUCTURE OF NOVEL COOLANTREFRIGERANT HEAT EXCHANGER

[0081] Reference is made to Figures 6-10, which show a coolant-refrigerant heat exchanger 100 in accordance with an embodiment of the present disclosure. Figure 6 is a perspective view of the coolant-refrigerant heat exchanger 100. Figures 7a and 7b together are a perspective exploded view of the coolant-refrigerant heat exchanger 100. Figure 8 is a magnified perspective view of a portion of the coolantrefrigerant heat exchanger 100. Figure 9 is a sectional view of the coolant-refrigerant heat exchanger 100, and Figure 10 is a partially exploded perspective view of a portion of the coolant-refrigerant heat exchanger 100.

[0082] The coolant-refrigerant heat exchanger 100 may be for use in an electric vehicle 151 shown in Figure 14. The electric vehicle 151 may include the passenger cabin 12, the traction battery 74, and the traction motor 76 (for driving one or more of the wheels shown at 99). The electric vehicle 151 may be any type of vehicle that employs a traction motor and a traction battery for supplying power to the traction motor. The electric vehicle 151 is shown as an SUV, but it could be an automotive, a light-duty truck, a heavy-duty truck, an off-road vehicle, a vehicle used in construction, an aircraft, or any other suitable type of vehicle. Furthermore, the electric vehicle 151 may contain only a traction motor (or several of them) for driving movement of the electric vehicle 151 , or alternatively, it may contain an internal combustion engine, such as a range extender engine to assist in recharging the traction battery 74 when the traction battery 74 at or near depletion. In yet other embodiments, the electric vehicle 151 may be a fuel-cell vehicle, generating electric power via a fuel cell, for powering the traction motor 76. [0083] It will be noted that the traction battery 74 shown in the figures is just one example of an energy source for the electric vehicle 151. In embodiments in which the electric vehicle 151 is a fuel-cell vehicle, the electric vehicle 151 includes a fuelcell stack and may also include a traction battery (albeit a smaller one than in a typical battery-electric vehicle). The fuel-cell stack and the traction battery (if one is provided) would constitute an energy source for the fuel-cell vehicle. In the embodiments shown herein, the energy source is a traction battery that is connected to the traction motor to provide electrical power to the traction motor.

[0084] The electric vehicle 151 may further include a thermal management system 150, which is described in more detail further below in relation to Figures 13- 22. The thermal management system 150 may include the coolant-refrigerant heat exchanger 100.

[0085] The coolant-refrigerant heat exchanger 100 includes a coolant flow path 102 (Figure 10) for transporting coolant (represented by arrows 104 in Figure 10) therethrough, and a refrigerant flow path 106 (Figures 10 and 11) for transporting refrigerant (represented by arrows 108 in Figure 10) therethrough. The coolant flow path 102 and the refrigerant flow path 106 are positioned so as to transfer heat from one of the coolant 104 and the refrigerant 108 to the other of the coolant 104 and the refrigerant 108. In the example, shown, the coolant-refrigerant heat exchanger 100 includes a plurality of flow plates 110. Each flow plate 110 has a first face 112a and a second face 112b shown in Figures 7b and 9, and a flow plate peripheral edge face 114 (Figure 7b). The plurality of flow plates 110 are connected together such that the coolant flow path 102 and the refrigerant flow path 106 are defined between mutually facing ones of the faces of adjacent ones of the plurality of flow plates 110. More specifically, with reference to Figures 9 and 10, in the embodiment shown, the coolant flow path 102 is defined between the second face 112b of the first plate (shown at 110a) and the first face 112a of the second plate (shown at 110b), between the second face 112b of a third plate (shown at 110c) and the first face 112a of a fourth plate (shown at 110d), between the second face 112b of a fifth plate (shown at 110e) and the first face 112a of a sixth plate (shown at 11 Of), and so on. Analogously, the refrigerant flow path 106 is defined between the first face 112a of the second flow plate 110b and the second face 112b of the third flow plate 110c, between the first face 112a of the fourth plate (shown at 110d) and the second face 112b of the fifth flow plate 110e, and so on. In the embodiment shown, there are 32 flow plates 110 which are sealingly joined together.

[0086] As can be seen in Figure 7A, the flow plate peripheral edge face 114 of the flow plates 110 is rectangular with rounded corners (a rounded rectangle) in the embodiment shown. However, it will be understood that the flow plate peripheral edge face 114 could have any other suitable shape, such as a circular shape, an elliptical shape, a regular or irregular polygonal shape with rounded corners having more or fewer than 4 sides or any other suitable shape. The shape of the flow plate peripheral edge face 114 preferably has rounded corners where corners are present, however, corners that have substantially no rounding may be provided instead.

[0087] The flow plates 110 may be made from any suitable material, such as, for example, aluminum. While it is known that aluminum has a higher thermal conductivity than certain materials such as stainless steel, aluminum is not the typical material used for coolant or refrigerant conduits in coolant-refrigerant heat exchangers in vehicles.

[0088] Figure 17 illustrates an intermediate state of manufacture of the coolantrefrigerant heat exchanger 100. As shown in Figure 17, the flow plates 110 each have a flange portion 230 that is used for joining the flow plates 110 together. The flange portions 230 of the flow plates 110 mate with one another. Braze material may be provided between the flange portions 230 and the flow plates 110 may then be heated to melt the braze material so as to sealingly join the flow plates 110 together. The outermost edges of the flange portions 230 are shown at 240. In some embodiments, the outermost edges 240 of the flange portions 230 have a shape that creates a valley 250 between successive ones of the flow plates 110 when they are sealingly joined together.

[0089] The flow plates 110, when sealingly joined together, may form a flow plate assembly 252, as shown in Figure 18. With reference to Figure 7a, in the embodiment shown, a first end cover plate 109 may be provided and may be sealingly joined to a first end of the plurality of flow plates 110 and may thus be included in the flow plate assembly 252. The first end cover plate 109 includes a refrigerant inlet 116a, a refrigerant outlet 116b, a coolant inlet 118a and a coolant outlet 118b. The first end cover plate 109 may be joined to the flow plates 110 in the same way that the flow plates 110 are joined to one another, and may be processed along with the flow plates to further form the heat exchange surface. A refrigerant filter 119 may be provided at the refrigerant inlet 116a to filter contaminants from the refrigerant 108 before it passes through the flow plates 110.

[0090] A second end cover plate 111 (Figure 9) may be provided and may be sealingly joined to a second end of the plurality of flow plates 110 and may thus be included in the flow plate assembly 252. The second end cover plate 111 may be joined to the flow plates 110 in the same way that the flow plates 110 are joined to one another, and may be processed along with the flow plates to further form the heat exchange surface.

[0091] The flow plate assembly 252 has a first end face 254, a second end face 256, and a flow plate assembly peripheral edge face 258, which are discussed further below. The flow plate assembly peripheral edge face 258 may itself have any suitable shape. For example, the flow plate assembly peripheral edge face may include a plurality of sides 258a and a plurality of corners 258b. The corners 258b may be large radius corners, as shown, or they may be small radius corners. The flow plate assembly peripheral edge face 258 may include four sides 258a, and may be generally rectangular, as shown, or it may have any other suitable number of sides 258a, either fewer than or greater that the number of sides shown in Figure 18. Furthermore, the sides 258a need not be straight, as shown. The sides 258a could have any other suitable shape.

[0092] With reference to Figures 7b and 8, each of the flow plates 110 has a plurality of ridges 120 thereon on each of the first and second faces 112a and 112b, which define grooves which act as channels for the flow of refrigerant 108 or coolant 104 as the case may be. In the embodiment shown, the ridges 120 on each flow plate 110 form a pattern that alternates with the pattern of the ridges 120 on each adjacent flow plate 110. In other words, the ridges on the odd-numbered flow plates 110, (i.e., the first plate, the third plate, the fifth plate, etc.), form a pattern that alternates with the pattern on the even-numbered flow plates 110, (i.e. the second plate, the fourth plate, the sixth plate, etc.). The patterns of the ridges 120 on both the odd-numbered flow plates 110 and the even-numbered flow plates 110 may be herringbone patterns. [0093] Figure 9 shows a sectional view of the coolant-refrigerant heat exchanger 100. As can be seen, the flow plates 110 have first and second refrigerant pass-through apertures 113 and first and second coolant pass-through apertures 115. The space between the first flow plate 110a and the second flow plate 110b is a first coolant space 121 . The space between the second flow plate 110b and the third flow plate 110c is a first refrigerant space 123. The space between the third flow plate 110c, the fourth flow plate 110d is a second coolant space 121 , and so on. The space between the fourth flow plate 110d and the fifth flow plate 110e is a second refrigerant space 123. The spaces between the flow plates 110 alternate between coolant spaces 121 and refrigerant spaces 123 throughout the series of flow plates 110. As can be seen, in the region of the refrigerant pass-through apertures 113, the first flow plate 110a is sealingly engaged with the second flow plate 110b, the second flow plate 110b is spaced from the third flow plate 110c, the third flow plate 110c is sealingly engaged with the fourth flow plate 110d, and the fourth flow plate 110d is spaced from the fifth flow plate 110e, and so on. Thus, the refrigerant 108 can flow in the refrigerant spaces 123. Additionally, in the region of the coolant pass-through apertures 115, the first flow plate 110a is spaced from the second flow plate 110b, the second flow plate 110b is sealingly engaged with the third flow plate 110c, the third flow plate 110c is spaced from the fourth flow plate 110d, the fourth flow plate 110d is sealingly engaged with the fifth flow plate 110e, and so on. Thus, the coolant 104 can flow in the coolant spaces 121.

[0094] The coolant-refrigerant heat exchanger 100 further includes a secondary heater 122 that is positioned to heat both the refrigerant 108 and the coolant 104 while in the coolant-refrigerant heat exchanger 100. The secondary heater 122 may be an induction heater and may thus include an induction coil 260 which extends in a selected path, and is positioned proximate to the flow plates such that the induction coil is energizable to heat the flow plates by induction.

[0095] The secondary heater 122 may further include any suitable driver circuit for generating an oscillating current in the induction coil 260. The driver circuit may be an electronic oscillator that draws current from a DC power source such as the traction battery 74 or from a secondary battery (not shown) that is at a lower voltage than the traction battery 74, and converts the current to AC. Alternatively, the driver circuit may be powered by an AC power source, such as a power source that itself draws power from the traction battery 74 or from the aforementioned optionally- provided secondary battery and converts the current to AC. The driver circuit may generate any suitable type of wave in the current, such as a sine wave, a square wave or a triangle wave. The driver circuit may be provided as part of the coolant-refrigerant heat exchanger 100 or may be provided separately from the coolant-refrigerant heat exchanger 100.

[0096] The induction coil 260 may surround the plurality of flow plates 110, as shown in Figures 19-31 . In the embodiment shown in Figure 19 the induction coil 260 surrounds the flow plate assembly peripheral edge face 258. However, in alternative embodiments, the induction coil 260 could surround the plurality of flow plates 110 in another way, such as by extend along the first and second end faces 254 and 256 and across the top and bottom portions of the flow plate assembly peripheral edge face 258.

[0097] In the embodiment shown in Figures 19 and 20, the induction coil 260 is mounted directly in contact with the flow plate assembly peripheral edge face 258. Because the flow plate assembly peripheral edge face 258 may have valleys 250, such as those shown in Figure 17, the valleys 250 cause at least a portion of the flow plate assembly peripheral edge face 258 to be spaced from the induction coil 260. It will be noted that this spacing between the flow plate assembly peripheral edge face 258 and the induction coil 260 does not raise any risk of damage to the induction coil 260 or to the flow plate assembly 252. This is because induction heating does not require the heater to be in direct contact with the element to be heated, unlike film heaters which can require such contact in order to eliminate the potential for hot spots in the heater, and the consequent damage that those hot spots cause.

[0098] The induction coil 260 includes an electrical conductor 262, which may be made from any suitable electrically conductive material such as copper. In the embodiment shown in Figures 19 and 20, the electrical conductor 262 is enveloped in an electrical insulation jacket 264, so as to prevent current from being conducted from the electrical conductor 262 into the flow plates 110. The electrical insulation jacket 264 may be made from any suitable material. For example, the electrical insulation jacket 264 may be made from fiberglass, or a suitable polymer. In other embodiments, the electrical insulation jacket 264 need not be provided. [0099] In the embodiment shown, the induction coil 260 extends helically about the flow plate assembly peripheral edge face 258. The induction coil 260 includes a plurality of loops 266, which may optionally be kept spaced from one another, as shown in Figures 19 and 20. However, it is alternatively possible for the loops 266 of the induction coil 260 to be positioned in contact with one another, particular in embodiments in which the electrical insulation jacket 264 is provided.

[00100] In the embodiment shown, the induction coil 260 may be connected to a suitable source that generates an oscillating current in the induction coil 260, which, in turn, generates heat via induction, directly in the flow plates 110.

[00101] Reference is made to Figure 21 , which shows another embodiment. In Figure 21 , the coolant-refrigerant heat exchanger 100 further includes an inner thermal insulation layer 268 that surrounds the flow plate assembly peripheral edge face 258, and is surrounded by the induction coil 260. The inner thermal insulation layer 268 may be made from a material that is not electrically conductive. As a result, the induction coil 260 is able to generate heat in the flow plates 110 via induction through the inner thermal insulation layer 266 with relatively little loss of efficiency. Examples of material from which the thermal insulation layer could be made include polymeric foam, fiberglass, solid polymeric material, and/or aerogel material. Any other suitable material may be used. The inner thermal insulation layer 268 inhibits the leakage of heat from the flow plates 110, which increases the efficiency of the coolant-refrigerant heat exchanger 100 in transferring heat to the coolant and/or refrigerant that is passing therethrough. The induction coil 260 preferably includes both an electrical conductor 262 and an electrical insulation jacket 264, however it is at least theoretically possible for the induction coil 260 to omit the electrical insulation jacket 264. In such an embodiment the loops 266 are positioned so as to be spaced from one another to prevent unintended electrical conduction between the sides of the loops 266. The inner thermal insulation layer 268 also helps to inhibit the heating of the electrical insulation jacket 264 from the heated flow plates 110, thereby protecting the electrical insulation jacket 264 from possible damage.

[00102] Reference is made to Figure 22, which shows another embodiment. In Figure 22, the coolant-refrigerant heat exchanger 100 further includes the inner thermal insulation layer 268 that surrounds the flow plate assembly peripheral edge face 258, and is surrounded by the induction coil 260, and further includes an outer thermal insulation layer 270. The inner and outer thermal insulation layers 268 and 270 may be made from a material that is not electrically conductive. As in the embodiment in Figure 21 , the induction coil 260 is able to generate heat in the flow plates 110 via induction through the inner thermal insulation layer 266 with relatively little loss of efficiency, while the inner thermal insulation layer 267 inhibits the leakage of heat from the flow plates 110, and the outer thermal insulation layer 270 further inhibits the leakage of heat from the flow plates 110.

[00103] Reference is made to Figure 23, which shows another embodiment. In Figure 23, the coolant-refrigerant heat exchanger 100 further includes a carrier 272 that includes at least one conductor groove 274 which holds the induction coil 260. In the embodiment shown, the carrier 272 may be made from any suitable material such as an electrically insulative material such as a non-conductive polymer, cellulose, fiberglass, glass, or any other suitable material. As a result, it is possible for the induction coil 260 to include the electrical conductor 262 and to omit the electrical insulation jacket 264. While a plurality of smaller grooves 274 are shown in the carrier 272 in the embodiment shown, it is possible for them to be replaced by a single helically-extending groove. The carrier 272 may further be manufactured from a material that is thermally insulative and may thus be referred to as an inner thermal insulation layer. As such it may be said that the inner thermal insulation layer includes at least one conductor groove 274 which holds the induction coil 260.

[00104] The carrier 272 surrounds the flow plate assembly peripheral edge face 258, and is surrounded by (and holds, via the at least one conductor groove 274) the induction coil 260.

[00105] Reference is made to Figures 24 and 25, which show another embodiment. In Figure 23, the coolant-refrigerant heat exchanger 100 further includes at least one susceptor 276 positioned between the flow plate assembly peripheral edge face 258 and the induction coil 260. In the embodiment shown, there are a plurality of susceptors 276. For example, four susceptors 276 may be provided which engage each side 258a of the flow plate assembly peripheral edge face 258.

[00106] The flow plates 110 have a first permeability and the at least one susceptor 276 has a second permeability that is greater than the first permeability. The susceptors 276 may therefore have an improved capability to convert the electromagnetic energy from the induction coil 260 to heat as compared to the flow plates 110 themselves. This is because the induction coil can generate heat in the susceptors 276 by magnetic hysteresis (due to their greater permeability) in addition to generating heat by eddy currents. By contrast, due to the low permeability of the flow plates 110 in embodiments in which they are made from a low permeability material such as aluminum, the induction coil 260 does not generate a significant amount of heat in the flow plates 110 via magnetic hysteresis. An example of a suitable material for the susceptors 276 is ferritic steel. Any other suitable material could be used however. For example, the susceptors 276 may be made from any suitable material that contains iron.

[00107] The at least one susceptor 276 is positioned to be heated inductively by the induction coil 260 and is engaged at least indirectly with the flow plate assembly 252 so as to heat the flow plate assembly 252 by thermal conduction. The susceptors 276 may be engaged with the flow plate assembly peripheral edge face 258 by a thermally conductive epoxy, a glue or some suitable adhesive layer. Alternatively, the susceptors 276 may be engaged with the flow plate assembly peripheral edge face 258 by being held in engagement mechanically such as by a plurality of straps, clamps or other mechanical elements pushing or pulling the susceptors 276 into engagement with the flow plate assembly peripheral edge face 258.

[00108] In the embodiment shown, the susceptors 276 each engage each one of the sides 258a of the flow plate assembly peripheral edge face 258, however, the susceptors 276 may each engage any suitable parts of the flow plate assembly peripheral edge face 258.

[00109] As a result of the presence of the susceptors 276, the induction coil 260 heats the susceptors 276 and the susceptors 276 in turn heat the flow plates 110, at least in embodiments where the susceptors 276 absorb most of the electromagnetic energy from the induction coil 260.

[00110] Additionally, it will be noted that, in embodiments in which the susceptors are made from steel and the flow plates 110 are made from aluminum, the susceptors hold heat for a longer period of time than aluminum. As a result, it may be possible to turn off the induction coil 260 at times while the susceptors 276 continue to heat the flow plates 110 and therefore continue to impart heat to the coolant and/or the refrigerant contained in the flow plates 110.

[00111] Reference is made to Figure 26, which show another embodiment. In Figure 26, the coolant-refrigerant heat exchanger 100 further includes the inner thermal insulation layer 268, which surrounds the flow plate assembly peripheral edge face 258, is positioned outside of the at least one susceptor 276, and is surrounded by the induction coil 260. In this embodiment, the inner thermal insulation layer 268 is non-conductive as in other embodiments, and so the induction coil 260 heats the at least one susceptor 276 through the inner thermal insulation layer 268. In a further embodiment, the coolant-refrigerant heat exchanger 100 could further include the outer thermal insulation layer 270 to similar effect as the outer thermal insulation layer 270 provides in other embodiments shown and described.

[00112] It will be noted that, in any instance where the term ‘the susceptors’ is used, it is intended for greater readability. It will be noted that the term ‘the susceptors’ could be replace with ‘the at least one susceptor’ in any statement made herein, unless it is a statement that necessarily and obviously requires the presence of a plurality of susceptors 276.

[00113] Reference is made to Figure 27, which shows another embodiment, which is similar to the embodiment shown in Figures 25 and 25 but which provides a plurality of susceptors 276 that do not extend beyond the sides 258a of the flow plate assembly peripheral edge face 258, and which are chamfered (at chamfers 278) to reduce the tightness of the bends of the induction coil 260.

[00114] Reference is made to Figure 28, which shows another embodiment, which is similar to the embodiment shown in Figure 27 but which provides the carrier 272, which surrounds the flow plate assembly peripheral edge face 258, and is surrounded by (and holds, via the at least one conductor groove 274) the induction coil 260. The carrier 272 may be as described in relation to Figure 23 (e.g. in terms of material properties), with a difference being that the carrier 272 in Figure 28 is positioned between the at least one susceptor 276 and the induction coil 260.

[00115] Reference is made to Figure 29, which shows another embodiment, which may be similar to the embodiment shown in Figure 26, but wherein the at least one susceptor 276 includes a first C-shaped susceptor 276a and a second C-shaped susceptor 276b. The first and second C-shaped susceptors 276a and 276b together at least partially surround the flow plate assembly peripheral edge face 258. In the embodiment shown, the first and second C-shaped susceptors 276a and 276b each have first and second free ends shown at 280 and 282 respectively, such that the first free ends 280 of the first and second C-shaped susceptors 276a and 276b are spaced from one another by a first gap G1 , and the second free ends 282 of the first and second C-shaped susceptors 276a and 276b are spaced from one another by a second gap G2. The first and second gaps G1 and G2 are provided so as to ensure that the first and second C-shaped susceptors 276a and 276b do not interfere with each other during mounting onto the flow plate assembly 252, to ensure that there is good contact between the opposing inner surfaces shown at 284 of the first and second C-shaped susceptors 276a and 276b and the mating sides 258a of the flow plate assembly peripheral edge face 258. The first and second C-shaped susceptors 276a and 276b may otherwise be as described in relation to the embodiment shown in Figures 25 and 25, e.g. in terms of material properties.

[00116] As in other embodiments that incorporate at least one susceptor 276, the first and second C-shaped susceptors 276a and 276b may be held in engagement with the flow plate assembly peripheral edge face 258 by a thermally conductive epoxy, a glue or some suitable adhesive layer.

[00117] Reference is made to Figures 30 and 31 , which show another embodiment, which may be similar to the embodiment shown in Figure 28, and includes at least one susceptor which is the first C-shaped susceptor 276a and the second C-shaped susceptor 276b, but in this embodiment the first C-shaped susceptor 276a and the second C-shaped susceptor 276b together include the at least one conductor groove 274. As a result of the conductor groove 274 being provided directly in the at least one susceptor 276 there is no need for a separate carrier for holding the induction coil 260. However, it will be understood that the induction coil 260 will include the electrical insulation jacket 264 in order to prevent electrical conduction into the first C-shaped susceptor 276a and the second C-shaped susceptor 276b. Additionally, the electrical insulation jacket 264 will be of a material that can withstand the heat that is generated in the first C-shaped susceptor 276a and the second C-shaped susceptor 276b since the electrical insulation jacket 264 is in direct contact therewith. [00118] In Figure 31 , a layer of a thermally conductive epoxy, a glue or some suitable adhesive layer is shown at 285.

[00119] In Figure 31 , the plurality of flow plates 110 are shown as a single element, even though the sectional view shown would pass through the thicknesses of several of the flow plates 110.

[00120] Reference is made to Figures 32 and 33, which show another embodiment, which may be similar to the embodiment shown in Figure 28, and includes at least one susceptor 276 which is positioned to be heated inductively by the induction coil 260 and which is engaged at least indirectly with the flow plate assembly 252 so as to heat the flow plate assembly 252 by thermal conduction.

[00121] In the embodiment shown, the flow plate assembly 252 includes at least one susceptor aperture 286 that extends through at least some of the flow plates 110. The at least one susceptor 276 is positioned in the at least one susceptor aperture 286. In the embodiment shown, the at least one susceptor 276 includes four susceptors 276 however any suitable number of susceptors 276 may be used. In the embodiment shown, each of the susceptors 276 is tubular. However, it is alternatively possible for each susceptor 276 to be a solid rod. In the embodiment shown, each of the susceptors 276 is cylindrical. However, it is alternatively possible for each susceptor 276 to be have other shapes such as a rectangular prism.

[00122] In Figure 33, the plurality of flow plates 110 are shown as a single element, even though the sectional view shown would pass through the thicknesses of several of the flow plates 110.

[00123] The material properties of the at least one susceptor 276 in the embodiment shown in Figures 32 and 33 may be the same as those for any of the other susceptors 276 shown and described herein.

[00124] Reference is made to Figures 34 and 35, which show another embodiment, which may be similar to the embodiment shown in Figures 32 and 33, and includes at least one susceptor 276 which is positioned to be heated inductively by the induction coil 260 and which is engaged at least indirectly with the flow plate assembly 252 so as to heat the flow plate assembly 252. In the embodiment shown the at least one susceptor 276 is positioned in at least one susceptor aperture 286, as in the embodiment shown in Figures 32 and 33. In the embodiment shown, the at least one susceptor 276 includes four susceptors 276, each of which may be cylindrical (or any other suitable shape) and tubular (or solid), as with the at least one susceptor 276 in Figures 32 and 33. In the embodiment shown in Figures 34 and 35 however, the coolant-refrigerant heat exchanger 100 includes a plurality of induction coils 260 instead of one induction coil 260, and each induction coil 260 has an associated one of the at least one susceptor 276 and heats the associated one of the at least one susceptor 276. In the embodiment shown, each induction coil 260 extends inside the associated one of the at least one susceptor 276.

[00125] It will be noted that Figure 35 omits certain elements so as not to obscure other elements. For example one of the susceptor apertures 286 is shown without a susceptor therein, however during operation there would be a susceptor 276 present in that susceptor aperture 286.

[00126] In any embodiment described herein, it will be understood that the inner thermal insulation layer 268 may be provided somewhere between the induction coil 260 and the at least one susceptor 276 if at least one susceptor 276 is provided, or somewhere between the induction coil 260 and the flow plate assembly 252 if no susceptors are provided.

[00127] It will be noted that the at least one susceptor 276 in each of the embodiments has been described as having a greater permeability than the permeability of the flow plates 110 in order to generate heat via magnetic hysteresis. However, it will also be noted that the at least one susceptor 276 may also have a greater resistivity to current than the resistivity of the flow plates 110. Materials with a higher resistivity are heated more as a result of inductance than materials that have a lower resistivity. Accordingly, the at least one susceptor 276, which may be made from a type of steel, may have a higher resistivity than the flow plates 110, which may be made from aluminum, and may therefore be better heated by the induction coil 260 than the flow plates 260 would be in the embodiment in Figure 19 where the induction coil 260 is heating the flow plates 110 directly (where the flow plates 110 are made from a low resistivity material such as aluminum). In some embodiments, the at least one susceptor 276 may be made from a material that has relatively higher resisitivity than that of the flow plates 110 and not necessarily a material that has a higher permeability than that of the flow plates 110. In a preferred embodiment however, the at least one susceptor 276 is made from a material that has both higher permeability and higher resistivity than that of the flow plates 110.

[00128] Worded another way, heating by induction is caused by one or both of: heating by generating eddy currents in the body to be heated (e.g. the flow plates 110 and/or the susceptor 276), and heating by generating magnetic hysteresis in the body to be heated (e.g. in the susceptor 276). In non-magnetic materials such as aluminum, then heating would only occur by generating eddy currents. In materials that are ferritic, such as certain types of steel, then heating can occur by both generating eddy currents and by generating magnetic hysteresis. The heating that would occur by generating eddy currents alone may be greater in the steel than it would be in the aluminum due to the higher resistivity present in the steel. In addition, the heating that is generated by magnetic hysteresis is present in ferritic steels and not present in aluminum.

[00129] While one or more induction coils 260 have been shown which are wrapped helically about an axis either to surround an element such as the flow plate assembly, or to be surrounded by an element such as a susceptor 476, it will be noted that the induction coil 260 may be an electric trace that is provided in a generally spiral arrangement in a plane on a substrate, or in a plate but as a self-supporting element that is not printed on a substrate. Such induction coils are provided currently in some induction cooktops. One or more such induction coils could be positioned on each side 258a of the flow plate assembly peripheral edge face 258 in order to heat the flow plates 110 or to heat one or more susceptors 276 that are positioned to heat the flow plates 110.

[00130] While the at least one susceptor 276 has been provided to assist in heating the flow plates 110 it will also be noted that at least one guard susceptor may be used to draw magnetic flux lines away from any elements that are to be protected, such as any electronic components of the coolant-refrigerant heat exchanger 100. Such embodiments may employ at least one guard susceptor that is outside of the induction coil 260, and which may have an outer thermal insulation layer 280 positioned outside of that. The elements to be protected such as the aforementioned electronics may be positioned outside of the outer thermal insulation layer 280. The guard susceptor would ensure that no magnetic field would extend beyond itself, thereby ensuring that inductive heating of the aforementioned electronics (or any other element to be protected) does not take place.

[00131] It will be noted that the use of the induction coil 260 for heating the flow plate assembly 252 is particularly advantageous in high wattage applications, such as for larger thermal management systems for large vehicles such as buses and the like. It will also be noted that the use of the induction coil 260 may be applicable to a heat exchanger that does not transport both refrigerant and coolant and does not carry out heat exchange between the two fluids. For example, it is possible for the induction coil 260 to be used in at least some embodiments on a vessel that carries only one fluid such as refrigerant only, or coolant only. Such a vessel may be similar to the coolant-refrigerant heat exchanger but might only include two ports instead of four ports, and may be formed from a plurality of flow plates similar to the flow plates 110 or may have some other suitable structure.

[00132] Aside from the induction coil 260 described above, the secondary heater 122 may include a first end heater 122b that is engaged with the first flow plate 110a for imparting heat into the plurality of flow plates 110 through the thickness of the first flow plate 110a, and a second end heater 122c for imparting heat into the plurality of flow plates 110 through the thickness of the second end cover plate 111. A heat spreader plate 125 may be provided between the second end heater 122c and the second end cover plate 111. The first end heater 122b and the second end heater 122c may each employ an induction coil that is shaped in a spiral as described above.

[00133] A feature of the secondary heater 122 is that it is sized to evaporate all of the refrigerant 108 passing through the coolant-refrigerant heat exchanger 100 (i.e. all the refrigerant 108 in the refrigerant flow path 106), so as to ensure that substantially all of the refrigerant 108 can be evaporated in the coolant-refrigerant heat exchanger 100 without any heat input to the refrigerant 108 from the coolant 104 in the coolant flow path 102. In some embodiments, the secondary heater 122 is sized to superheat all the refrigerant in the refrigerant flow path 106 in order to ensure that all of the refrigerant 108 is evaporated and that substantially none of the refrigerant 108 remains in its liquid phase. [00134] A controller 124 may be provided for controlling the operation of the secondary heater 122. Electrical connections shown at 126 and 128 are provided for providing power to the secondary heater 122 and for providing power to the controller 124.

[00135] A heat exchanger housing 130 may be provided for housing the abovedescribed components. The housing 130 may include a first housing portion 130a and a second housing portion 130b that is sealingly connected to the first housing portion 130a. O-rings 132 may be provided for sealing around the apertures shown at 134 in the housing 130 that permit the pass-through of the coolant inlet 118a, the coolant outlet 118b, the refrigerant inlet 116a and the refrigerant outlet 116b. Another seal member 136 is provided between the refrigerant filter 119 and the refrigerant inlet 116a.

[00136] Figure 11 shows a schematic representation of the coolant spaces 121 and the refrigerant spaces 123 and the routing of the coolant flow path 102 and the refrigerant flow path 106 in the embodiment shown in Figures 6-10. As can be seen, the coolant 104 travels from the coolant inlet 118a, through to the coolant spaces 121 and then along the coolant spaces 121 and back to the coolant outlet 118b. Similarly, the refrigerant 108 travels from the refrigerant inlet 116a, through to the refrigerant spaces 123 and then along the refrigerant spaces 123 and back to the refrigerant outlet 116b. Thus, in the embodiment shown in Figure 11 (and Figures 6-10), the coolant outlet 118b and the refrigerant outlet 116b are both at the same end of the plurality of flow plates 110 as the coolant inlet 118a and the refrigerant inlet 116a. In an alternative embodiment shown in Figure 12, the first end cover plate 109 and the second end cover plate 111 are configured to each have one inlet and one outlet. For example, the first end cover plate 109 may have the coolant inlet 118a and the refrigerant outlet 116b, and the second end cover plate 111 may have the coolant outlet 118b and the refrigerant inlet 116a. Thus, the coolant 104 may flow across the flow plates 110 from the first end to the second end, and the refrigerant 108 may flow across the flow plates 110 from the second end to the first end.

[00137] Regardless of whether the coolant flow path 102 and the refrigerant flow path 106 are as shown in Figures 6-11 , or are as shown in Figure 12, the coolant flow path 102 and the refrigerant flow path 106 may be said to be positioned in order to transfer heat from one of the coolant 104 and the refrigerant 108 to the other of the coolant 104 and the refrigerant 108, and the secondary heater 122 may be said to be positioned to heat both the refrigerant 108 and the coolant 104 in the coolantrefrigerant heat exchanger 100.

[00138] Several advantageous features of the coolant-refrigerant heat exchanger 100 are described as follows: The coolant-refrigerant heat exchanger 100 includes a plurality of flow plates 110. It has been found to be effective to provide the secondary heater 122 in the form of a band heater 122a that extends along substantially all of the peripheral edges of the flow plates 110, and also to provide the first end heater 122b, and to provide the second end heater 122c, such that heat is transferred through the height, the width, and through the thickness of the flow plates 110. The peripheral edge heater 122a and the first and second end heaters 122b and 122c may be solid elements formed from sheet material that is joined to the flow plates 110 or to the first and second end cover plates 109 and 111 respectively in any suitable way such as by a suitable adhesive. In some embodiments, one or more of the peripheral edge heater 122a and the first and second end heaters may be in the form of a film heater that is printed directly onto the surface on which it is intended to transfer heat to.

[00139] DESCRIPTION OF LAYOUT OF THERMAL MANAGEMENT SYSTEM INCORPORATING THE NOVEL COOLANT-REFRIGERANT HEAT EXCHANGER

[00140] Reference is made to Figure 13, which shows a thermal management system 150 for an electric vehicle, in accordance with an embodiment of the present disclosure. The electric vehicle is shown at 151 in Figure 14.

[00141] The thermal management system 150 may have a similar layout to the thermal management system 50 shown in Figure 5, and may have a refrigerant system 152 and a coolant system 154. Some differences between the thermal management system 150 and the thermal management system 50 are described as follows. One difference is that the high voltage heater 71 and its associated coolant conduit of Figure 5 are not necessary and are omitted from the thermal management system 150. Additionally, the coolant system 154 includes a battery loop 154a and a motor loop 154b, which are connected to one another by a first transfer conduit 156 and a second transfer conduit 158. The coolant system 154 further includes an additional 3-way valve relative to the coolant system 54 of the thermal management system 50. Thus, the coolant system 154 has a first 3-way valve 160, a second 3-way valve 162 and a third 3-way valve 164, and further has a battery loop pump 166, and a motor loop pump 168. Additionally, the coolant system 154 further includes a coolant check valve 169 on the second transfer conduit 157. Additionally, the coolant system 154 includes a battery loop bypass conduit 158 and a motor loop bypass conduit 159, which are not present in the coolant system 54. The arrangement of the refrigerant system 152 may be similar to that of the refrigerant system 52. While specific configurations for the coolant system 154 and the refrigerant system 152 are shown and while specific types of valves (e.g. on-off type control valves, 3-way valves, and check valves) are shown, it will be noted that the coolant system 154 and the refrigerant system may be configured differently. As a simple example, the 3 way valves 160, 162 and 164 could be replaced with a plurality of on-off type valves. Another simple example is that the check valves in both the refrigerant and coolant systems 154 and 152 could also be replaced with on-off type control valves. Additionally, the control valves V1 , V2, V3 and V4 and their associated refrigerant conduits could be replaced by a different arrangement of conduits, with a different number of valves including for example one or more 3-way valves.

[00142] A control system, shown at 170, may be provided for controlling the operation of the thermal management system 150. The control system 170 may include a PCB (printed circuit board) 170a on which there is a processor 170b and a memory 170c. The control system 170 may be said to be operatively connected to the control valves V1 , V2, V3 and V4, the expansion valves EXV1 , EXV2 and EXV3, the 3-way valves 160, 162 and 164, and the secondary heater 122 in order to control their operation. Lines representing wires to show the connection between the PCB 170a and the aforementioned valves and secondary heater are not shown in Figure 13 so as not to render these figures more difficult to understand. Furthermore, the control system 170 may include several sensors such as a cabin temperature sensor 172, a refrigerant temperature sensor 174 at the refrigerant inlet 116a of the coolantrefrigerant heat exchanger 100, and a secondary heater temperature sensor 176 which are all connected to the PCB 170a in order to transmit signals to the processor 170b related to the air temperature of the passenger cabin 12, the refrigerant temperature at the refrigerant inlet 116a of the coolant-refrigerant heat exchanger 100 and the temperature of the secondary heater 122, respectively.

[00143] It will be noted that the control system 170 need not include only the single PCB 170a, the processor 170b and the memory 170c. It is alternatively possible for the control system 170 to include a plurality of PCBs at various locations in the electric vehicle 151 , each of which has one or more processors and memory. For example, the PCB 170a may be only a part of the control system 170, and may be part of an ECM (electronic control module) for the electric vehicle 151 that controls the operation of many subsystems in the electric vehicle 151. The control system 170 may further include the controller 124 in the coolant-refrigerant heat exchanger 100. Communication between the PCB 170a and the controller 124 may be via a wired connection or may occur via a wireless connection.

[00144] Furthermore, it is not necessary for any of the temperature sensors 172, 174 and 176 to be directed connected to or to directly communicate with, the PCB 170a. For example, the secondary heater temperature sensor 176 may communicate directly with the controller 124, which in turn, may transmit the information to the PCB 170a.

[00145] A significant difference between the thermal management system 150 and the thermal management system 50 is that the thermal management system 150 includes the coolant-refrigerant heat exchanger 100 instead of the coolant-refrigerant heat exchanger 78.

[00146] DESCRIPTION OF THERMAL MANAGEMENT SYSTEM IN CABIN HEATING MODE WITH THE SECONDARY HEATER

[00147] Figure 13 shows the thermal management system 150 in a cabin heating mode using the secondary heater 122. In this mode, the control valves V1 , V3, and V4 are closed, and the control valve V2 is open, and the expansion valves EXV1 and EXV2 are closed and the expansion valve EXV3 is open.

[00148] The mode shown in Figure 13 may be used at vehicle startup in situations where the ambient temperature is below -15 degrees Celsius. In such situations, it is desirable to operate the refrigerant system 152 so as to heat the passenger cabin 12. Accordingly, the refrigerant 108 will flow through the interior condenser 62 in order to heat the interior air 24 of the passenger cabin 12. However, operation of the outside heat exchanger 58 as an evaporator may not be desirable, as there is a risk, depending on the level of humidity in the ambient air 22, of ice forming on the outside heat exchanger 58 as heat is drawn from the ambient air 22 into the outside heat exchanger 58, which would hamper its operation.

[00149] Accordingly, it is desirable to use the coolant-refrigerant heat exchanger 100 as the evaporator. However, the coolant 104 is below -15 degrees Celsius, and neither the traction battery 74 nor the traction motor 76 are sufficiently warm to provide sufficient heat to the coolant 104 for use in the coolant-refrigerant heat exchanger 100 to drive evaporation of the refrigerant 108. Furthermore, the 3-way valves 160 and 162 may be positioned to isolate the battery loop 154a from the motor loop 154b, and to bypass the coolant-refrigerant heat exchanger 100 in order to permit the traction battery 74 to warm up to its optimal operating temperature quickly.

[00150] Furthermore, in some situations the ambient temperature may be sufficiently low that the pressure of the refrigerant 108 is less than 1 atmosphere. For example, if one examines the pressure-enthalpy chart shown in Figure 15, which relates to the refrigerant 108 used in the thermal management system 150, it can be seen that, when the temperature of the refrigerant is below approximately -30 degrees Celsius, the pressure of the refrigerant 108 drops below 1 atmosphere. As a result, during operation of the compressor 56 in such an environment, it is possible to draw in contaminants into the refrigerant system 152 since the pressure at the inlet of the compressor 56 is less than the ambient pressure outside of the refrigerant system 152. Such contaminants can include particulate, moisture, or any other types of contaminants. Such contaminants can be harmful to the compressor 56 and can reduce the performance of the refrigerant system in any case.

[00151] In this situation, the control system 170 operates the coolant-refrigerant heat exchanger 100 in a secondary-heat-only mode in which the secondary heater 122 evaporates substantially all the refrigerant 108 in the refrigerant flow path 106 without any heat input from the coolant 104 in the coolant flow path 102. In some embodiments, the secondary heater 122 is heated sufficiently to superheat the refrigerant 108 in order to ensure that substantially all of the refrigerant 108 is evaporated and that substantially none of the refrigerant 108 remains in its liquid phase.

[00152] Thus, by providing the secondary heater 122 (Figure 7b, 8), a sufficient amount of heat can be imparted to the refrigerant 108 in the coolant-refrigerant heat exchanger 100 to raise the temperature of the refrigerant 108 to above the threshold temperature at which the refrigerant 108 has a pressure of 1 atmosphere.

[00153] The mode of operation shown in Figure 13 is just an example of a secondary-heat-only mode for the thermal management system 150, in which the secondary heater 122 evaporates the refrigerant 108 in the refrigerant flow path 106 without any heat input from the coolant 104 in the coolant flow path 102. When the control system 170 operates the thermal management system 150 in the mode shown in Figure 13, the control system 170 may be said to be operating the coolant-refrigerant heat exchanger 100, and may be said to programmed to operate the coolantrefrigerant heat exchanger 100, in a secondary-heat-only mode in which the secondary heater 122 evaporates the refrigerant 108 in the refrigerant flow path 106 without any heat input from the coolant 104 in the coolant flow path 102.

[00154] DESCRIPTION OF MODIFIED PRESSURE-ENTHALPY CHART

[00155] With reference to Figure 15, the dashed line curve shown at 180 represents the changes in the properties of the refrigerant 108 as it passes through the refrigeration system 152 shown in Figure 13. Point 182 represents the properties of the refrigerant immediately upstream of the compressor 14 after the refrigerant 108 has been heated by the secondary heater 122 for a period of time. As can be seen, the temperature of the refrigerant 108 at point 182 is above the aforementioned threshold temperature. Accordingly, the pressure of the refrigerant 108 at point 182 is above 1 atmosphere, thereby preventing the ingress of contaminants into the refrigerant system 152. Curve segment 180a is representative of the change in the properties of the refrigerant 108 due to operation of the compressor 56. Point 184 is representative of the properties of the refrigerant 108 downstream of the compressor 56 and upstream from the interior condenser 62. As can be seen, the pressure and the temperature of the refrigerant 108 both increase between point 182 and point 184. [00156] Curve segment 180b is representative of the change in the properties of the refrigerant 108 due to operation of the interior condenser 62. Point 186 is representative of the properties of the refrigerant 108 immediately downstream of the interior condenser 62 (and therefore upstream from the expansion valve (which is the expansion valve EXV3 when the thermal management system 150 is operated in the mode shown in Figure 13)). As can be seen, the temperature of the refrigerant 108 decreases and then remains constant during the phase change that occurs in the interior condenser 62.

[00157] Curve segment 180c is representative of the change in the properties of the refrigerant 108 due to the expansion valve (e.g. expansion valve EXV3 when the thermal management system 150 is operated in the mode shown in Figure 13). Point 188 is representative of the properties of the refrigerant 108 immediately downstream of the expansion valve and therefore upstream from the coolant-refrigerant heat exchanger 100). As can be seen, the pressure and temperature of the refrigerant 108 decrease as a result of passing through the expansion valve.

[00158] Curve segment 30d is representative of the change in the properties of the refrigerant 108 due to passage through the coolant-refrigerant heat exchanger 100. After passing through the coolant-refrigerant heat exchanger 100, the refrigerant 108 returns to point 182, which is representative of the properties of the refrigerant 108 immediately downstream of the coolant-refrigerant heat exchanger 100 and therefore upstream of the compressor 56. As can be seen, the pressure and the temperature remain substantially constant in the coolant-refrigerant heat exchanger 100 until the refrigerant reaches the boundary line shown at 189, representing the boundary between the liquid phase and the gas phase. As shown in Figure 15, the secondary heater 122 transfers to the refrigerant 108 sufficient heat superheat the refrigerant 108 by some amount after all of the refrigerant has been evaporated in the coolant-refrigerant heat exchanger 100, thereby driving a small increase in temperature of the refrigerant 108. This ensures that all of the refrigerant leaves the coolant-refrigerant heat exchanger 100 as a gas.

[00159] When operating in the mode shown in Figure 13, it will be noted that the curve 180 is the curve for the refrigerant 108 once the refrigerant 108 has been heated already by the coolant-refrigerant heat exchanger 100 and is in a steady cycle after the aforementioned threshold temperature. To reach this steady cycle from a state where the refrigerant 108 is initially at a temperature that is below the aforementioned threshold temperature, the thermal management system 150 may be operated for some period of time in the mode shown in Figure 13, in order to circulate refrigerant 108 through the coolant-refrigerant heat exchanger 100 (and the compressor 56, the interior condenser 62 and the expansion valve EXV3) in order to progressively heat the refrigerant 108 up. At some point during the progressive heating of the refrigerant 108, the refrigerant 108 will progress from a state where the refrigerant 108, at the point just upstream from the compressor 56, is at a pressure that is less than 1 atmosphere, to a state where the refrigerant 108, at the point just upstream from the compressor 56, is at a pressure that is greater than 1 atmosphere. The aforementioned transition from a state where the pressure of the refrigerant 108 is less than 1 atmosphere to a state where it is greater than 1 atmosphere, upstream from the compressor 56, is represented graphically in Figure 15. As can be seen in Figure 15, there is a dashed line curve shown at 190, which represents the changes in properties (temperature and pressure) of the refrigerant 108, that would take place if the secondary heater 122 were not present. Thus, upon vehicle startup at a cold ambient temperature, the initial state of the refrigerant 108 at the inlet to the compressor 56 is shown at point 192. Initially, when the refrigerant system 152 is operated, the compressor 56 brings the refrigerant 108 to the point shown at 194 (the change in properties represented by curve segment 190a). The refrigerant 108 then passes through the condenser 162, where the refrigerant 108 is lowered in temperature and condensed, represented by curve segment 190b. Downstream from the interior condenser 62, the refrigerant properties are shown at point 196. The refrigerant 108 then passes through the expansion valve (e.g. expansion valve EXV3) where its pressure is reduced, thereby reducing its temperature, represented by curve segment 190c. Downstream from the expansion valve, the refrigerant properties are shown at point 198. The point 198, while shown at the same pressure as point 192, need not be precisely at the same pressure as the point 192. The refrigerant 108 then passes through the coolant-refrigerant heat exchanger 100 where it undergoes a phase change and is superheated by some amount, thereby raising its temperature by some amount, and thereby also increasing its pressure. Curve segment 190d represents the change in properties of the refrigerant 108 that occur during the phase change (i.e. the evaporation) that occurs in the coolant-refrigerant heat exchanger 100. The superheating of the refrigerant 108 in the coolant-refrigerant heat exchanger 100 after the phase change is complete in the coolant-refrigerant heat exchanger 100 is represented by curve segment 199.

[00160] If the secondary heater 122 were sufficiently powerful, a single cycle through the refrigerant system 152 could bring the refrigerant 108 to the state represented by point 182, when the refrigerant 108 exits from the coolant-refrigerant heat exchanger 100 (as represented by the curve segment 199 as shown in Figure 15. However, the jump in temperature and pressure for the refrigerant 108 when passing through the coolant-refrigerant heat exchanger 108 may be smaller than that shown in Figure 15. In other words, the length of curve segment 199 maybe smaller than that shown in Figure 15. However, over time, after a number of cycles (i.e. after a number of passes theough the refrigerant system 152), the temperature of the refrigerant 108 at the inlet to the compressor 56 will progressively increase, until, eventually, the pressure of the refrigerant 108 at the inlet of the compressor 56 increases to above 1 atmosphere. In other words, eventually, there will be a point where the refrigerant 108 will have a pressure that is below one atmosphere, and the refrigerant 108 will complete a pass through the refrigerant system (i.e. through the compressor 56, the interior condenser 62, the expansion valve EXV3 and the coolantrefrigerant heat exchanger 100), whereby the superheating that occurs in the coolantrefrigerant heat exchanger 100 will result in the refrigerant 108 exiting the coolantrefrigerant heat exchanger 100 with a pressure that is greater than 1 atmosphere. Worded another way, this transition from a pressure of below 1 atmosphere to above 1 atmosphere may be said to occur by carrying out the following method of operating the refrigerant system 152, whereby the method includes:

[00161] a) compressing the refrigerant 108 in the refrigerant system 152, thereby bringing the refrigerant 108 from a first temperature and a first pressure (point 192) to a second temperature and a second pressure (point 194), wherein the first temperature is sufficiently low that the first pressure is less than 1 atmosphere;

[00162] b) condensing the refrigerant 108 after step a), thereby bringing the refrigerant 108 from the second temperature and the second pressure (point 194) to a third temperature and a third pressure (point 196); [00163] c) passing the refrigerant 108 through an expansion valve after step b), thereby bringing the refrigerant 108 from the third temperature and the third pressure (point 196) to a fourth temperature and a fourth pressure (point 198);

[00164] d) evaporating the refrigerant 108 after step c), in an evaporator, which is the coolant-refrigerant heat exchanger 100, wherein the coolant-refrigerant heat exchanger 100 is positioned to transfer heat between the coolant 104 in the coolant system 154 and the refrigerant 108, wherein the evaporating is carried out by heating the refrigerant 108 using the secondary heater 122 and without heating the refrigerant 108 using the coolant-refrigerant heat exchanger 100, to bring the refrigerant 108 from the fourth temperature and the fourth pressure (point 198) to a fifth temperature and a fifth pressure (point 182), wherein the fifth temperature is sufficiently high that the fifth pressure is greater than 1 atmosphere; and

[00165] e) compressing the refrigerant 108 after step d), thereby bringing the refrigerant 108 from the fifth temperature and the fifth pressure (point 182) to beyond the fifth temperature and beyond the fifth pressure (point 184).

[00166] While it is advantageous to increase the pressure of the refrigerant 108 to be above 1 atmosphere from a pressure that is less than 1 atmosphere, it will also be noted that the increase in the pressure of the refrigerant 108 in any case, even if it remains below 1 atmosphere may still be advantageous since it increases the density and therefore the mass flow rate of the refrigerant 108, thereby increasing the effectiveness of the refrigerant system 152 in its ability to perform heat exchange. Thus, the above described method can be more broadly worded, such that the first pressure of the refrigerant 108 may be any suitable pressure, which may be above or below one atmosphere, and such that the fifth pressure (point 182) may be any suitable pressure as long as it is greater than the first pressure (point 192) of the refrigerant 108.

[00167] DESCRIPTION OF FIRST ALGORITHM FOR CONTROLLING OPERATION OF THE SECONDARY HEATER

[00168] The secondary heater 122 may be controlled by the control system 170 using any suitable algorithm. For example, a suitable method for controlling the secondary heater 122 is shown at 200 in Figure 16. The method 200 starts at 202. At step 204, it is determined whether the thermal management system 150 is in a mode in which the secondary heater 122 would be used (such as, for example the mode shown in Figure 13). If not, control loops back to this determination step 204 until such time that the thermal management system 150 is in a suitable mode. Once it is determined that the thermal management system 100 is in a suitable mode, step 206 is carried out, which is to determine if the temperature of the passenger cabin 12 is less than whatever temperature the vehicle occupants have set it to (referred to herein as the target cabin temperature). This step involves the control system 170 receiving data from the cabin temperature sensor 172. If the passenger cabin 12 is already at or is greater than its target cabin temperature, then the control system 170 sets the secondary heater 122 to ‘off’ at step 208. The target cabin temperature may be any suitable value, such as 20 degrees Celsius as shown in the step 206. If the passenger cabin 12 is less than its target cabin temperature, then step 210 is carried out, which is to determine if the temperature of the secondary heater 122 is less than an upper threshold temperature (which is a maximum temperature that the secondary heater 122 is permitted to operate at). This step involves the control system 170 receiving data from the secondary heater temperature sensor 176. The upper threshold temperature may be any suitable temperature such as, for example, 120 degrees Celsius. If the secondary heater 122 is already at or is greater than its upper threshold temperature, then the control system 170 carries out step 212, which is to set the secondary heater 122 to ‘on’ at a power level that is lower than whatever power level it was on immediately prior to step 212 being carried out. After step 210 or step 212 being carried out, control is passed back to step 206. If the secondary heater 122 is determined to be at less than its upper threshold temperature, then step 214 is carried out, which is to set the secondary heater 122 to ‘on’ at any suitable power level, such as full power, and to pass control back to step 206.

[00169] While the description contained herein constitutes a plurality of embodiments of the present invention, it will be appreciated that the present invention is susceptible to further modification and change without departing from the fair meaning of the accompanying claims.

[00170] LIST OF ITEMS