Cooling and heating system for a vehicle and operating method for a cooling and heating system of a vehicle

Abstract

The present invention relates to a cooling and heating system (200) for a vehicle, comprising: at least one primary circuit (10) for circulating a refrigerant; at least one secondary circuit (100) for circulating a coolant, the at least one secondary circuit (100) being provided for thermal management of at least one thermal system (HVS, IRK) of the vehicle; and at least one heating module (210), which can be fluidically connected to a refrigerant supply (10, KMT) and is designed to combust the refrigerant and supply the heat generated thereby to the coolant in the at least one secondary circuit (100).

Description

[0001] 24-1451

[0002] Cooling and heating system for a vehicle and operating procedures for a vehicle's cooling and heating system

[0003] The present disclosure relates to a cooling and heating system for a vehicle, a vehicle with such a cooling and heating system, and an operating method for a cooling and heating system of a vehicle. The present disclosure relates in particular to a cooling and heating system with auxiliary heating.

[0004] State of the art

[0005] Electric vehicles often use so-called indirect cooling and / or heating systems. In an indirect cooling and / or heating system, heat is not exchanged with the environment, but rather via an intermediate medium, usually a secondary coolant. The indirect cooling and / or heating system typically consists of two separate circuits, generally referred to as the primary circuit and the secondary circuit. A refrigerant circulates in the primary circuit. The secondary circuit contains a coolant that exchanges heat with the primary circuit and is transported to the parts of the vehicle where cooling or heating is required – such as the high-voltage battery in electric vehicles or other components that need to be cooled or heated.

[0006] A particular challenge lies in ensuring the operational capability of the high-voltage storage system under cold-start conditions at low ambient temperatures and in increasing its power output. However, the cold-start performance achieved with conventionally installed heating systems is insufficient to meet these requirements, significantly limiting the efficiency and functionality of the high-voltage storage system in practical operation.

[0007] Disclosure of the invention

[0008] 18.10.2024 24-1451

[0009] It is an object of the present disclosure to specify a cooling and heating system for a vehicle, a vehicle with such a cooling and heating system, and an operating method for a vehicle's cooling and heating system, which enable improved thermal management at low ambient temperatures. In particular, it is an object of the present disclosure to ensure the efficiency and functionality of a drive energy storage device.

[0010] This problem is solved by the subject matter of the independent claims. Advantageous embodiments are specified in the dependent claims.

[0011] According to an independent aspect of the present disclosure, a cooling and heating system for a vehicle, in particular a hybrid or electric vehicle, is specified. The cooling and heating system comprises: at least one primary circuit for circulating a refrigerant; at least one secondary circuit for circulating a coolant, wherein the at least one secondary circuit is provided for thermal management of at least one thermal system of the vehicle; and at least one heating module, which is fluidically connectable to a refrigerant supply and is configured to combust the refrigerant and supply the heat thereby generated to the coolant in the at least one secondary circuit.

[0012] According to the invention, the cooling and heating system includes an additional heater that can be operated with the refrigerant of the primary circuit. The refrigerant, such as propane, performs a dual function: it serves both as the working fluid in the primary circuit and as the fuel for the additional heater. In this way, a cold drive energy storage device (e.g., with a temperature of less than 0°C) can be heated quickly and efficiently to increase the power that is normally only available to a limited extent during a cold start. As a result, improved thermal management is possible at low ambient temperatures, which in particular ensures the efficiency and functionality of the drive energy storage device.

[0013] 18.10.2024 24-1451

[0014] Preferably, the cooling and heating system is an indirect cooling and heating system with multiple circuits, comprising at least one primary circuit and at least one secondary circuit.

[0015] In an indirect cooling and heating system, heat exchange does not occur directly with the environment, but via an intermediate medium, namely the coolant of the at least one secondary circuit. The refrigerant circulates in the at least one primary circuit, while the coolant circulates in the at least one secondary circuit, exchanging heat with the at least one primary circuit and being transported to the areas in the vehicle where cooling or heating is required – such as the drive energy storage system in hybrid or electric vehicles, or other components that need to be cooled or heated.

[0016] Within the scope of this disclosure, the terms "refrigerant" and "refrigeration circuit" may be used when referring to the at least one primary circuit. Conversely, the terms "coolant" and "cooling circuit" may be used when referring to the at least one secondary circuit.

[0017] Preferably, the coolant of the at least one secondary circuit is selected from the group comprising, or consisting of, water, ethylene glycol, propylene glycol and water mixtures with additives (e.g. corrosion protection).

[0018] Preferably, the refrigerant is propane, specifically R290. Propane is a colorless, flammable gas belonging to the alkane group and chemically designated as CβHs. R290 is the designation for propane when used as a refrigerant.

[0019] Preferably, the at least one heating module comprises, or is, at least one gas burner. A gas burner is a device that uses gas as fuel to generate a flame which is used to directly or indirectly heat the coolant of the at least one secondary circuit.

[0020] 18.10.2024 24-1451

[0021] Preferably, the refrigerant supply to the at least one heating module is provided by the at least one primary circuit. In particular, the at least one heating module can be fluidly connected to the at least one primary circuit, for example via a valve, in order to use the refrigerant present in the at least one primary circuit as fuel. This can be done, for example, in emergency situations, such as when heating the vehicle interior is essential, or for other reasons.

[0022] Preferably, the refrigerant supply is provided by at least one refrigerant tank. The refrigerant tank can, for example, be a gas cartridge; however, the present disclosure is not limited to this.

[0023] Preferably, the at least one refrigerant tank, such as the gas cartridge, is replaceable. In particular, the at least one refrigerant tank can be configured so that it can be easily replaced after the gas has been used up, or replaced with a filled refrigerant tank.

[0024] Preferably, the at least one refrigerant tank is fluidly connectable to the at least one primary circuit. Such a connection can be made, for example, to fill the at least one primary circuit with refrigerant and / or to replace refrigerant consumed by the at least one heating module.

[0025] Preferably, the cooling and heating system further comprises at least one first valve.

[0026] The at least one first valve can be positioned and / or configured to connect the at least one heating module fluidically to the at least one primary circuit. This allows the at least one heating module to use the refrigerant from the at least one primary circuit as fuel when the valve is open.

[0027] Additionally or alternatively, at least one first valve can be placed and / or set up to fluidically connect at least one heating module to the at least

[0028] 18.10.2024 24-1451 to connect a refrigerant tank. This allows at least one heating module to use the gas from at least one refrigerant tank as fuel when the valve is open.

[0029] Additionally or alternatively, at least one first valve can be positioned and / or configured to connect at least one primary circuit to at least one refrigerant tank via a fluid connection. This allows the at least one primary circuit to be filled with refrigerant from the at least one refrigerant tank when the valve is open. This can be done, for example, to replace refrigerant consumed by the at least one heating module or to compensate for other refrigerant losses.

[0030] Preferably, the at least one first valve comprises, or is, a multi-way valve. A multi-way valve is a valve that can control several different flow paths in a system. It enables the controlled circulation of liquids or gases in different lines by switching between different flow paths.

[0031] Preferably, the at least one first valve comprises several individual valves. These individual valves can, for example, be shut-off valves, but are not limited to this and can also include three-way valves and / or other x-way valves.

[0032] Preferably, the cooling and heating system further comprises at least a second valve which is configured to selectively open and / or close a path for the heated coolant to the at least one thermal system.

[0033] Preferably, the at least one second valve comprises, or is, a multi-way valve.

[0034] Preferably, the at least one second valve comprises several individual valves. These individual valves can, for example, include or be shut-off valves.

[0035] 18.10.2024 24-1451, however, is not limited to this and may also include three-way valves and / or other x-way valves.

[0036] Preferably, the at least one thermal system includes a

[0037] The vehicle's drive energy storage system. A drive energy storage system is an energy storage device that stores electrical energy in the form of high-voltage direct current. This stored energy is used to power at least one of the vehicle's electric motors. Typically, these drive energy storage systems are composed of lithium-ion cells or modules configured in a battery pack. The drive energy storage system can also be referred to as a high-voltage storage system or battery.

[0038] Preferably, the drive energy storage device is an LFP storage device. An LFP storage device uses lithium iron phosphate (LiFePCL or LFP for short) as the cathode material in a lithium-ion battery. Particularly during a cold start (e.g., a storage device cooled to below 0°C), the LFP storage device delivers only very low power. With the embodiments of the present disclosure, a rapid and efficient increase in power output is possible in such a situation.

[0039] Preferably, the at least one thermal system includes an interior heating system for the vehicle. The interior heating system is a system that ensures the vehicle's interior is warmed to guarantee passenger comfort, particularly in cold environments.

[0040] Preferably, the cooling and heating system is configured to supply heat to the at least one thermal system depending on at least one temperature parameter using the at least one heating module, for example for a cold start of the vehicle.

[0041] Preferably, the at least one temperature parameter includes an ambient temperature or outside temperature. For example, the at least

[0042] 18.10.2024 24-1451 a thermal system using at least one heating module can be supplied with heat when the ambient temperature or outside temperature is equal to or less than a threshold. The threshold can be, for example, 0°C, but the present disclosure is not limited to this and can, for example, be determined depending on the performance characteristics of the drive energy storage system.

[0043] Preferably, the at least one temperature parameter includes a temperature of the drive energy storage device. For example, heat can be supplied to the at least one thermal system (i.e., the drive energy storage device) using the at least one heating module when the temperature of the drive energy storage device is equal to or less than a threshold. The threshold can be, for example, 0°C; however, the present disclosure is not limited to this and can be determined, for example, depending on the performance characteristics of the drive energy storage device.

[0044] Preferably, the at least one temperature parameter includes the temperature of a vehicle interior. For example, heat can be supplied to the at least one thermal system (i.e., the interior heating) using the at least one heating module when the temperature of the vehicle interior is equal to or less than a threshold. The threshold can be, for example, 0°C; however, the present disclosure is not limited to this and can be determined, for example, depending on user preferences.

[0045] According to another independent aspect of the present disclosure, a vehicle, in particular a hybrid or electric vehicle, is specified. The vehicle comprises the cooling and heating system described in this document; and the at least one thermal system.

[0046] Depending on the design, the hybrid or electric vehicle can be a pure electric vehicle (BEV) or a plug-in hybrid vehicle (PHEV). The term "vehicle" includes cars, trucks, buses, motorhomes, motorcycles, etc.

[0047] 18.10.2024 24-1451

[0048] The term refers to the transport of persons, goods, etc. In particular, it includes motor vehicles used for passenger transport.

[0049] According to a further independent aspect of the present disclosure, an operating method for a cooling and heating system of a vehicle, in particular a hybrid or electric vehicle, is specified. The cooling and heating system comprises at least one primary circuit for circulating a refrigerant; at least one secondary circuit for circulating a coolant, wherein the at least one secondary circuit is provided for thermal management of at least one thermal system of the vehicle; and at least one heating module, which is fluidically connectable to a refrigerant supply and is configured to combust the refrigerant and supply the heat thereby generated to the coolant in the at least one secondary circuit. The operating method comprises operating the at least one heating module to combust the refrigerant and supply the heat thereby generated to the coolant in the at least one secondary circuit.

[0050] The cooling and heating system of the operating process may be the cooling and heating system described in this document and may include some or all of the features described in this document.

[0051] Brief description of the drawings

[0052] Examples of the manifestation of the revelation are shown in the figures and are described in more detail below. They show:

[0053] Figure 1 schematically shows an indirect cooling and heating system for a vehicle, and

[0054] Figure 2 schematically shows an indirect cooling and heating system for a vehicle according to embodiments of the present disclosure.

[0055] Implementations of the revelation

[0056] 18.10.2024 24-1451

[0057] Unless otherwise noted, the same reference symbols are used for identical and equivalent elements in the following.

[0058] In the following description of the figures, water is used as a coolant. However, the present disclosure is not limited to this and the coolant can be another suitable coolant, such as ethylene glycol, propylene glycol, or a water mixture with additives (e.g., corrosion protection).

[0059] Figure 1 schematically shows an indirect cooling and / or heating system 1 for a vehicle.

[0060] The vehicle can be a hybrid or electric vehicle. Depending on the embodiment, the hybrid or electric vehicle can be a pure electric vehicle (BEV) or a plug-in hybrid vehicle (PHEV).

[0061] The term "vehicle" includes cars, trucks, buses, motorhomes, motorcycles, etc., used for the transport of people, goods, etc. In particular, the term includes motor vehicles for passenger transport.

[0062] The indirect cooling and / or heating system 1 comprises a refrigeration circuit 10 with a first heat exchanger 12 (also referred to as a "chiller"), a second heat exchanger 14 (e.g. a water-cooled condenser, WCC), a pump 16 for circulating a refrigerant, an expansion valve 18 and an optional additional (integrated) heat exchanger 20 for increasing efficiency.

[0063] The first heat exchanger 12 forms an interface to a cold water side of a coolant circuit 100 and cools the coolant (e.g., water) present in the coolant circuit 100, which is circulated by a pump 110A (e.g., a water pump). In the example shown, the coolant is used to cool a vehicle interior and a high-voltage storage system (HVS) or a battery of an electric drive in a hybrid or electric vehicle.

[0064] 18.10.2024 24-1451

[0065] The second heat exchanger 14 forms an interface to a hot water side of the coolant circuit 100 and heats the coolant (e.g., water) present in the coolant circuit 100, which is circulated by means of a pump HOB (e.g., water pump). In the example shown, the coolant is used to heat the vehicle interior and the high-voltage storage system HVS or the battery of the electric drive of the hybrid or electric vehicle.

[0066] The first heat exchanger 12 and the second heat exchanger 14 can be water heat exchangers, but the present disclosure is not limited to this.

[0067] Figure 2 schematically shows a cooling and heating system 200 for a vehicle according to embodiments of the present disclosure.

[0068] The cooling and heating system 200 may include or be the cooling and heating system shown in Figure 1, and may further include an auxiliary heater as described below.

[0069] The cooling and heating system 200 comprises at least one primary circuit 10 for circulating a refrigerant; at least one secondary circuit 100 for circulating a coolant, wherein the at least one secondary circuit 100 is provided for thermal management of at least one thermal system IRK, HVS of the vehicle; and at least one heating module 210, which is fluidically connectable to a refrigerant supply and is configured to combust the refrigerant and supply the heat thereby generated to the coolant in the at least one secondary circuit 100, in particular to the coolant of the hot water side of the cooling and heating system 200. The supply of heat to the coolant of the hot water side of the cooling and heating system 200 can be effected, for example, via one or more suitable heat exchangers.

[0070] 18.10.2024 24-1451

[0071] The refrigerant, such as propane, thus performs a dual function: It serves both as a working fluid in the primary circuit 10 and as fuel for the additional heating 210. In this way, for example, a cold drive energy storage device (e.g., with a temperature of less than 0°C) can be heated quickly and efficiently to increase the power that is normally only available to a limited extent during a cold start.

[0072] In some embodiments, the coolant of the at least one secondary circuit 100 is selected from the group comprising, or consisting of, water, ethylene glycol, propylene glycol and water mixtures with additives (e.g. corrosion protection).

[0073] In some embodiments, the refrigerant is propane, specifically R290. Propane is a colorless, flammable gas belonging to the alkane group and chemically designated CsHs. R290 is the designation for propane when used as a refrigerant.

[0074] In some embodiments, the at least one heating module 210 comprises, or is, at least one gas burner. A gas burner is a device that uses gas as fuel to generate a flame which is used to directly or indirectly heat the coolant on the hot water side of the at least one secondary circuit 100.

[0075] In some embodiments, the refrigerant supply to the at least one heating module 210 is provided by the at least one primary circuit 10. In particular, the at least one heating module 210 can be fluidically connected to the at least one primary circuit 10 in order to use the refrigerant present in the at least one primary circuit 10 as fuel. This can be done, for example, in emergency situations, such as when heating the vehicle interior is essential, or for other reasons.

[0076] 18.10.2024 24-1451

[0077] Additionally or alternatively, the refrigerant supply can be provided by at least one refrigerant tank (KMT). The refrigerant tank (KMT) can, for example, be a gas cartridge; however, the present disclosure is not limited to this.

[0078] Typically, at least one refrigerant tank (KMT), such as a gas cartridge, is replaceable. In particular, the at least one refrigerant tank (KMT) can be configured so that it can be easily replaced after the gas has been used up, or replaced with a filled refrigerant tank.

[0079] Optionally, the at least one refrigerant tank KMT can be fluidically connected to the at least one primary circuit. Such a connection can be made, for example, to fill the at least one primary circuit 10 with refrigerant and / or to replace refrigerant consumed by the at least one heating module 210.

[0080] In some embodiments, the cooling and heating system 200 further comprises at least one first valve 220, such as a multi-way valve. A multi-way valve is a valve that can control several different flow paths in a system. It enables the targeted circulation of liquids or gases in different lines by switching between different flow paths. Alternatively, the functionalities of the multi-way valve can be provided by several individual valves, such as shut-off valves.

[0081] The at least one first valve 220 can be positioned and / or configured to connect the at least one heating module 210 fluidically to the at least one primary circuit 10, as shown in Figure 2 (valve position “3”). This allows the at least one heating module 210 to use the refrigerant from the at least one primary circuit 10 as fuel.

[0082] Additionally or alternatively, at least one first valve 220 can be placed and / or configured to connect at least one heating module 210 fluidically to the

[0083] 18.10.2024 24-1451 to connect at least one KMT refrigerant tank (valve position "2"). This allows at least one heating module 210 to directly use the gas from at least one KMT refrigerant tank as fuel.

[0084] Additionally or alternatively, at least one first valve 220 can be positioned and / or configured to connect the at least one primary circuit 10 fluidically to the at least one refrigerant tank KMT (valve position "1"). This allows the at least one primary circuit 10 to be filled with refrigerant from the at least one refrigerant tank KMT when the valve 220 is open. This can be done, for example, to replace refrigerant consumed by the at least one heating module 210 or to compensate for other refrigerant losses.

[0085] In the valve position “0”, at least one valve 220 is completely shut off.

[0086] The at least one heating module 210 is designed to burn the refrigerant and supply the heat generated thereby to the coolant in the at least one secondary circuit 100, in particular to the coolant of the hot water side of the cooling and heating system 200, in order to heat the at least one thermal system IRK, HVS of the vehicle.

[0087] In some embodiments, the at least one thermal system IRK, HVS comprises a vehicle drive energy storage system HVS, such as an LFP storage system. Additionally or alternatively, the at least one thermal system IRK, HVS may include an interior air conditioning system IRK or an interior heating system.

[0088] In some embodiments, the cooling and heating system 200 further comprises at least one second valve 230A, 230B, which is configured to selectively open and / or close a path for the heated coolant to the at least one thermal system IRK, HVS. The at least one second valve 230A, 230B may comprise one or more shut-off valves; however, the present disclosure is not limited to this.

[0089] 18.10.2024 In the example of Figure 2, both valves 230A and 230B are open, so that both the drive energy storage HVS and the interior heating IRK are supplied with heat from the at least one heating module 210.

[0090] If, however, both valves 230A and 230B are closed, neither the drive energy storage HVS nor the interior heating IRK will be supplied with heat from at least one heating module 210.

[0091] If valve 230A is open and valve 230B is closed, only the drive energy storage HVS is supplied with heat from at least one heating module 210.

[0092] If valve 230A is closed and valve 230B is open, only the interior heater IRK is supplied with heat from at least one heating module 210.

[0093] In some embodiments, the cooling and heating system 200 is configured to supply heat to the at least one thermal system HVS, IRK depending on at least one temperature parameter using the at least one heating module 210, for example for a cold start of the vehicle.

[0094] The at least one temperature parameter can include an ambient temperature or an outside temperature. For example, heat can only be supplied to the at least one thermal system HVS, IRK using the at least one heating module 210 if the ambient temperature or outside temperature is equal to or less than a threshold. The threshold can be, for example, 0°C; however, the present disclosure is not limited to this and can be defined, for example, depending on the performance characteristics of the drive energy storage system HVS.

[0095] Additionally or alternatively, at least one temperature parameter can include a temperature of the drive energy storage system HVS. For example, the drive energy storage system HVS can be heated using at least one heating module 210.

[0096] On October 18, 2024, heat is supplied when the temperature of the drive energy storage system (HVS) is equal to or less than a threshold. The threshold can be, for example, 0°C; however, the present disclosure is not limited to this and can be defined, for example, depending on the performance characteristics of the drive energy storage system (HVS).

[0097] Additionally or alternatively, at least one temperature parameter can include the temperature of a vehicle interior. For example, heat can only be supplied to the interior heater IRK using the at least one heating module 210 if the temperature of the vehicle interior is equal to or less than a threshold. The threshold can be, for example, 0°C; however, the present disclosure is not limited to this and can be determined, for example, depending on user preferences.

[0098] According to the invention, the cooling and heating system includes an additional heater that can be operated with the refrigerant of the primary circuit. The refrigerant, such as propane, performs a dual function: it serves both as the working fluid in the primary circuit and as the fuel for the additional heater. In this way, a cold drive energy storage device (e.g., with a temperature of less than 0°C) can be heated quickly and efficiently to increase the power that is normally only available to a limited extent during a cold start. As a result, improved thermal management is possible at low ambient temperatures, which in particular ensures the efficiency and functionality of the drive energy storage device.

[0099] Although the invention has been further illustrated and explained in detail by means of preferred embodiments, the invention is not limited by the disclosed examples, and other variations can be derived from them by a person skilled in the art without departing from the scope of protection of the invention. It is therefore clear that a multitude of possible variations exist. It is also clear that the embodiments mentioned as examples are indeed only examples and are not intended in any way to limit, for example, the scope of protection, the possible applications, or the

[0100] 18.10.2024 24-1451

[0101] The configuration of the invention is not to be understood as such. Rather, the preceding description and the description of the figures enable the person skilled in the art to implement the exemplary embodiments in concrete terms, whereby the person skilled in the art, with knowledge of the disclosed inventive concept, can make various changes, for example with regard to the function or the arrangement of individual elements mentioned in an exemplary embodiment, without leaving the scope of protection defined by the claims and their legal equivalents, such as further explanations in the description.

[0102] October 18, 2024

Claims

24-1451 Patent claims 1. Cooling and heating system (200) for a vehicle, comprising: at least one primary circuit (10) for circulating a refrigerant; at least one secondary circuit (100) for circulating a coolant, wherein the at least one secondary circuit (100) is provided for thermal management of at least one thermal system (HVS, IRK) of the vehicle; and at least one heating module (210) which is fluidically connectable to a refrigerant supply (10, KMT) and is configured to combust the refrigerant and supply the heat generated thereby to the coolant in the at least one secondary circuit (100).

2. Cooling and heating system (200) according to claim 1, wherein the refrigerant is propane.

3. Cooling and heating system (200) according to claim 1 or 2, wherein the at least one heating module (210) comprises at least one gas burner or is at least one gas burner.

4. Cooling and heating system (200) according to one of claims 1 to 3, wherein the refrigerant supply is provided by the at least one primary circuit (10) and / or by at least one refrigerant tank (KMT).

5. Cooling and heating system (200) according to claim 4, wherein the at least one refrigerant tank (KMT) is replaceable.

6. Cooling and heating system (200) according to claim 4 or 5, further comprising at least one first valve (220) configured to: connect the at least one heating module (210) fluidically to the at least one primary circuit (10); and / or connect the at least one heating module (210) fluidically to the at least one refrigerant tank (RMT); and / or October 18, 2024 24-1451 to connect at least one primary circuit (10) fluidically with at least one refrigerant tank (KMT).

7. Cooling and heating system (200) according to one of claims 1 to 6, further comprising at least a second valve (230A, 230B) which is configured to selectively open and close a path for the heated coolant to the at least one thermal system (HVS, IRK).

8. Vehicle, in particular hybrid or electric vehicle, comprising: the cooling and heating system (200) according to any one of claims 1 to 7; and the at least one thermal system (HVS, IRK), in particular wherein the at least one thermal system (HVS, IRK) comprises a drive energy storage system (HVS) of the vehicle and / or an interior heating system (IRK) of the vehicle.

9. Vehicle according to claim 8, wherein the cooling and heating system (200) is configured to supply heat to the at least one thermal system (HVS, IRK) depending on at least one temperature parameter using the at least one heating module (210), in particular for a cold start of the vehicle.

10. Operating method for a cooling and heating system (HWS, IRC) of a vehicle, wherein the cooling and heating system (HWS, IRC) comprises: at least one primary circuit (10) for circulating a refrigerant; at least one secondary circuit (100) for circulating a coolant, wherein the at least one secondary circuit (100) is provided for thermal management of at least one thermal system (HWS, IRC) of the vehicle; and at least one heating module (210) which is fluidically connectable to a refrigerant supply (10, CMS) and is configured to combust the refrigerant and supply the heat thereby generated to the coolant in the at least one secondary circuit (100), wherein the operating method comprises: October 18, 2024 24-1451 Operating the at least one heating module (210) for the combustion of the refrigerant and supplying the heat generated thereby to the coolant in the at least one secondary circuit (100). October 18, 2024

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