Heat pump system
The heat pump system addresses efficiency issues at low temperatures by heating the refrigerant flow with a compressor outlet heater, ensuring efficient heating and cooling in vehicles without complex modifications, and optionally heating the battery.
Patent Information
- Application Number
- FR2023000427
- Authority / Receiving Office
- FR · FR
- Patent Type
- Patents
- Current Assignee / Owner
- Filing Date
- 2023-01-17
- Publication Date
- 2025-11-21
- Estimated Expiration
- 2043-01-17
AI Technical Summary
Heat pumps in vehicles face efficiency degradation at low temperatures, and existing solutions like adding electrical resistors in the air duct or integrating resistors inside the compressor are inefficient and impractical due to space constraints and energy inefficiencies.
A heat pump system with a heater coupled to the compressor outlet to heat the high-pressure refrigerant flow, eliminating the need for internal resistors and maintaining efficiency by using a standard compressor, and optionally incorporating a secondary refrigerant circuit for battery heating.
Maintains high efficiency at low temperatures by heating the refrigerant flow, reduces pressure losses, and allows for efficient heating and cooling of the passenger compartment and battery, without complex modifications to the compressor.
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Abstract
Description
Title of the invention: Heat pump system technical field
[0001] The present invention relates to the field of heat pumps and more particularly concerns a heat pump system, especially for vehicles, as well as a vehicle comprising such a system and also an associated method. Previous technique
[0002] Nowadays, air conditioning and heating systems are widespread in motor vehicles. Their use is dual and they must be able to cool the passenger compartment or heat it depending on the outside climatic conditions and the needs of the passengers inside the vehicle.
[0003] The use of heat pumps in this application, which is a common solution in heating and air conditioning applications in the service sector, has recently been adopted by vehicle manufacturers.
[0004] As with buildings, this technology faces the challenge of low heating efficiency at low temperatures. Indeed, performance degrades as the outside temperature drops, becoming poor below 5°C, mediocre below 0°C, and inoperative below -15°C.
[0005] A known solution is to add electrical resistors in the air blowing duct to the passenger compartment, but this technique has many disadvantages, including poor energy efficiency and significant variations in the air blowing temperature.
[0006] Other solutions have been developed for heat pumps in buildings, but are not applicable to motor vehicles. Indeed, these solutions consist of integrating one or more resistors inside the heat pump compressor.
[0007] However, a building heat pump compressor has a specific internal spiral tube architecture and large dimensions which easily allow such integration, which is not the case in a vehicle heat pump compressor.
[0008] It would therefore be advantageous to propose a simple, reliable and effective solution that would at least partially remedy these drawbacks. Description of the invention
[0009] To this end, the invention first relates to a heat pump system, particularly for vehicles, said system comprising a main refrigerant circuit configured to operate in a heating mode in which the flow of refrigerant flows in a direction called "heating", said main refrigerant circuit comprising a heat exchanger called "cold", a compressor placed downstream of the cold heat exchanger, in the direction of heating of the flow, and a heat exchanger called "hot" placed downstream of the compressor and upstream of the expansion valve, said expansion valve placed upstream of the cold heat exchanger, in the direction of heating of the flow, an air channel being defined between the cold heat exchanger and the hot heat exchanger, the system being notable in that the main refrigerant circuit comprises a heater coupled to the outlet of the compressor, placed in the flow of refrigerant and configured to heat the high-pressure refrigerant flow exiting said compressor.
[0010] The heater raises the temperature of the refrigerant flow exiting the compressor before it reaches the hot heat exchanger. Specifically, the refrigerant flow passing through the heater efficiently heats the flow. This reduces pressure losses and increases the system's inertia. Thus, when the outside air temperature is low, for example below 5°C, heating the high-pressure refrigerant flow helps maintain relatively high system efficiency. Using a heater at the compressor outlet eliminates the need to install a heating module, such as one or more electric heating elements, inside the compressor. This allows the use of a standard, small-sized compressor without the need for complex and costly modifications.Furthermore, the only available space in a vehicle compressor for mounting a resistor would potentially be in the "low pressure" section of said compressor, which would not allow for the aforementioned advantages, particularly maintaining efficiency at low outside air temperatures.
[0011] In one embodiment, the heater comprises one or more heating elements in which the refrigerant fluid is immersed in order to efficiently heat it at the outlet of the compressor.
[0012] Advantageously, the heater is electrically powered. This power supply method is simple and practical, particularly for electric or hybrid vehicles, where it is not possible to recover heat from the thermal circuits.
[0013] In one embodiment, at least one heating element is an electrical resistance, which is an inexpensive piece of equipment and easy to install and use.
[0014] Alternatively, at least one heating element could be of the induction coil type or any other suitable type of heating element.
[0015] Preferably, the heater comprises a plurality of electrical resistances, for example two, three or four, in order to increase the power of the heater.
[0016] Advantageously, the system includes a control module configured for control the heater, in particular to control the power of the heating element(s), especially to allow several levels of heating of the refrigerant fluid depending on the desired performance and the outside temperature.
[0017] In one embodiment, the heater comprises a hollow body in which at least one heating element is mounted and which has a refrigerant inlet connected to the compressor outlet and a heated refrigerant outlet. The heating element(s) are immersed in the refrigerant flow enclosed within the hollow body, thus enabling efficient heating of the refrigerant at the compressor outlet.
[0018] Preferably, the body has an elongated shape, in particular to house elongated electrical resistors or induction coils and thus heat the refrigerant over a significant length of the circuit.
[0019] Preferably, the at least heating element, particularly in the case of an electrical resistance, has the form of a plunge tube mounted in said hollow body in order to efficiently heat the refrigerant.
[0020] Advantageously, the heat pump system is reversible and also includes a cooling mode in which the direction of fluid flow, called the cooling direction, is opposite to the heating direction. Indeed, a reversible heat pump system also makes it possible to cool the passenger compartment, particularly in the event of high outside temperatures.
[0021] The invention also relates to a vehicle comprising a heat pump system as described above, in particular a motor vehicle or any other type of vehicle that can be equipped with such a system.
[0022] Advantageously, the vehicle is an electric or hybrid vehicle comprising an electric motor and a battery to power said electric motor. Indeed, for a combustion engine vehicle, the engine powers the compressor mechanically, and it is therefore not possible to power the heater other than by the 12 V battery. In an electric motor, the batteries are typically 400 V or 800 V. A separate power supply for the electric compressor, for example at 80 V, and for the heater, for example at 400 V, thus becomes possible.
[0023] Advantageously, the vehicle includes a so-called "battery" heat exchanger and a secondary refrigerant circuit, connecting said battery heat exchanger and the battery in order to exchange heat with said battery, and the system includes a control module configured to control the primary refrigerant circuit so that the refrigerant flows either directly from the heater to the hot heat exchanger in order to heat the passenger compartment or through the battery heat exchanger in order to heat the battery. This secondary refrigerant circuit allows the battery temperature to be regulated by depending on outside temperatures, which is important in ensuring its electrical performance, especially for an electric vehicle.
[0024] Advantageously, the heat pump system is reversible and also includes a cooling mode.
[0025] The invention also relates to a heating method using a system as described above, said method comprising a heating step of the high-pressure refrigerant fluid exiting the compressor.
[0026] Advantageously, when the system includes a control module, the method includes a step of activating the heater, in particular one or more heating elements of the heater, according to the outside temperature in order to obtain the desired performance. In particular, the lower the temperature, the more heating elements the control module activates. Brief description of the drawings
[0027] Other features and advantages of the invention will become apparent from the following description. This description is purely illustrative and should be read in conjunction with the accompanying drawings, in which:
[0028] [Fig.1] Fig.1 schematically illustrates a first embodiment of the system according to the invention.
[0029] [Fig.2] Fig.2 schematically illustrates one embodiment of the heater of the system of [Fig.1].
[0030] [Fig.3] Fig.3 schematically illustrates a second embodiment of the system according to the invention.
[0031] [Fig.4] Fig.4 schematically illustrates a third embodiment of the system according to the invention. Description of the implementation methods
[0032] Figures 1, 3 and 4 show three examples of system 1 according to the invention.
[0033] First embodiment
[0034] Figure 1 shows a first example of system 1 according to the invention. System 1 according to the invention is intended to be mounted in a vehicle (not shown).
[0035] The vehicle may be a motor vehicle (car, truck, bus, ...), in particular electric or hybrid, or any other type of vehicle such as, for example, a cable car cabin, an aircraft, a ship, a train, etc.
[0036] System 1
[0037] System 1 is configured to operate in a heating mode. In one embodiment, system 1 is further advantageously configured to operate in a cooling mode. In other words, in this example not limited to, system 1 is reversible.
[0038] Main refrigerant circuit 10
[0039] With reference to [Fig.1], the main refrigerant circuit 10 comprises, in the so-called "heating" direction 10A, a so-called "cold" heat exchanger 110, a compressor 120, a heater 130, a so-called "hot" heat exchanger 140, an expansion valve 150 and a control module 160.
[0040] The cold heat exchanger 110 is configured so that the refrigerant passing inside exchanges heat with the outside air supplied through the outside air intake 20.
[0041] The compressor 120 is configured to increase the pressure of the fluid passing through it.
[0042] With reference to [Fig.2], the heater 130 comprises an elongated cylindrical hollow body 131 provided with an inlet conduit 132 connected to the outlet of the compressor 120 and an outlet conduit 133 connected to the hot heat exchanger 140.
[0043] The heater 130 further comprises, in this non-limiting example, two tube-shaped electrical resistances 134 whose length is substantially the same, but slightly less, than the length of the elongated body 131.
[0044] The heater 130 further includes electrical connections 135 for supplying electrical power to the electric resistances 134. The electric resistances 134 are immersed in the flow of high-pressure refrigerant fluid exiting the compressor 120 in order to heat it.
[0045] The hot heat exchanger 140 is configured to exchange heat between the fluid and the air supplied through the air channel 30.
[0046] In the heating direction 10A, the cold heat exchanger 110 is called evaporator, and the hot heat exchanger 140 is called condenser in a manner known per se.
[0047] The expansion valve 150 is configured to lower the pressure of the refrigerant.
[0048] The control module 160 is configured to control the number of electric resistors 134 switched on in the heater 130 according to the temperature conditions outside and in the passenger compartment 40.
[0049] Outside air intake 20
[0050] With reference to [Fig.1], the outside air intake 20 allows outside air to be brought to the vehicle in contact with the cold heat exchanger 110.
[0051] Air channel 30
[0052] With reference to [Fig. 1], the air duct 30 brings air into contact with the hot heat exchanger 140 and projects it into the passenger compartment 40. Depending on the operating mode, the air duct 30 can supply air from outside or air from the passenger compartment 40, which is recycled before being reheated. Since air recycling is known in itself, it will not be described further here.
[0053] The air channel 30 includes a ventilation duct 310 in which is located the hot heat exchanger 140 and a fan 320 that can be activated by the vehicle user.
[0054] Passenger compartment 40
[0055] The passenger compartment 40 corresponds to the place in which the vehicle's users are located and whose temperature is regulated by system 1.
[0056] Second embodiment
[0057] With reference to [Fig. 3], a second example of system 1 according to the invention is shown. In this embodiment, system 1 comprises, in addition to the elements already described above, a secondary refrigerant circuit 50. The air duct 30, the cabin 40 and the control module 160 are present but are not shown for clarity in [Fig. 3].
[0058] The secondary refrigerant circuit 50 is a heating circuit for the electric battery 51 of the electric vehicle. The secondary refrigerant circuit 50 has two parts. The first part 50A is connected to the main refrigerant circuit 10 by two branches 52A and 52B, respectively between the heater 130 and the hot heat exchanger 140 for branch 52A and between the hot heat exchanger 140 and the expansion valve 150 for branch 52B.
[0059] A so-called "secondary" heat exchanger 53 is present on the first part 50A, between branches 52A and 52B.
[0060] This secondary heat exchanger 53 is configured to exchange heat between the fluid of the main refrigerant circuit 10 which passes through the first part 50A and the fluid of the circuit of the second part 50B.
[0061] The second part 50B includes the secondary heat exchanger 53 and a so-called "battery" heat exchanger 54. The battery heat exchanger 54 surrounds the electric battery 51.
[0062] Third embodiment
[0063] With reference to [Fig. 4], a second example of system 1 according to the invention is shown. In this embodiment, system 1 comprises, in addition to the elements already described in the two embodiments above, a reversing valve 170 configured to ensure the reversibility of system 1. The air duct 30, the cabin 40 and the control module 160 are present but are not shown for clarity in [Fig. 4].
[0064] The diverter valve is connected to the cold heat exchanger 110, to the compressor inlet 120, to the heater 130 and to the hot heat exchanger 140.
[0065] In the embodiment shown, the invention corresponds to the heater 130 is located between the high-pressure outlet of the compressor 120 and the diverter valve 170.
[0066] In system (1) as shown in [Fig.4], the refrigerant flows in the so-called "cooling" direction 10B.
[0067] Example of implementation
[0068] When the outside temperature is low, especially below 5°C, the user and any users in the passenger compartment 40 use the heat pump system 1 in heating mode, which corresponds to the embodiment shown in [Fig.1].
[0069] In a first use case, the outside temperature is sufficiently high that the use of the heater 130 is not necessary. In this case, the control module 160 does not trigger the activation of the electric heating elements 134 in the heater 130, and the vehicle's heat pump operates in a conventional and well-known manner.
[0070] When the outside temperature is low enough to reduce the coefficient of performance of the heat pump itself, system 1 is used in a first embodiment corresponding to the first embodiment presented above.
[0071] The control module 160 has the ability to activate only one of the two electric resistances 134 of the heater 130. The fluid which passes through the heater 130 at the outlet of the compressor 120 enters the heater 130 through its inlet conduit 132, is heated by one of the electric resistances 134 and exits its outlet conduit 133 to be conveyed in the main refrigerant circuit 10 to the hot heat exchanger 140.
[0072] The hot heat exchanger 140 heats the air supplied from outside through the air duct 30. The fan 320 blows the air which thus passes through the hot heat exchanger 140 and arrives in the passenger compartment 40 where the user and any passengers are located.
[0073] In the event that the outside temperature is even lower or the user wants faster heating, the control module 160 can activate the second electric resistance 134 in the heater 130.
[0074] The fluid at the compressor outlet 120 is therefore heated even more before passing through the hot heat exchanger 140 and allows the air blown into the passenger compartment 40 to be heated.
[0075] In the embodiment shown in [Fig.2], the heater 130 comprises two electric resistances 134. In other embodiments the heater 130 comprises more than two electric resistances 134.
[0076] A second embodiment corresponds to the second embodiment described above and in [Fig. 3]. The system 1 then contains a refrigerant fluid circuit. secondary goriganen 50 for maintaining the temperature of the electric battery 51.
[0077] The secondary refrigerant circuit 50 is connected to the main refrigerant circuit 10 of the heat pump, the heater 130 therefore also makes it possible to increase the heating performance of the electric battery 51 for outdoor conditions of low temperatures.
[0078] In the embodiment shown in [Fig.3], a branch 52A separates the fluid circuit into two: one part of the fluid exiting the heater 130 remains in the main refrigerant circuit 10 to reach the hot heat exchanger 140, while the other enters the secondary refrigerant circuit 50 for maintaining the temperature of the electric battery 51.
[0079] The secondary refrigerant circuit 50 is in two parts. In the first part 50A the fluid passes through the secondary heat exchanger 53 and then reaches the branch 52B where it joins the main refrigerant circuit 10 downstream of the hot heat exchanger 140.
[0080] The secondary heat exchanger 53 allows heat exchange between the fluid of the main refrigerant circuit 10 heated by the heater 130 and the fluid of the second part 50B of the secondary refrigerant circuit 50.
[0081] The fluid circulating in this second part 50B reaches the battery heat exchanger 54 after being heated in the secondary heat exchanger 53. This battery heat exchanger 54 allows the electric battery 51 to be heated to maintain its performance under low temperature conditions.
[0082] A third operating mode corresponds to the third embodiment shown above and in [Fig. 4]. In this embodiment, the heat pump system 1 is configured to be reversible and also able to operate in air cooling mode for the air conditioning of the passenger compartment 40 as well as the electric battery 51.
[0083] In the reversible system 1, to switch from the outside air heating mode as described above to the cooling mode, the user operates a control which modifies the reversing valve 170. Depending on its orientation, the reversing valve 170 directs the fluid from the cold heat exchanger 110 to the compressor 120 and then sends the fluid from the compressor 120 to the hot heat exchanger 140 in heating mode, and conversely directs the fluid from the hot heat exchanger 140 to the compressor 120 and then sends the fluid from the compressor 120 to the cold heat exchanger 110 in air conditioning mode, in which case the refrigerant circulates in the cooling direction 10B.
Claims
Demands
1. A heat pump system (1), particularly for vehicles, said system (1) comprising a main refrigerant circuit (10) configured to operate in a heating mode in which the refrigerant flow is in a direction referred to as the "heating" direction, said main refrigerant circuit (10) comprising a "cold" heat exchanger (110), a compressor (120) located downstream of the cold heat exchanger (110), in the heating direction (10A) of the flow, and a "hot" heat exchanger (140) located downstream of the compressor (120) and upstream of the expansion valve (150), said expansion valve (150) located upstream of the cold heat exchanger (110), in the heating direction (10A) of the flow, the system (1) being characterized in that the main refrigerant circuit (10) comprises a heater (130) coupled to the outlet of the compressor (120),placed in the refrigerant flow and configured to heat the high-pressure refrigerant flow exiting said compressor (120), said heater (130) comprising one or more heating elements (134) in which the refrigerant is immersed.
2. System (1) according to claim 1, wherein the heater (130) is electrically powered and wherein at least one heating element is an electrical resistance (134).
3. System (1) according to the preceding claim, wherein the heater (130) comprises a plurality of electrical resistances (134) and the system (1) comprises a control module (160) configured to control said plurality of electrical resistances (134).
4. System (1) according to any one of the preceding claims, wherein the heater (130) comprises a hollow, elongated body (131) in which at least one heating element (134) is mounted.
5. System (1) according to any one of the preceding claims, wherein the heat pump system (1) is reversible and further comprises a cooling mode.
6. Vehicle comprising a heat pump system (1) according to any one of the preceding claims.
7. Vehicle according to the preceding claim, said vehicle being an electric or hybrid vehicle comprising an electric machine and a power supply battery (51) for said electric machine.
8. Vehicle according to the preceding claim, wherein, the air duct (30) opening into the passenger compartment (40) of the vehicle, the main refrigerant circuit (10) of the system (1) comprises a so-called "battery" heat exchanger (54) and a secondary refrigerant circuit (50), connecting said battery heat exchanger (54) and the battery (51) in order to exchange heat with said battery (51), the system (1) comprising a control module configured to control the main refrigerant circuit (10) so that the refrigerant flows directly from the heater (130) to the hot heat exchanger (140) in order to heat the passenger compartment (40) or through the battery heat exchanger (54) in order to heat the battery (51).
9. A heating method using a system (1) according to any one of claims 1 to 5, said method being characterized in that it comprises a step of heating the high-pressure refrigerant fluid exiting the compressor (120).