CO2 Thermal and Humidity Coupling System for New Energy Electric Vehicles

Abstract

The present invention discloses a CO2 heat and humidity coupling system for new energy electric vehicles. The present invention includes a heat and humidity management system, a battery thermal management group, and a motor and electronic control thermal management group; the heat and humidity management system includes a compressor, an indoor heater, an outdoor heat exchanger, an intermediate heat exchanger, a gas-liquid separator, a battery cooler, an indoor evaporator, a dehumidification heat exchanger, and a radiator. The battery thermal management group is connected to a plate heat exchanger via an electronic water pump two by the battery cooler, and the plate heat exchanger is connected back to the battery cooler through a pipeline provided with a solenoid valve five. The motor and electronic control thermal management group is connected to the motor and electronic control components through a pipeline by the radiator via a solenoid valve three and an electronic water pump one. The present invention proposes a CO2 transcritical heat pump air-conditioning cycle system and an integrated vehicle heat and humidity coupling system for the recovery of waste heat from the three electric components, innovates the thermal system structure, and realizes efficient operation with a wide temperature range under multiple modes and working conditions.

Description

Technical Field

[0001] The present invention relates to the field of research on electric vehicle thermal systems, and more specifically, to a CO2 heat and moisture coupling system for new energy electric vehicles. Background Art

[0002] In winter, the electricity required for heating a new energy pure electric vehicle accounts for about 30% - 50% of the total vehicle power consumption. When using an electric heater (PTC) for heating, the vehicle's cruising range can be reduced by half, which has a great impact on the cruising range of pure electric vehicles. Currently, most electric vehicles at home and abroad use a three-heat-exchanger heat pump air conditioning system. However, when the ambient temperature is lower than -7°C, the efficiency of the heat pump air conditioning system using traditional refrigerants drops significantly, and PTC auxiliary heating is required. The rapid decay of the vehicle's cruising range hinders the popularization of new energy electric vehicles. Moreover, in the winter dehumidification mode, the air is cooled and dehumidified by the evaporator in the air conditioning box and then heated by the indoor condenser. The dehumidification load accounts for about 60% of the heating load.

[0003] The research on electric vehicle thermal systems mainly focuses on steam injection heat pump air conditioning systems and the application of new refrigerants. The application environment temperature of the R134a steam injection heat pump air conditioning system can be extended to -15°C, and the COP and heating capacity have been improved. However, the heat and supply air temperature still cannot meet the requirements under low-temperature cold start, and auxiliary heat is needed. To balance environmental protection, the fourth-generation refrigerants CO2 and R290 have become alternative solutions. Although R290 has good heating performance in severe cold, due to its strong flammability, a secondary cycle is required, and the system efficiency drops significantly.

[0004] Using CO2 as a refrigerant for automotive heat pump air conditioners is an effective solution to low-temperature heating and has great development value for complex automotive climate control systems. However, the CO2 transcritical heat pump system has problems such as high operating pressure, harsh cold source conditions, large high-pressure heat release temperature slip, and complex coupling with multi-grade waste heat sources.

[0005] In winter, to ensure driving safety, it is necessary to dehumidify and defog in a timely manner. Usually, the wet air inside the vehicle is cooled and dehumidified by the evaporator and then heated, which reduces the thermodynamic perfection degree of the system. The indoor wet load in winter accounts for about 60% of the total load of the heat pump system. There is a case using a DCHE independent dehumidification system, which uses the waste heat of the three electrics (battery, motor, electronic control) for dehumidification regeneration, reducing the energy consumption in the vehicle dehumidification mode. However, affected by the unstable regeneration heat source, the real-time regeneration efficiency cannot be guaranteed. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to research an efficient and environmentally friendly vehicle-mounted thermal management heat and moisture coupling system with wide operating condition adaptability, conduct research on heat and mass transfer of the CO2 integrated thermal system, especially the multi-source matching and coupling coordinated operation under complex variable operating conditions, broaden the regeneration demand temperature threshold of the DCHE dehumidification system, and utilize the heat and moisture system of new energy electric vehicles coupled with multi-grade heat sources, which is of great significance for solving the efficient application of electric vehicle heat pumps at low temperatures.

[0007] A CO2 heat and moisture coupling system for new energy electric vehicles of the present invention is realized through the following technical solutions, including a heat and moisture management system, a battery thermal management group, and a motor and electronic control thermal management group;

[0008] The thermal and humidity management system includes a compressor, an indoor heater, an outdoor heat exchanger, an intermediate heat exchanger, a gas-liquid separator, a battery cooler, an indoor evaporator, a dehumidification heat exchanger, and a radiator. The outlet of the compressor is connected to the indoor heater through a pipeline. The indoor heater is connected to two branches. Branch one, as the refrigeration condition, is connected to the outdoor heat exchanger through the pipeline provided with solenoid valve one. The outdoor heat exchanger is connected to the high-temperature section of the intermediate heat exchanger through the provided connecting pipeline. The intermediate heat exchanger is connected to the evaporator in parallel through two branches: one branch is a battery thermal management group composed of an electronic expansion valve two and a battery cooler, and the other branch is a vehicle interior cooling system composed of an electronic expansion valve one and an evaporator. After the two branches converge, they are connected to the gas-liquid separator through a pipeline, and then connected to the low-temperature section of the intermediate heat exchanger through a pipeline for heat exchange, and then connected to the suction port of the compressor; Branch two, as the heat pump condition, is connected to the outdoor heat exchanger through the pipeline provided with an electronic expansion valve three. The outdoor heat exchanger is connected to the intermediate heat exchanger through a pipeline, and then is respectively connected to the gas-liquid separator and the other end of the intermediate heat exchanger through solenoid valve two. The intermediate heat exchanger is connected to the suction port of the compressor; At this time, when battery cooling is required, the pipeline does not pass through solenoid valve two, but is connected to the battery cooler through electronic expansion valve two, and is connected to the gas-liquid separator and the other end of the intermediate heat exchanger through a pipeline, and then connected to the suction port of the compressor; The battery thermal management group is connected to the plate heat exchanger through an electronic water pump two from the battery cooler. The plate heat exchanger is connected back to the battery cooler through the pipeline provided with solenoid valve five. When it is judged that the heat dissipation amount and heat dissipation temperature of the battery meet the dehumidification heat exchange regeneration heat demand, the cooling water flows back to the battery cooler and first passes through the pipeline through electronic expansion valve six to be connected to the dehumidification heat exchanger, and then is connected back to the battery cooler through the pipeline after providing heat; The system operation in the motor and electronic control thermal management group is independent. The radiator is connected to the motor and electronic control components through solenoid valve three and electronic water pump one through a pipeline. When it is judged that the dehumidification heat exchange regeneration heat demand is met, the pipeline first passes through electronic expansion valve four to be connected to the dehumidification heat exchanger before entering the radiator, and then is connected back to the radiator through the pipeline after providing heat; When the heat in the battery thermal management group and the motor and electronic control thermal management group cannot meet the dehumidification heat exchange regeneration heat demand, the indoor heater is connected to the dehumidification heat exchanger through electronic expansion valve five, and then is connected to the outlet of the indoor heater through the pipeline after providing heat.

[0009] Temperature sensors are respectively arranged at the inlet and outlet of the compressor, the refrigerant outlet of the indoor heater, the refrigerant outlet of the outdoor heat exchanger, the outlet of the intermediate heat exchanger, the refrigerant outlet of the battery cooler, the refrigerant outlet of the evaporator, the refrigerant outlet of the dehumidification heat exchanger, the water side outlet of the radiator, and the water side outlet of the battery cooler.

[0010] A humidity sensor is arranged at the air side outlet position of the dehumidification heat exchanger.

[0011] Pressure sensors are respectively arranged at the inlet and outlet of the compressor, the refrigerant outlet of the battery cooler, the refrigerant outlet of the evaporator, and the refrigerant outlet of the outdoor heat exchanger.

[0012] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0013] The present invention proposes a CO2 transcritical heat pump air-conditioning cycle system and an integrated vehicle thermal and humidity coupling system for waste heat recovery of the three power sources, innovates the thermal system structure, and realizes efficient operation within a wide temperature range under multiple modes and working conditions; utilizes multi-grade heat sources to respond to the regeneration demand of the DCHE, realizes the heat and mass transfer coupling between the DCHE regeneration process and the energy flow of the thermal system, and reduces the impact of the moisture load on the vehicle energy consumption.

[0014] Through the innovation of the above electric vehicle thermal management system, a new method for improving the energy efficiency utilization and improvement of new energy electric vehicles under low-temperature environmental conditions during operation is realized based on the coupling of the DCHE dehumidification regeneration process and the CO2 transcritical thermal system energy flow. The low-temperature cruising range of the vehicle is improved with the goal of the overall vehicle thermal system energy efficiency, which has considerable economic and ecological benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 is a principle block diagram of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0016] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0017] The present invention is composed of a heat exchanger composed of high- and low-temperature multi-stage heat sources of the system and a dehumidification heat exchanger coupled to complete the treatment of the thermal and humidity loads inside the vehicle in winter;

[0018] The heat and humidity management system includes a compressor, an indoor heater, an outdoor heat exchanger, an intermediate heat exchanger, a gas-liquid separator, a battery cooler, an indoor evaporator, a dehumidification heat exchanger, and a radiator. The outlet of the compressor is connected to the indoor heater through a pipeline. The indoor heater is connected to two branches. Branch one, as the refrigeration condition, is connected to the outdoor heat exchanger through a pipeline with a solenoid valve one installed. The outdoor heat exchanger is connected to the high-temperature section of the intermediate heat exchanger through a set of connecting pipelines. The intermediate heat exchanger is connected to two evaporators in parallel through two branches: one branch is a battery thermal management group composed of an electronic expansion valve two and a battery cooler, and the other branch is a vehicle interior cooling system composed of an electronic expansion valve one and an evaporator. After the two branches converge, they are connected to the gas-liquid separator through a pipeline, and then connected to the low-temperature section of the intermediate heat exchanger through a pipeline for heat exchange, and then connected to the suction port of the compressor; Branch two, as the heat pump condition, is connected to the outdoor heat exchanger through a pipeline with an electronic expansion valve three installed. The outdoor heat exchanger is connected to the intermediate heat exchanger through a pipeline, and then connected to the gas-liquid separator and the other end of the intermediate heat exchanger respectively through a solenoid valve two. The intermediate heat exchanger is connected to the suction port of the compressor; At this time, when there is a demand for battery cooling, the pipeline does not pass through the solenoid valve two, but is connected to the battery cooler through the electronic expansion valve two, and is connected to the gas-liquid separator and the other end of the intermediate heat exchanger through a pipeline, and then connected to the suction port of the compressor; The battery thermal management group is connected to a plate heat exchanger through an electronic water pump two by the battery cooler. The plate heat exchanger is connected back to the battery cooler through a pipeline with a solenoid valve five installed. When it is judged that the heat dissipation amount and heat dissipation temperature of the battery meet the dehumidification heat exchange regeneration heat demand, the cooling water flows back to the battery cooler and is first connected to the dehumidification heat exchanger through a pipeline passing through an electronic expansion valve six, and then connected back to the battery cooler through a pipeline after providing heat; The system operation in the motor and electric control thermal management group is independent. The radiator is connected to the motor and electric control components through a pipeline with a solenoid valve three and an electronic water pump one. When it is judged that the dehumidification heat exchange regeneration heat demand is met, the cooling water enters the radiator and is first connected to the dehumidification heat exchanger through a pipeline passing through an electronic expansion valve four, and then connected back to the radiator through a pipeline after providing heat; When the heat in the battery thermal management group and the motor and electric control thermal management group cannot meet the dehumidification heat exchange regeneration heat demand, the indoor heater is connected to the dehumidification heat exchanger through an electronic expansion valve five, and then connected to the outlet of the indoor heater through a pipeline after providing heat.

[0019] Based on the operating characteristics of the complex matrix relationship of multiple heat sources, multiple operating conditions, and multiple modes in the electric vehicle thermal system, in order to improve the actual energy efficiency of the thermal system and at the same time broaden the applicability of the DCHE dehumidification system, it is proposed to establish a deep coupling of the CO2 thermal system, the three-electricity waste heat recovery system, and the dehumidification regeneration heat source demand, so as to realize the optimal configuration and efficient switching of multiple energy flows under multiple operating conditions and multiple working modes, and improve the vehicle's cruising range.

[0020] The transcritical CO2 heat and humidity coupling system for new energy electric vehicles is as Figure 1As shown. Multiple working mode switches are set to perform refrigeration mode, heating mode, dehumidification mode, battery cooling, motor / electronic control component cooling mode, and hybrid working modes based on multiple single working modes, etc. Through the utilization, transfer, and conversion laws of cold, heat, and humidity of each component, the optimal performance among the cold and heat system, waste heat recovery, and humidity regulation is achieved. The traditional automotive thermal management working modes are as follows:

[0021] (1) Refrigeration mode: When the refrigeration demand is turned on, the high-temperature and high-pressure CO2 refrigerant from the compressor outlet passes through the indoor heater. At this time, the air damper is adjusted so that the air does not pass through the indoor heater for heat exchange. The electronic expansion valve III is closed. The CO2 refrigerant enters the outdoor heat exchanger to release heat after passing through the solenoid valve I, then enters the intermediate heat exchanger for further cooling, and then passes through the electronic expansion valve I to throttle down and reduce pressure, and then enters the indoor evaporator to absorb the heat of the passenger compartment air. After separating the liquid droplets in the gas-liquid separator, it enters the intermediate heat exchanger for further heating to prevent liquid slugging of the compressor, and finally returns to the compressor to be heated and pressurized again to complete the refrigeration cycle.

[0022] (2) Heating mode: When the heating demand is turned on, the high-temperature and high-pressure CO2 refrigerant from the compressor outlet enters the indoor heater. At this time, the air damper is adjusted so that the passenger compartment air passes through the indoor heater for heat exchange with it. The air is heated and then enters the passenger compartment to provide warm air. The solenoid valve I is closed. The CO2 refrigerant is cooled and then enters the electronic expansion valve III to throttle down and reduce pressure, and then enters the outdoor heat exchanger to absorb the heat of the outdoor air for evaporation and heat absorption. The electronic expansion valve I and the electronic expansion valve II are closed, and the solenoid valve II is opened. The CO2 refrigerant passes through the intermediate heat exchanger, and the liquid droplets are separated in the gas-liquid separator to prevent liquid slugging of the compressor, and finally returns to the compressor to be heated and pressurized again to complete the heating cycle.

[0023] (3) Battery cooling mode: When the battery temperature is too high and a cooling demand instruction is issued, the electronic expansion valve II is opened. The low-temperature and high-pressure CO2 refrigerant at the outlet of the outdoor heat exchanger passes through the electronic expansion valve II to throttle down and reduce pressure, and exchanges heat with the battery heat absorbed by the plate heat exchanger in the battery cooler. At this time, if there is also a cooling demand in the passenger compartment, the battery cooler forms a cooling parallel circuit with the indoor evaporator. The CO2 refrigerant converges after evaporation, enters the gas-liquid separator and the intermediate heat exchanger, and then returns to the compressor for circulation.

[0024] (4) Motor / electronic control component cooling mode: When the motor / electronic control component issues a cooling demand instruction, the water circulation circuit of the outdoor radiator is opened. By adjusting the water flow, the heat in the motor / electronic control component is exchanged through the outdoor radiator and discharged to the outdoor air for cooling.

[0025] (5) Winter dehumidification mode: In the winter dehumidification mode of the traditional electric vehicle heat pump system, by opening the dehumidification switching valve (solenoid valve four), the two heat exchangers (indoor heater and indoor evaporator) in the air conditioning box are connected. The wet air first passes through the indoor evaporator for low-temperature cooling and dehumidification, and then is heated by the indoor heater and sent into the passenger compartment.

[0026] Different from the traditional electric vehicle heat pump system, the system uses the dehumidification heat exchanger DCHE for dehumidification in the winter dehumidification mode. The regeneration heat source of the dehumidification material in the dehumidification heat exchanger after dehumidification can be utilized by three heat sources in the electric vehicle according to the heat source temperature:

[0027] (1) Waste heat from the motor / electronic control, etc.: When the dehumidification heat exchanger has a regeneration requirement, the waste heat after cooling of the motor / electronic control, etc. is not directly discharged outdoors and can be used for the regeneration of the dehumidification heat exchanger. This part, especially the waste heat that can be utilized after the motor is cooled, has a relatively high temperature, generally about 65°C, and is discharged outdoors after releasing heat through the dehumidifying agent regeneration, but the amount of heat of the waste heat is small and can be preferentially utilized when the dehumidification regeneration demand is not large.

[0028] (2) Battery waste heat: When the dehumidification heat exchanger has a regeneration requirement, the waste heat after cooling of the battery is not directly discharged outdoors and can be used for the regeneration of the dehumidification heat exchanger. This part of the waste heat that can be utilized after the battery is cooled has a relatively low temperature, generally adjustable to about 35°C, and is discharged outdoors after releasing heat through the dehumidifying agent regeneration, which has certain requirements for the selection of the dehumidifying agent, but the amount of heat of the waste heat is more than that of the motor / electronic control waste heat and can be utilized or mixed with the motor / electronic control waste heat when the dehumidification regeneration demand is not large.

[0029] (3) Utilize the waste heat of CO2 refrigerant in the indoor heater: The utilization priority of the waste heat of the motor / electronic control components and the battery waste heat is higher than that of the utilization of the CO2 refrigerant waste heat. These two kinds of waste heat can also be utilized simultaneously as the regeneration heat of the dehumidification material, which can further reduce the energy consumption during waste heat discharge. However, when the waste heat of the motor / electronic control components and the battery waste heat cannot meet the regeneration heat demand of the dehumidification material, the heat of the CO2 refrigerant is utilized. During the heat release process of the indoor heater, the temperature of the CO2 refrigerant drops from about 100°C to about 30°C, and the temperature gradient is relatively large, which can meet the regeneration heat demand of various dehumidification materials. In addition, the key is that the outlet temperature of the indoor heater can be adjusted by regulating the refrigerant flow rate and the air volume in the passenger compartment to meet the regeneration heat demand of the dehumidification material. The CO2 refrigerant enters the electronic expansion valve three for the heating cycle after releasing heat through the dehumidification heat exchanger. When the heating mode is turned on, the dehumidification priority can be temporarily increased to ensure the driving safety.

[0030] By monitoring the regeneration heat demand and collecting and analyzing the appropriate waste heat temperature, the waste heat that is most suitable for the efficiency of the entire thermal management system is used for the regeneration of the dehumidification heat exchanger to meet the dehumidification demand inside the vehicle.

[0031] The above are only the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and modifications can be made, and these improvements and modifications should also be regarded as the protection scope of the present invention.

Claims

1. A CO2 thermal and humidity coupling system for new energy electric vehicles, characterized in that It includes a heat and humidity management system, a battery thermal management group, and an electric motor and electronic control thermal management group; The heat and humidity management system includes a compressor, an indoor heater, an outdoor heat exchanger, an intermediate heat exchanger, a gas-liquid separator, a battery cooler, an indoor evaporator, a dehumidification heat exchanger, and a radiator. The outlet of the compressor is connected to the indoor heater through a pipeline. The indoor heater is connected to two branches. Branch 1, as a refrigeration condition, is connected to the outdoor heat exchanger through a pipeline with a solenoid valve 1 installed. The outdoor heat exchanger is connected to the high-temperature section of the intermediate heat exchanger through a set of connecting pipelines. The intermediate heat exchanger is connected to two evaporators in parallel through two branches: one branch is a battery thermal management group composed of an electronic expansion valve 2 and a battery cooler, and the other branch is an in-vehicle temperature reduction system composed of an electronic expansion valve 1 and an evaporator. After the two branches converge, they are connected to the gas-liquid separator through a pipeline, and then connected to the low-temperature section of the intermediate heat exchanger through a pipeline for heat exchange, and then connected to the suction port of the compressor; Branch 2, as a heat pump condition, is connected to the outdoor heat exchanger through a pipeline with an electronic expansion valve 3 installed. The outdoor heat exchanger is connected to the intermediate heat exchanger through a pipeline, and then connected to the gas-liquid separator and the other end of the intermediate heat exchanger respectively through a solenoid valve 2. The intermediate heat exchanger is connected to the suction port of the compressor; At this time, when battery cooling is required, the pipeline does not pass through the solenoid valve 2, but is connected to the battery cooler through the electronic expansion valve 2, and is connected to the gas-liquid separator and the other end of the intermediate heat exchanger through a pipeline, and then connected to the suction port of the compressor; The battery thermal management group is connected from the battery cooler to the plate heat exchanger through an electronic water pump 2. The plate heat exchanger is connected back to the battery cooler through a pipeline with a solenoid valve 5 installed. When it is judged that the heat dissipation amount and heat dissipation temperature of the battery meet the dehumidification heat exchange regeneration heat demand, the cooling water flows back to the battery cooler after first passing through the electronic expansion valve 6 through a pipeline and connecting to the dehumidification heat exchanger, providing heat and then flowing back to the battery cooler through a pipeline; The system operation in the electric motor and electronic control thermal management group is independent. It is connected from the radiator to the electric motor and electronic control components through a solenoid valve 3 and an electronic water pump 1 through a pipeline. When it is judged that the dehumidification heat exchange regeneration heat demand is met, the pipeline first passes through the electronic expansion valve 4 through a pipeline and connects to the dehumidification heat exchanger before entering the radiator, provides heat and then flows back to the radiator through a pipeline; When the heat in the battery thermal management group and the electric motor and electronic control thermal management group cannot meet the dehumidification heat exchange regeneration heat demand, the indoor heater is connected to the dehumidification heat exchanger through an electronic expansion valve 5, provides heat and then is connected through a pipeline to converge with the outlet of the indoor heater; Temperature sensors are respectively arranged at the inlet and outlet of the compressor, the refrigerant outlet of the indoor heater, the refrigerant outlet of the outdoor heat exchanger, the outlet of the intermediate heat exchanger, the refrigerant outlet of the battery cooler, the refrigerant outlet of the evaporator, the refrigerant outlet of the dehumidification heat exchanger, the water side outlet of the radiator, and the water side outlet of the battery cooler; A humidity sensor is arranged at the air side outlet position of the dehumidification heat exchanger; Pressure sensors are respectively arranged at the inlet and outlet of the compressor, the refrigerant outlet of the battery cooler, the refrigerant outlet of the evaporator, and the refrigerant outlet of the outdoor heat exchanger.

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