CN114393970A - Transcritical carbon dioxide air conditioning system for electric bus - Google Patents

Abstract

A transcritical carbon dioxide air conditioning system for an electric bus, the system comprises a compressor, a three-way valve, an outside heat exchanger, a first drying filter, a second drying filter, an inside heat exchanger, and a gas-liquid separator , regenerator, the outlet of the compressor is connected to the first interface of the three-way valve, the second interface of the three-way valve is connected to the inlet of the heat exchanger outside the vehicle, and the third interface of the three-way valve is connected to the inlet of the heat exchanger inside the vehicle, The outlet of the outside heat exchanger is connected to the first ball valve, the first dry filter, the inside heat exchanger, the gas-liquid separator, the regenerator and the suction port of the compressor in sequence, and the other is connected to the gas-liquid separator. The invention adopts pure natural environment-friendly CO ₂ refrigerant, overcomes the problem of low heating efficiency of pure electric buses in winter, and adopts combined valve parts such as pressure relief valve and ball valve to prevent the system from being blocked or causing abnormal high pressure in the system under other abnormal conditions. The regenerator in the compressor can effectively increase the suction superheat of the compressor and prevent the compressor from liquid shock.

Description

A transcritical carbon dioxide air conditioning system for electric buses

technical field

The invention relates to the field of passenger car air conditioners, in particular to a transcritical carbon dioxide air conditioner system for electric buses.

Background technique

With the popularization of urban public transport and the support and subsidies of relevant national policies, there are more and more pure electric buses. Since there is no engine waste heat to use, at this stage, only PTC heaters or heat pumps can be used to achieve the purpose of heating in winter, but PTC The heater efficiency is less than 1, which greatly increases the power consumption of the vehicle in winter and reduces the cruising range; the working fluid of the heat pump system is R407C or R410A, both of which are mixed refrigerants, which are not environmentally friendly and In winter, the heating efficiency is lower than 2, and the ambient temperature can only work normally above -20 degrees Celsius, which cannot meet the heating needs of cold regions, nor can it meet the environmental protection requirements of European and American countries. It is understood that the industry is studying the technology of supplementing air and increasing enthalpy to increase the ambient temperature below -20 degrees Celsius for heating. However, the system has a complex structure, requires many valves and requires high control accuracy, and cannot solve the problem of exporting overseas. Some manufacturers use the environmentally friendly working fluid 1234yf to meet the needs of the single-cooling system, but the intellectual property rights of this working fluid have not been fully disclosed, resulting in the cost of refrigerants of thousands of yuan, and the air-conditioning refrigeration charge of the bus is relatively high. The cost of refrigerant alone needs to be increased by more than 10,000 yuan; in addition, the heating problem in winter cannot be effectively solved.

SUMMARY OF THE INVENTION

In order to solve the above problems, a transcritical carbon dioxide air conditioning system for electric buses is provided.

The purpose of this invention is to realize in the following way:

A transcritical carbon dioxide air conditioning system for an electric bus, the system comprises a compressor, a three-way valve, an outside heat exchanger, a first drying filter, a second drying filter, an inside heat exchanger, and a gas-liquid separator , regenerator, the outlet of the compressor is connected to the first interface of the three-way valve, the second interface of the three-way valve is connected to the inlet of the heat exchanger outside the vehicle, and the third interface of the three-way valve is connected to the inlet of the heat exchanger inside the vehicle, The outlet of the external heat exchanger is connected to the inlet of the first ball valve and the other is connected to the inlet of the third ball valve. The outlet of the first ball valve is connected to the inlet of the first dry filter, and the outlet of the first dry filter is connected to the electronic expansion valve. The inlet, the outlet of the electronic expansion valve is connected to the inlet of the in-vehicle heat exchanger, the outlet of the in-vehicle heat exchanger is connected to the inlet of the second ball valve, the outlet of the second ball valve and the outlet of the third ball valve are connected to the inlet of the gas-liquid separator, The outlet of the gas-liquid separator is connected to the inlet of the low-pressure side of the regenerator, the outlet of the low-pressure side of the regenerator is connected to the suction port of the compressor, and the outlet of the in-vehicle heat exchanger is also connected to the inlet of the high-pressure side of the regenerator. The outlet of the high pressure side is connected to the inlet of the fourth ball valve, the outlet of the fourth ball valve is connected to the inlet of the second filter drier, the outlet of the second filter drier is connected to the inlet of the third electronic expansion valve, and the outlet of the third electronic expansion valve is connected to the vehicle Inlet of external heat exchanger.

Further, the in-vehicle heat exchanger includes a first in-vehicle heat exchanger and a second in-vehicle heat exchanger, and the outlet of the first dry filter is connected to the inlet of the first in-vehicle heat exchanger through the first electronic expansion valve. and connecting the inlet of the second in-vehicle heat exchanger through the second electronic expansion valve.

Further, an outside fan is arranged on the outside of the outside heat exchanger, a first inside fan is arranged outside the first heat exchanger, and a second inside fan is arranged outside the second heat exchanger.

Further, a low pressure relief valve is arranged on the pipeline between the low pressure side outlet of the regenerator and the suction port of the compressor.

Further, a high pressure relief valve is arranged on the pipeline between the outlet of the compressor and the three-way valve.

Further, the refrigerant circulating in the system is CO2.

Further, the compressor is an inverter compressor.

During the refrigeration cycle, the high-temperature and high-pressure gas from the compressor flows through the three-way valve and flows into the outside heat exchanger for cooling. After the outside fan is forced to dissipate heat to the environment, the first ball valve is opened, and it is divided into two paths after passing through the first drying filter. After entering the first electronic expansion valve, the second electronic expansion valve throttles and cools down, and then enters the corresponding first and second in-vehicle heat exchangers for evaporation. Under the action of the second in-vehicle fan, it is sent into the cabin for cooling to meet the cooling demand of the air-conditioning system; the low-temperature and low-pressure refrigerants from the first in-vehicle heat exchanger and the second in-vehicle heat exchanger are combined and enter through the second ball valve into the air-conditioning system. In the gas-liquid separator, and then return to the compressor through the regenerator to complete the refrigeration cycle of the system.

During the heating cycle, the high-temperature and high-pressure gas from the compressor is divided into two paths through the three-way valve and flows into the first in-vehicle heat exchanger and the second in-vehicle heat exchanger for cooling. Under the action of the second in-vehicle fan, it is sent into the cabin for heating to meet the heating demand of the air-conditioning system; the medium-temperature and high-pressure refrigerants from the first in-vehicle heat exchanger and the second in-vehicle heat exchanger are combined and flow into the regenerative Heat exchange is carried out in the heat exchanger to realize the re-cooling of the refrigerant to achieve the purpose of supercooling, and then it enters the heat exchanger outside the car for evaporation after being throttled by the fourth ball valve, the second dry filter and the third electronic expansion valve. After the external fan is forced to absorb heat to the environment, it flows into the regenerator through the third ball valve and the gas-liquid separator to exchange heat with the refrigerant flowing into the previous in-vehicle heat exchanger, so as to realize the temperature rise of the refrigerant and improve the cooling back to the compressor. The temperature of the refrigerant is ensured to ensure that the refrigerant is a saturated gas, to prevent the compressor from liquid shock, and finally return to the compressor to complete the heating cycle.

Beneficial effects of the present invention: the present invention adopts pure natural environment-friendly CO ₂ refrigerant, overcomes the problem of low heating efficiency of pure electric buses in winter, and adopts pressure relief valve, ball valve and other components to prevent the system from being blocked or causing system pressure under other abnormal conditions If it is too high, it will automatically open and discharge part or all of the refrigerant to ensure that the system pressure is normal and no extreme situations such as explosion will occur. The regenerator in this system can effectively increase the suction superheat of the compressor during the heating process and prevent the compressor from liquid shock. Corresponding to it is the refrigeration cycle process. The regenerator only has refrigerant flowing on the low-pressure side, and the function of the regenerator changes, and the regenerator is only used as part of the system pipeline. In addition, the ball valve is a valve with throttling and flow adjustment. When heating at low temperature, it can achieve different ambient temperatures and adjust different opening degrees to meet the requirements of the heating system for the system superheat and ensure the safe operation of the compressor.

Description of drawings

Fig. 1 is the system principle diagram of the present invention.

Figure 2 is a schematic diagram of the refrigeration cycle of the present invention.

Figure 3 is a schematic diagram of the heating cycle of the present invention.

Among them, 1-compressor, 2-three-way valve, 3-outboard heat exchanger, 4-outdoor fan, 5-first ball valve, 6-first filter drier, 7-first electronic expansion valve, 8 - The first in-vehicle heat exchanger, 9- The first in-vehicle fan, 10- The second electronic expansion valve, 11- The second in-vehicle heat exchanger, 12- The second in-vehicle fan, 13- The second ball valve, 14 -The third ball valve, 15-gas-liquid separator, 16-regenerator, 17-fourth ball valve, 18-second filter drier, 19-third electronic expansion valve, 20-low pressure relief valve, 21-high pressure pressure relief valve.

Detailed ways

The present invention will be described in further detail below with reference to the accompanying drawings and specific embodiments.

It should be noted that the following detailed description is exemplary and intended to provide further explanation of the application. Unless otherwise defined, all technical and scientific terms used herein have the same technical meaning as commonly understood by one of ordinary skill in the art to which this application belongs.

A transcritical carbon dioxide air conditioning system for an electric bus, the system comprises a compressor 1, a three-way valve 2, an external heat exchanger 3, a first drying filter 6, a second drying filter 18, and an internal heat exchanger , gas-liquid separator 15, regenerator 16, the outlet of the compressor 1 is connected to the first interface of the three-way valve 2, the second interface of the three-way valve 2 is connected to the inlet of the external heat exchanger 3, and the The third interface is connected to the inlet of the in-vehicle heat exchanger, the outlet of the out-of-vehicle heat exchanger 3 is connected to the inlet of the first ball valve 5, and the other is connected to the inlet of the third ball valve 14, and the outlet of the first ball valve is connected to the first filter drier 6, the outlet of the first filter drier 6 is connected to the inlet of the electronic expansion valve, the outlet of the electronic expansion valve is connected to the inlet of the in-vehicle heat exchanger, the outlet of the in-vehicle heat exchanger is connected to the inlet of the second ball valve 13, the second The outlet of the ball valve 13 and the outlet of the third ball valve 14 are both connected to the inlet of the gas-liquid separator 15, the outlet of the gas-liquid separator 15 is connected to the low-pressure side inlet of the regenerator 16, and the low-pressure side outlet of the regenerator 16 is connected to the compressor 1 The outlet of the in-vehicle heat exchanger is also connected to the high-pressure side inlet of the regenerator 16, the high-pressure side outlet of the regenerator 16 is connected to the inlet of the fourth ball valve 17, and the outlet of the fourth ball valve 17 is connected to the second dry filter The inlet of the filter 18 and the outlet of the second filter drier 18 are connected to the inlet of the third electronic expansion valve 19 , and the outlet of the third electronic expansion valve 19 is connected to the inlet of the outside heat exchanger 3 .

The in-vehicle heat exchanger includes a first in-vehicle heat exchanger 8 and a second in-vehicle heat exchanger 11 , and the outlet of the first dry filter 6 is connected to the first in-vehicle heat exchanger 8 through the first electronic expansion valve 7 . The inlet of the second electronic expansion valve 10 is connected to the inlet of the second in-vehicle heat exchanger 11 .

The outside of the outside heat exchanger 3 is provided with an outside fan 4 , the outside of the first heat exchanger 8 is arranged with a first inside fan 9 , and the outside of the second heat exchanger 11 is arranged with a second inside fan 12 .

A low pressure relief valve 20 is provided on the pipeline between the low pressure side outlet of the regenerator 16 and the suction port of the compressor 1 .

A high pressure relief valve 21 is arranged on the pipeline between the outlet of the compressor 1 and the three-way valve 2 .

The main purpose of the high pressure relief valve 21 and the low pressure relief valve 20 is to prevent the system from being blocked or other abnormal conditions causing the system pressure to be too high. In extreme situations such as explosions.

The refrigerant circulating in the system is CO2.

The compressor 1 is an inverter compressor.

During the refrigeration cycle, the high-temperature and high-pressure gas from the compressor 1 flows through the three-way valve 2 and flows into the outside heat exchanger 3 for cooling. After the outside fan 4 is forced to dissipate heat to the environment, the first ball valve 5 is opened, and the first ball valve 5 is opened. After the heat exchanger 6 enters into the first electronic expansion valve 7 and the second electronic expansion valve 10 in two ways, after throttling and cooling, they enter the corresponding first in-vehicle heat exchanger 8 and second in-vehicle heat exchanger 11 for evaporation, and after cooling Under the action of the first in-vehicle fan 9 and the second in-vehicle fan 12, the air is sent into the cabin for cooling to achieve the cooling demand of the air-conditioning system; from the first in-vehicle heat exchanger 8 and the second in-vehicle heat exchanger 11 The low-temperature and low-pressure refrigerant that comes out is combined and enters the gas-liquid separator 15 through the second ball valve 13, and then returns to the compressor 1 through the low-pressure side of the regenerator 16 to complete the system refrigeration cycle. The regenerator only has refrigerant on the low-pressure side. Circulation, the function of the regenerator changes, and the regenerator is only used as part of the system pipeline.

During the heating cycle, the high-temperature and high-pressure gas from the compressor 1 passes through the three-way valve 2 into two paths and flows into the first in-vehicle heat exchanger 8 and the second in-vehicle heat exchanger 11 for cooling. Under the action of the in-vehicle fan 9 and the second in-vehicle fan 12, they are sent into the cabin for heating to achieve the heating demand of the air-conditioning system; After the refrigerant is combined, it flows into the high pressure side of the regenerator 16 for heat exchange, and the refrigerant is re-cooled to achieve the purpose of supercooling, and then passes through the fourth ball valve 17, the second dry filter 18 and the third electronic expansion valve 19. After throttling, it enters the outside heat exchanger 3 for evaporation. After being forced to absorb heat to the environment by the outside fan 4, it flows into the low pressure side of the regenerator 16 through the third ball valve 14 and the gas-liquid separator 15 to exchange heat inside the vehicle. The refrigerant flowing into the compressor exchanges heat, realizes the temperature rise of the refrigerant, raises the temperature of the refrigerant back to the compressor, ensures that the refrigerant is a saturated gas, and prevents liquid shock of the compressor, that is, the temperature of the compressor inlet is further increased, and finally returns to the compressor. Compressor 1 completes the heating cycle.

The three-way valve in this embodiment is mainly to realize the switching of the flow direction of the refrigerant in the cooling/heating mode, and the ball valve cooperates with the three-way valve;

The main function of the gas-liquid separator is to prevent the refrigerant at the inlet of the compressor from being in a mixed state of gas and liquid under low ambient temperature, and the compressor will suffer from liquid shock after inhaling the liquid refrigerant and cause damage;

The invention adopts pure natural and environmentally friendly CO ₂ refrigerant, which overcomes the problem of low heating efficiency of pure electric buses in winter, and adopts pressure relief valve, two-way valve and other components to prevent the system from being blocked or causing the system pressure to be too high under other abnormal conditions. It automatically opens and discharges part or all of the refrigerant at any time to ensure that the system pressure is normal and no extreme conditions such as explosion will occur. The regenerator in this system increases the degree of superheat during the heating process to prevent the liquid hammer from occurring in the compressor. In the process of low temperature heating cycle, the regenerator can effectively increase the superheat degree of the refrigerant gas returning to the compressor and prevent the compressor from liquid shock. Corresponding to it is the refrigeration cycle process. The regenerator only has refrigerant flowing on the low-pressure side, and the function of the regenerator changes, and the regenerator is only used as part of the system pipeline. In addition, the ball valve is a valve with throttling and flow adjustment. When heating at low temperature, it can achieve different ambient temperatures and adjust different opening degrees to meet the requirements of the heating system for the system superheat and ensure the safe operation of the compressor.

The above are only the preferred embodiments of the present invention. It should be pointed out that for those skilled in the art, some changes and improvements can be made without departing from the overall concept of the present invention, and these should also be regarded as the present invention. scope of protection.

Claims (9)

1. A trans-critical carbon dioxide air conditioning system for an electric bus is characterized in that: the system comprises a compressor (1), a three-way valve (2), an external heat exchanger (3), a first drying filter (6), a second drying filter (18), an internal heat exchanger, a gas-liquid separator (15) and a heat regenerator (16), wherein an outlet of the compressor (1) is connected with a first interface of the three-way valve (2), a second interface of the three-way valve (2) is connected with an inlet of the external heat exchanger (3), a third interface of the three-way valve (2) is connected with an inlet of the internal heat exchanger, one path of an outlet of the external heat exchanger (3) is connected with an inlet of a first ball valve (5), the other path of the outlet is connected with an inlet of a third ball valve (14), an outlet of the first ball valve is connected with an inlet of the first drying filter (6), an outlet of the first drying filter (6) is connected with an inlet of an electronic expansion valve, an outlet of the electronic expansion valve is connected with an inlet of the internal heat exchanger, an outlet of the internal heat exchanger is connected with an inlet of the second ball valve (13), the outlet of the second ball valve (13) and the outlet of the third ball valve (14) are connected with the inlet of a gas-liquid separator (15), the outlet of the gas-liquid separator (15) is connected with the low-pressure side inlet of a heat regenerator (16), the low-pressure side outlet of the heat regenerator (16) is connected with the air suction port of a compressor (1), the outlet of the heat exchanger in the vehicle is also connected with the high-pressure side inlet of the heat regenerator (16), the high-pressure side outlet of the heat regenerator (16) is connected with the inlet of a fourth ball valve (17), the outlet of the fourth ball valve (17) is connected with the inlet of a second drying filter (18), the outlet of the second drying filter (18) is connected with the inlet of a third electronic expansion valve (19), and the outlet of the third electronic expansion valve (19) is connected with the inlet of the heat exchanger outside the vehicle (3).

2. The transcritical carbon dioxide air conditioning system for electric buses according to claim 1, wherein: the vehicle-mounted heat exchanger comprises a first vehicle-mounted heat exchanger (8) and a second vehicle-mounted heat exchanger (11), wherein an outlet of the first drying filter (6) is connected with an inlet of the first vehicle-mounted heat exchanger (8) through a first electronic expansion valve (7) and is connected with an inlet of the second vehicle-mounted heat exchanger (11) through a second electronic expansion valve (10).

3. The transcritical carbon dioxide air conditioning system for electric buses according to claim 2, wherein: the outer side of the outer heat exchanger (3) is provided with an outer fan (4), the outer side of the first heat exchanger (8) is provided with a first vehicle inner fan (9), and the outer side of the second heat exchanger (11) is provided with a second vehicle inner fan (12).

4. The transcritical carbon dioxide air conditioning system for electric buses according to claim 1, wherein: and a low-pressure relief valve (20) is arranged on a pipeline between the outlet of the low-pressure side of the heat regenerator (16) and the air suction port of the compressor (1).

5. The transcritical carbon dioxide air conditioning system for electric buses according to claim 1, wherein: and a high-pressure relief valve (21) is arranged on a pipeline between the outlet of the compressor (1) and the three-way valve (2).

6. The transcritical carbon dioxide air conditioning system for electric buses according to claim 1, wherein: the refrigerant circulating in the system is CO₂。

7. The transcritical carbon dioxide air conditioning system for electric buses according to claim 1, wherein: the compressor (1) is a variable frequency compressor.

8. The transcritical carbon dioxide air conditioning system for electric buses according to any one of claims 2-7, wherein: during refrigeration cycle, high-temperature and high-pressure gas from a compressor (1) flows into an external heat exchanger (3) for cooling after passing through a three-way valve (2), after being forcibly radiated to the environment by an external fan (4), a first ball valve (5) is opened, and after passing through a first drying filter (6), the gas is divided into two paths to enter a first electronic expansion valve (7), a second electronic expansion valve (10) for throttling and cooling and then enters a corresponding first internal heat exchanger (8) and a second internal heat exchanger (11) for evaporation, and cooled air is sent into a carriage for cooling under the action of a first internal fan (9) and a second internal fan (12), so that the refrigeration requirement of an air conditioning system is met; the low-temperature and low-pressure refrigerant coming out of the first vehicle interior heat exchanger (8) and the second vehicle interior heat exchanger (11) is converged and then enters the gas-liquid separator (15) through the second ball valve (13), and then returns to the compressor (1) through the heat regenerator (16) to complete the system refrigeration cycle.

9. The transcritical carbon dioxide air conditioning system for electric buses according to any one of claims 2-7, wherein: during heating circulation, high-temperature and high-pressure gas from the compressor (1) is divided into two paths through the three-way valve (2) and flows into the first vehicle interior heat exchanger (8) and the second vehicle interior heat exchanger (11) for cooling, and the heated air is sent into a compartment for heating under the action of the first vehicle interior fan (9) and the second vehicle interior fan (12), so that the heating requirement of the air conditioning system is met; the medium-temperature high-pressure refrigerant coming out of the first vehicle-interior heat exchanger (8) and the second vehicle-interior heat exchanger (11) is converged and then flows into the heat regenerator (16) for heat exchange to realize the purpose of supercooling the refrigerant again, and then enters the vehicle-exterior heat exchanger (3) for evaporation after being throttled by the fourth ball valve (17), the second drying filter (18) and the third electronic expansion valve (19), and then flows into the heat regenerator (16) through the third ball valve (14) and the gas-liquid separator (15) after being forced to absorb heat to the environment by the vehicle-exterior fan (4) to exchange heat with the refrigerant flowing into the previous vehicle-interior heat exchanger, so that the temperature of the refrigerant is increased, the temperature of the refrigerant returning to the compressor is increased, the refrigerant is ensured to be saturated gas, the liquid impact of the compressor is prevented, and finally the refrigerant returns to the compressor (1) to complete the heating cycle.

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