Vehicle Air-Conditioning Injection Circuit for Frost-Suppressed Heating
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Solution Overview
Problem
The existing vehicle air-conditioning devices face limitations in achieving sufficient heating qualification due to low refrigerant flow rates and frost formation in outdoor heat exchangers, which leads to inefficient heating and increased power consumption during defrost operations.
Innovation Solution
The implementation of an air-conditioning device with an injection circuit that includes pressure reducing means and a water circulation circuit, allowing for gas injection to the compressor and heat exchange between decompressed refrigerant and water, which enhances refrigerant flow rates and suppresses frost formation by controlling refrigerant flow and using heated water for additional heating.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If refrigerant is distributed to the injection circuit to increase compressor discharge amount, then heating qualification is improved, but heat exchange amount between refrigerant and decompressed refrigerant becomes smaller due to low temperature
Solution Approach 1:
A water circulation circuit is introduced as an intermediary heat transfer medium. The circuit includes a water pump, water circulation passage, and water-air heat exchanger. Water absorbs heat from the refrigerant in the water-refrigerant heat exchanger and transfers it to the outdoor air through the water-air heat exchanger, enabling efficient heat transfer despite temperature differences.
Solution Approach 2:
The system changes the thermal parameters of the outdoor air by circulating heated water through the water-air heat exchanger. This pre-heats the outdoor air before it contacts the evaporator, increasing the temperature differential and heat exchange efficiency between the refrigerant and outdoor air.
2Reliability
If defrost operation is executed to remove frost from outdoor heat exchanger, then heat absorption qualification is restored, but air temperature blown into vehicle interior lowers and power consumption increases
Solution Approach 1:
The system converts the harmful effect of cold outdoor air into a beneficial pre-heating process. The water circulation circuit uses waste heat from the refrigerant to pre-heat the outdoor air through the water-air heat exchanger, reducing the temperature differential that causes frost formation while maintaining heating efficiency.
Solution Approach 2:
The water circulation circuit performs preliminary heating of the outdoor air before it reaches the evaporator. By pre-heating the air through the water-air heat exchanger, the system reduces frost formation on the outdoor heat exchanger, preventing the need for frequent defrost operations.
3Power
If refrigerant flow rate is increased to improve heating qualification, then heating performance is enhanced, but frost formation in outdoor heat exchanger increases
Solution Approach 1:
The system changes the temperature parameter of the outdoor air by circulating heated water through the water-air heat exchanger. This pre-heats the outdoor air, reducing the temperature differential between the refrigerant and outdoor air, thereby reducing frost formation on the outdoor heat exchanger while maintaining heating performance.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This solution improves heating qualification by increasing refrigerant flow rates and reduces frost formation, maintaining comfort and efficiency while minimizing power consumption during heating operations.
Implementation Method 1
the injection circuit has pressure reducing means
Implementation Method 2
a discharge side heat exchanger which performs heat exchange between the refrigerant decompressed by this pressure reducing means and the refrigerant discharged from the compressor
Implementation Method 3
a water-refrigerant heat exchanger which performs heat exchange between the refrigerant decompressed by this pressure reducing means and the water flowing in the water circulation circuit
Implementation Method 4
a compressor which compresses a refrigerant
Implementation Method 5
a radiator disposed in this air flow passage to let the refrigerant radiate heat
Implementation Method 6
a heat absorber disposed in the air flow passage to let the refrigerant absorb heat
Implementation Method 7
an outdoor heat exchanger disposed outside the vehicle interior to let the refrigerant radiate or absorb heat
Data Source
AI summary
There is disclosed a vehicle air-conditioning device in which a heating qualification by gas injection can sufficiently be obtained. The vehicle air-conditioning device comprises a compressor 2 which compresses a refrigerant, an air flow passage 3 through which air to be supplied into a vehicle interior flows, a radiator 4 disposed in the air flow passage to let the refrigerant radiate heat, a heat absorber 9 disposed in the air flow passage to let the refrigerant absorb heat, an outdoor heat exchanger 7 disposed outside the vehicle interior to let the refrigerant radiate or absorb heat, and a controller. The controller executes a heating mode in which the refrigerant discharged from the compressor 2 radiates heat in the radiator 4 and the refrigerant by which heat has been radiated is decompressed and then absorbs heat in the outdoor heat exchanger 7. The vehicle air-conditioning device comprises an injection circuit 40 which distributes a part of the refrigerant flowing out from the radiator 4 to return the refrigerant to the middle of compression by the compressor 2, and the injection circuit 40 has an expansion valve 30, and a discharge side heat exchanger 35 which performs heat exchange between the refrigerant decompressed by the expansion valve 30 and the refrigerant discharged from the compressor 2 before flowing into the radiator 4.