Vehicle Heat Pump Injection Circuit for Stable Heating and Defrost
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Solution Overview
Problem
The existing vehicle air-conditioning devices face limitations in heating qualification due to low refrigerant flow rates and frost formation in outdoor heat exchangers, leading 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
1Quantity of substance
If an injection circuit is used to increase refrigerant flow rate, then heating qualification is improved, but the refrigerant temperature is low which limits heat exchange efficiency
Solution Approach 1:
A three-way valve is introduced as an intermediary device to control and optimize the mixing of refrigerant flows. The valve regulates the proportion of refrigerant from the outdoor heat exchanger that is mixed with refrigerant from the radiator, enabling precise control over the temperature and flow rate of refrigerant entering the compressor, thereby resolving the contradiction between increasing refrigerant flow rate and maintaining heat exchange efficiency
Solution Approach 2:
The system dynamically changes the temperature parameter of the refrigerant by controlling the mixing ratio through the three-way valve. By adjusting the proportion of warmer refrigerant from the radiator mixed with colder refrigerant from the outdoor heat exchanger, the system optimizes the refrigerant temperature to improve heat exchange efficiency while maintaining adequate flow rate for heating qualification
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 injection circuit enables continuous useful action by maintaining refrigerant flow through the outdoor heat exchanger even during defrost operations. The three-way valve directs refrigerant flow to continue absorbing heat from outdoor air, preventing complete cessation of the heat absorption function during defrost cycles, thereby reducing the need for frequent and prolonged defrost operations
Solution Approach 2:
The system converts the harmful effect of frost formation into a benefit by using the defrost operation itself to preheat the refrigerant through the injection circuit. The refrigerant flowing through the outdoor heat exchanger during defrost absorbs some heat, and when mixed with refrigerant from the radiator, provides warmer air to the vehicle interior, reducing the negative impact of defrost operations
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
pressure reducing means for decompressing the refrigerant flowing out from the radiator
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 radiator disposed in this air flow passage to let the refrigerant radiate heat
Implementation Method 4
a heat absorber disposed in the air flow passage to let the refrigerant absorb heat
Implementation Method 5
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.