Vehicle Heat Pump Defrost Control With Refrigerant Injection
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Solution Overview
Problem
In vehicle air conditioning systems, the defrosting of outdoor heat exchangers often obstructs heat exchange due to frost formation, leading to hindered heating of the vehicle interior, especially in hybrid and electric cars where efficient heating is crucial.
Innovation Solution
An air conditioning device with a control system that manages the refrigerant flow to defrost the outdoor heat exchanger without hindering interior heating, using modes like dehumidifying and cooling type defrosting, hot gas defrosting, and reverse cycle defrosting, and operates the injection circuit to return refrigerant to the compressor, ensuring continuous heating capability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high-temperature refrigerant is passed through the outdoor heat exchanger to perform defrosting, then the outdoor heat exchanger can be defrosted, but heat exchange between outdoor air and refrigerant is obstructed and vehicle interior heating is hindered
Solution Approach 1:
The refrigerant flow path is segmented into multiple circuits: a defrosting circuit that directs high-temperature refrigerant to the outdoor heat exchanger, and a heating circuit that maintains refrigerant flow through the heat absorber for interior heating. This segmentation allows simultaneous defrosting and heating operations without mutual interference.
Solution Approach 2:
The system dynamically switches between different operational modes (heating mode, defrosting mode, and simultaneous defrosting-heating mode) based on real-time conditions such as frost accumulation level and interior temperature requirements. The control means adjusts refrigerant flow distribution dynamically to optimize both defrosting efficiency and heating performance.
2Productivity
If refrigerant flow is increased for defrosting, then defrosting efficiency improves, but heating capability is reduced
Solution Approach 1:
The system merges the defrosting function and heating function into a single coordinated operation by introducing a third operational mode where both functions run simultaneously. The control means manages refrigerant distribution to ensure adequate flow to both the outdoor heat exchanger (for defrosting) and the heat absorber (for heating), combining previously separate operational sequences into a concurrent process.
3Reliability
If defrosting mode is executed to remove frost, then outdoor heat exchanger performance is restored, but vehicle interior heating is obstructed
Solution Approach 1:
The system performs preliminary assessment of frost accumulation levels and interior heating requirements before initiating defrosting operations. When both defrosting and heating are needed, the control means preemptively activates the simultaneous defrosting-heating mode, preventing the need to interrupt heating for defrosting and maintaining heating comfort throughout the process.
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
The solution effectively defrosts the outdoor heat exchanger without obstructing vehicle interior heating, reducing power consumption and maintaining heating capability, especially in electric and hybrid cars, by optimizing refrigerant flow and operation modes.
Implementation Method 1
a compressor which compresses a refrigerant
Implementation Method 2
a radiator disposed in this air flow passage to let the refrigerant radiate heat
Implementation Method 3
an outdoor heat exchanger disposed outside the vehicle interior to let the refrigerant radiate or absorb heat
Implementation Method 4
a heat absorber disposed in the air flow passage to let the refrigerant absorb heat
Implementation Method 5
an injection circuit which distributes a refrigerant flowing out from a radiator, decompresses this distributed refrigerant, performs heat exchange between this refrigerant and the refrigerant flowing out from the radiator, and returns the refrigerant to the middle of compression by a compressor
Data Source
AI summary
There is disclosed an air conditioning device for vehicle in which in a defrosting mode to defrost an outdoor heat exchanger, the defrosting of the outdoor heat exchanger can be achieved without hindrance while maintaining heating of a vehicle interior. A refrigerant discharged from a compressor 2 radiates heat in a radiator 4 and the refrigerant by which heat has been radiated is decompressed and then absorbs heat in an outdoor heat exchanger 7 to heat the vehicle interior. The air conditioning device for vehicle includes an injection circuit 40 which distributes a part of the refrigerant flowing out from the radiator 4 to return the part to the compressor 2. When a controller 32 passes the high-temperature refrigerant through the outdoor heat exchanger 7 to perform defrosting, the controller operates the injection circuit 40 to return the refrigerant to the compressor 2.