Vehicle air conditioning device
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Vehicle air conditioning devices with heat pump systems face a significant issue where frosting on the outdoor heat exchanger leads to reduced heat transfer efficiency and deteriorated heating performance, as frost acts as a thermal resistance and decreases air flow, hindering the absorption of heat from outdoor air.
Innovation Solution
The system incorporates control mechanisms that adjust the target subcool degree of the refrigerant, compressor speed, indoor and outdoor blower volumes, and air ratios to manage the refrigerant evaporation temperature, thereby delaying frosting and maintaining heating capability by increasing the radiator pressure and outdoor heat exchanger pressure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the heat pump system operates in heating mode with the outdoor heat exchanger functioning as an evaporator, then heat can be absorbed from outdoor air, but frosting occurs on the outdoor heat exchanger which deteriorates heat transfer properties and decreases air flow
Solution Approach 1:
The control means performs preliminary action by detecting the refrigerant evaporation temperature of the outdoor heat exchanger and determining whether frosting is occurring before it severely impacts performance. Based on this detection, the system proactively adjusts the target subcool degree and compressor speed to prevent further frosting accumulation, thereby maintaining heating capability without waiting for severe performance degradation
Solution Approach 2:
The system changes operational parameters dynamically by adjusting the target subcool degree (increasing it when frosting is detected) and modifying compressor speed. These parameter changes alter the refrigerant temperatures and pressures to raise the outdoor heat exchanger temperature above the frosting point, thereby eliminating the harmful frosting condition while maintaining heating function
2Reliability
If the target subcool degree is increased to delay frosting, then the outdoor heat exchanger pressure increases and frosting is delayed, but the system complexity increases due to control adjustments
Solution Approach 1:
The control means implements feedback control by continuously detecting the refrigerant evaporation temperature of the outdoor heat exchanger, comparing it against threshold values to determine frosting conditions, and adjusting the target subcool degree accordingly. This closed-loop feedback mechanism maintains reliable heating performance through automated adjustments without requiring complex manual intervention or additional hardware
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 approach effectively delays frosting on the outdoor heat exchanger, preventing the deterioration of heating performance by maintaining optimal pressures and flow rates, ensuring consistent heating capabilities despite frosting conditions.
Implementation Method 1
a compressor which compresses a refrigerant
Implementation Method 2
a radiator which lets the refrigerant radiate heat to heat the air to be supplied from the air flow passage to the vehicle interior
Implementation Method 3
a heat absorber which lets the refrigerant absorb heat to cool the air to be supplied from the air flow passage to the vehicle interior
Implementation Method 4
an outdoor heat exchanger disposed outside the vehicle interior to let the refrigerant absorb heat
Implementation Method 5
water in outdoor air forms frost to adhere to the outdoor heat exchanger
Data Source
AI summary
There is disclosed a vehicle air conditioning device of a heat pump system which delays proceeding of frosting onto an outdoor heat exchanger, thereby eliminating or inhibiting deterioration of a heating capability due to the frosting. The vehicle air conditioning device executes a heating mode in which a controller lets a refrigerant discharged from a compressor 2 radiate heat in a radiator 4, decompresses the refrigerant by which heat has been radiated, and then lets the refrigerant absorb heat in an outdoor heat exchanger 7, and on the basis of a difference ΔTXO=(TXObase−TXO) between a refrigerant evaporation temperature TXObase of the outdoor heat exchanger 7 in non-frosting and a refrigerant evaporation temperature TXO of the outdoor heat exchanger 7, the controller corrects a target subcool degree TGSC that is a target value of a subcool degree of the refrigerant in the radiator 4 in an increasing direction in accordance with increase of the difference ΔTXO.