Integrated EV Air-Conditioning Circuit for Battery Heating and Defrost
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Solution Overview
Problem
Existing air-conditioning systems in electric vehicles face challenges in maintaining optimal temperature conditions for battery modules, as they struggle with frost formation on outdoor heat exchangers, leading to reduced heating performance and system instability.
Innovation Solution
An integrated-type air-conditioning system with a refrigerant circuit and coolant circuits that utilize a single indoor heat exchanger and integrated heat exchanger to control temperature, prevent frost formation, and manage heating and cooling efficiently through a controller that adjusts valve and pump operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a heat pump system is used for indoor heating with an outdoor heat exchanger serving as an evaporator, then heating performance is improved, but the outdoor heat exchanger becomes frosted when the surface temperature drops below freezing, leading to deterioration in heating performance and system stability
Solution Approach 1:
The patent combines the outdoor heat exchanger and integrated heat exchanger into a unified system where the outdoor heat exchanger serves dual purposes: as an evaporator during heat pump mode and as a defrosting heat source during defrost mode. The refrigerant circuits are merged to allow flexible switching between modes, enabling the outdoor heat exchanger to prevent its own frosting by reversing its function.
Solution Approach 2:
The system dynamically switches between heat pump mode and defrost mode based on the frosting condition of the outdoor heat exchanger. The control system monitors the state and adjusts the refrigerant flow paths using switching valves, transforming the static outdoor heat exchanger into a dynamic component that can change its function to prevent frosting.
2Temperature
If separate cooling/heating systems are used for battery module and indoor air conditioning, then optimal temperature control for battery is achieved, but the system structure becomes complex and the circuit becomes large
Solution Approach 1:
The integrated heat exchanger is designed to serve multiple functions: it cools the battery module during charging/discharging operations and works as part of the heat pump system for indoor heating. The single heat exchanger replaces what would traditionally require separate cooling and heating components, reducing system complexity while maintaining optimal battery temperature control.
Solution Approach 2:
The refrigerant circuit is segmented into multiple paths with switching valves that can direct refrigerant flow to different components based on operational requirements. This allows the system to selectively cool the battery or provide indoor heating using the same physical infrastructure, avoiding the need for completely separate systems.
3Power
If the outdoor heat exchanger surface area increases to improve heat exchange capacity, then heating performance is improved, but the frost formation area increases, leading to more severe frosting problems
Solution Approach 1:
The patent converts the harmful effect of the outdoor heat exchanger frosting into a beneficial defrosting process. By switching to defrost mode, the system uses the refrigerant flowing through the outdoor heat exchanger to melt the frost, transforming the frost problem into an opportunity to clean and maintain the heat exchanger surface.
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 system effectively maintains optimal temperature conditions for battery and PE parts, prevents frost on outdoor heat exchangers, and ensures efficient heating and cooling performance by simplifying the structure and making the circuit compact.
Implementation Method 1
during heat exchange between a refrigerant introduced into the outdoor heat exchanger and outdoor air, when the temperature of the surface of the outdoor heat exchanger drops below freezing, the surface of the outdoor heat exchanger is frosted
Implementation Method 2
when the temperature of the surface of the outdoor heat exchanger drops below freezing, the surface of the outdoor heat exchanger is frosted
Implementation Method 3
the outdoor heat exchanger is not capable of absorbing heat, and thus the temperature and pressure of the refrigerant decrease, leading to deterioration in heating performance
Implementation Method 4
the liquid refrigerant may flow into a compressor, resulting in deterioration in the stability of the system
Data Source
AI summary
An embodiment integrated-type air-conditioning system includes a refrigerant circuit including first and second refrigerant lines, a first coolant circuit including a battery, and a second coolant circuit including a PE part. The first refrigerant line includes a compressor, an indoor heat exchanger, a first expansion device, and an outdoor heat exchanger, and the second refrigerant line includes a second expansion device and an integrated heat exchanger. The second refrigerant line branches from a branch point between the indoor heat exchanger and the first expansion device in the first refrigerant line and branches from a point between the compressor and the indoor heat exchanger through a switching valve to be connected to the compressor. The first coolant circuit and the second coolant circuit are each connected to the integrated heat exchanger so as to allow a coolant to exchange heat with a refrigerant.