Indirect EV Thermal Circuit for High-Demand Battery Cooling
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Solution Overview
Problem
Conventional thermal management systems in hybrid and electric vehicles are insufficient for efficiently managing heat, particularly when high cooling power is required, such as during rapid discharging or charging of batteries.
Innovation Solution
An indirect air-conditioning circuit with a refrigerant fluid loop and a heat-transfer fluid loop, featuring multiple heat exchangers, bypass pipes, and valves, allows for enhanced heat exchange and redirection of refrigerant fluid to optimize cooling performance, including the use of internal and external radiators and expansion devices to manage heat effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a conventional indirect air-conditioning circuit is used with a secondary thermal management loop, then the system can provide basic cooling function, but the cooling power is insufficient when high cooling demand occurs during rapid battery discharging or charging
Solution Approach 1:
The system dynamically switches between different operational modes (first mode: batteries cooled by heat-transfer fluid; second mode: batteries cooled by refrigerant fluid) based on cooling demand. This dynamic adaptation allows the system to provide sufficient cooling power during rapid charging/discharging while maintaining efficient thermal management under normal conditions.
Solution Approach 2:
The refrigerant fluid loop is designed to serve dual purposes: it can cool the batteries directly when high cooling power is needed, and it can also provide conventional air-conditioning. This multi-functionality allows a single system to handle both high-demand thermal management and standard climate control requirements.
2Productivity
If the refrigerant fluid loop is configured to allow direct circulation through multiple pathways, then the cooling performance and COP are improved, but the system complexity increases with additional valves and bypass pipes
Solution Approach 1:
The refrigerant fluid loop is segmented into distinct pathways with dedicated functions: a first bypass pipe for high-demand cooling mode and a second bypass pipe for conventional air-conditioning mode. This segmentation allows the system to optimize performance for each mode while maintaining manageable complexity through clear functional separation.
Solution Approach 2:
Shut-off valves serve as intermediaries that control and direct refrigerant fluid flow between different pathways based on operational requirements. These valves enable the system to switch between modes without requiring complete redesign of the fluid circulation architecture, thus managing complexity while maintaining flexibility.
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 manages thermal loads by increasing cooling power and improving the coefficient of performance (COP), enabling efficient cooling of batteries and electronic components even under high demand conditions.
Implementation Method 1
a two-fluid heat exchanger arranged jointly on the first loop for refrigerant fluid and on the second loop for heat-transfer fluid, so as to allow exchanges of heat between said loops
Implementation Method 2
an evaporator, placed in contact with a flow of air internal to the motor vehicle in order to cool same
Implementation Method 3
a first heat exchanger, referred to as a condenser, placed in contact with a flow of air external to the motor vehicle in order to release heat
Implementation Method 4
an expansion device
Implementation Method 5
a first internal heat exchanger, allowing an exchange of heat between the high-pressure refrigerant fluid leaving the two-fluid heat exchanger and the low-pressure refrigerant fluid leaving the evaporator/condenser
Data Source
AI summary
A thermal management device having an indirect air conditioning circuit for a motor vehicle is disclosed. The device has a first refrigerant fluid loop (A) with a compressor, a two-fluid heat exchanger, a first expansion device, an evaporator, a second expansion device, an evaporator/condenser, and a first by-pass line including a first stop valve, a first and a second internal heat exchanger. A second by-pass line includes a third expansion device arranged upstream from a cooler, a shunt branch comprising a first external radiator. The device also has a second heat transfer fluid loop (B) in which a heat transfer fluid is intended to flow. The two-fluid heat exchanger is arranged jointly on the one hand on the first refrigerant fluid loop downstream of the compressor, between said compressor and the first expansion device, and on the second heat transfer fluid loop (B).