Indirect EV Thermal Circuit for High Cooling Load Heat Rejection
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Solution Overview
Problem
Current thermal management devices for electric or hybrid vehicles, particularly in indirect air conditioning circuits, face challenges in efficiently evacuating heat accumulated in refrigerant fluids, especially during high cooling power requirements such as battery charging or discharging.
Innovation Solution
The thermal management device incorporates an indirect air conditioning circuit with a bifluid heat exchanger, internal heat exchangers, and bypass loops, including a diversion branch and external radiators, to redirect refrigerant fluid and enhance heat transfer between refrigerant and heat transfer fluid loops, allowing for improved cooling and dehumidification modes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an indirect air conditioning circuit with a secondary thermal management loop is used, then the thermal management of batteries and electronic components is achieved, but the heat accumulated in the refrigerant cannot be efficiently evacuated when high cooling power is required
Solution Approach 1:
The refrigerant loop is segmented into multiple circulation paths: a first circulation path through the evaporator for cooling, and a second circulation path through the condenser for heat rejection. The circulation device enables selective activation of these paths based on thermal management requirements, allowing efficient heat evacuation when high cooling power is needed.
Solution Approach 2:
The circulation device dynamically switches between different refrigerant circulation modes: first circulation mode (evaporator only), second circulation mode (condenser only), and third circulation mode (both evaporator and condenser simultaneously). This dynamic adaptation enables the system to provide high cooling power when batteries require rapid heat rejection during charging/discharging operations.
2Adaptability or versatility
If a reversible air conditioning circuit with heat recovery is implemented, then heat energy from outside air can be returned to the passenger compartment, but the device complexity increases
Solution Approach 1:
The heat exchangers are designed to perform multiple functions: the evaporator can serve as an evaporator in cooling mode or as a condenser in heating mode, and the condenser can serve as a condenser in cooling mode or as an evaporator in heating mode. This multi-functionality enables reversible operation without requiring separate dedicated heat exchangers for each mode, thereby limiting the increase in device complexity.
3Loss of energy
If the refrigerant circulation path is extended to include additional heat exchangers, then the heat transfer efficiency is improved, but the pressure loss increases
Solution Approach 1:
The circulation device enables dynamic selection of refrigerant circulation paths based on operational requirements. When high heat transfer efficiency is needed, the system can activate the condenser path in addition to the evaporator path. When pressure loss becomes excessive, the system can switch to using only the evaporator path, thereby adaptively balancing heat transfer efficiency against pressure loss.
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 configuration enhances the cooling power and coefficient of performance (COP) by effectively managing heat transfer, ensuring efficient thermal management even during high cooling demand scenarios like rapid battery charging or discharging.
Implementation Method 1
a two-fluid heat exchanger arranged jointly on the first refrigerant fluid loop and on the second heat transfer fluid loop, so as to allow heat exchanges between said loops
Implementation Method 2
a first internal heat exchanger, allowing heat exchange between the high-pressure refrigerant at the outlet of the two-fluid heat exchanger and the low-pressure refrigerant at the outlet of the evaporator/condenser or of the first bypass line
Implementation Method 3
said bypass loop comprising a first external radiator
Data Source
Figure 1
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AI summary
The present invention concerns a thermal management device comprising an indirect air conditioning circuit (1) for a motor vehicle, comprising: - a first refrigerant fluid loop (A) comprising a compressor (3), a two-fluid heat exchanger (5), a first expansion device (7), an evaporator (9), a second expansion device (11), an evaporator/condenser (13), and - a first by-pass line (30) comprising a first stop valve (33), - a first internal heat exchanger (19), - a second internal heat exchanger (19'), - a second by-pass line (40) comprising a third expansion device (17) arranged upstream from a cooler (15), - a shunt branch (80) comprising a first external radiator (84), - a second heat transfer fluid loop (B) in which a heat transfer fluid is intended to flow, the two-fluid heat exchanger (5) being arranged jointly on the one hand on the first refrigerant fluid loop (A) downstream of the compressor (3), between said compressor (3) and the first expansion device (7), and on the other hand on the second heat transfer fluid loop (B).