Refrigerant Circuit for Traction Energy Store Temperature Control
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Solution Overview
Problem
Existing temperature management systems for traction energy stores in electric vehicles suffer from inefficiencies due to high thermal resistance and exergy losses, particularly in convective heat exchangers and coolant circuits, which affect the charging capacity, efficiency, and service life of the battery cells.
Innovation Solution
A device with a refrigerant circuit that uses a storage-side heat exchanger in direct thermal contact with the traction energy store and an ambient heat exchanger, employing phase change of the refrigerant to effectively manage heat, minimizing thermal resistance and optimizing temperature control through a refrigerant circuit with a compressor and expansion valve, allowing for both cooling and heating operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a convective heat exchanger with a coolant circuit is used to cool the traction energy store, then the battery cells can be cooled, but high thermal resistance and exergy losses occur reducing system efficiency
Solution Approach 1:
The patent employs a refrigerant circuit where the refrigerant undergoes phase transitions (evaporation and condensation) to transfer heat. The refrigerant evaporates at the storage-side heat exchanger absorbing heat directly from the traction energy store, then condenses at the ambient-side heat exchanger releasing heat to the environment. This phase change mechanism enables efficient heat transfer with minimal thermal resistance and exergy losses compared to conventional convective cooling systems.
2Temperature
If a convective heat exchanger with a coolant circuit is used, then cooling is achieved, but the system complexity increases due to multiple components and circuits
Solution Approach 1:
The patent integrates the cooling function directly into the traction energy store by incorporating a storage-side heat exchanger in direct thermal contact with the battery cells. This merges the thermal management function with the energy storage structure itself, eliminating the need for separate coolant circuits and complex heat exchanger assemblies, thereby reducing overall system complexity while maintaining effective cooling.
3Temperature
If electrical energy is used to overcome high thermal resistance in the coolant circuit, then temperature control is achieved, but the charging capacity and efficiency of the battery are reduced
Solution Approach 1:
The patent converts the waste heat generated by the traction energy store during operation into a useful resource by capturing it through the refrigerant evaporation process. The refrigerant absorbs this waste heat directly at the storage-side heat exchanger, preventing thermal buildup that would reduce charging capacity. This transforms the harmful thermal energy into a controllable parameter, maintaining optimal battery temperature and preserving charging efficiency without requiring additional electrical energy input.
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 solution reduces exergy losses and improves the thermal inertia and efficiency of the temperature management system, maintaining optimal operating conditions for the traction energy store by efficiently managing heat through direct thermal contact and phase change processes, thus enhancing the battery's performance and longevity.
Implementation Method 1
Due to latent heat during the transition between the first and second aggregate state of the refrigerant, heat can be effectively removed from the traction energy store
Implementation Method 2
Due to latent heat during the transition between the first and second aggregate state of the refrigerant, heat can be effectively removed from the traction energy store
Implementation Method 3
Due to latent heat during the transition between the first and second aggregate state of the refrigerant, heat can be effectively removed from the traction energy store and dissipated to the environment
Implementation Method 4
Due to latent heat during the transition between the first and second aggregate state of the refrigerant, heat can be effectively removed from the traction energy store and dissipated to the environment
Implementation Method 5
A high resistance of the heat conduction, as it occurs with a convective heat exchanger on the traction energy store, can be avoided by the direct thermal contact between the traction energy store and the refrigerant circuit
Data Source
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AI summary
A device (100) for temperature control of a traction energy storage device (102) of an electrically powered motor vehicle is described. The device comprises a traction energy storage device (102) for storing electrical energy. This device exchanges energy with an electric drivetrain of the motor vehicle. Furthermore, the device (100) comprises a storage-side heat exchanger (104), which is in direct thermal contact with the traction energy storage device (102) for heat exchange, and an ambient-side heat exchanger (106), which is designed for heat exchange with the environment of the motor vehicle. A refrigerant circuit (108) supplies a refrigerant in a first state of matter to the storage-side heat exchanger (104) and in a second state of matter to the ambient-side heat exchanger (106).