Multi-Mode Cooling Circuit for EV Battery Thermal Management
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Solution Overview
Problem
Existing cooling systems for electrical energy storage devices in vehicles, particularly at high ambient temperatures or during fast DC charging and high driving speeds, face insufficient cooling power and inefficiency when relying on refrigeration circuits, leading to increased energy consumption and reduced performance.
Innovation Solution
A modular cooling system that integrates a chiller and ambient air coolers, with control elements forming different circuits to optimize heat transfer and energy efficiency, allowing for flexible configurations that prioritize energy-efficient cooling and heat management by routing the main cooling circuit through the chiller, ambient air coolers, and heat sources in various modes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If cooling is carried out by means of the refrigeration circuit, then the energy storage device can be cooled, but the refrigeration power is insufficient at high driving speeds and fast DC charging
Solution Approach 1:
The cooling system is divided into two independent circuits: a refrigeration circuit for low-temperature cooling and a main cooling circuit with ambient air coolers for high-power cooling. This segmentation allows each circuit to operate independently and be optimized for different cooling scenarios, resolving the insufficiency of single-circuit refrigeration at high power demands.
Solution Approach 2:
The main cooling circuit serves multiple functions: it can cool the energy storage device using ambient air coolers during high-power scenarios, and it can also serve as a heat source for the refrigeration circuit's heat pump function during heating scenarios. This multi-functionality allows the system to meet both high cooling power demands and energy efficiency requirements.
2Temperature
If cooling is carried out by means of the refrigeration circuit, then the energy storage device can be cooled, but the power consumption increases due to the refrigerant compressor
Solution Approach 1:
The system converts the waste heat from the refrigerant compressor and refrigeration circuit into a useful resource by routing it through the chiller to the main cooling circuit. During heating scenarios, this waste heat becomes the heat source for the heat pump function, improving overall energy efficiency while maintaining effective cooling during operation.
Solution Approach 2:
The main cooling circuit serves itself by using ambient air coolers that require no additional power input beyond the pump. The system leverages free ambient air as the cooling medium, eliminating the need for high-power refrigerant compression and significantly reducing energy consumption during high-power cooling scenarios.
3Power
If the refrigeration circuit is used for cooling the energy storage device, then cooling is provided, but the overall cooling system is overloaded
Solution Approach 1:
The cooling load is segmented between two independent circuits: the refrigeration circuit handles low-power cooling needs, while the main cooling circuit with ambient air coolers handles high-power cooling needs. This segmentation prevents overloading of the refrigeration circuit and allows each circuit to be sized appropriately for its specific function.
Solution Approach 2:
The chiller acts as an intermediary component that enables heat transfer between the refrigeration circuit and the main cooling circuit. It allows the system to flexibly route heat energy between circuits based on operational requirements, enabling the main cooling circuit to offload thermal management tasks from the refrigeration circuit during high-power scenarios.
4Power
If ambient air coolers are used in the main cooling circuit, then cooling power is increased, but the system complexity increases with multiple circuits
Solution Approach 1:
The main cooling circuit is designed to serve multiple functions: it can cool the energy storage device during high-power scenarios, and it can also serve as a heat source for the refrigeration circuit's heat pump function. This multi-functionality justifies the additional circuit complexity by providing versatile thermal management capabilities that a single circuit cannot achieve.
Solution Approach 2:
The chiller serves as a flexible intermediary that can operate in different modes depending on system requirements. It enables bidirectional heat transfer between the refrigeration circuit and main cooling circuit, allowing the system to adapt to different operational scenarios without requiring separate dedicated systems for each function.
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 provides enhanced cooling efficiency and energy efficiency by optimizing heat transfer pathways, ensuring sufficient cooling power for the electrical energy storage device, especially during high-demand conditions, and enabling energy-efficient heating applications by utilizing waste heat.
Implementation Method 1
a chiller, through which a refrigeration circuit and, separated fluidically therefrom, a main cooling circuit can flow, in order to transfer heat energy between the refrigeration circuit and the main cooling circuit
Implementation Method 2
one or more ambient air coolers
Implementation Method 3
direct refrigerant cooling, in which the energy storage device is cooled directly by the refrigeration circuit, i.e. the refrigerant evaporates in evaporator plates
Data Source
AI summary
A cooling system for a motor vehicle has an electrical energy storage device for driving the motor vehicle; a chiller through which a refrigeration circuit and, fluidically separated therefrom, a main cooling circuit can flow; one or more control elements; at least one heat source, and one or more ambient air coolers. In a first mode, the control elements form the main cooling circuit such that the main cooling circuit can flow through the chiller, the energy storage device and none of the ambient air coolers. In a second mode, the control elements form the main cooling circuit such that the main cooling circuit can flow through the chiller, the energy storage device and at least one of the ambient air coolers. In a third mode, the control elements form the main cooling circuit such that the main cooling circuit can flow through the chiller, at least one of the ambient air coolers and the heat source.