Dual-Circuit Battery Thermal Management Using Low-GWP Refrigerants
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Solution Overview
Problem
There is a need for effective and safe methods to regulate the temperature of a motor vehicle battery, while minimizing the use of flammable products, especially in proximity to the hottest parts of the vehicle.
Innovation Solution
A method using a vapor compression circuit with a first heat-transfer composition comprising 2,3,3,3-tetrafluoropropene (HFO-1234yf) and a secondary circuit with a second heat-transfer composition comprising 1-chloro-3,3,3-trifluoropropene (HCFO-1233zd) to regulate the battery temperature, with the secondary circuit operating at a uniform pressure and potentially without a compressor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If HFC-134a refrigerant is used in the battery cooling system, then effective heat transfer is achieved, but harmful contribution to greenhouse effect increases due to high GWP
Solution Approach 1:
The patent changes the chemical composition parameter of the refrigerant from HFC-134a to HFO-1234yf, which has significantly lower GWP while maintaining effective heat transfer properties. This substitution resolves the contradiction by modifying the refrigerant's environmental characteristics without sacrificing thermal performance
Solution Approach 2:
The patent uses a smaller amount of refrigerant (maximum 150g) compared to traditional automotive AC systems, reducing the overall environmental impact while maintaining cooling effectiveness. The system is designed to operate efficiently with minimal refrigerant charge
2Object-generated harmful factors
If HFO-1234yf refrigerant is used to reduce GWP, then greenhouse effect contribution is reduced, but flammability risk increases
Solution Approach 1:
The patent introduces a secondary circuit with HCFO-1233zd refrigerant as an intermediary between the battery and the HFO-1234yf refrigerant. This mediator allows heat transfer while keeping the flammable HFO-1234yf away from the battery, thus reducing flammability risk while maintaining low GWP benefits
Solution Approach 2:
The cooling system is divided into two separate circuits: a primary circuit using HFO-1234yf for low-GWP cooling, and a secondary circuit using HCFO-1233zd as a safety buffer near the battery. This segmentation isolates the flammable refrigerant from potential ignition sources while preserving environmental benefits
3Device complexity
If a single-circuit vapor compression system is used, then device complexity is reduced, but flammable refrigerant proximity to battery increases safety risks
Solution Approach 1:
The system is segmented into two circuits with distinct functions: the primary circuit handles main cooling with HFO-1234yf, while the secondary circuit provides safe heat transfer near the battery using HCFO-1233zd. This segmentation reduces safety risks despite increased structural complexity
Solution Approach 2:
The secondary circuit with HCFO-1233zd acts as an intermediary layer between the battery and the flammable HFO-1234yf refrigerant, enabling heat transfer while maintaining safety distance from potential ignition sources
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 method effectively and safely regulates the battery temperature within the optimal range of 15 to 40°C, reducing the risk of flammable refrigerant exposure and enhancing heat management efficiency, while potentially reducing energy consumption and vehicle weight.
Implementation Method 1
a vapor compression circuit in which a first heat-transfer composition comprising 2,3,3,3-tetrafluoropropene circulates
Implementation Method 2
the exchange of heat between the battery and the second heat-transfer composition; the exchange of heat between the second heat-transfer composition and the first heat-transfer composition
Implementation Method 3
a fluid capable of changing (liquid/gas) state commonly denoted refrigerant or heat-transfer fluid
Implementation Method 4
The condenser, by virtue of forced ventilation, brings about the condensation of the gas which arrives in the gaseous state at high pressure and high temperature
Implementation Method 5
The evaporator is a heat exchanger which removes heat from the air which will be blown into the passenger compartment or battery of the vehicle
Data Source
AI summary
The invention relates to a method for controlling the temperature of a battery in an electric or hybrid motor vehicle by means of a system comprising a vapor compression circuit in which flows a first heat transfer composition comprising 2,3,3,3-tetrafluoropropene, and a secondary circuit in which flows a second heat transfer composition comprising 1-chloro-3,3,3-trifluoropropene that has a ratio of the Z form to the E form of less than or equal to 9, the method involving: —heat exchange between the battery and the second heat transfer composition; —heat exchange between the second heat transfer composition and the first heat transfer composition. The invention also relates to a system for carrying out said method.