Phosphate Ester Immersion Cooling Fluids for EV Battery Safety
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Solution Overview
Problem
Traditional cooling systems for electrical componentry, such as battery modules in electric vehicles, face challenges with flammability, electrical conductivity, and heat dissipation efficiency, particularly under high loading conditions, as they often rely on water/glycol solutions that can cause short circuits and are not suitable for fast charging demands.
Innovation Solution
An immersion cooling system utilizing a heat transfer fluid comprising phosphate esters with intramolecular mixtures of alkyl and aryl groups, which are low in flammability, viscosity, and electrical conductivity, allowing for efficient heat dissipation while maintaining safety by circulating the fluid through a pipeline system.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If water/glycol solutions are used as heat transfer fluids for indirect cooling, then heat dissipation efficiency is improved, but electrical safety deteriorates due to high conductivity causing short circuits
Solution Approach 1:
The patent introduces an electrically insulating fluid as an intermediary substance that transfers heat from electrical components without causing short circuits. This mediator fluid replaces conductive water/glycol solutions, allowing thermal energy to be removed while maintaining electrical isolation between components.
Solution Approach 2:
The patent replaces the conventional indirect cooling mechanism (through conductive heat transfer via contact with water/glycol) with a direct immersion cooling system using insulating fluids. This substitution eliminates the need for electrical isolation barriers while maintaining cooling effectiveness.
2Reliability
If traditional immersion cooling fluids like trimethyl phosphate or tripropyl phosphate are used, then electrical resistivity is improved, but flammability deteriorates due to low flash point
Solution Approach 1:
The patent employs composite heat transfer fluids containing phosphoric acid esters combined with other chemically compatible substances. This composite formulation achieves both high electrical resistivity and high flash point by synergistically combining materials that individually provide different properties.
Solution Approach 2:
The patent modifies the chemical composition parameters of immersion cooling fluids by selecting phosphoric acid esters with specific molecular structures (containing aryl and alkyl groups) that inherently possess both high electrical resistivity and high flash point, thereby changing the fluid's physical and chemical properties to meet dual requirements.
3Reliability
If phosphate esters with high electrical resistivity are used, then electrical safety is improved, but viscosity increases reducing pumpability
Solution Approach 1:
The patent optimizes the molecular structure parameters of phosphoric acid esters by selecting specific chain lengths and branching patterns that balance electrical resistivity with fluidity. By adjusting these chemical parameters, the fluid maintains high insulating properties while preserving low viscosity for effective circulation.
4Productivity
If fast charging is implemented to increase productivity, then charging speed is improved, but heat generation increases requiring more effective cooling
Solution Approach 1:
The patent implements continuous circulation of the heat transfer fluid through the battery pack during fast charging operations. This continuous action ensures uninterrupted heat removal, allowing sustained high charging rates without thermal accumulation that would otherwise limit charging speed.
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 absorbs and dissipates heat generated by electrical componentry, preventing thermal runaway and enabling fast charging while ensuring safety, with the phosphate ester fluid exhibiting a high flash point, low viscosity, and high electrical resistivity, making it suitable for a wide range of electrical components.
Implementation Method 1
the heat transfer fluid comprises one or more than one phosphate ester of formula (I)... effectively absorbs and dissipates heat generated by electrical componentry
Implementation Method 2
a circulating system capable of circulating the heat transfer fluid out of the reservoir, through a circulating pipeline of the circulating system, and back into the reservoir
Data Source
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AI summary
An immersion cooling system includes electrical componentry, a heat transfer fluid, and a reservoir. The electrical componentry is at least partially immersed in the heat transfer fluid within the reservoir, and a circulating system circulates the heat transfer fluid out of the reservoir, through a circulating pipeline, and back into the reservoir. The heat transfer fluid includes one or more phosphate ester compounds containing intramolecular mixtures of alkyl and aryl groups and exhibits favorable properties in a circulating immersion cooling system, such as low flammability, low pour point, high electrical resistivity and low viscosity for pumpability.