Phosphate Ester Immersion Coolant for Battery Heat and Electrical Isolation

Resolve Bottlenecks,
Find Innovative Solutions
Generate Solutions

Solution Overview

Problem

Traditional cooling systems for electrical componentry, such as air cooling and indirect liquid cooling, face challenges in efficiently dissipating heat from high-loading, high-capacity batteries due to flammability, low electrical resistivity, and high conductivity, which can lead to short circuits and thermal runaway.

Innovation Solution

A heat transfer fluid comprising a mixture of phosphate esters with specific alkyl and phenyl substitutions is developed, offering low flammability, low pour point, and high electrical resistivity, suitable for immersion cooling systems.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If water/glycol solutions are used for indirect cooling, then heat dissipation efficiency is improved, but electrical safety deteriorates due to high conductivity and short circuit risk

Engineering Contradiction:
Improveheat dissipation efficiencyVSAvoidelectrical safety
Core Design Contradiction:
TemperatureVSReliability

Solution Approach 1:

The patent introduces an electrically insulating coolant as an intermediary substance that replaces conductive water/glycol solutions. This mediator enables direct contact cooling while preventing electrical conduction and short circuits, thus resolving the contradiction between heat dissipation efficiency and electrical safety

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent changes the electrical conductivity parameter of the cooling fluid by selecting substances with inherently low or negligible conductivity (such as certain oils, fluorinated compounds, or specialized esters). This parameter change allows the coolant to simultaneously achieve efficient heat transfer and electrical insulation, eliminating the trade-off between thermal performance and electrical safety

Inventive Principle:
Principle #35Parameter changes

2Temperature

If traditional coolants are used for immersion cooling, then direct heat transfer is improved, but flammability increases leading to thermal runaway risk

Engineering Contradiction:
Improveheat transfer efficiencyVSAvoidflammability
Core Design Contradiction:
TemperatureVSObject-affected harmful factors

Solution Approach 1:

The patent changes the flash point and chemical stability parameters of the coolant by selecting substances with high flash points and inherent fire resistance (such as fluorinated compounds, certain esters, or specially formulated oils). This enables immersion cooling to achieve efficient direct heat transfer while eliminating flammability hazards that could lead to thermal runaway

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent converts the potential harm of direct contact between coolant and battery into a benefit by using electrically insulating and fire-resistant substances. The direct immersion that could previously cause short circuits or fires now provides superior heat dissipation while inherently preventing these harmful effects, thus converting a potentially dangerous approach into a safe and effective solution

Inventive Principle:
Principle #22Blessing in disguise (Convert harm into benefit)

3Quantity of substance

If high-capacity batteries are used for increased energy storage, then energy density is improved, but heat generation increases requiring more effective cooling

Engineering Contradiction:
Improveenergy storage capacityVSAvoidheat generation
Core Design Contradiction:
Quantity of substanceVSTemperature

Solution Approach 1:

The patent implements continuous circulation of the coolant through the battery pack, ensuring uninterrupted heat removal from high-capacity batteries. The system maintains constant coolant flow that continuously absorbs and transports heat away from the battery cells, preventing heat accumulation even as energy storage capacity increases

Inventive Principle:
Principle #20Continuity of useful action

Solution Approach 2:

The patent uses an optimized coolant as an intermediary heat transfer medium that efficiently bridges the thermal gap between high-capacity battery cells and the external cooling system. This intermediary substance enables effective heat extraction from densely packed, high-energy-density batteries without compromising electrical safety or requiring complex cooling infrastructure

Inventive Principle:
Principle #24Intermediary (Mediator)

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 phosphate ester mixture effectively dissipates heat from electrical componentry, preventing thermal runaway and ensuring safe operation under high loading conditions.

Implementation Method 1

The heat transfer fluid comprises a mixture of phosphate esters... exhibits favorable properties in a circulating immersion cooling system

Methodology Applied
Scientific EffectHeat transfer: Conduction (thermal)

Implementation Method 2

a circulating system capable of circulating the heat transfer fluid out of the reservoir, through a circulating pipeline

Methodology Applied
Scientific EffectConvection: Convection

Data Source

PatentEP4116391B1Phosphate tester heat transfer fluids and their use in an immersion cooling system
Publication Date: 2025.10.08 LANXESS CORPORATION
  • EP4116391B1 patent drawingFigure 1
  • EP4116391B1 patent drawingFigure 2
  • EP4116391B1 patent drawingFigure 3

AI summary

A heat transfer fluid for immersion cooling of electrical componentry includes a mixture of certain trialkyl phosphate esters and triaryl phosphate esters. Also disclosed is an immersion cooling system employing the heat transfer fluid and a method of cooling electrical componentry using the immersion cooling system. The mixture of phosphate esters of the present disclosure exhibits favorable properties in a circulating immersion cooling system, such as low flammability, low pour point, high electrical resistivity and low viscosity for pumpability.