Immersion Cooling Fluids That Eliminate Phantom Voltage in EV Batteries
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Solution Overview
Problem
Immersion cooling fluids for electric vehicle batteries often induce phantom voltage due to their interaction with electric fields, leading to false short circuit detection and battery deactivation, as they possess permanent dipole moments and low dielectric constants, which are not adequately addressed by existing fluids.
Innovation Solution
The use of hydrofluoroolefin compounds with specific structural formulas, such as those represented by Structural Formula (IA), which have low dielectric constants and dipole moments, eliminating the phantom voltage phenomenon while maintaining non-flammability and thermal stability, are employed as working fluids in immersion cooling systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If immersion cooling fluids with permanent dipole moments are used, then heat transfer efficiency is improved, but phantom voltage is induced causing false short circuit detection
Solution Approach 1:
The patent changes the dielectric constant parameter of the cooling fluid from low (causing phantom voltage) to high (≥6.0), which eliminates the phantom voltage phenomenon while maintaining effective heat transfer. This parameter change resolves the contradiction by selecting fluids with specific dielectric properties that satisfy both thermal performance and electrical safety requirements.
Solution Approach 2:
The patent employs composite cooling fluids containing multiple components including fluorinated compounds, hydrocarbons, and other additives in specific proportions. This composite approach allows optimization of both thermal conductivity and dielectric constant, achieving high heat transfer efficiency while maintaining high dielectric constant to prevent phantom voltage induction.
2Reliability
If fluids with low dielectric constants are used, then electrical insulation is improved, but phantom voltage phenomenon occurs
Solution Approach 1:
The patent inverts the conventional approach by changing the dielectric constant parameter from low to high (≥6.0). This counterintuitive parameter change eliminates phantom voltage while maintaining electrical insulation, as the high dielectric constant prevents dipole alignment that causes capacitive coupling and phantom voltage in low dielectric constant fluids.
3Object-affected harmful factors
If non-flammable fluids are used, then safety is improved, but thermal conductivity may be reduced
Solution Approach 1:
The patent uses composite formulations combining fluorinated compounds (providing non-flammability) with hydrocarbons and other additives (enhancing thermal conductivity). This composite approach achieves both safety and thermal performance, overcoming the limitation of single-component non-flammable fluids that typically have lower thermal conductivity.
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
These hydrofluoroolefin compounds effectively eliminate phantom voltage, ensuring the safe operation of electric vehicle batteries by preventing false short circuit detection, while maintaining the necessary properties for effective heat transfer and environmental sustainability.
Implementation Method 1
compositions that include a hydrofluoroolefin compound... having low dielectric constants and dipole moments such that the phantom voltage phenomenon is eliminated
Implementation Method 2
the interaction of electric fields with the molecular dipoles of certain of such cooling fluids is problematic... Asymmetric molecules possess permanent dipole moments due to unsymmetrical charge distribution within the molecular structure
Implementation Method 3
Direct contact liquid cooling of electrochemical cells has been identified as a means of improving thermal performance
Implementation Method 4
P. E. Tuma, 'Fluoroketone C2F5C(O)CF(CF3)2 as a Heat Transfer Fluid for Passive and Pumped 2-Phase Applications,' 24th IEEE Semi-Therm Symposium
Data Source
AI summary
An electrochemical cell pack includes a housing having an interior space; a plurality of electrochemical cells disposed within the interior space; and a working fluid disposed within the interior space such that the electrochemical cells are in thermal communication with the working fluid. The working fluid has a dielectric constant of less than 3 and a dipole moment of less than 1.5 D.