Non-aqueous Dielectric Heat Transfer Fluids for EV Thermal Management
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Solution Overview
Problem
Current heat transfer fluids in electric vehicles and similar systems face challenges in achieving satisfactory heat transfer performance, compatibility with device components, and efficient power usage, particularly in situations where heat conveyance dominates over local heat transfer.
Innovation Solution
The development of non-aqueous dielectric heat transfer fluids with specific density, specific heat, and dynamic viscosity properties, optimized using a normalized effectiveness factor (NEFfluid) to enhance heat removal and minimize power consumption, and the use of a method involving a heat transfer circuit with pumps and heat exchangers to determine the optimal fluid properties for improved system performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If aqueous heat transfer fluids are used for indirect cooling, then compatibility with electric vehicle components is maintained, but heat removal efficiency is insufficient for direct cooling applications
Solution Approach 1:
The patent changes the fundamental parameter of the heat transfer fluid from aqueous to non-aqueous composition, enabling direct cooling capability while maintaining component compatibility through careful selection of dielectric fluids with appropriate thermal and electrical properties
Solution Approach 2:
The patent introduces non-aqueous dielectric heat transfer fluids as an intermediary substance that enables direct thermal contact with electrical components, serving as a mediator that transfers heat efficiently without compromising electrical safety or component compatibility
2Productivity
If heat transfer fluid circulation power is increased, then heat removal performance improves, but energy consumption increases
Solution Approach 1:
The patent optimizes fluid properties including viscosity, density, and specific heat capacity to maximize heat removal efficiency per unit of power consumed, selecting non-aqueous fluids with superior thermodynamic properties that reduce circulation power requirements
Solution Approach 2:
The patent uses the Mouromtseff equation as a reference model and creates an optimized version adapted for heat conveyance-dominated systems, copying the structure but modifying the parameters to reflect actual system performance and reduce energy consumption estimates
3Ease of operation
If the Mouromtseff equation is used to compare heat transfer fluids, then quick comparison is achieved, but accuracy is reduced in heat conveyance dominated situations
Solution Approach 1:
The patent creates a modified version of the Mouromtseff equation that copies its computational simplicity but adjusts the exponents and parameters to accurately reflect heat conveyance-dominated physics, maintaining ease of use while improving prediction accuracy
Solution Approach 2:
The patent modifies the parameters of the existing equation to better match the physics of heat conveyance-dominated systems, changing the weighting of different fluid properties to reflect their actual importance in the dominant heat transfer mechanism
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 solution enables effective heat management in electric vehicles and other electrical apparatuses by maximizing heat removal while minimizing power usage, improving thermal management and safety, and optimizing system performance through the selection of appropriate heat transfer fluids based on NEFfluid values.
Implementation Method 1
circulating at least one non-aqueous dielectric heat transfer fluid through the heat transfer circuit to transfer heat with the apparatus
Implementation Method 2
The removal of heat from electric vehicle components such as batteries and electric motors during electric vehicle operation is commonly done using aqueous heat transfer fluids, which indirectly remove heat from the hot surfaces
Data Source
AI summary
This disclosure relates to heat transfer fluids for use in heat transfer systems. The heat transfer fluids comprise at least one non-aqueous dielectric heat transfer fluid. The non-aqueous dielectric heat transfer fluid has density (ρ), specific heat (cp), and dynamic viscosity (μ) properties. The heat transfer fluids have a normalized effectiveness factor (NEFfluid) as determined by the following equation:NEFfluid=DEFfluidDEFreference;wherein DEFfluid is a dimensional effectiveness factor for the heat transfer fluid that is determined based on an equation designated in Table 1 below for a selected pump and a selected heat transfer circuit dominant flow regime; wherein DEFreference is a dimensional effectiveness factor for a reference fluid that is determined using the same equation designated in Table 1 for DEFfluid above for the same selected pump and the same selected heat transfer circuit dominant flow regime; andTABLE 1(Heat Transfer Fluid and Reference Fluid)Selected Heat Transfer Circuit Flow RegimeSelected PumpLaminarTransition (Blasius)Positive Displacement Pumpρ1 cp1 μ−1ρ0.25 cp1 μ−0.25Centrifugal Pumpρ0.19 cp1 μ−0.19ρ0.04 cp1 μ−0.04wherein the heat transfer fluid has a NEFfluid value equal to or greater than 1.0. This disclosure also provides a method for improving performance of a heat transfer system, a method for improving performance of an apparatus, and a method for selecting a heat transfer fluid for use in a heat transfer system. The heat transfer fluids and methods of this disclosure are applicable in situations where the heat transfer system is dominated by heat conveyance.