Evaporative Cooling Battery System with Porous Wick

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Solution Overview

Problem

Existing battery systems face challenges in efficiently dissipating heat while maintaining a lightweight and small form factor, leading to potential thermal runaway and reduced battery life, especially in high-energy density applications like electric vehicles.

Innovation Solution

The implementation of an evaporative cooling mechanism using a porous wick in thermal contact with battery cells, submerged in a heat transfer fluid within a pressure vessel, which evaporates to maintain the cells within a predetermined temperature range.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If forced air convection is used for cooling, then ease of manufacture is improved, but heat dissipation efficiency deteriorates

Engineering Contradiction:

Improveease of implementationVSAvoidheat dissipation efficiency

Core Design Contradiction:

Ease of manufactureVSPower

Solution Approach 1:

The patent replaces the mechanical forced air convection system with a passive evaporative cooling system using capillary action. The porous wick material automatically draws liquid coolant through capillary forces without requiring fans or mechanical drive systems, eliminating the mechanical complexity while achieving superior heat dissipation through phase change cooling.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent utilizes the phase transition of the coolant from liquid to vapor as it evaporates from the porous wick surface. This phase change absorbs large amounts of latent heat from the battery cells, providing highly efficient passive cooling without mechanical systems.

Inventive Principle:

Principle #36Phase transitions

2Power

If indirect cooling with external radiator is used, then heat dissipation efficiency is improved, but weight and form factor increase

Engineering Contradiction:

Improveheat dissipation efficiencyVSAvoidsystem weight

Core Design Contradiction:

PowerVSWeight of moving object

Solution Approach 1:

The patent merges the cooling function directly into the battery cell structure by surrounding each cell with a porous wick that contacts the cell surface. The coolant is contained within the battery housing itself, eliminating the need for separate external radiators and heavy cooling loops, thus achieving efficient cooling while minimizing weight and form factor.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The cooling system is nested within the battery cell structure itself. The porous wick is positioned around the battery cell, and the coolant is contained within the battery housing, creating a compact integrated system where the cooling mechanism is embedded within the energy storage unit rather than being an external addition.

Inventive Principle:

Principle #7Nested doll (Nesting)

3Power

If direct immersion in liquid is used, then heat dissipation efficiency is improved, but weight and volume increase

Engineering Contradiction:

Improveheat dissipation efficiencyVSAvoidliquid volume and weight

Core Design Contradiction:

PowerVSWeight of moving object

Solution Approach 1:

The patent employs a porous wick material that provides a large surface area for evaporative cooling without requiring large volumes of liquid. The porous structure capillary-transports the coolant close to the battery cell surface, enabling efficient heat transfer with minimal liquid inventory, thus reducing weight and volume compared to full immersion cooling.

Inventive Principle:

Principle #31Porous materials

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 solution effectively dissipates large heat loads while maintaining a lightweight and compact design, preventing thermal overload and extending battery life by ensuring temperature stability within operational limits.

Implementation Method 1

a battery cell in thermal contact with a porous wick

Methodology Applied

Scientific EffectThermal conduction: Conduction (thermal)

Implementation Method 2

Evaporation of the heat transfer fluid from the porous wick maintains the temperature of the battery cell

Methodology Applied

Scientific EffectEvaporation: Evaporation

Implementation Method 3

Evaporation of the heat transfer fluid from the porous wick maintains the temperature of the battery cell

Methodology Applied

Scientific EffectLatent heat: Latent Heat

Implementation Method 4

Direct immersion in a liquid with a high specific heat capacity facilitates cooling by thermal conduction and convection in the liquid

Methodology Applied

Scientific EffectThermal convection: Convection

Data Source

PatentUS20220367943A1Battery system and method with evaporative cooling

Publication Date: 2022.11.17 UNIVERSITY OF MALTA

AI summary

A battery system includes a pressure vessel with a lid which encloses a battery pack having at least one battery cell in thermal contact with a porous wick. The battery pack is partly submerged in a heat transfer fluid, which is in a liquid phase. Evaporation of the heat transfer fluid from the porous wick maintains the temperature of the battery cell within an operational temperature range.