L-V PCM Battery Cooling via Evaporation and Condensation
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Solution Overview
Problem
Existing battery cooling methods are inefficient in managing temperature within rechargeable battery cells, leading to reduced battery life, capacity, and safety risks due to excessive heat, with conventional methods like forced air and liquid convection requiring high energy and being limited by thermal conductivity and fabrication costs.
Innovation Solution
A 3-D phase change heat management system using a liquid to vapor phase change material (L-V PCM) within a vacuum-sealed enclosure, where the L-V PCM evaporates and condenses to efficiently transfer heat away from battery cell surfaces, and optionally combined with solid to liquid PCM containers for additional heat storage and dissipation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If forced air convection is used to cool battery cells, then cooling effectiveness is improved, but energy consumption increases as the third power of air flow speed
Solution Approach 1:
The patent uses liquid-to-vapor phase change material that evaporates when contacting heated battery cell surfaces and condenses on cooler surfaces, transferring heat without requiring forced convection. This phase change mechanism provides passive cooling that eliminates the need for high-power fans while maintaining effective temperature management.
Solution Approach 2:
The phase change material system operates autonomously based on temperature gradients within the battery pack. The L-V PCM naturally evaporates from hot cell surfaces and condenses on cooler surfaces without external control, creating a self-regulating cooling system that reduces energy consumption compared to forced air convection.
2Temperature
If forced liquid convection is used to cool battery cells, then cooling effectiveness is improved, but flow resistance becomes too large to keep required electrical power low enough for dense cell packaging
Solution Approach 1:
The patent employs liquid-to-vapor phase change material that utilizes evaporation and condensation cycles for heat transfer. This approach eliminates the need for liquid circulation systems and pumps, thereby avoiding the flow resistance issues that plague forced liquid convection in densely packed battery configurations.
Solution Approach 2:
The system uses vapor-phase heat transfer instead of liquid-phase forced convection. The vapor generated from L-V PCM evaporation naturally flows and condenses on cooler surfaces, providing effective cooling without the mechanical complexity and flow resistance associated with pumped liquid systems.
3Productivity
If solid to liquid phase change materials are packaged with cells, then charging and discharging speed is improved, but thermal conductivity remains poor limiting PCM capacity
Solution Approach 1:
The patent transitions from solid-to-liquid phase change materials to liquid-to-vapor phase change materials. The L-V PCM with higher thermal conductivity efficiently absorbs heat from battery cell surfaces through evaporation and transfers it to cooler surfaces through condensation, overcoming the thermal conductivity limitations of traditional solid-liquid PCMs while maintaining effective heat storage capacity.
4Temperature
If 2-D heat pipes with liquid to vapor PCM are used, then heat transfer is improved, but fabrication cost becomes too expensive for industrial applications
Solution Approach 1:
The patent uses a simplified liquid-to-vapor phase change system where L-V PCM is placed in contact with battery cell surfaces without requiring complex 2-D heat pipe fabrication. The direct evaporation and condensation of L-V PCM provides effective heat transfer at a fraction of the cost of manufactured heat pipe structures.
Solution Approach 2:
The system replaces expensive, complex 2-D heat pipe structures with a simpler, more cost-effective L-V PCM-based passive cooling system. This approach uses readily available phase change materials and simple containment structures instead of requiring expensive fabrication processes, making it suitable for industrial battery manufacturing.
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 approach effectively maintains cell surface temperatures near room temperature, extending battery life, increasing charging and discharging speed, and enhancing safety by reducing temperature differences and energy consumption for cooling.
Implementation Method 1
the L-V PCM evaporates and condenses to efficiently transfer heat away from battery cell surfaces
Implementation Method 2
the L-V PCM evaporates and condenses to efficiently transfer heat away from battery cell surfaces
Implementation Method 3
A 3-D phase change heat management system using a liquid to vapor phase change material (L-V PCM)
Implementation Method 4
the L-V PCM evaporates and condenses to efficiently transfer heat away from battery cell surfaces
Data Source
AI summary
A 3-D “phase change heat exchange” structure and method are used in a rechargeable battery to dissipate heat from surfaces of the battery cells and lower the temperature inside the battery cells. The battery cells are placed inside an enclosure and spaced apart from each other with free spaces in between. A liquid to vapor phase change material (L-V PCM) is provided inside the enclosure. A hydrophilic thin film or wick or fiber structure is provided on the cell surfaces to help form a thin liquid layer of the L-V PCM over cell surfaces. During operation, the L-C PCM is evaporated at the cell surfaces and condenses back to a liquid either on the battery enclosure or in an external heat exchanger, and drips back on top of the cells. The designs extend the battery life and improve the battery performance significantly.