Variable-Conductance Heat Pipe for High-Altitude Battery Cooling
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Solution Overview
Problem
Regulating the temperature of battery packs in low-speed, high-altitude, long-endurance aircraft is challenging due to the difficulty in protecting the battery from cold without significant heating power, and existing cooling solutions, such as cooling fans, pose reliability issues and are ineffective in thin high-altitude air.
Innovation Solution
The use of a variable conductance heat pipe (VCHP) system, which includes an evaporator and condenser with a wick structure and a non-condensing gas reservoir, allows for efficient heat transfer by varying its conductance based on temperature changes, minimizing heating burden and providing reliable cooling without moving parts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If cooling fans are used for battery cooling, then cooling effectiveness is improved, but reliability deteriorates due to moving parts and high-altitude air thinness
Solution Approach 1:
The patent replaces the mechanical cooling fan system with a thermally-driven heat pipe system that uses phase change and capillary action. The heat pipe contains working fluid that evaporates at the evaporator (absorbing heat from battery) and condenses at the condenser (releasing heat to ambient air), with the working fluid returning via capillary wick structure. This eliminates moving parts while maintaining cooling effectiveness through passive thermal management.
Solution Approach 2:
The heat pipe system utilizes phase transitions of the working fluid (evaporation at evaporator, condensation at condenser) to transfer heat from the battery. The phase change process absorbs and releases latent heat efficiently, providing reliable cooling without mechanical components that would fail in high-altitude conditions.
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 VCHP system effectively regulates battery pack temperature by adjusting its conductance in response to temperature changes, ensuring reliable operation in high-altitude conditions without the need for significant heating power or moving parts, thus enhancing the reliability and efficiency of battery cooling.
Implementation Method 1
an evaporator and condenser with a wick structure
Implementation Method 2
an evaporator and condenser with a wick structure and a non-condensing gas reservoir, allows for efficient heat transfer by varying its conductance based on temperature changes
Implementation Method 3
an evaporator and condenser with a wick structure
Implementation Method 4
an evaporator and condenser with a wick structure and a non-condensing gas reservoir, allows for efficient heat transfer
Data Source
AI summary
An apparatus including a battery pack comprising a plurality of individual batteries arranged around a battery cavity such that each individual battery is in thermal contact with at least one neighboring individual battery. A variable-conductance heat pipe (VCHP) having an evaporator end and a condenser end, is positioned so that at least part of the evaporator end being positioned in the battery cavity and in thermal contact with each of the plurality of individual batteries. The apparatus includes a thermally insulating cover having an inside and an outside, wherein the battery pack and the part of the VCHP evaporator end in the battery cavity are positioned inside the thermally insulating cover and at least part of the condenser end of the VCHP is outside the thermally insulating cover, and wherein the VCHP is substantially the only thermal path between the battery pack and the outside. Other implementations are disclosed and claimed.