Porous Graphite Foam Cooling Chamber for Off-Grid Cold Storage
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Solution Overview
Problem
In regions with scarce electricity distribution, maintaining vaccines, transplant organs, or food at recommended temperature ranges for extended periods without refrigeration systems and electricity is challenging, as existing technologies rely on electricity for cooling.
Innovation Solution
An apparatus using a porous graphite foam insert within an insulated enclosure, where a vacuum pump reduces the pressure of sealed air to below the vapor pressure of a liquid, causing evaporation and maintaining temperatures below ambient air, without the need for grid-supplied electricity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If modern refrigeration systems are used to maintain articles at reduced temperatures, then temperature control is improved, but dependency on electricity and refrigeration systems worsens
Solution Approach 1:
The patent replaces the electrical refrigeration system with a manual vacuum pump system. The vacuum pump creates a pressure differential that drives evaporative cooling through the porous graphite foam insert, eliminating the need for electrical compressors and refrigerants while maintaining temperature control capability.
Solution Approach 2:
The patent utilizes evaporative phase transition of a liquid (such as water or alcohol) within the porous graphite foam insert. When the liquid evaporates from the porous material, it absorbs latent heat of vaporization, causing the insert and contacted articles to cool down to temperatures below ambient air temperature without requiring electrical power.
2Duration of action of stationary object
If ice houses with saw dust insulation are used to store ice, then extended storage is improved, but cooling capability and temperature range are limited
Solution Approach 1:
The patent employs porous graphite foam material as the thermal management insert. The porous structure provides both insulation properties similar to traditional saw dust and enhanced capillary action for liquid distribution. The high surface area to volume ratio of the porous structure accelerates evaporative cooling while the graphite material provides thermal conductivity to distribute cooling uniformly throughout the chamber.
Solution Approach 2:
The patent changes the physical parameters of the cooling system by using a vacuum environment to lower the boiling point of the cooling liquid. This allows evaporative cooling to occur at lower temperatures and ambient pressures, extending the usable temperature range below what traditional ice-based systems can achieve while maintaining extended storage duration.
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
Effectively maintains articles at temperatures between 2° C. and 8° C. or below, ensuring the stability and effectiveness of vaccines and food, even in areas without reliable electricity, by utilizing a manually powered vacuum pump and porous graphite foam to manage temperature without electricity.
Implementation Method 1
a volume of a liquid is wicked into the pores of the porous insert
Implementation Method 2
activating the vacuum pump to reduce the pressure of the volume of sealed air within the interior chamber to a pressure that is below the vapor pressure of the liquid, such that the liquid evaporates
Implementation Method 3
reduce the pressure of the sealed air within the interior chamber to a pressure that is below that of the vapor pressure of the liquid
Implementation Method 4
an enclosure having an outer wall and a lid that defines an interior chamber for holding a volume of sealed air, and insulates the chamber from the ambient air
Data Source
AI summary
An apparatus for maintaining the temperature of an article at a temperature that is below the ambient air temperature includes an enclosure having an outer wall that defines an interior chamber for holding a volume of sealed air. An insert is disposed inside of the chamber and has a body that is made of a porous graphite foam material. A vacuum pump penetrates the outer wall and fluidly connects the sealed air in the interior chamber with the ambient air outside of the enclosure. The temperatures of the insert and article is maintained at temperatures that are below the ambient air temperature when a volume of a liquid is wicked into the pores of the porous insert and the vacuum pump is activated to reduce the pressure of a volume of sealed air within the interior chamber to a pressure that is below the vapor pressure of the liquid.