Conformable Evaporative Structure for Body Cooling
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Solution Overview
Problem
Existing evaporative structures for human body cooling, such as those using the heat pipe principle, face challenges in maintaining efficient heat transfer and preventing structural collapse under vacuum conditions, particularly when used with personal protective equipment (PPE) that restricts heat loss through convection or evaporation, and have limitations in the area of efficient heat transfer due to the disposition of wicking materials.
Innovation Solution
A conformable evaporative structure with a flexible, impermeable envelope containing a wick layer, breathable spacer fabric, and flexible ribs to maintain vapor flow pathways, integrated with a heat sink for condensation and a heat exchanger to release heat, all maintained under vacuum, utilizing a barrier film and wick material for efficient heat transfer and structural support.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a substantial vacuum level is maintained within the envelope for useful evaporation to occur, then evaporation efficiency is improved, but the woven structure collapses into its vapour flow voids
Solution Approach 1:
The envelope interior is segmented into discrete voids by the three-dimensional arrangement of wicking materials. Each void is bounded by wicking elements that prevent the envelope walls from collapsing inward, while still allowing vapor to flow through the segmented spaces. This segmentation maintains structural integrity under vacuum while preserving evaporation pathways.
Solution Approach 2:
The envelope is constructed from flexible material that can withstand vacuum conditions without rigid support. The flexibility allows the envelope to maintain its shape and prevent collapse of the internal wicking structure, while the thin film construction minimizes thermal resistance and allows for conformability to body surfaces.
2Strength
If lengths of wicking are disposed in alternate voids within the woven structure, then structural support is improved, but the area of efficient heat transfer is limited
Solution Approach 1:
The wicking function is extracted from the envelope walls and concentrated into discrete three-dimensional elements positioned at strategic locations. This allows the envelope walls to remain open and accessible for heat transfer, while the extracted wicking elements provide structural support and vapor generation capability without limiting the overall heat transfer area.
Solution Approach 2:
The wicking materials are arranged in three-dimensional space rather than being confined to two-dimensional planes within the woven structure. This dimensional transition allows wicking elements to be positioned throughout the volume of the envelope, maximizing both structural support and heat transfer area by utilizing the third dimension for wicking placement.
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 transfer and prevents structural collapse, allowing for efficient cooling of the body by maintaining vapor flow and heat transfer areas, even under vacuum conditions, thereby reducing heat strain and improving thermal comfort.
Implementation Method 1
a layer of flexible wick material disposed adjacent to a major face of said envelope, adapted to hold a working fluid in liquid phase for evaporation by heat conducted through said envelope
Implementation Method 2
for evaporation by heat conducted through said envelope
Implementation Method 3
one or more flexible rib(s) within said layer of breathable fabric, adapted to maintain pathway(s) for the flow of working fluid in vapour phase towards a condensation zone
Implementation Method 4
a heat sink means is integrated with the evaporative structure at the condensation zone for condensation of said working fluid within the evaporative structure
Implementation Method 5
a heat exchanger is arranged in communication with the heat sink means, the heat exchanger being arranged to release heat to the environment
Implementation Method 6
the evaporative structure is maintained under vacuum
Data Source
Figure 1
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AI summary
A generally planar, conformable evaporative structure, particularly for incorporation in a garment or an item of personal protective equipment as part of a system to cool the wearer's body, comprises an envelope (8, 9) of substantially impermeable, flexible material containing: a layer of flexible wick material (10) disposed adjacent to a major face of the envelope and adapted to hold a working fluid in liquid phase for evaporation by heat conducted through the envelope; a layer of flexible, breathable fabric (11) in parallel with the layer of wick material; and an array of flexible ribs such as open helical coils (13) within the layer of breathable fabric adapted to maintain pathways (12) for the flow of working fluid in vapour phase towards a condensation zone.