Advanced Liquid-Cooling Garment Using Highly Thermally Conductive Sheets
- Created: Friday, 01 January 2010
This garment provides metabolic heat rejection applicable to surgical cooling vests, combat fatigues, and firefighter and hazmat suits.
This design of the liquid-cooling garment for NASA spacesuits allows the suit to remove metabolic heat from the human body more effectively, thereby increasing comfort and performance while reducing system mass. The garment is also more flexible, with fewer restrictions on body motion, and more effectively transfers thermal energy from the crewmember’s body to the external cooling unit. This improves the garment’s performance in terms of the maximum environment temperature in which it can keep a crewmember comfortable.
The garment uses flexible, highly thermally conductive sheet material (such as graphite), coupled with cooling water lines of improved thermal conductivity to transfer the thermal energy from the body to the liquid cooling lines more effectively. The conductive sheets can be layered differently, depending upon the heat loads, in order to provide flexibility, exceptional in-plane heat transfer, and good through-plane heat transfer. A metal foil, most likely aluminum, can be put between the graphite sheets and the external heat source/sink in order to both maximize through-plane heat transfer at the contact points, and to serve as a protection to the highly conductive sheets. Use of a wicking layer draws excess sweat away from the crewmember’s skin and the use of an outer elastic fabric ensures good thermal contact of the highly conductive underlayers with the skin.
This allows the current state of the art to be improved by having cooling lines that can be more widely spaced to improve suit flexibility and to reduce weight. Also, cooling liquid does not have to be as cold to achieve the same level of cooling. Specific areas on the human body can easily be targeted for greater or lesser cooling to match human physiology, a warmer external environment can be tolerated, and spatial uniformity of the cooling garment can be improved to reduce vasoconstriction limits.
Elements of this innovation can be applied to other embodiments to provide effective heat transfer over a flexible and surface-conformable fashion without the limitation of fluid freeze points.
This work was done by Warren P. Ruemmele, Grant C. Bue, and Evelyne Orndoff of Johnson Space Center and Henry Tang of Muniz Engineering. For more information, download the Technical Support Package (free white paper) at www.techbriefs.com/tsp under the Bio-Medical category. MSC-24189-1