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UC in the Himalaya: Next Effort to Focus on Adaptive Tent for Greater Warmth


University of Cincinnati prototype designs – specifically a very thin, but warm sleeping bag as well as a sleeping platform – will be tested in the Himalaya Mountains in September. Below are some additional technical details related to sleeping bag effort as well as information related to expected future efforts.

Date: 8/22/2011 12:00:00 AM
By: M.B. Reilly
Phone: (513) 556-1824
Photos By: Dottie Stover

UC ingot   Thermal management in high altitudes requires adaptation by the human body as well as new technologies to cope with less energy release (i.e. body heat production) since the average human body produces 116W of heat energy at sea level but only about 70W at an elevation of about 14,000 feet.
UC's Brian Davies in the thin but warm sleeping bag to be tested in the Himalaya.
UC's Brian Davies in the thin but warm sleeping bag to be tested in the Himalaya.



One of the design ideas – a very thin but warm sleeping bag specifically designed to hold in and reflect body heat – will be tested by a University of Cincinnati team in the Himalaya during September 2011. This concept is  directed toward enhancing the energy efficiency of capturing body heat by over 50 percent than is currently the norm with sleeping bags now commonly used at high altitudes. Typically, only 1 to 6 percent of high altitude body heat is captured effectively.

FUTURE EFFORT: ADAPTIVE TENT FOR GREATER WARMTH

According to Brian Davies, associate professor in the University of Cincinnati’s School of Architecture and Interior Design, future design efforts in the coming year will explore development of a tent that will be able to adapt to thermal-conditioned environments. In other words, a tent interior that  automatically adapts to the changing environment in order to preserve/retain body heat at higher elevations. It’s expected that this would be accomplished by means of a system of microprocessor controlled active insulation features on the tent surface.  

It is common to employ heart and breathing sensors above 14,000 feet that use about 2mW from the converted energy of the body heat with a thermoelectric source.  Such battery-free wireless systems powered by hybrid power sources – namely body heat and ambient light – are already being considered for monitoring brain waves after a head injury and for other applications.

Basically, a thermoelectric generator is powered by the heat dissipated from a person’s temples, with additional power sometimes coming by silicon photovoltaic cells which draw additional power from the presence of ambient light. Currently, such systems are wearable and integrated into a device resembling headphones. While in use, the system can provide of average of more than 1mW of heat, which is more than enough to maintain a more comfortable temperate inside a specialized tent within a cold environment.

The proposed insulated environment inside a tent can be achieved by a change in the fiber-alignment pattern. Imagine a tent surface which contains a number of loose short fibers glued to the inside surface of a tent (fibers are ideally glued just like Velcro). That change in fiber alignment can achieve a thermal- conductivity change from 0.1W/m2K to over 0.7W./m2K depending on the fiber alignment.

For an active tent system, to be developed in the next year, Davies proposes using such fibers, which can be either aligned or randomized in a manner thereby automatically adjusting to the environment.  Such aligned microstructures are often used in materials science applications, commonly used in liquid crystal displays. Or, think of how human body hair can “stand up” or collapse against the skin’s surface when there is an electric discharge.

The electric potential generated in the thermoelectric effect and wirelessly communicated with the attached fibers will be adjusted to increase or decrease the thermal insulation of the tent in an automatic manner. This potential will be used to manipulate fiber alignment.

Said Davies, “The main development of our design research will include attaching now commercially available carbon nanofiber mats made from carbon nanotubes to a standard polyester type tent and then attaching electrodes to the conductive fibers by a vapor-deposition gold electroding process.  Should the body be in a condition that is producing low heat and thus in need of greater warmth, the insulation will realign to guard and preserve heat. This unique system will be a low energy usage thermal management system uniquely designed for high altitude tent applications.”
Prototype sleeping bag in design at UC.
Prototype sleeping bag in design at UC.




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