Heat Transfer Switching Devices

ABSTRACT: We propose research & development efforts aimed at determining the technical feasibility of novel liquid-droplet-based thermal switches. Specifically, through combined modeling and experimental work, we aim to demonstrate the technical feasibility of achieving (1) On-state thermal conductance>2000 W/m2 K, (2) Switching ratio>10, (3) Switching voltage<50 V, (3) Projected mass loss (evaporation)<1% over 15 years, (4) Projected power consumption<1 mW/cm2, (5) Insensitivity to launch vibration at up to 2000 g. BENEFIT: Although most research and development of thermal management tends to focus on"getting heat out"for example, computer processor chips, automotive engines, building HVAC systems, and manufacturing plants the retention of heat and the dynamic regulation of heat flow play very important roles, particularly when external heaters are required to compensate for cold operating conditions or large temperature swings, such as the current focus of the Air Force Operationally Responsive Space program. Virtually identical thermal management technology is badly needed by NASA, where the push to smaller and lower cost missions has become increasingly important. Commercial launches are scheduled to begin in 2015 to replace the constellation of satellites employed by Iridium Communications for truly mobile communications. 66 satellites are to be placed into LEO. CubeSat launches provide education and novel means of characterizing the earth. The importance of thermal management extends throughout the DoD, including predominantly Navy, where high efficiency translates into long unattended missions. Forward-looking applications of the Department of Energy and the Department of Transportation will require dynamic heat-retaining technology to improve automobile efficiency for both the internal combustion engine and fuel cell powered electric motors. Additional nongovernmental commercialization opportunities include nuclear power plants, transportation, oil refineries, chemical manufacturing, An estimate of the total available market (TAM), first consider US governmental space applications. DoD and NASA launch roughly 100 satellites per annum from Vandenberg, Kennedy, and Canaveral. This does not include the growing number of commercial spaceports include Kodiak, New Mexico and MARS (Virginia). Very roughly then 100 satellites are launched from US soil per annum. Thermal switch device fabrication costs can be estimated at roughly $5k/wafer, which is based on a 5 mask layer microfabrication process and will contain 4 devices. Note that this cost will decline steeply in higher volume. If each satellite requires 10 devices, plus necessary redundant devices (2x), the TAM is $2.5M/annum, not including additional devices for research and development purposes. This estimate is subject to large uncertainty of course, since designs and prototypes are yet to be constructed.