ULTRAMET — Department of Defense SBIR Phase I: Cryogenic heat exchangers for cooling gaseous helium are hampered by the fact that helium

Description

Cryogenic heat exchangers for cooling gaseous helium are hampered by the fact that helium is a low-density gas. As a result, heat transfer coefficients tend to be low. To compensate for this, Ultramet will design and fabricate an open-cell foam-based heat exchanger using technology that was originally developed for high-power microwave integrated circuits for naval radars. In that application, heat fluxes over 1 kW/cm2 were absorbed by the foam while simultaneously maintaining a surface temperature of only 53°C. Using the models that were developed in that work, an analogous system will be developed using low-cost, high thermal conductivity foams. By using foams to create a compact heat exchanger, the heat exchange surface area can be increased by two orders of magnitude relative to a parallel-plate heat exchanger, and the overall effectiveness of the heat exchanger can be increased by roughly a factor of five.