Y. Lang, Y. Joshi and W. Nakayama
CALCE Electronic Products and Systems Consortium
University of Maryland
College Park, MD 20742
This study investigates the issues involved in the design of compact two -phase thermosyphon systems . In such systems the locations of the evaporator and condenser need be given a high degree of freedom. Anticipating situations where gravity does not provide sufficient potential to drive the condensate, a pump-assisted circulation loop was studied. Also, enhancement of boiling heat transfer in compact space was achieved by an enhancement structure having mutually connected microchannets. The key components used in the experiment are; a simulated chip (0.907 cm2) with an enhancement structure (6.8 mm high), a dielectric coolant (PF-5060,boiling point 56 oC), a naturally cooled condenser occupying a 6.5 x 6.5 x 17.8 cm 3 volume, and a displacement pump (2 - 40 ml/min). The relative height between the evaporator and the condenser, the pumping rate, and the heat input were systematically varied. These parameters affect the overall thermal resistance from the chip to the ambient in a complex way. However, close examination of the data suggests that there could be an optimum point in the para metric domain where the thermal resistance is minimized with a least assistance from the pump.
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