Proceedings of the International Heat Transfer Conference, Kyongju, South Korea, 1998

Performance of a Compact Two-Chamber Two-Phase Thermosyphon: Effect of Evaporator Inclination, Liquid Fill Volume and Contact Resistance

C. Ramaswamy, Y. Joshi, W. Nakayama and W. Johnson
CALCE Electronic Products and Systems Consortium
University of Maryland, College Park, MD 20742


This study investigates the effect of evaporator inclination (from 0o to 90o) on the performance of an enhanced microstructure based thermosyphon that has shown very high heat transfer rates (up to 100 W/cm2 for fluorocarbons with a wall superheat excursion of 27.8oC). The results show a slight improvement in the boiling performance for a vertical orientation. The response of the setup was then studied for varying liquid fill volumes. This is of particular importance to practical applications where the liquid volume reduces corresponding to a reduction in the evaporator size. The results show negligible effect of variation in liquid volume, as long as the boiling surface is submerged. The performance deteriorates for partially submerged surfaces. Finally, the effect of different bonding techniques in the fabrication of the enhanced structure was investigated and the results show that a tip soldered structure has a large contact resistance and results in poor performance compared to a diffusion bonded structure.

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