Heat Transfer Enhancement of a Loop Heat Pipe with Bidispersed Wicks
Date Issued
2010
Date
2010
Author(s)
Juan, Chun-Chia
Abstract
The purpose of this article is to develop high-performance bidispersed wicks utilized in a LHP’s evaporator and to improve heat transfer crisis in formerly monoporous wicks. The influence of heat transfer performance about difference pore-size parameters will be discussed. The study was conducted by sintering the nickel powder clusters, which mixed with binder into a bidispersed wick. A two-level factorial plan of statistical design was introduced involving two variables: the average cluster size (53、82μm), and the cluster size distribution range (14、42μm). Moreover, the statistical model was built to determine the optimized parameter combination of the bidispersed wick. Finally, the heat transport capability of the LHP between monoporous wicks and bidispersed wicks has been investigated.
The experimental results indicated that average cluster size is the major effect (92.8%) on LHP’s performance about pore-size parameters, and the effect of cluster size distribution range was not significant (2.9%) within the parametric range. The better pore-size parameter tended to smaller average cluster size and wider cluster size distribution range. The best pore size parameter of the bidispersed wick was 20μm~62μm, which obtained by follow-up experiments.
Experimental results also showed that at the sink temperature of 10℃ and the allowable evaporator wall temperature of 85℃ the maximum heat transfer capacity of monoporous wick achieved 400W and the minimum total thermal resistance was 0.16℃/W. Comparing to the monoporous wick, the corresponding values of the best bidispersed wick was 575W for heat transfer capacity and 0.13℃/W for total thermal resistance. In addition to the heat transfer ability of porous wicks, the best Bidispersed wick showed higher heat transfer coefficient of 23.3 kW/m2℃ at 400W than monoporous wick of 10.3 kW/m2℃ by 2.3 times. In conclusion, bidispersed wicks are very attractive for high heat flux applications.
Subjects
Loop heat pipe
Bidispersed wick
Heat transfer coefficient
High heat flux
Type
thesis
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