A performance estimation method of Loop Heat Pipe with a wick permeability model considering dry-out of wick pores

Abstract

In this paper, we propose a practical simulation method for designing Loop Heat Pipe (LHP) which is applied to cooling system for electronic devices. To realize rapid evaluation of cooling performance of LHP, the proposed performance estimation method calculates maximum heat transfer of LHP using 1D thermal-fluid network analysis. However, it is difficult to simulate phase-change of working fluid in LHP accurately with 1D model, since each component of LHP is modeled into a simple 1D network and its detailed shape is not considered enough. Especially, evaporator wick is indispensable component of LHP for determining its maximum heat transfer, and it is required to predict wick dry-out, where working fluid is dried in many pores of wick and LHP does not work as a result. The proposed simulation method introduces a wick pore inactivation model which depends on both input heat and wick pore diameter distribution to consider wick dry-out. The inactivation model applied to calculating wick permeability which determines pressure loss of wick. By fitting the wick permeability model to measured temperature distribution and maximum heat transfer of a LHP prototype for server systems, we show that our model estimates maximum heat transfer within allowable error compared to the experimental value.