Modeling of a Loop Heat Pipe with Evaporator of Circumferential Vapor Grooves in Primary Wick

Abstract

A new configuration of internal geometry of LHP evaporator is investigated. Cylindrical evaporator has circumferential vapor escape channels instead of axial channels, commonly used in evaporators; only one axial groove is presented to provide vapor collection and direction to the vapor line. These circumferential grooves are combined with circumferential micro-threads on evaporator case internal surface. Mathematical model of LHP has been developed with emphasis on simulation of heat-mass transfer in evaporator. The model was verified by the test results obtained for the LHP with axial-groove wick evaporator. The model was then modified and applied to the new evaporator wick geometry. Comparative studies reveal the main reason for considerable improvement of the performance for new configuration: significant reduction of the two-phase layer between wall and wick. Two mechanisms are found to be able to contribute in such thickness reduction. There is effect of liquid trapping in the microthreads, and like-heat-pipe effect along circumferential grooves.