Capillary Limit of a Miniature Loop Heat Pipe with Multiple Evaporators and Multiple Condensers

Abstract

An experimental investigation of a miniature loop heat pipe with multiple evaporators and multiple condensers were conducted in order to evaluate its capillary limit. The experimental tests were conducted by varying heat load to one or both evaporators, with and without active temperature control of compensation chamber (CC) using the thermoelectric devices, and variable tilts between the evaporators and the CCs. The physical process of the loop and thermal conductance of the heat leak from evaporator to (CC) were discussed based on the test results. The difference of the temperature profiles between with and without active control of CC temperature was evaluated. The effect of the gravity on capillary limit and CC temperature was also evaluated by comparing the test result in horizontal position with that in vertical position. The loop recovery after capillary limit was exceeded was also described. Nomenclaturethermal conductance between the evaporator and the CC mass flow rate capillary pressure heat leak heat load to evaporator radius of curvature of the wick at the vaporlliquid interface CC temperature vapor temperature in the evaporator grooves total pressure drop in LHP difference in specific volume between the liquid and vapor phases surface tension force latent heat of vaporization of the working fluid contact angle between the liquid and solid

The Effects of Vapor Space Height on the Vapor Chamber Performance

“…Heat pipe diameter, length, material, and working fluid play important roles on heat pipe performance. Recent research on heat pipes focused more on the wick design [4], miniature pipes [5], and loop heat pipes [6][7][8]. To explore better wick structures for high-performance miniature heat pipes Lin et al [5] used the folded sheet fin to create capillary flow channels with fully and partially opened grooves made by an electric-discharge-machining technique.…”

Thermal Vacuum Testing of a Proto-flight Miniature Loop Heat Pipe with Two Evaporators and Two Condensers

“…An MLHP Breadboard was built and tested in the laboratory and thermal vacuum environments and demonstrated excellent performance [15][16][17][18][19][20] . In addition, an analytical model was developed to simulate the steady state and transient operation of the MLHP 21 .…”