Multi-Evaporator Two-Phase Loop Cooling System

This paper describes the development and testing of a multi-evaporator hybrid loop heat pipe (ME-HLHP) for cooling a solid-state laser system. The ME-HLHP architecture, which is under development for a variety of cooling applications for NASA, DoD, and the commercial sector, provides the operational robustness of a loop heat pipe (LHP) and the expandability/controllability of a capillary pumped loop (CPL). The overall design goal was to develop a cooling system capable handling heat fluxes of up to 50 W/cm 2 . In support of that goal, a 4-evaporator ME-HLHP breadboard cooling system was designed, fabricated, analyzed, and successfully tested at heat loads up to 2000 W. Heat source temporal temperature stability to better than 1 K was obtained. The ME-HLHP design included a unique design feature, known as the liquid cooled shield (LCS), which enabled the cooling system to operate with vapor temperatures considerably below the surrounding laboratory ambient temperature. This program was therefore the first demonstration of LCS technology with the ME-HLHP architecture. This paper will describe all aspects of the project including concept development, analysis, design, manufacturing, and testing.