Validation Design for a Multi-Evaporator Miniature Loop Heat Pipe for Spacecraft Applications

Abstract

A miniature loop heat pipe with multiple evaporators and multiple condensers for thermal control of small spacecraft and instruments was successfully developed. The miniature loop heat pipe had a 6.35 mm primary wick and used thermoelectric converters to control its operating temperature. A breadboard and a protoflight unit were built and tested under laboratory and thermal vacuum environments. Both loops demonstrated excellent thermal performance, including 100% startup success, tight temperature control under various heat loads and sink conditions, and heat-load sharing between evaporators. An analytical model designed to simulate steady-state and transient behaviors of the miniature loop heat pipe was also developed, and the model predictions agreed very well with experimental data. The maturity of this technology has been advanced from “proof of concept” to “prototype demonstration in a relevant environment.”