Technology Overview of a Multi-Evaporator Miniature Loop Heat Pipe for Spacecraft Applications

A miniature loop heat pipe with multiple evaporators and multiple condensers was developed for thermal control of small spacecraft and instruments requiring low mass, low power, and compactness. Multiple evaporators afford flexible placement of instruments inside the spacecraft and facilitate heat-load sharing among instruments. Multiple condensers allow the radiators to be placed at various locations on the spacecraft surface and exposed to different thermal environments. Thermoelectric converters are used to provide heating and cooling to the reservoir for loop operating temperature control. A breadboard and a protoflight unit of the miniature loop heat pipe with two evaporators and two condensers were built and tested in a thermal vacuum chamber to demonstrate the thermal performance. In addition, an analytical model was developed to simulate the steady-state and transient behaviors of the miniature loop heat pipe during thermal performance tests.