3D Printed Loop Heat Pipe with Deployable Radiator

Advanced Cooling Technologies, Inc. has developed low-cost and rapidly-deployable 3D Printed Loop Heat Pipes (3DP-LHPs) to enable high-performance SmallSats. The 3DP-LHP features a 3D printed evaporator, which is fully built as a single, assembly-free part using automated laser powder bed fusion of 316L SS powder. This process eliminates the many high-risk, labor-intensive manufacturing steps that are associated with conventional evaporator fabrication. The current paper discusses the development of an ammonia 3DP-LHP with Deployable Radiator Panel (DRP) prototype, designed to enhance the heat rejection of an ESPA-Sat by 2-3x over the current state-of-the-art, thereby enabling future large satellite missions within SmallSat SWaP-C. Therefore, the 3DP-LHP is intended to serve as a flexible thermal link for coupling between body-fixed and deployable radiators, with a stated heat load of 250 W and a thermal conductance requirement of 50 W/K for this work. The discussion includes such details as the radiator panel sizing, LHP layout, evaporator-compensation chamber design, hinge mechanism, pressure and thermal budget, etc. The LHP features a small 4-inch long and 1-inch OD 3D printed evaporator. The fabrication and assembly process, including various systems-level details such as the thermal interface material selection, are also detailed in the discussion. Finally, the 3DP-LHP qualification test procedures and results are presented, including shock and vibration, deployment, and thermal-vacuum tests, amongst others. This work elevates the 3DP-LHP to TRL 5-6 through the successful demonstration of a flight-ready prototype in a thermal-vacuum environment.