Design and Ambient Testing of the Flight Starter Pump Cold Plate

Capillary Pumped Loops (CPLs) have been under development for almost two decades and are emerging as a design solution for many spacecraft thermal control systems. Three Capillary Pumped Heat Transport Systems (CPHTS) using CPL technology have been selected for accommodating the two Earth Observing System (EOS-AM) instruments that require advanced waste heat dissipation. The Capillary Pumped Loop Flight Experiment (CAPL-2) ^{[Ref 7]}, which was carried on board STS-69, successfully demonstrated an EOS-like capillary system utilizing a prototyped starter pump cold plate (SCP).

The CAPL-2 SCP is almost identical to the EOS-AM configuration and was designed, built, and demonstrated to overcome the start-up difficulty under fully flooded conditions. The SCP was rigorous ground tested as part of a simulated EOS-AM / CAPL-2 capillary loop, and the SCP successfully met or surpassed all of its performance requirements. Of particular noteworthiness was the robustness of the SCP and its ability to tolerate high superheat and pressure surge during start-up. The SCP also demonstrated strong deprime resistance under stressful conditions such as condenser cycling, power cycling, and low subcooling tests.