Experimental Investigation and Modeling of Stagnation and Recovery of Dissimilar Length Tubes on a Facesheet

Radiator stagnation is being explored to design single loop thermal control systems using Galden HT170 for heat rejection systems requiring large turn-down ratios. A previous Small Business Innovation Research (SBIR) Phase 1 studied sequential stagnation in a system of different length tubing. As part of a follow-on Phase 2, tests were performed to study the effects of adding a facesheet in a manner consistent with typical spacecraft radiator effectiveness. Onset of stagnation for different tubes was demonstrated for a given inlet temperature by lowering mass flow rate. Temperature and/or mass flow rate were increased to investigate stagnation recovery. A Thermal Desktop® model was built to simulate the test. Test results and modeling comparisons are presented.