Thermal Control of an Airborne Electronics Bay.pdf

1Thermal Control of an Airborne Electronics Bay Michel Engelhardt, Sr. Principal Engineer II, Mechanical Engineering BAE Systems Inc., NES, 450 Pulaski Road MS 01-E10, Greenlawn, New York 11740 United States (631) 912-2769 FAX (631) 912-2721 michel.engelhardt@ An integrated thermal management system controls the temperature of an Electronics Bay located in a fighter aircraft pod within a prescribed temperature setting and temperature tolerance. The thermal management system integrates an open loop Air Cycle Machine (ACM) Environmental Control System (ECS) with a closed loop Thermal Control System (TCS). The ACM provides uncontrolled cooling to the closed loop TCS via an air-to-air cross flow heat exchanger. The main components of the ECS are the ACM, ram air inlet scoop/outlet, heat exchanger, and ducting. The TCS includes an innovative thermal control system, an effective in-line duct heater, an airframe skin thermal blanket, desiccant, and an air circulation fan. In addition, the TCS controls the Relative Humidity (RH) in the Electronics Bay throughout the mission of the aircraft. In-flight thermal analyses and test result indicate that the Electronics Bay temperature can be controlled by the TCS within +1° C of its prescribed temperature setting at take-off without condensation of moisture. The electronics bay temperatures are held between preset lower and upper bound temperatures throughout typical high performance aircraft missions. This paper describes the TCS and ECS components used to control the Electronics Bay air temperature, humidity, and pressure. In addition, this paper provides a summary of the thermal-fluid analytical models, TCS and ECS performance predictions, and comparison against test data. Nomenclature Ac = Surface area for convective heat transfer Ai = Internal air flow area of the i th duct section AK = Area for conduction heat transfer Ar = Area for radiation heat transfer As = Area for heat transfer into the heat exchanger Cp = Specific hea