HEAT TRANSPORT ACROSS STRUCTURAL BOUNDARIES

NASA IS CURRENTLY EVALUATING CENTRALIZED THERMAL CONTROL SYSTEMS FOR FUTURE SPACE STATION APPLICATIONS. THE CENTRALIZED SYSTEM IS REQUIRED TO SERVE MODULAR SUBSYSTEM HEAT LOADS THAT ARE ADDED OR REMOVED FROM THE SPACECRAFT AS MISSION OBJECTIVES DICTATE. THE INTERFACE CONNECTION BETWEEN THE MODULE AND CENTRALIZED SYSTEM MAY BE FIXED OR MAY BE REQUIRED TO ROTATE OR GIMBAL. THIS ACTIVITY PROVIDESAN INNOVATIVE CONCEPT FOR INTERFACE CONNECTIONS BY EXTENSIONOF PREVIOUS EFFORTS IN THE DEVELOPMENT OF SLIDING, FIXED ANDROTATING THERMAL JOINTS USING HEAT PIPES. TYPICALLY, ONE HEAT PIPE IS MADE RE-ENTRANT WITH A CYLINDRICAL CAVITY TO ACCEPT THE SECOND HEATPIPE. THE GAP BETWEEN THE TWO HEAT PIPES IS FILLED WITH A THERMALLY CONDUCTIVE FLUID WHICH TRANSFERS HEAT FROM THE CONDENSER OF ONE HEAT PIPE TO THE EVAPORATOR OF THE OTHER. IN ADDITION TO PROVIDING A GOOD INTERFACE HEAT TRANSFER COEFFICIENT (H=17,000 BTU/HR-FT- DEGREES F.), THE FLUID SERVES AS A BEARING LUBRICANT FOR ROTATING CONNECTIONS.