FERROFLUIDIC ENHANCEMENT OF CONTACT HEAT TRANSFER COEFFICIENTS AT SPACECRAFT THERMAL AND STRUCTURAL JOINTS

THE RELIABLE TRANSPORT OF HEAT BY CONDUCTION ACROSS THERMAL AND STRUCTURAL JOINTS HAS BEEN IDENTIFIED AS A MAJOR DESIGN CHALLENGE FOR THE SPACE STATION TO BE LAUNCHED IN THE MID-1990S. AREAS OF KEY CONCERN ARE THE HEAT ACQUISITION AT COLD PLATES, SUCH AS CURRENTLY DESIGNED FOR SHUTTLE EXPERIMENTS, AND THE HEAT TRANSFER FROM THE MAIN THERMAL BUSTO HEAT PIPE RADIATORS. IN EACH CASE, RELATIVELY HIGH HEAT TRANSFER CONDUCTANCES CAN BE ACHIEVED BY HIGH CLAMPING FORCES THAT MUST BE ESTABLISHED AT SPACE-ERECTABLE INTERFACEJOINTS. THESE APPROACHES CAN RESULT IN RATHER COMPLEX, HEAVY, AND COSTLY DEVICES. THE OBJECTIVE OF THE PROPOSED RESEARCH IS TO EXAMINE THE FEASBILITY OF EMPLOYING A FERROFLUID AT THERMALLY CONDUCTIVEINTERFACES TO ENHANCE HEAT TRANSFER. THE MAGNETIC PROPERTIES OF THE FLUID WILL BE USED IN CONJUNCTION WITH THEPROPER ORIENTATION OF MAGNETIC FIELD LINES, DEVELOPED BY PERMANENT MAGNETS, TO DISTRIBUTE THE FLUID OVER THE JOINT AND AID IN RETAINING THE FLUID IN THE VACUUM OF SPACE. THE PLANNED APPROACH IS TO DEVELOP TEST APPARATUS AND EVALUATE THE ENHANCED INTERFACE CONDUCTANCE IN VACUUM RESULTING FROM THE INCLUSION OF VARIOUS CANDIDATE FERRO-FLUIDS BETWEEN TYPICAL INTERFACE MEMBERS. DESIGN CONCEPTS FOR RELIABLY STOWING, DEPLOYING, AND CONTROLLING THE FERROFLUID PRIOR TO AND DURING INTERFACE ASSEMBLY OR REPLACEMENT WILL BE DEVELOPED. IF SUCCESSFUL, THE APPROACH MAY ELIMINATE THE NEED FOR WELDED JOINTS IN SPACE AND ALLOW THE HEAT PIPES OR EXPERIMENTS TO BE READILY SNAPPED INTO THE MAIN THERMAL BUS OR ONTO COLD PLATES, RESPECTIVELY, IN MODULAR FASHION.