GRAPHITE/PHASE-CHANGE-MATERIAL THERMAL STORAGE COMPOSITE

THERMAL MANAGEMENT OF FLUCTUATING POWER IN SPACECRAFT IS AIDED BY THE USE OF SUITABLY PLACED THERMAL ENERGY STORAGE (TES), WHICH OFTEN USES LATENT HEAT OF PHASE-CHANGE MATERIALS (PCMS) FOR THE STORAGE MEDIUM. AN OUTSTANDING PROBLEM WITH TES IS HOW TO GET THE THERMAL RESPONSE FAST ENOUGH TO ACCOMMODATE PULSE-POWER SITUATIONS. TO ADDRESS THIS NEED, THE FEASIBILITY IS BEING DEMONSTRATED OF HIGH-FLUX TES BASED ON GRAPHITE/PHASE-CHANGE MATERIAL COMPOSITES. THE EXTRAORDINARILY HIGH THERMAL CONDUCTIVITY OF CERTAIN FORMS OF GRAPHITE IS JOINED WITH THE HIGH EFFECTIVE HEAT CAPACITY (NEAR THE TRANSITION TEMPERATURE) OF PCMSTO PRODUCE NOVEL MATERIALS HAVING UNSURPASSED SPEEDS OF CONDUCTIVE HEAT ABSORPTION AND HEAT RELEASE. THE APPROACH, BASED ON THE NEWLY DEVELOPED METAL/PCM COMPOSITE TECHNOLOGY, INDICATES THAT HIGHEST PERFORMANCE IS ACHIEVED WITH HIGHLY DISPERSED 50-50 COMPOSITES. MATERIALS BEING INVESTIGATED INCLUDE SELECTED HIGH-THERMAL-CONDUCTIVITY TYPES OF CARBON FIBERS AND EXFOLIATED GRAPHITE. THERMAL PERFORMANCE TESTS ON GRAPHITE/PCM COMPOSITES ARE BEING PERFORMED AT BOTH AMBIENT AND ELEVATED TEMPERATURES. RESULTS ARE BEING ANALYZED IN TERMS OF THE HOMOGENEOUS MODELS USED IN METAL/PCM STUDIES. METHODS OF ACHIEVING A HIGH-HEAT-TRANSFER INTERFACE BETWEEN THE VOLUME OF THE TES COMPOSITE AND HEAT SOURCES AREBEING INVESTIGATED.