A THERMAL MANAGEMENT SYSTEM FOR A THERMOPHOTOVOLTAIC/GENERALPURPOSE HEAT SOURCE POWER SUPPLY

DIRECT ENERGY CONVERSION EMPLOYING GALLIUM-ANTIMONY THERMOPHOTOVOLTAIC (TPV) CELLS CAN ACHIEVE CONVERSION EFFICIENCIES AND SPECIFIC POWER (W/KG) ABOUT TWICE AS HIGH AS THE ACHIEVABLE EFFICIENCIES AND SPECIFIC POWER FOR THERMOELECTRIC CONVERSION. ON THE OTHER HAND, THERMOPHOTOVOLTAIC CELLS MUST OPERATE BELOW 350 K, VERSUS 550 K FOR THERMOELECTRIC CELLS. THE REDUCED OPERATING TEMPERATURE INCREASES THE SIZE OF THE RADIATOR REQUIRED TO REMOVE THE WASTE HEAT FROM THE TPV SYSTEM. THE LOWER RADIATOR TEMPERATURE MEANS THAT THE THERMAL CONTROL SYSTEM REPRESENTS ROUGHLY A 25% SHARE OF THE LOCAL TPV SYSTEM MASS,VERSUS A 5% SHARE FOR A THERMOELECTRIC SYSTEM. BECAUSE THE THERMAL CONTROL SYSTEM REPRESENTS AN UNUSUALLY HIGH PERCENTAGE OF SYSTEM MASS, IT IS AN UNUSUALLY RICH TARGET FOR MASS REDUCTION. THIS PROJECT APPLIES INNOVATIVE LOW MASS AND THERMAL MANAGEMENT TECHNOLOGIES TO A SYSTEM DURING A STAGE WHERE DESIGNED-IN SOLUTIONS CAN BE INTEGRATED. PHASE I IS DEVELOPING A PRELIMINARY DESIGN TO COOL TPV CELLSWITH LOW MASS HEAT PIPE RADIATORS. MASS IS REDUCED BY THREEDISCRETE MEANS: (1) USE OF LOW MASS COMPONENTS SIMILAR TO HEAT PIPE ENVELOPES ALREADY UNDER DEVELOPMENT; (2) REDUCTIONOF TEMPERATURE DROPS THROUGH THE USE OF A TWO-PHASE HEAT TRANSFER SYSTEM; AND (3) SAVINGS AT A SYSTEMS LEVEL BECAUSE ONLY THE TPV CELLS WILL BE IN CONTACT WITH THE HEAT REJECTION SYSTEM, MINIMIZING CONDUCTIVE LOSSES.