RESEARCH IS PROPOSED LEADING TO THE DEVELOPMENT OF A REFRIGERATOR FOR USE IN SPACECRAFT TO PROVIDE COOLING FOR LOW TEMPERATURE STORAGE OF FOOD AND BIOLOGICAL SAMPLES IN THE TEMPERATURE RANGE 0 DEGREES F AND CAPACITIES IN THE RANGE 1 TO 2 KW.

RESEARCH IS PROPOSED LEADING TO THE DEVELOPMENT OF A REFRIGERATOR FOR USE IN SPACECRAFT TO PROVIDE COOLING FOR LOW TEMPERATURE STORAGE OF FOOD AND BIOLOGICAL SAMPLES IN THE TEMPERATURE RANGE 0 DEGREES F AND CAPACITIES IN THE RANGE 1 TO 2 KW. THE SYSTEM PROPOSED OPERATES ON THE STIRLING REFRIGERATION CYCLE. THIS IS A CLOSED, THERMODYNAMIC REGENERATIVE CYCLE IN WHICH THE GASEOUS WORKING FLUID EXPERIENCES REPEATED COMPRESSION AND EXPANSIONOF THE WORKING FLUID AT DIFFERENT TEMPERATURE LEVELS. THE STIRLING REFRIGERATOR HAS MANY ADVANTAGES OVER THE MORE CONVENTIONAL VAPOR-COMPRESSION SYSTEM WITH AN ORGANIC WORKING FLUID; IT CAN USE THE SPACECRAFT LIFE-SUPPORT GASES AS THE WORKING FLUID. THIS OBVIATES PROBLEMS OF LEAKAGE ANDTHUS RELIEVES THE SEAL PROBLEM. THE INVENTORY OF FLUIDS ON BOARD IS REDUCED. MOREOVER, SINCE THE WORKING FLUID DOES NOT EXPERIENCE A PHASE CHANGE THERE IS NO PROBLEM OF FLUID MANAGEMENT OF LIQUIDS AND VAPORS. THE PRESSURE AND TEMPERATURE LEVELS CAN BE INDEPENDENTLY CHOSEN AND VARIES OVER A WIDE RANGE TO ACHIEVE A SPECIFIC COOLING LOAD PROFILE. THERE ARE NO LIMITS TO THE UPPER TEMPERATURE FOR HEAT REJECTION OR THE LOWER TEMPERATURE FOR HEAT ABSORPTION. STIRLING REFRIGERATORS ARE NOT WIDELY USED AT NEAR-AMBIENT TEMPERATURES BUT ARE THE SYSTEM OF CHOICE FOR MINIATURE CRYOCOOLERS IN INFRARED AND OTHER CRYOGENIC ELECTRONIC APPLICATIONS. THE TECHNOLOGY IS THUS WELL DEVELOPED AND ESTABLISHED WITH NO APPARENT FUNDAMENTAL PROBLEMS AWAITING SOLUTION.