USING POROUS METALS FOR VAPOR-LIQUID SEPARATION IN LIQUID METAL RANKINE CYCLE SPACE POWER SYSTEMS

SEPARATING LIQUID DROPLETS FROM THE BOILER OUTPUT TO PROVIDEA HIGH-QUALITY VAPOR STREAM FOR THE TURBINE OF A RANKINE CYCLE POWER SYSTEM IS DIFFICULT IN SPACE BECAUSE OF GRAVITY,SIZE, AND WEIGHT CONSIDERATIONS. ENTRAINED LIQUID DROPLETS CAUSE RAPID EROSION OF THE TURBINE BLADES AND REDUCE THE SYSTEM'S RELIABILITY. A POROUS METAL BARRIER IS USED AS A VAPOR-LIQUID SEPARATOR. THE BASIC CONCEPT IS THAT THE LIQUID IMPINGING ON A POROUS METAL SURFACE CAN FLOW THROUGH IT TO A LOWER PRESSURE REGIME WHEREAS VAPOR FLOW IS RESTRICTED BECAUSE OF CAPILLARY FORCES. WHEN THE LOWER PRESSURE SIDE OF THE POROUS SURFACE IS COUPLED TO A JET PUMP, SO DESIGNED THAT IT CAN RECIRCULATE THE LIQUID FLOW, THEN A COMPACT AND RELIABLE VAPOR-LIQUID SEPARATOR HAVING NO MOVING PARTS IS AVAILABLE TO THE RANKINE CYCLE SPACE POWER SOURCE. PHASE I OF THIS RESEARCH IS DEVOTED TO EXAMINING SPECIFIC DESIGN CONCEPTS USING A VARIETY OF POROUS MATERIALS, GEOMETRIES, AND WORKING FLUIDS. BOTH THE DIRECT-CYCLE POTASSIUM-COOLED REACTOR SYSTEM AND THE LITHIUM-POTASSIUM REACTOR SYSTEM WILL BE EXAMINED. THE POROUS BARRIER LOCATION MAY BE AT VARIOUS LOCATIONS OR COMBINATIONS THEREOF, INCLUDING THE BOILER OUTLET, PIPING SECTIONS, OR SPECIFIC LOCATIONS IN THE TURBINE. EXPERIMENTAL DATA FROM GASEOUS DIFFUSION BARRIER TECHNOLOGY AND FROM LOW-GRAVITY (AIRCRAFT FLIGHT) TESTS OF THE MEDIUM POWER REACTOR EXPERIMENT (MPRE) WILL BE USED. VIABLE MATERIALS AND GEOMETRIES WILL BE ASSEMBLED AND TESTED DURING PHASE II USING WATER-STEAM MIXTURES. ARRANGEMENTS WILL BE MADE WITH THE OAK RIDGE NATIONAL LABORATORY TO TEST SOME LIQUID METAL SYSTEMS IN EXISTING FACILITIES. THESE PHASE II TESTS SHALL INCLUDE THOSE SYSTEMS DEEMED VIABLE FOR SPACE APPLICATIONS AND THOSE CONSIDERED COMMERCIALLY ATTRACTIVE.