THIS PROJECT IS TO DEVLOPE A LOW-TEMPERATURE ROTARY EXPANDER FOR USE WITH A LONG-LIVED HELIUM LIQUEFIER FOR RELIQUEFACTION OF VAPOR BOIL-OFF FROM HELIUM STORAGE DEWARS.

THIS PROJECT IS TO DEVLOPE A LOW-TEMPERATURE ROTARY EXPANDER FOR USE WITH A LONG-LIVED HELIUM LIQUEFIER FOR RELIQUEFACTION OF VAPOR BOIL-OFF FROM HELIUM STORAGE DEWARS. THE LIQUEFIER IS A THREE-FLUID, CLOSED-CYCLE, LINDE-HAMPSON (CASCADE JOULE-THOMSON) SYSTEM OPERATING WITH ARGON, NEON, AND HELIUM WORKING FLUIDS. NEON IS PERFERRED TO THE MORE CUSTOMARY HYDROGEN WORKING FLUID TO AVOID THE PROBLEM OF CONTAINING HIGH-PRESSURE HYDROGEN FOR LONG PERIODS. UNFORTUNATELY, NEON CONDENSES AT AN APRECIABLY HIGHER TEMPERATURE THAN HYDROGEN (27 DEGREES VS. 20 DEGREES K) SO THAT SUPPLEMENTARY COOLING OF THE HELIUM IS NECESSARY BEFORE THE FINAL STAGE HEAT-EXCHANGER AND JOULE-THOMSON EXPANSION. THE SUPPLEMENTARY COOLING CONSISTS OF AN EXPANSION IN AN ISENTROPIC SUPERSONIC NOZZLE WITH THE HIGH-SPEED GAS DRIVING AN IMPULSE TURBINE PRODUCING WORK CONSUMED BY A LOW-PRESSURE, CENTRIFUGAL BOOSTER COMPRESSOR FOR THE HELIUM WORKING FLUID. THE EXPANDER/COMPRESSOR WILL BE MOUNTED ON HYDROSTATIC GAS BEARINGS ENERGIZED BY A FRACTION OF THE HIGH-PRESSURE HELIUM FLOW DRAINING TO THE LOW-PRESSURE HELIUM ENVIRONMENT SURROUNDING THE UNIT. HIGH-IMPACT PLASTIC MATERIALS RATED FOR CRYOGENIC SERVICE WILL BE USED FOR THE TURBINE AND COMPRESSOR DISCS. THE NOZZLE AND HYDROSTATIC BEARING JOURNALS AND HOUSINGS WILL BE ELECTRO FORMED RUBY OR OTHER HARD SEMI-PRECIOUS STONES. HIGH- PRESSURE HELIUM GSA COMPRESSED TO APPROXIMATELY 200 ATM WILL BE PRE-COOLED TO LIQUID NEON TEMPERATURES BEFORE EXPANSION TO 0 ATM AND FURTHER JOULE-THOMSON EXPANSION TO 1 ATM.