Fig.3 Construction of Turbo-expander

Construction of Turbo-expander

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A helium refrigerator-liquefier system was developed to cool down the magnet for the 1MW MHD power generator facility. The liquefaction capacity was 250 l/h, and refrigeration power was 2.9kW at 20k. It took about 2 to 3 weeks to fill the cryostat with 2,700 l liquid helium.

The system is constructed with a screw-type compressor, a reciprocating compressor, a large vacuum chamber with a heat exchanger, three small vacuum chambers with a turbo-expander, a 5000 l liquid helium dewar vessel with a Joule-Thomson valve and a purification system.

The turbo-expander was developed by Electro-Technical Laboratory. This turbo-expander with an alternator was constructed with a turbine wheel, bearings, a magnet, and a diffuser, in a small vacuum chamber.

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