23 September 2011

DEVELOPMENT OF HIGH SPEED PELTON TYPE EXPANDER-GENERATOR FOR RECOVERY OF THE THROTTLING LOSS IN CARBON DIOXIDE REFRIGERATION SYSTEM

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High Speed Pelton Type Expander-Generator was developed for recovery of the
throttling loss in carbon dioxide refrigeration system. Many types of efficient positive
displacement expanders have been investigated to recover throttling loss. Different from
these work, compact and low cost type Pelton expander with high speed generator was
chosen and evaluated. Pelton expander consists of nozzle, impeller and generator. The
nozzle is an energy conversion device from the pressurized potential energy to the kinetic
energy of refrigerant jet flow. Pressure distribution along the nozzle and jet momentum at the
exit of the nozzle was measured with various nozzles and highly efficient nozzle design was
found. The impeller extracts the kinetic energy of refrigerant jet flow. Various shapes of
impellers were tested and highly efficient impeller design was found. The CO2 heat pump
cycle applying Pelton Expander-Generator with highly efficient nozzle and impeller designs
turned out to improve system performance by eight percent.