1 KW Capacity Refrigeration System at 80 K ( LINIT-R1 )

Abstract

A newly developed and tested cryogenic system for the 80 K temperature range is presented. The plant consists of i compressor unit and one cold box. The system runs fully automatically, has a very low noise level and can easily be operated by not specially trained personnel. The refrigeration is produced in a nitrogen circuit in the following manner: Nitrogen, compressed by an oil injected screw compressor, enters the cryogenic heat exchangers and then passes through two gas bearing turboexpanders to achieve the required low temperature. The expanded cold nitrogen gas is sent back to the heat exchangers where it completes the refrigeration circuit by fulfilling the heat recovery duties and returning to the nitrogen compressor at the beginning of the cycle. A nitrogen gas sidestream is separated from the cooled high pressure main stream, cooled further, liquefied, undercooled and finally expanded with a throttling valve into a separator containing the cooler of the user’s coolant circuit. Here the liquid nitrogen evaporates, fulfilling the plant’s cooling duties, and reenters the main circuit gas flow coming from the turboexpanders.