Changing steam chamber volume in screw expander

UDC 621.594

Changing steam chamber volume in screw expander

Danilov M.M. , Ivanova Z.N.

Operating parameters of screw expanders are comparable with the parameters of low-temperature turbo expanders which are used in the gas refrigeration unit for freezing carbon dioxide in the expanding flow of working medium. For the efficiency estimation of using screw expander in the freezing carbon dioxide mod we need to study in detail the process of decompression in the steam chamber. This knowledge is important for the opportunity of using current mathematical model for carbon dioxide freezing from the volume of expanding flow passing through expander with known value of the pressure distribution and flow speed. In this article is presented method of working medium expansion rate definition in the steam chamber. To achieve it are represented algorithms of creating diagrams of reduction male and female rotors swept volume and diagram of changing steam chamber free volume depending on the male rotor angle of rotation. Also in this article are shown the examples of creating above diagrams for the rotor with diameter 315 mm and ratio the length to diameter 0.9. Calculated by using the diagrams expansion angle gives us the opportunity to calculate velocity and time of expansion. These two parameters are the initial values for the carbon dioxide crystallization process estimation.

Keywords: carbon dioxide, gas refrigeration unit, screw expander, swept volume, steam chamber, expansion velocity, expansion time, rotation angle of the male/female rotor.

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