Study of Effective Parameters on Helium Liquefaction Cycle using Exergy Analysis

Eslami, Mahdi | 2017

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 50094 (08)
  4. University: Sharif University of Technology
  5. Department: Mechanical Engineering
  6. Advisor(s): Afshin, Hosein
  7. Abstract:
  8. Liquefaction of gases is one of the applications of cryogenic science. Among the gases, Helium has the lowest boiling point, which at a pressure of 1atm is approximately 4.2K. Liquid helium can be used to cool superconductors in transportation equipment, military radars, and medical imaging equipment. For helium liquefaction, various cycles are used; these cycles have different parameters in their structure such as of input mass fraction to expanders, heat exchanger effectiveness, expander arrangement and ... which their analysis for improving the performance of the cycle is important. In this research, the aim is to study 2, 3 and 4 expander cycle with various parameters and structure. For the analysis of the liquefaction cycle, the exergy equations were used; using these equations, the exergy losses that are due to the irreversibility of the cycle can be calculated. Also, in this study, the 32-parameters MBWR equation of state was used. The simulation results showed that, with increasing number of pre-cooling stages, the efficiency of the cycle would be close to a saturation state. The optimum discharge pressure of compressor section, which represents the energy consumption of the cycle, is also reduced by improving the efficiency of the equipment and other parameters. In addition to studying the effect of different parameters on cycle performance, the effects of various structures such as different arrangement of expander, intermediate pressure and type of final expansion step on the cycle were investigated
  9. Keywords:
  10. Exergy ; Liquefaction ; Helium Gas ; Exergy Analysis ; Liquefier Cycle

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