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Studying the Effect of Applying Different Refrigerants in Ground Source Heat Exchangers

Shadi Diznab, Mohammad Amin | 2018

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 51238 (08)
  4. University: Sharif University of Technology
  5. Department: Mechanical Engineering
  6. Advisor(s): Hakkaki-Fard, Ali
  7. Abstract:
  8. Economical strategy of developed countries imposes to improve energy efficiency and a rational renewable energies usage in the buildings. Ground source heat pumps are one of the most important tools in the way moving toward this goal. This study focuses on studying the effect of applying different refrigerants in the direct expansion ground source heat exchangers. In order to compare the performance of the ground source heat pumps using different refrigerants, a specific methodology is presented and implemented. First on this study, the thermal performance of a geothermal borehole filled with both CO2 and a zeotropic mixture of CO2 and R32 (20/80) is studied and the quality, temperature, and pressure profiles are presented and analysed. Then, a methodology for comparison the performance of the whole system and sizing the borehole pipes is presented. After simulation of the whole system, coefficient of performance of the cycle and the compression ratio for the compressor are calculated for CO2, R134a, R22, R32, R410a, and the zeotropic mixture of CO2 and R32 (20/80). Finally, the thermal performance of the system using two boreholes, with the goal of reducing the pressure drop, is studied. The results indicate that CO2 has the largest coefficient of performance (5.03) and the least compression ratio (4.23) among the other refrigerants. Due to some difficulties which are the result of using these refrigerants, implementing the zeotropic mixture of CO2 and R32 seems to be a plausible choice
  9. Keywords:
  10. Borehole ; Heat Pumps ; Renewable Energy Resources ; Geothermal Energy ; Heat Exchangers ; Zeotropic Refrigerant Mixture

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