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Session: Poster session & Sponsor Exhibition
Session starts: Monday 07 October, 14:00

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Jing-Fu Wang (Beijing University of Technology)
Yongzhi Zhang (Beijing University of Technology)
Yong Zhang (Beijing University of Technology)
Jifen Liu (Beijing University of Technology)
Wei Wang (Beijing University of Technology)

Abstract:
The rapid development of social economy is restricted by the energy shortage and the environment deterioration. The development and utilization of renewable energy has been listed as priority areas for energy development. As one of the alternative energy, geothermal energy gets more and more attention. Usually high temperature geothermal energy is the most suitable energy in power generation, but most geothermal energy is low-medium temperature heat source. The key technology which limits the development of low-medium temperature geothermal power generation system is its low efficiency. In this paper, a new low-medium temperature geothermal power generation system with Organic Rankine cycle (ORC) and single screw expander as power engine was developed, which aims to improve the efficiency of low-medium temperature geothermal power generation. Firstly, based on the principles of thermodynamics, the basic operation principle of this power system was analyzed. Then the method of determining the main parameters of this system was proposed. On the basis of theoretical analysis, two circulation types of this system, that are saturated ORC and vapor-liquid two-phase ORC, respectively, were analyzed. In this system, two kinds of refrigerant R601 and R134a were used as the working fluid. The results show that the vapor-liquid two-phase ORC is better than saturated ORC, and the performance of R601 is better than R134a on the basis of comprehensive comparisons at geothermal fluid temperature between 80℃~120℃. However, R134a is better at geothermal fluid temperature between120℃~150℃. In this temperature ranges, the evaporation temperature should be less than critical temperature of working fluid. A regenerative organic Rankine cycle system for low-medium temperature geothermal power generation was also studied in this paper. The influences of evaporation temperature, condensing temperature and extraction pressure on regenerative organic Rankine cycle system, respectively, were analyzed. The properties of ORC system with and without regenerator were compared. It is found that the thermal efficiency of ORC system with regenerator was higher compared to the one without regenerator.