Abstract: A total flow system with binary cycle was used in geothermal power generation with low-medium temperature, and compared with flash system. The optimal flash temperature was derived theoretically. Different parts of the total flow system with binary cycle were analyzed with the exergy loss, so as to propose the direction of reducing the exergy loss and optimizing the system which is reducing the minimum temperature difference of hot side and cold side of heat exchanger. Under the given condition, these two plants were calculated according to their system models. As shown by the calculation result, the maximum total capacity of total flow system with binary cycle is higher than that of the flash system by 12.7%. The power of the total flow system with binary cycle increases with the rise of the evaporation temperature of the organic fluid, and the power of the flash system firstly increases and then decreases while the flash pressure rises up.

Key words: geothermal generation, screw expander, total flow system with binary cycle, flash system