Dynamic Performance Analysis and Optimization of Medium-Deep Geothermal Heat Pump Steam System

Industry, transportation and building energy consumption are the three giants of China's energy consumption, in which the total industrial energy consumption accounts for 70%. There is a great demand for thermal energy in industrial production and processing. In order to utilize abundant geothermal energy in the field of industrial, a Modelica based dynamic simulation model of a high-temperature heat pump steam system is built with Dymola platform, which utilize the energy in the medium-deep geothermal as the low-temperature heat source to produce high-temperature steam for industrial production or processing, This paper also analyzed the demand of geothermal energy resources in the system, the dynamic simulation and research on different source temperatures from medium-deep layer are carried out. By controlling the frequency of the compressor and the opening of the throttle valve, the outlet superheat of different evaporators is controlled respectively, and the heating capacity is optimized at a fixed flash tank steam outlet temperature of 120℃, the electric energy consumed by the control strategy is minimized. For the steam subsystem, the influence of the flash evaporator inlet valve’s opening on the steam generation process is analyzed and discussed. Finally, the performance parameters of the system under the optimized control algorithm are compared and discussed, the best matching control strategy for different modes is obtained. The simulation results showed that the dynamic performance of the system converge well, and the maximum coefficient of performance of the system reached 3.5. Thus, the feasibility of the proposed system control strategy is validated.