Simulation And Experimental Study On The Performance Of A Hybrid Solar-geothermal Power Generation System

In order to solve the problem that the efficiency of a single geothermal power generation system decreases in the daytime and is affected by the ambient temperature,the solar energy and geothermal energy are combined for complementary power generation,and two coupling modes of solar overheated working medium and solar heating geothermal water are proposed.In this paper,the heat transfer process of solar energy and geothermal energy coupling power generation is analyzed mathematically,and the numerical model is established by MATLAB software.The influence of solar radiation intensity on the efficiency of trough solar collector and the outlet temperature of heat transfer oil is studied,which provides data support for experimental research.The generation power and efficiency of the system are simulated time by time,and the influence of environment temperature on the performance of single geothermal power generation and the comprehensive influence of environment temperature and solar radiation intensity on the performance of coupled generation system are studied.The results show that the higher the solar radiation intensity is,the higher the collector efficiency is,and it tends to be stable gradually.For each 5℃rise in the ambient temperature of a single geothermal system,the average power generation decreases by 0.11k W;for each 500W/m~2rise in radiation intensity,the average power generation increases by0.075k W.Because of the heat loss and optical loss in the solar energy collection system,the daily average efficiency of the coupled power station is 6.83%lower than that of the single geothermal power station.Adding solar energy can effectively improve the power output of geothermal power station,and it needs less solar energy,so the investment is small.On the basis of numerical simulation,the original 500W geothermal ORC power generation experimental platform is optimized and transformed.The experimental platform can be used for solar heating geothermal water and solar overheating two coupling power generation.The evaluation indexes of heat exchanger,such as heat exchange performance,heat efficiency,Exergy efficiency and temperature efficiency,are studied experimentally,and the optimal operation condition law is obtained.At the same time,some problems in the system are found,and improvement measures are put forward.In the experiment,the conditions of geothermal water with different temperatures are simulated and kept unchanged,and the flow rate of working medium is changed.The data processing and analysis of the working medium at the inlet and outlet of each component in the experiment show that the optimal flow rate of working medium,the optimal evaporation pressure and the optimal evaporation temperature make the heat exchange performance and power generation performance of the system optimal.The steam quantity of working medium and superheat degree of superheater outlet are two key factors that affect the power generation performance of the system.The optimal operating conditions of the system are all in the range of superheat degree lower than 5℃,but the system is unstable at this time.In a sunny day,the continuous power generation experiment of the system is carried out 24 hours a day.Under the condition that the geothermal water temperature is 110℃,the power generation power of the solar energy superheated working medium coupling system is 132.86W higher than that of the single geothermal system,and the thermal efficiency is 0.93%higher than that of the single geothermal system;for the solar energy heating geothermal water coupling power generation system,the power generation power is 72.85W higher than that of the single geothermal power generation system,the thermal efficiency is 0.63%higher than that of the single geothermal power generation system.Generally speaking,the efficiency of solar heating medium is better than that of geothermal water,but solar heating geothermal water has higher stability.The relative error between the simulation results and the experimental results is less than 15%,and the overall deviation is small,which verifies the correctness of the numerical simulation.It can be considered that the simulation method proposed in this paper has a certain guiding role in the experimental research.