Optimum Parameters Matching Ability And Experiment Study Of Flash-binary Geothermal Power System With Steady State

With the shortage of fossil energy and the increasement of smog,the utilization of new and renewable energy becomes more and more attractive.Geothermal utilization has positive effect on reducing CO₂ emission.The capacity of geothermal power plants will increase 500MW in 2020 proposed by China government.The plants main distribute in Tibet,Yunnan and Western Sichuan.However,there are only few geothermal plants with 47MW capacity in China.It is necessary to develop new geothermal plants with mid-high geothermal resource in the future in China.The models of single flash,double flash,binary cycle and single flash-binary power systems are built based on the theory of thermodynamics.The effects of temperature,pressure and flow rate on the thermal performance indexes are analyzed.R245fa is selected as working fluid in a binary cycle.The higher resource temperature is,the higher thermal performance of flash-binary system.When the temperature is higher than 130℃,it is better to use flash-binary power system for geothermal resource because it is helpful for reducing the volume of equipments.The total capital cost models of double flash and flash-binary systems are built.The exexgyeconomics of two models are analyzed based on exergy cost rate balance.The levelized power costs of two systems are calculated.The sensitive of flow rate,capacity utilization factor and ininternal rate to levelized power cost are analyzed.The minimum levelized power costs of flash-binary and double flash systems are0.06803US$/k Wh and 0.07331US$/k Wh respectively.The economic feasibilities between flash-binary and double flash systems are compared based on payback period,net present value and internal rate of return methods.The payback periods of single-flash and double flash power systems are 6.4 years and 7 years.The average rate of return,net present value and internal rate of return of flash-binary system are greater than double flash system.The heat source temperature is an important parameter for power sensitive of thermodynamics and thermoeconomics.Two objective functions of stability are established for flash-binary system.The relative errors of two functions are less than 5%when the flash and evaporate pressure value fluctuate is 10%of the best flash and evaporate pressure respectively,which can be considered as steady operation.The Pareto optimal boundaries are obtained by multi-objective optimization of flash-binary system and the best points are gotten on the boundaries.An experiment bench of flash-binary power system is built.The parameter’s vibrations are observed by test data.Thermodynamic performances are calculated by test data with steady operation.The actual isotropic efficiency is about 0.25 calculated based on test data.Two error correction models are proposed based on test data.The thermal performances of error correction model 2 have a high consistent with the experimental parameters.The most exergy destruction mainly focuses on rejection water and condenser,which should be optimized first.