Dynamic Simulation And Performance Analysis Of Micro Gas Turbine Cycle

As the demand for distributed energy supply increases,in order to recover the waste heat of the system,realize the cascade utilization of energy,and improve the efficiency,the advanced thermal cycle based on micro gas turbine plays an increasingly important role in the power system.Among them,the regenerative cycle based on micro gas turbine and the humid air turbine cycle(HAT cycle)become the important research directions.As a power generation system close to the user,the transient response conditions encountered,such as start-up,shutdown and load changes,are more than the basic load power generation system,so it is crucial to grasp the dynamic performance of the micro gas turbine cycle system.In this paper,the dynamic simulation and performance analysis of the micro-turbine recuperation cycle and the micro-turbine wet air turbine cycle(it referred to as the micro-HAT cycle in the next paper)are carried out,and the model parameters are corrected using the test data.The main work and results of this paper are as follows:1.Dynamic Simulation and Verification of a Recuperative Micro Gas TurbineFirstly,the design parameters of key components and compressor efficiency curves are corrected by using the on-design and off-design operation data of Bowman TG80,a recuperative micro turbine.Secondly,the influence of the plenum volume and components thermal inertia is studied and the value of rotational inertia is determined by using the characteristics of open-loop control during the shutdown process.Finally,based on the model parameter correction results,the start-up and load following processes of the micro-gas turbine are simulated,and the accuracy of the model is analyzed by comparison with the test data The research results show that: 1)The relative error between the simulated and the test of the efficiency under different loads is effectively reduced after corrected.2)The thermal inertia of components has a significant impact,while the influence of plenum volume can be ignored.3)Using the rotation speed operation data during shutdown,the estimated value of the rotational inertia is 0.009 kg m2.4)The simulation results of the key variables are in good agreement with the real operational data,which illustrate that the ability of the dynamic model in the simulating of the start-up,load following and shutdown processes of the regenerative micro turbine.2.Dynamic simulation and verification of micro HAT cycleUsing the operation data,further parameter correction work is carried out on the added model in the humid air turbine cycle.The load following process is simulated based on the correction results,and the accuracy of the model is verified by comparison with the test data.The results show that: 1)The estimated heat exchange area of the aftercooler is 199.31m2,the estimated heat exchange area of the economizer is 31.13m2,and the estimated height of the humidifier is 0.88 m.2)When the output power 80 k W,the relative error between the simulated values of the compressor outlet temperature,turbine outlet temperature,humidifier outlet water temperature and the test data is within 1%.3)In the load following process,the load tracking ability is good,and the simulation results can roughly reflect the dynamic change process of the actual gas turbine.3.Study on dynamic performance of micro HAT cycle with different structuresFirstly,the dynamic characteristics of two types of systems with or without aftercooler during the ramp-up process are simulated and compared.Secondly,the dynamic characteristics of three kinds of systems with different split ratios in load rejection are studied.Finally,the dynamic characteristics of the humidifier influent water volume with a disturbance of ±10%,20%,50% are simulated and analyzed.The research results show that: 1)In the process of ramping operation,the heat capacity of aftercooler has a small effect on the fuel flow and speed,which can be ignored,but it has a greater impact on the time required for the system to reach a steady state;When the load increases,the moisture content of the system that without aftercooler is more obvious,and the surge margin of the system with the aftercooler is lower;The temperature change of the inlet and outlet of the humidifier liquid side and gas side is small regardless of with or without the aftercooler,indicating that the system has a large thermal inertia.2)In the process of load rejection,although the minimum opening of fuel valve is given,the speed overshoot is still more than 8%,so the load rejection command should be avoided at higher power;The variation of fuel flowrate,speed,and turbine outlet temperature is consistent in the five cycles;The inlet temperature of humidifier will drop by 50 K instantly,which will cause large thermal shock and harm the heat exchanger.3)When the water inflow of the humidifier increases instantaneously,the temperature change trend is obvious,and the change range increases with the increase of disturbance.When the disturbance is + 50%,the inlet air temperature can rapidly decrease by 30K;when the disturbance is + 50%,the inlet temperature can rapidly decrease by 30K;when the disturbance is + 50%,the moisture content at the outlet will increase by about 22%,and when the disturbance is-50%,the moisture content will decrease by about 36%;the greater the water disturbance,the longer it takes to reach the new steady state.