Simulation study and performance analysis of free piston linear generator (FPLG) used for ORC system

Abstract

Due to advantage of low friction loss, simple structure and good sealing, free piston linear generator (FPLG) presents great application potential in ORC system. In this study, the FPLG simulation model was built using GT Suite and MATLAB/Simulink, and the model accuracy was verified through comparison with experimental data and error analysis. The influence of FPLG operation parameters, model parameters and full consideration of friction and EV characteristics on FPLG performance were studied. All the relative errors are within 10%, namely, the FPLG model has high reliability. Each indicator varies significantly with intake pressure, but relatively weakly with intake temperature. There is an optimal external load for maximum power output, and an optimal pipeline diameter for maximum velocity and average power output. As friction coefficient increases, both velocity and power output increase first and then decrease. When friction coefficient is 1200 N-s/m, average power output and velocity reach the maximum value of 102 W and 0.83 m/s, respectively. The velocity gradually decreases with the increasing flux linkage, while electromagnetic force and power output show a increasing trend. The research results can provide reference significance for optimization of FPLG and provide guidance for the application in ORC system.