Nonlinear distributed parameter model and dynamic characteristics of parabolic trough direct steam generation solar collectors

Direct steam generation (DSG) in parabolic trough solar power system has long solar collector and obvious distributed parameter characteristics. Therefore, a nonlinear distributed parameter model for parabolic trough DSG solar collectors was built in this paper. As a boundary condition, fluid temperature and mass flow had to be provided at the inlet as well as the pressure at the outlet, and the finite differential approach with an upwind scheme was adopted to discrete and solve the model. Compared with experimental results from the literature, the correctness of the model was validated by simulation results during the main conditions such as solar radiation intensity, inlet fluid temperature and inlet mass flow change. Simulation results show that fluid temperature at the outlet decreases quickly when solar radiation intensity is declined; Furthermore, the responses of fluid temperature and mass flow at the outlet delay largely and stabilize slowly when mass flow or temperature at the inlet declined slightly; Most significantly, a pulsation phenomenon of outlet mass flow may happen in some conditions, which should be avoided or declined in practical application. © 2014 Chinese Society for Electrical Engineering.