Performance Analysis On Parabolic Trough Solar Power System

As a kind of solar energy conversion technology suitable for large-scale grid-connected power, parabolic trough solar power is increasingly becoming international hot-spot of research and application. China embraces many advantages such as sufficient solar energy, vast unutilized land and relatively complete infrastructure, which is favorable for solar power plant development. As one of the most potential solar power technologies, parabolic trough solar power technology is greatly limited by its low efficiency. In this paper, the model of parabolic trough solar power plant was developed and simulated for the parameters of operating performance, which provides the basis for developing parabolic trough solar thermal power plant with typical weather in China.Firstly, the system model was developed, and module parameters were analyzed and determined. Double-loop cycle power system was established with three parts as solar field system, heat transfer system and power cycle system. The main parts of the system such as superheater, reheater, steam generator, preheater, turbine, condenser and feedwater heater, were analyzed on thermal performance, as well as the thermodynamics properties of fluids in them. Based on reference data in rated power, the inlet and outlet temperature of fluids in superheater, reheater, steam generator and preheater were simplified calculated. The inlet and outlet temperature and mass flow rate of HTF in solar field were determined.Secondly, the influences of weather conditions, temperature of HTF and cooling methods to system performance were simulated and analyzed. DNI was the main influential factor, while wet-bulb temperature and wind speed were slightly. And also, Lhasa was selected as the location for further study. According to the simulation, the output of system increased with the increase of HTF temperature, while the growth shows a downward trend. Due to the limit of solar field system and heat transfer system, the optimum parameters of HTF in solar field were determined to be385℃for outlet temperature and293℃for inlet temperature. Of which, the outlet temperature of HTF in preheater was299℃with303.27kg/s in mass flow; and that in reheater was258℃with43.41kg/s. Through result of simulations, monthly outputs of power system with wet cooling system were higher than those with dry cooling system, and difference of annual output is5.9%. So, wet cooling system was the better way for the power system.Finally, the EUD analysis and exergy analysis in grey model were conducted. According to EUD analysis, the most exergy cost resulted in solar field with61.8%of exergy in all. Exergy analysis was conducted with a grey model of energy system, resulting in exergy efficiency to be27.9%. Solar field system is the weakest sector with exergy efficiency of38.2%, and exergy loss is up to85.7%of all exergy loss. The key to improve exergy efficiency is to improve the efficiency of solar field system, as to reduce optical exergy loss and heat-collecting exergy loss.