| Thermal energy storage(TES)system is the key technology for large-scale commercial application of concerntrating solar power plants.The addition of TES system can effectively restrain the intermittent change of solar energy input,which makes the solar thermal power plant can generate electricity continuously.Now the molten salt TES system is the most widely used,but the concrete TES system with its cost advantages is winning more and more attention.In this paper,for a 50 MW parabolic trough solar thermal power station with 6-hour charging time,the main equipments of the indirect two-tank TES system were designed and the mathematical models were established to carry on the dynamic simulation research.At the same time,the concrete heat transfer model of concrete TES unit was established,the heat storage characteristics were studied and the optimization design of heat storage unit was carried out,then the concrete TES of a 50 MW parabolic trough solar thermal power station was designed on the basis of heat storage unit.In this paper,design and calculation of heat exchanger,storage tanks and molten salt pumps in indirect two-tank TES system were carried out,and the mathematical models were built according to mass and energy conservation equation.The charging characteristics of TES were studied in Simulink sumulation platform of MATLAB.The inlet flow rate and tempereture of the heat transfer oil were changed to make perturbation experiment,and the experimental results were analyzed by theory.In this paper,the heat transfer model of the concrete TES unit was established based on the modified lumped heat capacity parameter method.The heat transfer equations were rewritten according to the standard format of pdepe function,and the original partial differential equations were simplified to oridinal partial equations to solve The tempereture distributions of the heat storage medium and the fluid in the charging process.The effects of thermal conductivity,diameter ratio and the total length of concrete modules on the effective charging time and efficiency were studied by contrast calculation.This paper also carried on the optimization design to the concrete TES unit,finally applied to the concrete TES system.The performance of indirect two-tank TES and concrete TES was analyzed by using the heat storage capacity utilization factor.The conclusion of this paper is helpful for the TES system selection of the technical scheme of large-scale parabolic trough solar power plants... |
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