| The solar energy is widely distributed and rich in resources.The energy utilization is clean and renewable.The solar thermal power generation system converts solar energy into electrical energy,which can be combined with a thermal storage system to output stable and dispatchable electricity.The high-temperature thermochemical heat storage system can convert energy into chemical energy for storage,and to some extent can overcome shortcomings of solar radiation such as intermittent and unstable.It can enable the thermal power generation system to achieve continuous and stable power supply and have great significance for the use of solar power.Metal oxides are used as heat storage medium,and the reversible redox reaction between metal oxides and oxygen is used to realize the storage and release of heat.The reaction temperature is high and it has broad development prospects.In this paper,the system with the most potential material in metal oxides as the heat storage medium Co304/CoO is used as the research object to realize the modeling and simulation of the heat storage system.The temperature distribution in the heat storage system is calculated by COMSOL software.Finally the temperature of the system is controlled.High-temperature thermochemical heat storage uses high-temperature air as heat transfer fluid and reactive substances.The heat storage process involves fluid flow,heat conduction,convective heat transfer,and gas-solid reactions.Based on the analysis of the material exchange,energy exchange,and the kinetic characteristics of redox reaction in the heat storage process,the mechanism model of the high-temperature thermochemical heat storage system is established.Based on the obtained mechanism model,a three-dimensional simulation model of the heat storage system is built,and the model is solved using COMSOL software based on finite element numerical calculation.The thermal storage system can be divided into two stages:sensible heat storage and thermochemical heat storage,after analyzing the working process of it.The two parts of the high temperature thermochemical heat storage are simulated respectively,and the simulation results of the model are compared with the experimental data in the literature to verify the simulation model.Based on the analysis of the factors affecting the temperature change of the heat storage process,the influence of the temperature change of the inlet of the heat storage reactor and the air flow on the heat storage process and the redox reaction process were explored.Finally,the temperature control scheme of the heat storage system is proposed.The integration of the solar thermal power generation system and the heat storage system is analyzed to obtain the control requirements of the heat storage system.The control strategy is formulated,and the temperature is controlled by PID. |
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