| As we all know,solar energy is widely distributed and is the most abundant renewable clean energy in the earth.The development of solar energy as an alternative energy has broad prospects.Compared with fossil fuels,solar thermal power is a way to reduce the emission of carbon dioxide and the consumption of coal resources,which is very friendly to the envir onment and has no pollution.Solar Brayton cycle is an environmentally friendly technology for distributed power generation.It is a potential and effective method to improve the efficiency of solar Brayton cycle by recovering waste heat to produce steam a nd inject back into the system.Solar thermal power generation system is generally installed outside under harsh environment,where sometimes encounter bad weather such as strong breeze.The main reason of multiple solar energy generators' collapse incidents in recent years was due to insufficient intensity of its material.Secondly,the coupling mechanism and effect of mechanics,optics and heat transfer in the dish Brayton solar thermal power generation system have not been studied deeply.These are restr icting the further promotion and application of dish solar thermal power generation system.Therefore,it is quite necessary to carry out the investigation on the recognition analysis of the reliability of structure performance of dish Brayton solar thermal power generation system by the numerical simulation and experiment,combined with relevant theory and algorithm in the paper,as well as the coupling effect of mechanics,optics and heat transfer studied in the process of power generation of the dish Brayton solar thermal power generation system.The research results not only provide a theoretical basis for the design and application of the dish Brayton solar thermal power generation system,but also have important theoretical and practical significance to improve the comprehensive performance of the dish Brayton solar thermal power generation system and control the environmental pollution.The main research work of this paper is as follows:(1)The flow field model and finite element model of dis h solar thermal power generation system are established.The inherent vibration characteristics of azimuth angle(0°~180°)and altitude angle(0°,45°)under different wind excitations are analyzed.The modal analysis of the power generation system is carried out by combining modal testing and simulation,which provides theoretical support for the fluid-solid coupling resonance response analysis under sinusoidal wind-induced vibration.(2)A harmonic response simulation model of dis h solar thermal power generation system is established based on fluid-solid coupling method.The harmonic response characteristics under sinusoidal wind-induced vibration with a period of 2s are analyzed.And the vibration state of the hinge point between cantilever beam and bracket is al so analyzed.The surface deformation of the concentrator can be inferred from the displacement change of four hinge points,thus providing a theoretical basis for the design and optimization of power generation system.At the same time,according to differ ent wind loads and azimuths,the changes of wind force and wind moment on the concentrator and those changes under variable wind speed and turbulent wind speed are studied.The results show that the amplitude of forced vibration induced by wind increases with the increase of wind speed,and the wind force and moment of the concentrator increase with the increase of wind speed at the same azimuth and altitude angle.(3)The physical and mathematical models of the heat absorber are established.Based on the field synergy theory,the heat loss mechanism of the heat absorber in the dish solar thermal power generation system under different geometric parameters(inclination angle,opening size,opening position,cavity geometry)is analyzed,the mechanism of redu cing the heat loss of natural convection in the cavity of the heat absorber is revealed and several new characteristics of the heat loss of natural convection in the cavity of the heat absorber are obtained,which provides a good theoretical basis for ensu ring the optimal heat transfer performance of the heat absorber.(4)A concept of direct normal irradiance parameter for critical design is proposed,and a mathematical model for calculating annual power generation of solar thermal power generation system is established.The effects of solar multiple,direct normal irradiance,thermal energy storage and thermal energy dispatching fraction on solar energy utilization efficiency are analyzed.Finally,the general optimization design parameters such as solar m ultiple,thermal energy storage and thermal energy dispatching fraction are determined.The result shows that under specific weather conditions,solar thermal power plants with smaller critical design normal direct radiation parameters can adapt to larger solar fields,thus more solar energy can be utilized more effectively;when the thermal energy storage is high,higher thermal energy dispatching fraction can ensure that more solar energy can be effectively utilized.(5)Thermodynamic models including sol ar energy loss of concentrator,external irreversibility of heat engine and heat conduction bridge loss are established,and the temperature of heat absorber,cooling water,working fluid and the efficiency of heat exchanger hot end,heat exchanger cold en d and regenerator are defined as optimization variables.The dimensionless outputs such as power,thermal efficiency and ecological performance are optimized by non-dominant sequencing genetic algorithm and its sensitivity is analyzed.The results show that the temperatures of cooling water and working medium and the efficiency of regenerator have great influence on the optimal performance of the system. |
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