Thermal Performance Analysis Of Parabolic Trough Solar Power Generation System With Direct Air-Cooling

With the increasing emphasis on environmental pollution and the consumption of traditional fossil fuels,the development and use of clean renewable energy is an inevitable choice for sustainable development.As an emerging way of renewable energy utilization,solar thermal power generation technology can utilize China's abundant solar radiation resources,and also can solve the intermittent and unstable solar energy characteristics by adding heat storage equipment.In view of the distribution characteristics of solar radiation resources and water resources in China,this dissertation focuses on the following four aspects of trough solar direct air cooling power generation system:(1)Establishing a trough solar power generation system model(direct air cooling unit and water cooling unit),using Matlab software to compile the operating mode of the trough solar thermal unit,calculating and analyzing thermal performance indexes of power generation system,such as generation capacity,thermal efficiency of collector field and solar-to-electricity efficiency,etc.The accuracy of the water cooling unit model is verified.(2)For the variable working condition model of the cold-end system of trough solar direct air cooling unit,the control variate method is used to study the influence of unit load,ambient temperature and oncoming wind speed on the power generation system,and the back pressure change trend is analyzed.And the optimal back pressure under different operating conditions is obtained by calculating the power generation and fan power consumption of the air-cooled unit under different ambient temperature and unit load,and the operation of the air cooling unit is optimized.(3)Taking the 50MW trough solar direct air cooling thermal power station in Delingha area as an example to study the influence of heat storage capacity and concentrator field aperture on the thermal performance of the unit,and comparing the levelized cost of electricity to study and choose the optimization system.Based on these,the influence of DNI and ambient temperature on the thermal efficiency of the collector field are analyzed.The operating conditions of the power generation system under meteorological conditions of summer solstice and winter solstice are simulated.It can be seen that the thermal performance of the power generation system on the summer solstice day is better than that on the winter solstice day.(4)Based on three evaluation indexes,solar-to-electricity efficiency,annual power generation and levelized cost of electricity(LCOE),a 50MW parabolic trough solar direct air-cooled generation system is analyzed as a case.The different performances between the air-cooled unit and water-cooled unit are compared.The high solar-to-electricity efficiency and the lowest cost targets provides guidance for future investment and construction.