| Along with the rapid development of China's economy, the demand for electricity is getting larger and larger. Most of the amount heavily relies on coal-fired electricity. Therefore, energy shortage and environmental degradation, caused by continuously increasing energy demand, will become increasingly evident. China must change the current coal-dominated electricity structure and make effective use of renewable energy resources to help transform its economy into a low-carbon one. It is a widely accepted fact that parabolic trough solar thermal power plants will change the current coal-fired electricity matrix, save conventional energy resources, and reduce CO2 emission, which has attracted more attention during recent years. To improve performance and reduce costs, Direct Steam Generation (DSG) solar power plant has been proposed as a future development of the parabolic trough solar power technology. In this dissertation, DSG parabolic trough solar concentrator and solar field were studied through simulation and calculation. Various optical losses were studied for different seasons and regions, including cosine loss, incident angle modifier, end loss and shading loss. The thermal performance of a DSG parabolic trough solar collector was reduced to a great extent due to these losses.Heat transfer performance of a DSG absorber was then analysed. Phase change in the DSG absorber was accounted for by separate analysis of the liquid, boiling and dry steam zones. So, thermal analysis of a DSG absorber could be divided into three regions to follow the phase changes in the absorber. Based on the different flow patterns, respective heat transfer coefficients in the DSG absorber were discussed and employed. Furthermore, detailed heat transfer and hydrodynamic models under steady state were developed and solved by adopting VB language in order to predict and evaluate the performance of the DSG solar parabolic trough concentrator in different conditions. The results showed that the computed values from the VB software were in agreement with the experimental data obtained by S.D.odeh. The relative error of the temperature and pressure at the outlet of the DSG absorber were respectively 2.0% and 0.2%. The average pressure drop in the two-phase flow region was approximately 451.9Pa/m. It was 18 times as much as the pressure drop in the subcooled water region and 1.28 times as much as the pressure drop in the dry steam zone.Based on the simulation results from MCRT method, the distribution function of the concentrated flux on the absorber surface was derived in practical application. Three-dimensional numerical simulation of coupled heat transfer characteristics in the DSG absorber tube was easily performed by combining the distribution function and the FLUENT software in order to investigate the temperature distribution of the DSG absorber tube outer surface. In consequence of the uneven solar energy flux distribution on the outer wall, the temperature distribution of the DSG absorber tube outer surface was extremely non-uniform. The circumferential temperature difference of the DSG absorber tube outer surface increased along the flow direction.The system model for a DSG solar power plant of 5MWe was established and solved in order to predict and evaluate the operational performance of the DSG parabolic trough solar power plant in Tibet. The unit exergetic cost for the plant was calculated by employing the thermoeconomic method. The distribution of exergetic cost in design conditions was analyzed. Exergy Loss in the solar field hit 23245.4kW, accounting for 72.9% of total solar exergy input. Finally, a visual experimental system for a DSG absorber tube was designed and established, which laid a foundation for making an intensive study of phase change in the DSG absorber.
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