| Since first industrial evolution,human society has consumed a large amount of fossil fuel which has disadvantages of finite reserves and environment pollution.Therefore,energy crises and environment pollution are becoming the most two crucial problems for human society developing.As a sustainable energy,solar energy shares advantages of abundant,wide distribution and environmental-friendly,so it is regarded as one of the most promising solution to environment pollution and energy crises.At present,solar thermal power generation is one main application of solar energy which includes Solar Power Tower,Parabolic Trough Collector,Parabolic Dish Collector and Linear Fresnel Collector.Besides,the solar parabolic dish collector?PDC?is the most efficient solar energy utilization technologies.In present work,a PDC system is employed to investigate the performance of photo-thermal conversion.In present work,a PDC system composed of a parabolic concentrator and a cylindrical cavity receiver is taken as object.Then the mathematical and physical models of photo-thermal conversion of PDC are established.The whole photo-thermal conversion process is divided into two sub-processes,namely Part?optical performance is evaluated by Monte Carlo Ray Tracing method?MCRT?and the solar flux distribution on walls is obtained.Part?thermal performance is solved by Finite Volume Method?FVM?in which the solar flux on walls is treated as a source term.The influences of receiver position?f,rim angle?rim,wall absorptivity?,Heat Transfer Fluid?HTF?inlet mass flow rate m,receiver tilt angle?tilil and wall infrared emissivity?on photo-thermal conversion performance are considered.The important conclusions are summarized as follows:?1?In legitimate range,decreasing?f,?rimim and?will elevate photo-thermal conversion efficiency?p-t-t by 2.22%,2.4%,1.8%and improve?exx by 0.84%,0.95%,0.8%.?2?In legitimate range,reducing m as lower as possible will decline?p-t-t by 6.2%but improve?exx by 19.64%.From the view of exergy efficiency,PDC photo-thermal performance shows better when m is smaller.?3?The solar flux distribution of walls and optical efficiency?optpt greatly increase with the growing of?.The adding of?will increase the heat losses slightly while Tout??p-t-t and?exx will largely augment.?p-t-t and?exx will increase by 8.28%and 3.21%with every 0.1 growing of?.Therefore,improving wall absorptivity of solar is an effective measure to increase system photo-thermal conversion performance... |
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