The Experimental Study On Performance Of Disc Type Solar Heat Receiver

As a kind of renewable energy, solar energy is tremendous and pollution-free, itdistributes all over the world, so in environmental pollution increasingly serious andconventional energy increasingly short today, solar energy has been got universalattention by all countries.Solar thermal power generation is an efficient large-scale use of solar energy style,there are mainly trough, tower and disc three kinds. Compared with trough and towersolar thermal power generation, disc solar thermal power generation system starts withsmall loss and photoelectric efficiency as high as29.4%, ranks first in three systems,so it becomes the focus of study. As one of the core components in dish concentratingsolar thermal power generation system, solar heat receiver absorbs solar energy asmuch as possible which reflected by parabolic dish concentrator and its heat-absorbingproperties directly affect the light and heat conversion efficiency, thereby influence theoverall thermal power system reliability and economy, so study the cavity receiver hasa very important significance.This project proposed a new type cavity receiver firstly, and then developed adish solar collector system included the receiver, preliminary studied collectorperformance of the system and analyzed the heat-absorbing property of cavity absorber.The main research contents and results of this topic can be listed as follows:1. In view of heat loss of cavity receiver has a large proportion in dish thermalpower generation system, comprehensively considered the factors related to heat loss,receiver shape and internal heat transfer component to cavity receiver thermalperformance, this topic developed an overall hemispheric shape cavity absorber, therewas insulation material outside the receiver. The area ratio between day lighting mouthand inside surface was1:8, chose8gravity heat pipes as heat transfer elements, pipesis180mm length, tube diameter is14mm and wall thickness is2mm, pipes wereuniform arranged in a circle which radius is85mm, inclination were15°, sections inheat receiver is90mm which absorbed solar radiation in receiver, the adiabatic sectionis40mm in the part of insulation layer. Within the heat pipes was inorganic heattransfer working fluid. Pyromark2500selective absorption coating was coloured onpipes evaporator.2. Established a dish type solar collector system contained the new cavity heatreceiver in Gaolan county, Lanzhou city and preliminary studied the heat-absorbing performance of the receiver. The experimental results of November29,2011,December1,2011, December5,2011and December22,2011(winter solstice) showedthat the temperatures at the center of the cavity and the lighting port center, theheat-absorbing power, and solar thermal conversion efficiency were completelyconsistent with the trend of direct solar radiation intensity. First gradually increasedwith time then declined after reached the maximum and the maximums of cavity centertemperature and lighting port center temperature were always around the direct solarradiation intensity maximum. Through calculation we found that the maximum ofheat-absorbing power was always around the peak of solar thermal conversionefficiency. On2011Winter solstice, when direct solar radiation was505.5W/m2, theheat power was1686W; the thermal efficiency was80.6%. The results showed that thenew cavity absorber had good heat-absorbing performance, and the sun direct solarradiation intensity in experiment was an important factor on power and thermalefficiency in dish solar thermal power generation system, finally analysed theexperimental system problems and proposed the corresponding solutions.The innovation of this paper: developed a new type cavity receiver andpreliminarily revealed the heat-absorbing performance of the cavity receiver.The dish solar thermal power generation system is one of the solar thermal powergeneration systems which have the simple structure, the flexible layout, the high powerefficiency, the high system optimization and cost reduction potential, the little initialinvestment, the widely application foreground. The research on this system is rarely athome and abroad. This project designed a new cavity absorber, and got heat-absorbingperformance in Lanzhou weather conditions. The academic research results hadimportant reference value for experimental demonstration and application of the dishsolar thermal power generation system.The research of this subject was supported by the National Natural Science FundProject (51166008/E0607), National Science and Technology Department Spark PlanKey Project (2010GA860004), National Science and Technology Support Plan Issue(2011BAD15B03), Education Department Project of Gansu Province (0803-06),“Longyuan Youth Innovative Talent Support Program” Project (09-0165),Construction of Scientific and Technological Research Project of Gansu Province(JK2010-29), Gansu Province Technology Support Program (1011GKCA030), HigherSchool Basic Scientific Research Operating Expenses of Gansu Province (09-0258)and Lanzhou University of Technology “Hongliu Outstanding Talents Plan”(Q201101).