【作者】 王子龙；

【导师】 张华；

【作者基本信息】 上海理工大学 ， 制冷与低温工程， 2011， 博士

【摘要】 能源和环境问题是当今世界面临重要难题。太阳能已成为实现能源可持续发展的重点。太阳能聚光技术能将太阳光汇聚到面积很小的高性能聚光太阳能电池上，提高太阳光辐照能量密度，提高效率；同时，廉价的聚光系统和小面积的太阳能电池可以大幅度地降低系统的成本及稀缺昂贵的太阳能电池材料。高聚光的太阳能电池散热问题是影响光伏电池性能和系统可靠性的重要因素。本文针对高倍数聚光光伏系统中高热流密度光伏电池的散热问题，确保光伏电池工作在正常的温度范围内的安全性等难题，设计了特殊的热管散热器并进行了相关的实验研究。主要开展的研究工作如下：1.本文基于太阳能聚光系统和太阳能聚光电池特性，分析世界典型城市太阳能聚光系统的能量传递特性。本文对上海、拉萨、西安、柏林、悉尼和纽约6个典型城市的太阳高度角、太阳方位角、太阳直射辐射强度等太阳参数进行了详细的理论计算，并根据相关单晶硅和三结砷化镓光伏组件的性能参数，对上述6个城市的日发电量进行了理论计算，计算结果表明，聚光组件的日发电量是单晶硅组件的1.85倍左右，而拉萨、悉尼和西安是比较适合光伏系统发展的理想地点。计算了温度对聚光光伏组件和单晶硅光伏组件性能的影响，结果表明，聚光光伏组件的温度系数要明显低于单晶硅光伏组件，因此适合于高倍聚光条件下。2.本文设计了与聚光太阳能电池匹配的热管。热管蒸发端与聚光太阳能电池接触，其传热性能和热管蒸发端温度分布对电池性能和热管效率影响显著。建立了热管散热器蒸发端数值模拟计算模型，设置了边界条件、控制方程和物性参数。通过数值计算，模拟分析得到太阳能聚光比、热管倾斜角度和充液量等参数对蒸发端底面温度分布和蒸发端内部蒸发沸腾传热特性。对热管散热端的矩形翅片的传热特性进行了数值模拟，分析了翅片间距和翅片长度对翅片换热的影响。数值模拟的结果为热管散热器的设计和安全运行提供了指导。3.搭建了高倍数碟式聚光光伏系统，对设计的热管散热器进行了试验研究。得到不同充液率、不同聚光比时，光伏电池和蒸发端底面温度的实验结果，并与仿真结果进行了对比，其中光伏电池的温度相差在5～9K之间，蒸发端底面的温度相差8～12K之间；根据各种工况下对聚光光伏系统中热管的实验研究结果，得到热管散热器蒸发端平均蒸发沸腾换热系数的参数关联式。4.实验研究了聚光比为75X、100X、125X、150X、175X、200X时聚光光伏系统的特性，当聚光比为200X，平均太阳直射辐照强度为600W/m2、环境平均温度为28.9℃时，得到聚光光伏电池的平均开路电压是2.72V、平均短路电流是0.65A、平均功率密度是2.07W/cm2、平均转换效率是26%、平均电池温度是63.51℃。实验得到光伏电池的功率、转换效率和填充因子随着太阳能电池温度增加而降低特性。5.基于所搭建的碟式高倍聚光光伏发电系统以及光伏电池的单二极管模型等效电路，建立了三结聚光GaInP/GalnAs/Ge叠层光伏电池电学特性的数学模型，深入分析了在聚光比分别为120X、130X、140X和150X下电池的电学特性，并与实验测量值进行了对比。高倍聚光条件下，三结砷化镓光伏电池电学特性的理论计算值与实际测量结果存在着一定的误差，聚光比相同时，开路电压的误差为2.08%，电池效率的误差为12.4%；电池温度相同时，开路电压的误差为2.04%，电池效率的误差为8.4%。本课题得到教育部博士点基金项目“聚光光伏系统中太阳能电池的冷却问题研究（编号200802520006）”和上海市研究生创新基金项目(JWCXSL1021)支持。更多还原

【Abstract】 With the frequent emergency of the coal, oil and other traditional fossil fuels, theenergy shortage had become the bottleneck of the international socio-economicdevelopment. The development of new energy would be more serious. Solar energywhich were rich resources, cleanliness without any pollution, inexhaustible and withoutthe mining and transportation had broad prospects. Its development, utilization andconversion had been become a hotspot for seeking new energy. Using of solar powerwould be an important method of new energy utilization. Concentrator photovoltaicsystems may provide many economic advantages combining with the high efficiencymulti-junction solar cells and cheap optical concentrators, if high concentration ratiowas used in a system. Considerable efforts were directed towards the development ofthe high efficient III-V based single-and multi-junction solar cells that work well underhighly concentrated light. The multi-junction approach to solar cells made possible cellefficiencies far in excess of the best efficiencies achievable, both in principle and inpractice, by conventional single-junction cells. The main idea behind high concentrationwas to achieve cost reductions through saving in semiconductor utilized. As acomparison, flat-plate PV targets cost reductions through thinner PV layers and lowercost of the PV material used itself. The problem of heat dissipation has more and moreinfluence on performance of solar cell and reliability of system in high concentrationphotovoltaic system. Aiming at heat dissipation with high heating flux and ensure solarcells working under normal temperature range in high concentration photovoltaicsystem. The two-phase closed thermosyphon radiator has been designed in this paper.The two-phase closed thermosyphon does not have capillary, and the working fluidtransfers heat though its boiling and condensing, then circumfluent by its own gravity.The structure of the two-phase closed thermosyphon is simple and processabilityconvenient, therefore it is one of the most effective way to solve heating dissipationwith high heating flux.1. Based on the concentration photovoltaic system and the characteristics of solarcells, the energy transfer characteristics in the concentration photovoltaic system oftypical cities in the world have been analyzed. In this paper, sun parameters, such assolar elevation angle, solar azimuth, direct solar radiation intensity, of six typical citieswhich are Shanghai, Lhasa, Xi’an, Berlin, Sydney and New York have been calculatedin detailed. According to the performance parameters of single crystal silicon and triple junction gallium arsenide photovoltaic modules, a detailed theoretical calculation for thedaily generating capacity of these six cities are carried out. The results show that thedaily generating capacity of the concentration photovoltaic modules is about1.85timesthan that of the single crystal silicon. Lhasa, Sydney and Xi’an are more suitable as theideal location for the development of the photovoltaic modules. The impact of thetemperature on the performance of concentration PV modules and single crystal siliconPV modules is considered and it shows that the temperature coefficient of theconcentration PV modules is lower than that of the single crystal silicon PV modulessignificantly. Therefore, it is appropriate for high concentration conditions.2. A heat pipe matching the concentration photovoltaic system is designed in thispaper. The solar cell contacts with evaporator of heat pipe, the temperature distributionof evaporator effect on solar cell performance and heat pipe efficiency significantly. Thenumerical simulation model of evaporator of heat pipe radiator is established. Theboundary condition, the energy equations and the physical parameters are set. Thetemperature distribution of heat pipe bottom surface and boiling heat transfer inside theevaporator which influence by the design parameters such as concentration ratio,inclination angle and charge of working fluid has been analyzed. The numericalsimulation is adopted to study heat transfer performance of the rectangular finned. Theimpact of the side length and pitch of fin upon heat dissipating capacity have beenanalyzed as well. The results of numerical simulation provide directions for the designand safe operation of the heat pipe radiator.3. The test of heat pipe radiator is made by putting up high concentrationphotovoltaic system. By the contrast with numerical results and experimental resultswhich are under different working fluid rate and concentration ratio, it can conclude thatthe temperature difference between solar cell and heat pipe bottom surface are about5～9K and8～12K respectively. According to the experimental results of the heat piperadiator which based on the field test, the parameters correlation formula of averageboiling heat transfer coefficient in evaporator have been obtained.4. The experiment researches the characteristics of concentration photovoltaicsystems at the concentration ratio of75X、100X、125X、150X、175X、200X. Atthe concentration ratio of200X, the average direct solar radiation intensity and theaverage temperature are600W/m2and28.9℃respectively, the average open circuitvoltage of concentration solar cell is2.72V, the average open circuit voltage of concentration solar cell is2.72V, the average short circuit current of concentration solarcell is0.65A, the average power density of concentration solar cell is2.07W/cm2, theaverage efficiency of concentration solar cell is26%, the average temperature ofconcentration solar cell is63.51℃. The power、 efficiency and fill factor ofconcentration solar cell decreases as the temperature increases.5. The mathematical model of electrical characteristic for triple-junction solar cellwhich had excellent performance both in efficiency and temperature characteristic wasestablished based on the one-diode equivalent circuit cell model. Detailed analysis onthe influence factors of output electrical characteristic of open-circuit voltage and cellefficiency for triple-junction solar cell under high concentration (120X、130X、140Xand150X) had been done, and the calculated results was compared with experimentaldate. The results show that under high concentrated light intensity, the open-circuitvoltage and cell efficiency of the triple-junction solar cell were increasing as theconcentration ratio increased. What opposite with it was the open circuit voltage andcell efficiency were decreased as the temperature of the solar cell increased. The errorsof open circuit voltage and cell efficiency between the experimental results andcalculated values were2.04%and8.4%respectively.The research is support by the Ministry of Education Doctoral DisciplineFoundation (No.200802520006) and The Innovation Fund Project For Graduate Studentof Shanghai(JWCXSL1021).更多还原