【作者】 谢飞；

【导师】 张国贤； 金健；

【作者基本信息】 上海大学 ， 机械电子工程， 2013， 博士

【摘要】 太阳能是新能源领域中研究的重点，为了高效利用太阳能，近年来对太阳能电热综合利用（PV/T）进行了大量的研究。但目前对PV/T的研究都是从整体效率出发，论证PV/T的可行性。在PV/T研究过程中的一些关键的问题由于涉及到多个学科，往往被忽略，本文针对这几个关键问题进行了深入的研究。PV/T系统聚光多是采用中低倍聚光，由于聚光形式各异，其光学效率各不相同，因此很难对比不同聚光方式之间的区别，评价各自聚光方式的优劣。聚光的PV/T系统都采用对日追踪，追踪误差对效率有着明显的影响。本文通过分析比较追踪角度误差对这几种聚光系统的影响，得出接收器为管式的槽式抛物面反射聚光系统对追踪精度的要求最低，菲涅尔反射聚光在追踪误差小于±3°时与其相当，追踪误差对效率的影响小于15%，总的能量损失小于33%，透镜折射和平板接收器的槽式抛物面反射聚光对追踪误差较为敏感。综合比较不同的聚光方式和接收器光强分布特点，提出对PV/T系统而言菲涅尔反射聚光最为合适。聚光的太阳能系统都用到太阳追踪，从方式上分成主动追踪和被动跟踪，主动追踪精度相对较高，被动跟踪精度相对较低。追踪关键是追踪算法，如何实现高精度追踪和采用什么样的追踪算法，对追踪精度有何要求，目前对此研究相对较少。追踪系统缺乏了这些理论支持，PV/T系统只能作为一种实验装置，难以实际应用。本文对主动追踪的算法进行分析，用空间坐标系变换的方法推导了高度角、方位角关于儒略日时间的表达式，同时对赤经因素对太阳位置的影响进行分析。通过与现有公式进行比较，证明了推导的正确性，为主动追踪控制提供了重要的理论依据。通过数据计算对比，在考虑赤经因素影响下，高度角的最大误差小于0.5°，方位角的最大误差小于0.8°，提高了追踪算法的计算精度。温度对PV/T系统的电-热利用有着明显的影响，冷却和热交换系统至关重要。传统的研究实验只关注进出口温度和流速，对流道的布置、形式和导热工质并没有进行研究。实际上真正对PV/T系统综合效率影响最大的是流道的布置和流道的形式。太阳能电池串联时温度分布越均匀，电池散热越好，PV/T综合效率才越高。本文对电池的冷却、热交换系统进行了相应的分析设计，通过流道的布置使接收器温度分布均匀；通过流道形式的正交试验，得出流道间隙和波纹夹角对波纹流道的热交换效果影响最大，据此优化流道结构。同时制备了一类γ-Al₂O₃的纳米流体，对其热物性进行测试，得出了热交换的相关参数，为后续的仿真分析提供了依据。通过对PV/T系统在Trnsys软件中进行运行分析，得知在无冷却条件下聚光倍数过高，会造成太阳能电池的表面温过高，继而影响电池效率。当太阳能电池在有冷却条件下工作时，冷却系统应使太阳能电池的温度控制在80¹00℃之间，以达到较为理想的电能、热能输出。研究表明，采用主动追踪的菲涅尔反射聚光的PV/T系统，可以节省电池芯片的使用，提高太阳能的综合利用率。通过对全年的运行效果分析可以看出，对于太阳能电池的聚光应用，在有冷却系统时发电效率基本不受影响，但聚光可以很大程度上节省电池芯片的使用，使单位面积发电量大大提高，同时还可以将一部分热能利用，使太阳能的综合利用率到达43.4%。更多还原

【Abstract】 Solar energy has the potential to play an important role in renewable energy. Inrecent year many research has been done in photovaltic and themal （PV/T） toimprove usage efficience. At present most reseach are about total efficiency and thefeasibility of PV/T. Several key issues always ignored because of they are belong todifferent subject. This thesis discusses these issues and do further investigation.PV/T system always adopt low-concentration, different concentration type leadto different optical efficiency. So it’s difficult to find out which method is best. Allconcentrating PV/T system has sun tracking equipment. The tracking accurateinfluences the efficiency. In this thesis the author analysis and compare the influencewith different type concentration in tracking error. Get a conclusion that theparabolic trough reflecter with tube receiver has minimum influence by the trackingerror. Fresnel reflecter has the same influence when the tracking error less than±3°.The tracking error impact on the efficiency of less than15%, and the total energyloss is less than33%. Lens refracter and surface receiver are more sensitive to thetracking error. In a word, the Fresnel reflection system is suitable for PV/T system.Concentrating solar systems always has equipment tracking the sun. It can bedivided into active tracking and passive following. Active tracking is more accuratethan passive following. At present less scholar focus on tracking algorithm and howto realize.Without these theories support the tracking system for PV/T is just testequipment and hard for practical application. In this paper analysis the trackingalgorithm, and use space coordinate system transformation derived the expressionfor altitude angle and azimuth angle with Julian time of day. At the same timeconsidered the affect with right ascension to the solar position. Compared with theexisting formula proved the derivation is correct, and provides an important theoryfor solar position algorithm. From experiment and analysis the maximum error whenconsider the right ascension factors is less than0.5°, azimuth error is less than0.8°,improve the calculation accuracy.Temperature is a significant effect for PV/T system, so cooling and heatexchange systems are very inportant. Traditional researches only concerned with theinlet and outlet temperature and flow rate, never considered about the channel layoutand thermal conductivity. In fact, the channel layout and form always decide thePV/T system efficiency. Because in series PV the temperature distribution the moreuniform the better for PV/T efficiency. In this paper analysis the PV cooling and theheat exchange. Through the flow channel arrangement uniformed the PVtemperature distribution. Through the orthogonal test derived that the channel gapand the corrugated angle is the most obvious effect on heat exchange in corrugatedchannel. During these conclusions optimized the channel structure. Made a kind ofγ-Al₂O₃nano-fluid, test the thermal properties, get the character in heat exchange, and provide original data for later simulation analysis.From PV/T system running in analysis software Trnsys, get a result that the highconcentration without colling system will cause the PV cell temperature raise anddamage itself. But when cooling system work and controlled solar cell temperaturebetween80¹00℃, will achieve ideal electrical and thermal energy output.Research shown that Fresnel reflection concentrator with active tracking PV/Tsystem can save PV cell use, and improve the solar energy utilization. Through thefull year analysis indicate that concentration PV/T system with colling system workin good condition and save PV cell use. The total solar energy utilization efficiencyreaches43.4%.更多还原