聚焦光伏系统余热发电的研究

发布时间：2018-12-31 08:20

【摘要】：聚焦光伏系统余热发电的研究,以导热油为介质对聚光工作下的砷化镓电池进行冷却,导热油带走的余热利用于有机朗肯循环(ORC)进行再发电。 进行系统元器件的选择与设计,并对系统热力性能做了分析。由于冷却介质选择的是导热油,故需对ORC循环工质进行匹配选择。充分考虑各种因素,选取臭氧耗损潜值(ODP)为0的四种工质：R600、R134a、R236fa、R245fa作为候选工质。对工质应用于ORC的热力性能做了对比分析。从热力学第一定律分析,随着蒸发温度的升高,工质的蒸发压力、输出净功、热效率以及膨胀比都是升高的；从热力学第二定律分析,热力完善度((?)效率)是先升高后下降,存在一个最大值,此时系统的总不可逆损失最小。综合考虑,得出R245fa具有较好的环保性和安全性,以及较高的热效率和热力完善度；适用于低温余热有机朗肯循环发电系统。 太阳能砷化镓电池与导热油的光热转换实验,聚光下的砷化镓电池采用导热油冷却与水冷和风冷同时进行实验。结果表明：三种冷却方式中,导热油冷却与水冷和风冷相比,砷化镓电池的平均温度分别降低了5.75℃和40.04℃；平均输出功率高出0.69W和4.81W；平均转换效率提高了1.83%和11.96%。 为了平衡ORC与聚光砷化镓电池对蒸发温度的不同要求,需要对ORC的蒸发温度进行优化。首先使用层次分析法将蒸发温度的优化分为目标层、准则层、指标层三个层次。准则层分别为系统能效准则、热经济性准则、系统输出能量准则。指标层分别为总能效率、当量(?)效率、APR(面积功率比)、VPR(体积功率比)、系统净输出功率。使用不同的指标去优化蒸发温度得出的结论不一致。因此,进一步使用层次分析法.熵值法对蒸发温度进行综合评价。通过综合评价,最后得出目标层,蒸发温度在76℃时,ORC的综合评价值最高。对整个系统来说,蒸发温度从85℃降到76℃,ORC热效率降低了2.76%,而聚光砷化镓电池转换效率提高了3.58%；整体效率提高了0.82%。ORC输出功率降低了17.7W,而聚光砷化镓电池输出功率升高了36W；整体输出功率提高了18.3W。 搭建系统实验平台,用电加热作为模拟热源,使用R22为工质,设定集热箱中热水温度为80℃,进行初步实验并作简要分析。 本文研究得到广西自然科学基金项目(NO.2011GXNSFA018029)、国家自然科学基金项目(NO.51266001)的支持。
[Abstract]:Focusing on the research of photovoltaic system waste heat generation, the heat conduction oil is used as the medium to cool the gallium arsenide cells working under concentrated light. The waste heat taken away by the heat conduction oil is used in organic Rankine cycle (ORC) to generate electricity again. The system components are selected and designed, and the thermodynamic performance of the system is analyzed. Because the cooling medium is heat conducting oil, it is necessary to match the working fluid of ORC cycle. Taking all kinds of factors into account, four kinds of working medium with ozone depletion potential value (ODP) of 0: R600 R134a1 / R236fa-R245fa were selected as candidate working medium. The thermodynamic performance of the working fluid applied to ORC is compared and analyzed. According to the first law of thermodynamics, the evaporation pressure, the output net work, the thermal efficiency and the expansion ratio of the working fluid are all increased with the rise of the evaporation temperature, and the thermal consummation degree (?) from the second law of thermodynamics. The efficiency) is that the total irreversible loss of the system is the minimum when the total irreversible loss of the system increases first and then decreases, and there is a maximum value. It is concluded that R245fa has good environmental protection, safety, high thermal efficiency and thermal consummation, and is suitable for low temperature waste heat organic Rankine cycle power generation system. The photothermal conversion experiment between solar GaAs battery and heat conduction oil was carried out. The thermal conductivity oil cooling and air cooling were used in the GaAs battery under concentrated light. The experiment was carried out at the same time as water cooling and air cooling. The results show that the average temperature of GaAs cells is reduced by 5.75 鈩，

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