连接方式和流量对太阳能光伏光热系统性能影响的数值分析

发布时间：2018-06-01 19:51

本文选题：光伏光热 + 连接方式　；参考：《西南交通大学》2017年硕士论文

【摘要】：太阳能光伏光热(PVT)热水系统是将传统的太阳能热水系统与PVT集热器相结合,该技术可以同时满足用户用电和生活热水两种需求,有效提高了太阳能的综合利用效率。集热器连接方式和流量对强制循环式PVT热水系统的运行性能影响较大,然而有关最佳连接方式的研究还未见报道,关于流量的研究较多但都只针对某一种连接方式的系统为研究对象。本文选择不同工况、不同城市,研究了连接方式和流量对系统性能的影响,研究结果对不同辐射区的大型太阳能集热器安装方式的选取具有参考价值。根据能量守恒定律,综合考虑环境温度、太阳辐射量和当地热水负荷等因素,建立了不同连接方式太阳能PVT热水系统动态传热模型,利用FORTRAN语言进行编程,并对该数学模型进行了实验验证,对比模拟结果和实验数据确定了该数学模型的准确性。建立的PVT热水系统由12块平板型PVT集热器(2m ×1 m)组成,共5种连接方式,集热器串联数量分别为N=1、2、3、4、6。首先,分别以发电量、实际集热量以及实际综合能量为优化目标进行了计算,不同连接方式系统采用相同的单位面积质量流量,0.02 kg·m~(-2)·s~(-1)。以腾冲为例的计算结果表明:在两种不同工况下,获得最大日发电量的连接方式都为N=1,而获得最大日实际集热量的连接方式并不一致;以年发电量、年实际集热量和年实际综合能量为优化目标时对应的最佳连接方式分别为:N=1、N=4和N=2。然后,分别在我国太阳资源较富区和资源一般区各选择了5个城市。计算结果表明,以全年实际综合能量为优化指标,太阳资源较富区,建议全年采用选择#=2 一种连接方式;太阳资源一般区,建议选择N=3的连接方式,其中对于汕头,全年气温较高热水负荷较小,与N=3相比,N=2的年实际综合能量增加了 40MJ;最后,研究了 5种连接方式下,单位面积质量流量在0.01～0.04kg·m~(-2)·s~(-1)范围内变化对系统性能的影响。以腾冲为例,结果表明:当N=1,流量超过0.025 kg·m~(-2)·s~(-1)后,系统发电量呈下降趋势,其它连接方式的系统发电量随流量的增加而增加;当N=1,流量超过0.02kg·m~(-2)·s~(-1)后,系统实际集热量呈下降趋势,当N=2,系统实际集热量一直持续缓慢增长的趋势,当N=3、4、6,流量超过0.025 kg·m~(-2)·s~(-1)后,系统实际集热量呈波动性增长,且当日辐射不足时波动性更明显;以全年实际综合能量为优化指标,最佳连接方式为N=2,对应的最佳流量为0.035 kg·m~(-2)·s~(-1),大于工程建议的0.01～0.02 kg·m~(-2)·s~(-1)流量范围。
[Abstract]:Solar photovoltaic (PV) hot water system is a combination of traditional solar water heating system and PVT collector. This technology can meet the needs of both consumer electricity and domestic hot water and effectively improve the comprehensive utilization efficiency of solar energy. The connection mode and flow rate of collector have great influence on the operation performance of forced circulation PVT hot water system. However, the research on the optimal connection mode has not been reported yet. There are many researches on traffic flow, but they are only for systems with one connection mode. In this paper, the effects of connection mode and flow rate on the system performance are studied in different working conditions and cities. The results are valuable for the selection of installation modes of large solar collectors in different radiation areas. According to the law of conservation of energy, considering the factors of environment temperature, solar radiation and local hot water load, the dynamic heat transfer model of solar PVT hot water system with different connection mode is established, and the dynamic heat transfer model is programmed by FORTRAN language. The accuracy of the mathematical model is confirmed by comparing the simulation results with the experimental data. The PVT hot water system is composed of 12 flat PVT collectors with 2 m 脳 1 m. There are 5 kinds of connection modes. First of all, the power generation, the actual heat collection and the actual comprehensive energy are taken as the optimization objectives respectively. The same mass flow rate of 0.02 kg per unit area is adopted in the different connection mode systems (0.02 kg / m ~ (-2) / s ~ (-1) ~ (-1) / m ~ (-1) / m ~ (-1). Taking Tengchong as an example, the results show that, under two different working conditions, the connection mode of obtaining the maximum daily generating capacity is Nu 1, but the connection mode of obtaining the maximum daily heat collection is not the same, and the annual power generation is not the same. When the annual actual heat collection and the annual actual integrated energy are the optimization objectives, the optimal connection modes are: 1 / N1 / NX / N4 and 2 / 2, respectively. Then, five cities were selected in the rich solar resources and the general resources areas in China. The calculation results show that, taking the actual comprehensive energy as the optimization index, the solar resources are relatively rich, so it is suggested to choose one kind of connection mode for the whole year, and for the general area of solar resources, to choose the connection mode of NX3, among which, for Shantou, The annual actual comprehensive energy of Nnu 2 is increased by 40 MJ compared with that of N3. Finally, the influence of the mass flow rate of unit area in the range of 0.01~0.04kg MJ / 2) sb-1) on the system performance is studied under the five connection modes, and the results are as follows: (1) in this paper, the actual energy is increased by 40 MJ in comparison with that of N3. Finally, the influence of the mass flow rate per unit area on the system performance is studied. Taking Tengchong as an example, the results show that the power generation of the system decreases with the increase of flow rate when the flow rate is more than 0.025 kg / m ~ (-1) and increases with the increase of flow rate in other connection modes, and the actual heat capacity of the system decreases when the flow rate exceeds 0.02kg / MU ~ (-2) sn ~ (-1). When NX2, the actual heat collection of the system has been increasing slowly. When the flow rate is more than 0.025 kg / m ~ (-1), the actual heat collection of the system is fluctuating, and the fluctuation is more obvious when the radiation is insufficient, and the overall energy is taken as the optimization index, and the actual total energy of the whole year is taken as the optimization index. The optimum connection mode is Nu 2, the corresponding optimal flow rate is 0.035 kg / m ~ (2) / s ~ (-1) / s ~ (1), which is larger than the suggested flow range of 0.01g / m ~ (2) m ~ (-1) / m ~ (2) / m ~ (-1) / m ~ (-1).
【学位授予单位】：西南交通大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TU822

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