石墨烯纳米流体在PV/T系统中的分频性能分析

文章对质量浓度分别为0.02‰,0.05‰,0.1‰的水基石墨烯纳米流体的分频特性进行了研究。采用双光程法测试了光谱透过率,可理论分析石墨烯纳米流体的分频性能。在90 min模拟光照的条件下,分析不同浓度石墨烯纳米流体和水作为分频液时分频型PV/T系统集热效率、电效率和综合效率的变化情况。结果表明：0.02‰石墨烯纳米流体的光谱透过率最高,在400～900 nm的单晶硅电池较佳响应波段,其透过率为66.8%;将取热温度设定为40℃,0.1‰纳米流体达到40℃时,热效率最高达39.7%;水作为PV/T系统分频液时,PV电池输出效率最高为10.9%;同时,利用性能评价函数MF(The Merit Function)来评估分频液对PV/T系统综合性能的影响,当达到取热温度40℃时,0.1‰石墨烯分频液瞬时MF值最高达1.85。     

以钨青铜纳米流体为工质的PV/T系统性能研究

纳米流体对太阳辐射光谱的选择性吸收特性与太阳能光电光热综合利用具有很好的结合性。设计并搭建了具有光谱分频的直吸式平板型PV/T系统,采用水基钨青铜纳米流体搭配硅太阳能电池以实现对太阳辐射的分波段利用。结果表明,光谱分频PV/T系统比传统PV/T系统的热效率和工质出口温度分别提高5.2%和0.53℃;其中,太阳电池温度降低了3.24℃,电效率下降1.9%,综合效率提高3.3%。     

不同结构PV/T系统的热电性能研究

设计并搭建了两种不同集热结构的PV/T系统,试验采集了环境、温度、功率等参数,获得了两个系统的温度特性、热效率、发电效率。试验结果表明,PV/T系统效率主要受环境因素影响,集热结构对其性能也产生不同程度的影响。无空腔PV/T系统的冷却效果好于有空腔系统,发电效率较高;有空腔PV/T系统的热效率较高,一次能源节约率略高于无空腔系统。     

基于水基SiO_2纳米流体PV/T系统辐射性能研究

为研究辐射在水基SiO_2纳米流体PV/T系统的传递特性,用两步法制备不同的水基SiO_2纳米流体。利用分光分度仪测试不同工质在不同光程和体积分数下的透射率,结合Mie和Rayleigh散射理论建立系统的辐射传递模型,同时对该系统进行了实验测试。结果表明:水基SiO_2纳米流体对光电可用辐射有高透过性,对低频辐射有高吸收性,与Si-PV光伏响应曲线基本匹配;当流体体积分数小于0.5%时,透射率实验值与理论值吻合度好;当光程大于10 mm时,90%的低频辐射被工质吸收,低于80%的光电可利用辐射传递到Si-PV表面;以水基SiO_2纳米流体作为PV/T辐射分频工质,可有效降低Si-PV的温升速率,且其光热总效率可达75%以上。     

有、无玻璃盖板工况对PV/T系统性能的影响

同时参考热力学第二定律和第一定律,以(炯)效率和能量效率作为判据,在一些结构参数和环境参数变化的条件下,对有、无玻璃盖板工况下PV/T系统的综合性能进行了对比分析,并尝试对玻璃盖板在PV/T系统中的应用给出一些建议.     

热管式太阳能PV/T热泵系统的性能研究

文章搭建了热管式太阳能PV/T热泵系统的实验装置,并根据实验装置建立了系统的数学模型,通过实验测试对数学模型进行了验证。研究了系统的热效率、电效率和COP等主要性能参数在全天的变化规律,分析了系统COP偏低的原因和改进措施。结果表明,在测试工况下,日平均热效率为35.4%,日平均电效率为11.0%,日平均COP为2.77,实验值与模拟值的误差均在±15%以内。该研究为热管式太阳能PV/T热泵系统的设计优化与性能研究提供了参考。     

无盖板型水冷式PV/T模块光电/光热综合性能实验研究

无盖板PV/T组件相比于盖板式PV/T组件有更高的光电转换效率,在电能输出方面的优势明显。基于此,提出一种无盖板型水冷式PV/T模块,并搭建由光伏对比模块、水冷式PV/T模块以及无冷却水循环的PV/T对比模块构成的实验平台开展对比实验,研究温度、流量对无盖板PV/T模块电、热转换效率的影响。结果表明,在水冷作用下,PV/T模块的光伏组件温度显著降低,与PV/T对比模块相比发电效率提升11.54%;环境平均温度为21.7 ℃、平均辐照度650 W/m²的测试条件下,流量0.12 m³/h时模块的电效率为17.44%,热效率为19.80%,综合效率达到65.69%,考虑到循环泵消耗的电能,表面积1.93 m²的水冷式PV/T模块全天可存储有效能3.72 MJ。     

太阳能PV/T系统电热输出性能及其Matlab仿真研究

建立了太阳能PV/T(Photovoltaic/Thermal)系统的热电模型,编制了Matlab程序,采用迭代法对电热参数进行耦合求解。研究了PV/T系统在呼和浩特不同季节下的热电效率,电池温度和性能曲线的变化,通过与实验数据对比,验证了该模型具有较高的精度。实验结果显示了环境温度、风速、入射辐射量对太阳能PV/T系统热、电以及综合性能的影响:PV/T系统夏季的日平均电效率、热效率及正午组件最大功率分别为14.1%、34.5%和180.8 W,冬季的日平均电效率、热效率及正午组件最大功率分别为16.1%、24.8%和190.3 W。     

新型平板热管式太阳能PV/T集热系统的性能研究

文章搭建了新型平板热管式太阳能PV/T集热系统实验台,测试了该集热系统的热电性能。此外,建立了该集热系统的数学模型,并将该集热系统的测量结果和模拟结果进行对比分析,以验证该数学模型的准确性。最后,在相近的测试条件下,对新型平板热管式太阳能PV/T集热系统和传统圆形热管式太阳能PV/T集热系统的热电性能进行对比分析。分析结果表明,在相近的测试条件下,与传统圆形热管式太阳能PV/T集热系统相比,新型平板热管式太阳能PV/T集热系统的日平均热效率和日平均电效率分别提升了16.8%和3.5%,总集热量和总发电量分别提升了78.4%和35.5%。     

双玻光伏组件PV/T集热器特性及实验研究

利用双玻光伏组件设计了一种新的PV/T(photovoltaic/thermal)太阳能集热器,并对其热转换和传输特性进行研究.制备了透光率分别为50％和10％的2种双玻光伏组件PV/T空气集热系统样机,并对其特性进行实验研究.结果表明透光率50％的PV/T太阳能集热器,其吸热板温度高于双玻光伏组件温度,透光率10％P...     

System performance studies on a photovoltaic/thermal (PV/T) air heating collector

A computer simulation model is presented for the analysis of a solar photovoltaic/thermal (PV/T) hybrid collector with air as heat transfer fluid and algorithm for making quantitative prediction regarding the performance of the system is described. Thermal efficiency curves for the solar PV/T hybrid collectors corresponding to various type of absorbers have been derived. In order to appreciate the model, numerical calculations have been made for evaluating the system performance corresponding to typical climate of Delhi, India     

Advancement in solar photovoltaic/thermal (PV/T) hybrid collector technology

This article presents an overview on the research and development and application aspects for the hybrid photovoltaic/thermal (PV/T) collector systems. A major research and development work on the photovoltaic/thermal (PVT) hybrid technology has been done since last 30 years. Different types of solar thermal collector and new materials for PV cells have been developed for efficient solar energy utilization. The solar energy conversion into electricity and heat with a single device (called hybrid photovoltaic thermal (PV/T) collector) is a good advancement for future energy demand. This review presents the trend of research and development of technological advancement in photovoltaic thermal (PV/T) solar collectors and its useful applications like as solar heating, water desalination, solar greenhouse, solar still, photovoltaic-thermal solar heat pump/air-conditioning system, building integrated photovoltaic/thermal (BIPVT) and solar power co-generation.     

Analysis of PV/T flat plate water collectors connected in series

Photovoltaic-thermal (PV/T) technology refers to the integration of a PV and a conventional solar thermal collector in a single piece of equipment. In this paper we evaluate the performance of partially covered flat plate water collectors connected in series using theoretical modeling. PV is used to run the DC motor, which circulates the water in a forced mode. Analytical expressions for N collectors connected in series are derived by using basic energy balance equations and computer based thermal models. This paper shows the detailed analysis of thermal energy, exergy and electrical energy yield by varying the number of collectors by considering four weather conditions (a, b, c and d type) for five different cities (New Delhi, Bangalore, Mumbai, Srinagar, and Jodhpur) of India. Annual thermal and electrical energy yield is also evaluated for four different series and parallel combination of collectors for comparison purpose considering New Delhi conditions. This paper also gives the total carbon credit earned by the hybrid PV/T water heater investigated as per norms of Kyoto Protocol for New Delhi climatic conditions. Cost analysis has also been carried out.It is observed that the collectors partially covered by PV module combines the production of hot water and electricity generation and it is beneficial for the users whose primary requirement is hot water production and collectors fully covered by PV is beneficial for the users whose primary requirement is electricity generation. We have also found that if this type of system is installed only in 10% of the total residential houses in Delhi then the total carbon credit earned by PV/T water heaters in terms of thermal energy is USD $144.5 millions per annum and in terms of exergy is USD $14.3 millions per annum, respectively.     

分配联箱气液两相流流型对垂直并联管分配特性的影响

对垂直Ｕ型单联管系统低质量流量的流量分配特性进行了理论和实验研究,获得气叮和气液两质量流量分配特性,以及各分支管的流型记录,分析了分配联箱中流型对流量分配以及各分支管中流的型的影响。