Comparative thermal performance evaluation of an active solar distillation system

In this paper, thermal models of all types of solar collector‐integrated active solar stills are developed based on basic energy balance equations in terms of inner and outer glass temperatures. In this paper, hourly yield, hourly exergy efficiency, and hourly overall thermal efficiency of active solar stills are evaluated for 0.05 m water depth. All numerical computations had been performed for a typical day in the month of 07 December 2005 for the climatic conditions of New Delhi (28°35′N, 77°12′E, 216 m above MSL). The thermal model of flat‐plate collector integrated with active solar still was validated using the experimental test set‐up results. Total daily yield from active solar still integrated with evacuated tube collector with heat pipe is 4.24 kg m^?2 day^?1, maximum among all other types of active solar stills. Copyright © 2007 John Wiley & Sons, Ltd.     

Simulation and experimental investigation of two hybrid solar domestic water heaters with drain water heat recovery

In this paper, the performance of two solar domestic hot waters (SDHW) with drain water heat recovery (DWHR) units is investigated. Both SDHW systems are recently installed at the Archetype Sustainable Twin Houses at Kortright Center, Vaughan, Ontario. The first SDWH system in House A consists of a flat plate solar thermal collector in combination with a gas boiler and a DWHR unit. The second SDHW system in House B includes an evacuated tube solar collector, an electric tank, and a DWHR unit. Both systems are modeled in TRNSYS, and the models are validated by experimental data. The addition of the DWHR and the flat‐plate solar thermal collector would result in 1831 kWh of annual energy saving in House A. While the addition of the DWHR and the evacuated tube collector in House B would result in an annual energy saving of 1771 kWh. Subsequently, the models are used to investigate the performance of similar systems for five major Canadian cities of Halifax, Montreal, Toronto, Edmonton, and Vancouver. The conjunctions of solar thermal collectors with DWHR units are found most beneficial in Edmonton. It is also noted from experimental and simulated results that flat‐plate solar collector‐based water heater produced more thermal energy than the system based on the evacuated tube solar collector for all major Canadian cities. Copyright © 2015 John Wiley & Sons, Ltd.     

Thermal modeling of a combined system of photovoltaic thermal (PV/T) solar water heater

In this paper, an integrated combined system of a photovoltaic (glass–glass) thermal (PV/T) solar water heater of capacity 200 l has been designed and tested in outdoor condition for composite climate of New Delhi. An analytical expression for characteristic equation for photovoltaic thermal (PV/T) flat plate collector has been derived for different condition as a function of design and climatic parameters. The testing of collector and system were carried out during February–April, 2007. It is observed that the photovoltaic thermal (PV/T) flat plate collector partially covered with PV module gives better thermal and average cell efficiency which is in accordance with the results reported by earlier researchers.     

Perspectives for solar thermal applications in Taiwan

Taiwan has long depended on imported fossil energy. The government is thus actively promoting the use of renewable energy. Since 2000, domestic installations of solar water heaters have increased substantially because of the long-term subsidies provided for such systems. However, data on the annual installation area of solar collectors in recent years indicated that the solar thermal industry in Taiwan has reached a bottleneck. The long-term policy providing subsidies must thus be revised. It is proposed that future thermal applications in Taiwan should focus on building-integrated solar thermal, photovoltaic/thermal, and industrial heating processes. Regarding building-integrated solar thermal systems, the current subsidy model can be continued (according to area of solar collectors); nevertheless, the application of photovoltaic/thermal and industrial heating systems must be determined according to the thermal output of such systems.     

Photovoltaic/thermal solar hybrid system with bifacial PV module and transparent plane collector

Electric energy production with photovoltaic (PV)/thermal solar hybrid systems can be enhanced with the employment of a bifacial PV module. Experimental model of a PV/thermal hybrid system with such a module was constructed and studied. To make use of both active surfaces of the bifacial PV module, we designed and made an original water-heating planar collector and a set of reflecting planes. The heat collector was transparent in the visible and near-infrared spectral regions, which makes it compatible with the PV module made of crystalline Si. The estimated overall solar energy utilization efficiency for the system related to the direct radiation flux is of the order of 60%, with an electric efficiency of 16.4%.     

Numerical and experimental analysis of the flat plate solar water heater systems' thermal performance

In this paper, improving the thermal performance of flat plate solar water heater systems by inserting different tube configurations inside the riser pipes has been numerically and experimentally studied. This study is focused on increasing the moving of energy from riser pipes to the operating fluid within the riser pipes. To achieve that, the diameter of the riser pipes was increased along with the insertion of different tube configurations within them, namely, smooth, helical, and wavy tubes, keeping the same amount of the operating liquid. A comparison was performed to determine the best in terms of coefficient of heat transfer of the operating liquid, mass flow rate of the operating liquid, pressure drop, and water temperature in the storage tank, as a thermal performance indication of the system under study. The findings show the model consisting of a straight tube inside the riser pipe provides the best thermal performance. In terms of thermal performance, the straight model outperforms the conventional model by 12.3%. An experimental and numerical comparison between the optimum model (straight model) was conducted. The study proves that the average difference between numerical results and experimental findings is 7.2%.     

复合式太阳能空调/热水综合系统研究

将常规压缩制冷技术与太阳能热水器技术、除湿冷却技术相结合 ,提出了一个复合式太阳能空调 热水系统方案 ,并进行了可行性分析。该系统不仅可以进行冷凝热回收 ,节能效果明显 ,而且对高热、高湿地区以及气候变化有很强的适应性     

蜂窝热管平板式太阳能热水器的实验研究

把蜂窝技术和热管技术结合起来应用于平板式太阳能热水器，可以大大减少热损失，提高日平均效率。经多次实验证明，蜂窝热管平板式太阳能热水器的日平均效率可以比真空管式热水器的高，热损系数则要小很多，具有推广应用价值。     

Detailed comparison of the performance of flat-plate and vacuum tube solar collectors for domestic hot water heating

The performance of a DHW system fitted with flat-plate and vacuum collectors has been analysed. Simulations were carried out on the basis of equal aperture or gross areas of basis using TMY data for hour-by-hour dynamic simulation generated for 1036 sites located in different regions of the world. The performance indicators of solar fractions and number of days were determined for specific water mean temperatures in the storage tank of 37 °C, 45 °C and 55 °C. It has been shown that vacuum tube collectors provide slightly better DHW performance indicators than typical flat-plate collectors having the same aperture area. However, since the space that needs to be provided and directly or indirectly paid for is what matters to the user of solar heating systems, the analysis was also carried out on equal gross area basis; on this basis, the advantages of using vacuum collectors are not obvious.     

Exergetic optimization of a solar photovoltaic thermal (PV/T) air collector

In this paper, an exergetic optimization has been developed to determine the optimal performance and design parameters of a solar photovoltaic thermal (PV/T) air collector. A detailed energy and exergy analysis has been carried out to calculate the thermal and electrical parameters, exergy components, and exergy efficiency of a typical PV/T air collector. The thermal and electrical parameters of a PV/T air collector include solar cell temperature, back surface temperature, outlet air temperature, open‐circuit voltage, short‐circuit current, maximum power point voltage, maximum power point current, etc. An improved electrical model has been used to estimate the electrical parameters of a PV/T air collector. Furthermore, a new equation for the exergy efficiency of a PV/T air collector has been derived in terms of design and climatic parameters. A computer simulation program has been also developed to calculate the thermal and electrical parameters of a PV/T air collector. The results of numerical simulation are in good agreement with the experimental measurements noted in the previous literature. Moreover, the simulation results obtained in this paper are more precise than the one given by the previous literature, and the new exergy efficiency obtained in this paper is in good agreement with the one given by the previous literature. Finally, exergetic optimization has been carried out under given climatic, operating, and design parameters. The optimized values of inlet air velocity, duct length, and the maximum exergy efficiency have been found. Parametric studies have been also carried out. Copyright © 2010 John Wiley & Sons, Ltd.     

Thermal modelling of a hybrid photovoltaic thermal water heater in parallel configuration

A hybrid photovoltaic thermal water heater was designed, fabricated and tested for remote locations at the campus of Krishna Institute of Engineering and Technology, Ghaziabad, India. Performance has been experimentally evaluated from May 2010 to April 2011 under field conditions in forced circulation mode (series and parallel). The output water temperature has been obtained as 0.5–2.5°C from parallel configuration higher than the series configuration in the month of October 2010. In order to validate the results, a thermal model has been developed and verified for parallel configuration. The theoretical results are found to be in good agreement with the experimental. Instantaneous exergy efficiency is found to be higher for parallel configuration (3.0–15.0%) than for the series arrangement. The overall instantaneous exergy efficiency is found in the range of 2.2–4.1% for parallel configuration.     

A review on photovoltaic/thermal hybrid solar technology

A significant amount of research and development work on the photovoltaic/thermal (PVT) technology has been done since the 1970s. Many innovative systems and products have been put forward and their quality evaluated by academics and professionals. A range of theoretical models has been introduced and their appropriateness validated by experimental data. Important design parameters are identified. Collaborations have been underway amongst institutions or countries, helping to sort out the suitable products and systems with the best marketing potential. This article gives a review of the trend of development of the technology, in particular the advancements in recent years and the future work required.     

真空玻璃盖板热管平板式太阳能热水器的研制

介绍了研究成功的采用真空玻璃盖板的热管平板式太阳能热水器,测试了其性能,并与全玻璃真空管太阳能热水器和蜂窝热管太阳能热水器进行了比较。实测得到,真空玻璃盖板热管平板式热水器的日平均效率比后两分别大13．3％和6．5％,平均热损系数比后两分别小52．5％和21．5％。真空玻璃盖板平板式太阳能热水器性能优越,有很好的应用前景。     

Plasma treatment of zinc oxide-nanoparticles:polyaniline blend as an active layer for the hybrid bulk heterojunction solar cell applications

In this experimental work, plasma treatment of the active layer in the bulk heterojunction solar cells was studied. The active layers consisting of zinc oxide nanoparticles:polyaniline were spin-coated on indium tin oxide covered glasses then kept in the cold plasma medium for different treatment times. The J-V characteristics were considered under air mass 1.5G standard illumination, and variations of the open-circuit voltages and short circuit currents were studied under different treatment times. The results show that there is an optimum treatment time to improve the properties of the layers. In order to understand the origin of this effect, the Hall coefficient, along with ultraviolet-visible spectra were measured, and for studying the topological impact of plasma on the surface of the layers, atomic force microscopy and Fourier-transform infrared spectroscopy were considered. The measurements confirmed the time dependency of the open-circuit voltages and short circuit currents of the cells on the plasma treatment times. Atomic force microscopy of the layers shows the significant topological effects of the plasma treatments on the surface of the active layers for different treatment times.     

Utility-scale solar photovoltaic hybrid system and performance analysis for eco-friendly electric vehicle charging and sustainable home

Electricity energy has a crucial importance role for social and economic developments all over the world. Nowadays, the worldwide generation of electricity mostly depends on conventional sources. These sources are limited in the environment and also responsible for ecological problems like environmental pollution. Renewable energy sources have important aspects such as feasibility, efficiency, and environment-friendly in comparison to conventional energy resources. In order to overcome environmental problems, this proposed study focuses on solar photovoltaic hybrid system for eco-friendly electric vehicle charging and house based on machine learning system. In order to realize numerical study, Homer Pro and PVSOL software are used. Various parameters of economic feasibility, sizing strategies with logical advancements, and optimization methods are numerically considered and analyzed to compare measurement one.     

空气-水复合平板型太阳能集热器

提出了一种适用于太阳能供热采暖工程的新型太阳能空气-水复合平板集热器。该集热器可以单独使用空气、水或同时以空气和水作为集热工质。测试显示,该集热器空气循环集热效率为55%～65%,水循环集热效率为32%～34%,能够满足太阳能供热采暖工程的要求。该集热器成本不高,适用于在我国北方广大农村地区推广使用。     

太阳能空调综合系统在住宅小区应用的可行性探讨

经济性是制约太阳能空调普及推广应用的难题。文中介绍了一种太阳能空调和热水站综合系统方案,即在居民住宅楼的屋顶布置太阳能集热器阵,结合地源水低温热源系统,建设全年供应全体住户生活热水的太阳能热水站,以及夏季和冬季供应顶一、二层住户空调冷、热水的综合系统．提出了一种双效与单效耦合的板壳式溴化锂吸收式制冷机循环方案,白天日照时段采用双效循环运行并进行蓄热,而在其余时段切换为单效循环利用蓄热运行。该方案不仅效率高、而且其单位体积蓄能罐的蓄能密度极大,可实现无需用辅助能源而完全靠太阳能进行昼夜空调。由于综合利用系统中集热器的投资费用被所有热水用户分摊,空调用户的投资可很快从节省的电费中得到回收。     

Comparative study based on exergy analysis of solar air heater collector using thermal energy storage

This communication presents the comparative experimental study based on energy and exergy analyses of a typical solar air heater collector with and without temporary heat energy storage (THES) material, viz. paraffin wax and hytherm oil. Based on the experimental observations, the first law and the second law efficiencies have been calculated with respect to the available solar radiation for three different arrangements, viz. one arrangement without heat storage material and two arrangements with THES, viz. hytherm oil and paraffin wax, respectively. It is found that both the efficiencies in case of heat storage material/fluid are significantly higher than that of without THES, besides both the efficiencies in case of paraffin wax are slightly higher than that of hytherm oil case. Copyright © 2011 John Wiley & Sons, Ltd.     

Energy efficiency of a solar drying system

A solar collector, part of a drying system using solar energy as a heat source, was developed and reported previously and used in product-drying applications. In this study, energy efficiency analyses of the drying system in terms of the collector efficiency were investigated. The results obtained show that the present collector used in this solar drying system is an efficient and effective unit for practical drying applications.     

基于高温工质R245fa的太阳能平板集热器集热过程动态模拟

提出了一种以R245fa为循环工质的气液分离双级太阳能集热系统.对第一级集热系统的集热过程进行了动态数值模拟.结果表明,系统的集热过程受太阳辐射强度的影响最大,受系统肩动温度的影响较小.当系统从环境温度启动达到工质蒸发状态时.减少循环工质的质量或增大集热面积均能有效地减少系统的运行时间,而增大系统集热面积是较佳方案.