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Comparative investigation of performances for HIT-PV and PVT systems
摘要： Crystalline silicon heterojunction solar cells are a promising candidate for high efficiency solar cells, and the heterojunction photovoltaic (HIT-PV) module is strongly dependent on the temperature. In this study, we design three heterojunction photovoltaic modules to improve the performance by preventing from over-heating, with, glass, Tedlar/Polyethylene terephthalate/Tedlar (TPT) and aluminum substrates, respectively. The efficiencies of those HIT-PV modules are investigated under four different outdoor climates. The aluminum-module shows the best thermal dissipation; while the glass-module/TPT-module have the better electrical efficiency and electrical energy, since there is the high reflectivity layer on the surface of the glass (and TPT) substrates rather than the aluminum substrate. In order to increase the output power of HIT-PV modules, we design a heterojunction photovoltaic thermal (HIT-PVT) system based on HIT solar cells and aluminum thermal collector. The measured results of HIT-PVT system show that the coolant circulation increase the output power, and the HIT-PVT module can provide the domestic hot water supply (up to 51.2 °C) under outdoor conditions. In addition, the cost of HIT-PVT systems are much lower than those of the conventional photovoltaic systems, and the investment payback time can be less than 3 years.
关键词： Electrical energy,HIT-PV module,Three substrates,Aluminum thermal collector
更新于2025-09-23 15:23:52
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PERFORMANCE ENHANCEMENT OF CENTRALLY FINNED TWIST INSERTED SOLAR COLLECTOR USING CORRUGATED BOOSTER REFLECTORS
摘要： Performance enhancement of centrally finned twist (CFT) inserted solar collector using corrugated booster reflectors (CBR) have been approached experimentally. The experimental trials have been made with two different twist ratios (Y = 3 and 6) for typical twist (TT) and centrally finned twist (CFT) under same working conditions. The results were compared with the plain tube solar thermal collector (SC) with CBR and also with the plain tube SC with flat booster reflectors (FBR). The experimental result of the plain tube CBR SC has been verified with the standard equations and found the deviations within ±10.32% for Nusselt number and ±9.14% for friction factor. The CBR has 1.6% higher effective reflector area than the FBR. Hence, the CBR augmented the Nusselt number around 8.25% over the FBR. When compared to the plain tube CBR SC, the CFT of minimum twist ratio (Y = 3) offered 11.08% higher thermal efficiency. In addition, empirical correlations have been derived for predicting the Nusselt number and friction factor. The deviations of the predicted value from the experiment value fall within ±11.02% for Nusselt number and ±10.88% for friction factor.
关键词： Solar thermal collector,Corrugated booster reflectors,Flat booster reflectors,Typical twist,Centrally finned twist
更新于2025-09-23 15:21:01
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Graphene oxide/multia??walled carbon nanotubea??Therminol??66 hybrid nanofluids for lowa??toa??medium temperature volumetric solar collectors
摘要： Nano-composites of graphene oxide (GO) and multi-walled carbon nanotube (MWCNT) were prepared by a simple physical method and well dispersed into Therminol? 66 to form hybrid nanofluids with mass fractions in the range of 10 to 150 ppm. The suspension stability, optical absorption properties and photo-thermal conversion characteristics of GO/MWCNT nanofluids were tested and evaluated. GO nanosheets can avoid the self-entanglement and agglomeration of MWCNTs and ensure long-time suspension stability. The solar energy absorption capability increased with the composite concentration, and the majority of incoming radiation could be absorbed in a fluid layer of 1.5 cm. There existed an optimum concentration of 100 ppm related to the indoor experiment, and the temperature could be increased up to 94°C with the corresponding efficiency improved from 52% (Therminol? 66) to 70% (100 ppm). Besides, a line focusing Fresnel lens was utilized for the outdoor solar concentrating experiment, and the photo-thermal conversion performance of hybrid nanofluids increased with the composite mass fraction from 30 to 100 ppm. A highest temperature of 153°C was achieved at 100 ppm concentration. The thermal oxidation without degradation of Therminol? 66 occurred after indoor/outdoor experiments, and slightly enhanced the optical absorption owing to the solar radiation induced heating effect. The GO-MWCNT/Therminol? 66 nanofluids exhibit a good prospect in volumetric solar thermal systems from low to medium temperatures.
关键词： photo-thermal conversion performance,solar thermal energy,volumetric solar thermal collector,nanofluid,thermal oxidation
更新于2025-09-23 15:19:57
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The hybrid Photovoltaic-Thermal double-pass solar system for drying applications
摘要： In this paper, is devoted to evaluating the performance of the double-pass hybrid Photovoltaic-Thermal (PVT) solar system proposed for drying purposes theoretically and experimentally as well as the system is designed, fabricate and modeled in order to simulate the productivity of this system. The hot air extracted from the PVT collector can be used as a heat source for the drying application. The critical parameter such as temperature distribution, useful heat gain, electrical power, and thermal efficiency are computed using MATLAB 2015b program built for this purpose. Results show that the higher output fluid temperature was 63°C at a lesser mass flow rate which 0.017 kg/s and the maximum efficiencies of electrical, thermal and overall at a higher mass flow rate which reached 12.65%, 56.73%, and 85% respectively at mass flow rate 0.031 kg/s. In addition, the optimum electrical power and thermal energy reached 50.57 W and 389.37 W at 0.031 kg/s.
关键词： dryer,performance,photovoltaic cell,heat gain,thermal collector
更新于2025-09-23 15:19:57
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Performance analysis of a hybrid photovoltaic/thermal and liquid desiccant system
摘要： Air dehumidification is widely applied in the civilian and industrial use, however, conventional vapor compression air-conditioning system consumes substantial power. Using renewable energy in the air handling process has potential to further reduce the power consumption, meanwhile ease the carbon emission. This paper proposes a novel liquid desiccant system integrated with a photovoltaic/thermal collector for deep dehumidification. The generated electric power drives a vapor compression chiller for cooling the desiccant solution for a two-stage dehumidification, and the releasing heat from the collector is used for the desiccant regeneration. Simulation studies indicated the proposed system has a superior power saving ability of 55.65% comparing with the conventional one, besides the equivalent power generation efficiency reaches 8.7%.
关键词： photovoltaic/thermal collector,two-stage dehumidification,Liquid desiccant dehumidification
更新于2025-09-16 10:30:52
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Performance optimization of a photovoltaic/thermal collector using microencapsulated phase change slurry
摘要： In a photovoltaic/thermal (PV/T) collector, a portion of absorbed solar energy is transformed into electrical energy, and the remaining part is transformed into thermal energy. Increasing waste heat collection and energy conversion rates are important to improve the performance of the PV/T collector. The utilization of microencapsulated phase change slurry (MPCS) in a PV/T collector to cool photovoltaic modules is an effective way, and electrical and thermal performances of the collector are improved. To investigate influences of operating parameters on performances of PV/T collector, numerical simulation is put into effect to analyze influences of the mass fraction of MPCS on the collector performance. The influences of MPCS mass flow rate and collector channel height on collector performances are also studied. When the flow rate is 0.005 kg/s and the channel height is 0.010 m, the PV/T collector obtains the best net efficiency with a MPCS mass concentration of 20 wt%. But electrical efficiency difference between 15 and 20 wt% is not obvious. With the growth in mass fraction, PV temperature drops more and more slowly because outlet fluid has not fully melt. Take PV/T collector performances into consideration, 15 wt% MPCS is a better choice to cool photovoltaic modules.
关键词： microencapsulated phase change slurry,photovoltaic/thermal collector,electrical and thermal performances,energy conversion efficiency
更新于2025-09-12 10:27:22
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Integrative modelling and optimisation of a desiccant cooling system coupled with a photovoltaic thermal-solar air heater
摘要： An integrated model of a desiccant cooling system with a hybrid photovoltaic thermal collector-solar air heater (PVT-SAH) was developed and coupled with a building model to enable a performance evaluation and optimisation of the system. A double pass PVT-SAH system that incorporates heat pipes was used to increase the air temperature of the PVT-SAH outlet in order to regenerate the desiccant in a desiccant wheel. The integrated model was then used to quantify the performance of the hybrid desiccant cooling system in terms of Solar Fraction (SF) and the Coe?cient of Performance (COP) and its response to the various sizes of PVT-SAH systems. The model outputs showed that the selection of the PVT-SAH design parameters can be critical in improving the system’s utilisation in a desiccant cooling process. For a commercial building case study in a hot and humid climate, the annual Solar Fraction and the electrical COP of the cooling system reached up to 96.6% and up to 19.8 respectively, when the design of the PVT-SAH was optimised. The optimal electrical COP was higher than those for non-optimal designs that ranged from 0.6 to 15.1. The minimum size of the PVT-SAH that is required for the hybrid desiccant cooling system to exceed a typical COP for commercial buildings (2.6–3.0) was found to be 0.35 m2 per m2 of the conditioned ?oor area.
关键词： Desiccant cooling system,Integrated modelling of solar desiccant systems,Photovoltaic thermal collector-solar air heater,Design optimisation
更新于2025-09-12 10:27:22
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Energy and exergy analysis of solar heat driven chiller under wide system boundary conditions
摘要： In the paper, a solar driven ammonia-water chiller is investigated, as one of the systems having potential for reduction of resources depletion. An energy and exergy analysis is proposed for correct diagnostics while designing and operating the cycle. The boundary conditions for the analyses are set in accordance with Professor Szargut’s primary instructions. They are however widened to solar collector component. Solar radiation is treated as the driving energy or exergy, respectively. The analyses are supplemented with a sensitivity diagnosis revealing the most significant parameters modifying the efficiency and irreversibilities distribution. According to the findings, design COP of the chiller equals 0.444 while its net exergy efficiency is 0.026. Solar collector component is the most burdened with exergy destruction and loss in the whole cycle.
关键词： Exergy analysis,irreversibility,solar radiation exergy,solar thermal collector,ammonia-water chiller
更新于2025-09-10 09:29:36