Analysis of a Hybrid Solar Collector Photovoltaic Thermal (PVT)

AbstractA solar hybrid photovoltaic thermal (PVT) is a set of combined solar collector, which consists of a photovoltaic module (PV) for the conversion of electrical energy and solar plan for the high efficiency thermal energy conversion, in the same frame.An attempt made to analyze the hybrid solar collector using Computational Fluid Dynamics (CFD) to simulate the PVT solar collector to a better understanding of heat transfer capabilities in this type of systems. In the present work, the fluid flow and heat transfer in the module are studied using the ANSYS14 software. The heat transfer phenomenon conjugate between the photovoltaic cells and the coolant is modeled using the FLUENT software. The transfer of heat by the solar radiation is not modeled; however, the effects of radiation are taken for consideration when calculating the conditions for heat flux limit for the collector region. The geometric model and fluid domain for the CFD analysis is generated using ANSYS software DesingModeler, mesh geometry is carried out by ANSYS Meshing Software

Hypericum sp.: essential oil composition and biological activities

Phytochemical composition of Hypericum genus has been investigated for many years. In the recent past, studies on the essential oils (EO) of this genus have been progressing and many of them have reported interesting biological activities. Variations in the EO composition of Hypericum species influenced by seasonal variation, geographic distribution, phenological cycle and type of the organ in which EO are produced and/or accumulated have also been reported. Although many reviews attributed to the characterization as well as biological activities of H. perforatum crude extracts have been published, no review has been published on the EO composition and biological activities of Hypericum species until recently (Crockett in Nat Prod Commun 5(9):1493–1506, 2010; Bertoli et al. in Global Sci Books 5:29–47, 2011). In this article, we summarize and update information regarding the composition and biological activities of Hypericum species EO. Based on experimental work carried out in our laboratory we also mention possible biotechnology approaches envisaging EO improvement of some species of the genus.Fundação para a Ciência e a Tecnologia (FCT) - project PTDC/AGR AAM/70418/2006, SFRH/BD/ 13283/2003

THERMAL PERFORMANCE OF FLAT PLATE SOLAR COLLECTOR

In this paper, a theoretical and experimental studyof flat platesolar water collector with reflectors.A mathematical model based on energy balance equations saw the thermal behavior of the collector is investigated. The experimental test was made at the unit research applies in renewable energy (URAER) located in southern Algeria.An increase of 23% for solar radiation incident on the collector surface with the addition of the planers reflectors in the day of May, this increase causes an improvement of the performance of the collector,the fluid temperature increases with an average of 5%. Thetests conducted on the flat plate solar water collector in open circuit enabled the determination of thermal performance of the collector by estimating the daily output The thermal efficiency of the collector ranges from 1% -63% during the day, a mean value of 36%obtained

Model Validation of an Empirical Photovoltaic Thermal (PV/T) Collector

AbstractWithin solar energy technologies, the hybrid photovoltaic–thermal (PV/T) systems offer an attractive option because the absorbed solar radiation is converted into thermal and electrical energy (the conversion can be done separately or simultaneously). In this paper, an attempt is made to investigate the thermal and electrical performance of a solar photovoltaic thermal collector. A detailed thermal model is developed to calculate the thermal parameters of a typical PV/T collector. The thermal parameters of this collector include solar cell temperature, outlet water temperature, thermal efficiency and useful thermal energy. Some corrections are done on heat loss coefficients in order to improve the thermal model of a PV/T collector. A computer simulation program is developed in order to calculate the thermal and electrical parameters of a PV/T collector. The absorber is realized with the galvanized iron of high quality, allowing a good transfer of heat with lower cost compared to copper. This PVT has the advantage of its simple implementation and its low cost compared to other configurations. The results of numerical simulation are in good agreement with the experimental measurements noted in the previous literature. It is observed that the thermal simulation results obtained in this paper is more precise than the one given by the previous literature. It is also found that the thermal efficiency of PV/T collector is about 54.51% in the mode of water heat exchanger, and 16.24% in air heat extraction, the electrical efficiency is 11.12%, for a sample climatic, operating and design parameters