Sharif Digital Repository

The use of solar energy concentration systems for achieving performance enhancements in the Photovoltaic/thermal hybrid solar systems and reduction of initial costs is an idea that has been studied for years. In this article a new structure for parabolic trough photovoltaic/thermal collector is proposed and its thermal and electrical performances are experimentally investigated. The receiver of this concentrator contains a triangular channel with an outer surface covered with photovoltaic cells and thermoelectric modules with a specific arrangement so that in addition to absorbing heat, a larger portion of the solar radiation is directly converted to electricity. Hence, the performance of... 

The application of the solar energy in thermal desalination devices is one of the most beneficial applications of the renewable energies. In this study, a novel solar desalination system is introduced, which is benefited from the undeniable advantages of pulsating heat pipe (PHP) as a fast responding, flexible and high performance thermal conducting device. Results show a remarkable increase in the rate of desalinated water production and the maximum production reaches up to 875mL/(m2.h). However, the optimum water depth in basin and the filling ratio of the PHP are measured 1cm and 40%, respectively  

The paper aims to present a supply model to satisfy the required household final energy carriers, freshwater and industrial cooling loads for a deprived area of access that is located in hot and humid climate. To this aim, a multi-generation hybrid solar thermophotovoltaic integrated system with capability of adjusting heat to power ratio dynamically is introduced. Appropriate analytical tools are developed to obtain the optimal capacity of any systems and energy flows subject to the technology and demand constraints, the financial limitation and the constraints defined by the politicians and local government. The demand constraints are identified through the field studies and the comfort... 

Global warming escalation has extended average temperature of earth beyond its safe limit. To avert this environmental-threat, solar energy has acquired substantial attention of remarkable researchers in this century. To effectively utilize solar energy by transforming into thermal and electrical energy, the involvement of nanofluids having intensified thermal, optical and magnetic properties, has become very popular. The foremost objective of this article is to provide a comprehensive review on the applications of nanofluids in solar energy systems like solar collectors, photovoltaic cells, solar stills, and thermal energy storage, which are thoroughly discussed in this paper. The effect of... 

Dust deposition on the surface of solar systems is one of the main parameters that significantly affects the performance of such systems. In this study, the effect of dust deposition density on the performance of photovoltaic modules (PV) and photovoltaic-thermal systems (PVT) is numerically investigated. Accordingly, all layers of a monocrystalline silicon PV module for both systems are simulated. Moreover, the effect of various system parameters on the performance of both clean and dusty PV module and PVT system are studied. The studied parameters included: solar radiation intensity, ambient temperature, coolant inlet temperature, and coolant inlet velocity. The obtained results indicate... 

Anti-reflection and self-cleaning coatings on the glass substrate are used to improve the performance of solar systems. TiO2 are one of the most used semiconductors for this application. In this research meso-porous TiO2 coatings (that synthesized by the sol-gel process) with the various extent of porosity (using different concentrations of Pluronic F127, as pore-forming agent) have been investigated. The coating's thickness and porosity and anti-reflective properties were studied by FE-SEM and UV/VIS spectrometer (transmission spectra test), respectively. It was found that the use of F127 leads to the formation of pores smaller than 30 nm and increases the surface roughness from 1.5 (for... 

The techno-economic and environmental performance of hybrid solar hydrogen energy systems was investigated to provide combined cooling, heating and power (CCHP) demands of a standalone greenhouse in Iran to achieve sustainable agriculture based on an optimization procedure. From the environmental point of view, by deploying hybrid energy systems, 83%, to 100% of emissions can be avoided. Also a sensitivity analysis was performed on the hybrid energy systems in order to study the effect of major parameter variation on the systems justification. It was concluded that hybrid solar systems are economically competitive with conventional systems, for high solar intensity locations with high diesel... 

During the last decades, the adoption of more strict safety and environmental regulations, as well as a rise in energy costs, sparked an increasing interest in the design of renewable energies systems, particularly solar systems, to supply both electrical power and heat. Because of their capability to simultaneously supply both electricity and heat, concentrating photovoltaic-thermal and thermoelectric hybrid systems have recently attracted scholarly attention. In this study, a detailed three-dimensional computational model of a novel concentrating photovoltaic-thermal solar system combined with thermoelectric modules in an integrated design with a triangular absorber and corresponding... 

The purpose of this study is to apply managerial economics and methods of decision analysis to study the optimal pattern of innovation activities for development of new energy technologies in developing countries. For this purpose, a model of energy research and development (R&D) planning is developed and it is then linked to a bottom-up energy-systems model. The set of interlinked models provide a comprehensive analytical tool for assessment of energy technologies and innovation planning taking into account the specific conditions of developing countries. An energy-system model is used as a tool for the assessment and prioritization of new energy technologies. Based on the results of the... 

Photodegradation of Escherichia coli bacteria in presence of Ag-TiO2/Ag/a-TiO2 nanocomposite film with an effective storage of silver nanoparticles was investigated in the visible and the solar light irradiations. The nanocomposite film was synthesized by sol-gel deposition of 30 nm Ag-TiO2 layer on ∼200 nm anatase(a-)TiO2 film previously doped by silver nanoparticles. Both Ag/a-TiO2 and Ag-TiO2/Ag/a-TiO2 films were transparent with a SPR absorption band at 412 nm. Depth profile X-ray photoelectron spectroscopy showed metallic silver nanoparticles with diameter of 30 nm and fcc crystalline structure were self-accumulated on the film surface at depth of 5 nm of the TiO2 layer and also at the...