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    Comparison of performance prediction of solar water heaters between artificial neural networks and conventional correlations

    , Article International Journal of Global Energy Issues ; Volume 31, Issue 2 , 2009 , Pages 122-131 ; 09547118 (ISSN) Razavi, J ; Riazi, M. R ; Raoufi, F ; Sadeghi, A ; Sharif University of Technology
    The aim of this study was to develop a predictive method for heat transfer coefficients in solar water heaters and their performance evaluation of such heaters with different materials used as heat collectors. Two approaches have been used: conventional method and an Artificial Neural Network (ANN) to predict the performance of solar water heaters and to compare these two approaches. This performance is measured in terms of outlet temperature by using a set of conventional feed forward multi-layer neural networks. The actual experimental data which were used as our network's input gathered from published literature (for polypropylene tubes) and from the experiments carried out recently using... 

    Improved efficiency in front-side illuminated dye sensitized solar cells based on free-standing one-dimensional TiO2 nanotube array electrodes

    , Article Solar Energy ; Volume 184 , 2019 , Pages 115-126 ; 0038092X (ISSN) Peighambardoust, N. S ; Khameneh Asl, S ; Mohammadpour, R ; Khameneh Asl, S ; Sharif University of Technology
    Elsevier Ltd  2019
    Although morphological disorder of nanotube structure is further down than the nanoparticular electrode, its density of traps are the hindering effects in the charge transport. In this study, crack-free TiO2 nanotube membranes, which obtained through a re-anodizing process, are fixed on transparent fluorine–tin-oxide glass by applying a few drops of Titanium Isopropoxide without needing the TiO2 powder paste. Front-side illuminated dye sensitized solar cells fabricated by undoped, N-doped and blue TiO2 nanotube membranes are investigated. The electrical characteristics of TiO2 nanotube based dye sensitized solar cells are followed by theoretical analysis using simple one-diode model.... 

    Experimental determination of natural convection heat transfer coefficient in a vertical flat-plate solar air heater

    , Article Solar Energy ; Volume 82, Issue 10 , 2008 , Pages 903-910 ; 0038092X (ISSN) Hatami, N ; Bahadorinejad, M ; Sharif University of Technology
    In this study, natural convection heat transfer in a vertical flat-plate solar air heater of 2.5 m height and 1 m width, with one- and two-glass covers was studied experimentally. Totally six cases of airflow (two for air heater with one glass cover and four for air heater with two-glass covers) were considered. These cases included states that air could flow within spaces between absorber plate and glass covers or air was enclosed in such spaces. Absorber plate temperature, back-plate temperature, glass cover temperatures, mass flow rates of air within channels and the solar radiation were measured. The following relations are suggested:. For channels in which air could flow:Nu = 0.7362... 

    A single layer deposition of Li-doped mesoporous TiO2beads for low-cost and efficient dye-sensitized solar cells

    , Article New Journal of Chemistry ; Volume 45, Issue 5 , 2021 , Pages 2470-2477 ; 11440546 (ISSN) Golvari, P ; Nouri, E ; Mohsenzadegan, N ; Mohammadi, M. R ; Martinez Chapa, S. O ; Sharif University of Technology
    Royal Society of Chemistry  2021
    Herein, we report a new strategy for improving the efficiency and reducing the fabrication cost of dye-sensitized solar cells (DSCs) by elimination of the three- or four-fold layer deposition of TiO2. This is performed by replacing a single layer deposition of mesoporous TiO2 beads, with sub-micrometer size, high surface area and tunable pore size, synthesized by a combination of sol-gel and solvothermal methods. Furthermore, superior electronic properties gained by a reduction in electronic trap states are achieved through doping of pristine TiO2 beads with lithium. The beads have a spherical shape with monodispersed texture consisting of anatase-TiO2 nanocrystals and ultra-fine pores. The... 

    Optimal energy management of a campus microgrid considering financial and economic analysis with demand response strategies

    , Article Energies ; Volume 14, Issue 24 , 2021 ; 19961073 (ISSN) Javed, H ; Muqeet, H. A ; Shehzad, M ; Jamil, M ; Khan, A. A ; Guerrero, J. M ; Sharif University of Technology
    MDPI  2021
    An energy management system (EMS) was proposed for a campus microgrid (μG) with the incorporation of renewable energy resources to reduce the operational expenses and costs. Many uncertainties have created problems for microgrids that limit the generation of photovoltaics, causing an upsurge in the energy market prices, where regulating the voltage or frequency is a challenging task among several microgrid systems, and in the present era, it is an extremely important research area. This type of difficulty may be mitigated in the distribution system by utilizing the optimal demand response (DR) planning strategy and a distributed generator (DG). The goal of this article was to present a... 

    Thermal residual stresses in silicon thin film solar cells under operational cyclic thermal loading: A finite element analysis

    , Article Solar Energy ; Volume 135 , 2016 , Pages 366-373 ; 0038092X (ISSN) Namvar, A ; Dehghany, M ; Sohrabpour, S ; Naghdabadi, R ; Sharif University of Technology
    Elsevier Ltd  2016
    In manufacturing amorphous silicon solar cells, thin films are deposited at high temperatures (200-400 °C) on a thick substrate using sputtering and plasma enhanced chemical vapor deposition (PECVD) methods. Since the thin films and substrate have different thermal expansion coefficients, cooling the system from deposition temperature to room temperature induces thermal residual stresses in both the films and substrate. In addition, these stresses, especially those having been induced in the amorphous silicon layer can change the carrier mobility and band gap energy of the silicon and consequently affect the solar cell efficiency. In this paper, a 2D finite element model is proposed to... 

    Stable and efficient CuO based photocathode through oxygen-rich composition and Au-Pd nanostructure incorporation for solar-hydrogen production

    , Article ACS Applied Materials and Interfaces ; Volume 9, Issue 33 , 2017 , Pages 27596-27606 ; 19448244 (ISSN) Masudy Panah, S ; Siavash Moakhar, R ; Chua, C. S ; Kushwaha, A ; Dalapati, G. K ; Sharif University of Technology
    Enhancing stability against photocorrosion and improving photocurrent response are the main challenges toward the development of cupric oxide (CuO) based photocathodes for solar-driven hydrogen production. In this paper, stable and efficient CuO-photocathodes have been developed using in situ materials engineering and through gold-palladium (Au-Pd) nanoparticles deposition on the CuO surface. The CuO photocathode exhibits a photocurrent generation of ∼3 mA/cm2 at 0 V v/s RHE. Time-of-flight secondary ion mass spectrometry (TOF-SIMS) analysis and X-ray spectroscopy (XPS) confirm the formation of oxygen-rich (O-rich) CuO film which demonstrates a highly stable photocathode with retained... 

    Optimal policy of energy innovation in developing countries: Development of solar PV in Iran

    , Article Energy Policy ; Volume 37, Issue 3 , 2009 , Pages 1116-1127 ; 03014215 (ISSN) Shafiei, E ; Saboohi, Y ; Ghofrani, M.B ; Sharif University of Technology
    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... 

    Impact of innovation programs on development of energy system: case of Iranian electricity-supply system

    , Article Energy Policy ; Volume 37, Issue 6 , 2009 , Pages 2221-2230 ; 03014215 (ISSN) Shafiei, E ; Saboohi, Y ; Ghofrani, M. B ; Sharif University of Technology
    The paper presents further experiments with an extended version of a comprehensive model for assessment of energy technologies and research and development (R&D) planning to evaluate the impact of innovation programs on development of Iranian electricity-supply system. This analytical instrument is a model of energy R&D resource allocation with an explicit perspective of developing countries which has been linked to a bottom-up energy-systems model. Three emerging electricity generation technologies of solar PV, wind turbine and gas fuel cell are considered in the model and the impact of innovation programs on cost-reducing innovation for them is examined. The main results provided by the...