@article { author = {Bashirpour, Mohammad and Poursafar, Jafar and Kolahdouz, Mohammadreza}, title = {Solar cell efficiency enhancement using a hemisphere texture containing metal nanostructures}, journal = {Energy Equipment and Systems}, volume = {8}, number = {2}, pages = {103-110}, year = {2020}, publisher = {University of Tehran}, issn = {2383-1111}, eissn = {2345-251X}, doi = {10.22059/ees.2020.43223}, abstract = {One major problem of the conventional solar cells is low conversion efficiency. In this work, we have proposed a new design including hemisphere texturing on top and metallic plasmonic nanostructure under the silicon layer to enhance the optical absorption inside the photosensitive layer.    The finite-difference time-domain (FDTD) method has been used to investigate the interaction of light with the proposed structure. The simulation results demonstrated that the designed structure gives rise to 40% light absorption enhancement and 27% solar cell efficiency enhancement compared to a simple cell structure. The hemisphere texturing acts as a light concentrator and results in local electric field enhancement inside the silicon layer, and metallic nanostructure excites the plasmons. By combining the advantages of these two designs, the short circuit of the proposed structure showed more than 65% enhancement compared to the conventional structure.}, keywords = {Hemisphere Surface,Plasmonic,Nanostructures,Silicon,Solar Cells}, url = {https://www.energyequipsys.com/article_43223.html}, eprint = {https://www.energyequipsys.com/article_43223_6bc2b0ccc74ea5a6bfbbdda4c6004e2f.pdf} } @article { author = {Moein Addini, Maryam and Gandjalikhan Nassab, S.Abdolreza}, title = {Interaction of laminar natural convection and radiation in an inclined square cavity containing participating gases}, journal = {Energy Equipment and Systems}, volume = {8}, number = {2}, pages = {111-126}, year = {2020}, publisher = {University of Tehran}, issn = {2383-1111}, eissn = {2345-251X}, doi = {10.22059/ees.2020.43224}, abstract = {Two-dimensional numerical study of flow and temperature fields for laminar natural convection and radiation in the inclined cavity is performed in the present work. The walls of the square cavity are assumed kept at constant temperatures. An absorbing, emitting, and scattering gray medium is enclosed by the opaque and diffusely emitting walls. The set of governing equations, including conservation of mass, momentum, and energy for fluid flow, is solved numerically by the CFD method, while radiation computation is based on the numerical solution of the radiative transfer equation. The finite volume method has been adopted to solve the governing equations, and the discrete ordinates method (DOM) is used to model the radiative transfer in the absorbing-emitting medium. The effects of Rayleigh number from 103 to 106 and inclination angle in a broad range from 0 to 90o on temperature and velocity distributions and Nusselt numbers are investigated. It was found that the total heat transfer in the cavity is increased under thermal radiation, and variation of inclination angle causes a sweep behavior in the flow pattern inside the cavity.}, keywords = {Laminar Natural Convection Flow,Inclined Cavity,Radiation,DOM}, url = {https://www.energyequipsys.com/article_43224.html}, eprint = {https://www.energyequipsys.com/article_43224_44ac4b1c9475cc52e1619746e4ce51e2.pdf} } @article { author = {Sharifzadeh, Reza and Afshari, Asghar}, title = {Large eddy simulation of propane combustion in a planar trapped vortex combustor}, journal = {Energy Equipment and Systems}, volume = {8}, number = {2}, pages = {127-141}, year = {2020}, publisher = {University of Tehran}, issn = {2383-1111}, eissn = {2345-251X}, doi = {10.22059/ees.2020.43225}, abstract = {Propane combustion in a trapped vortex combustor (TVC) is characterized via large eddy simulation coupled with filtered mass density function. A computational algorithm based on high order finite difference (FD) schemes, is employed to solve the Eulerian filtered compressible Navier-Stokes equations. In contrast, a Lagrangian Monte-Carlo solver based on the filtered mass density function is invoked to describe the scalar field. The impact of injection strategy on temperature distribution and flame structure in a planar single-cavity TVC is investigated. A fuel jet and an air jet are injected directly into the cavity from the forebody and the afterbody, respectively.  Different injection schemes are contemplated by altering fuel and air jet locations representing the different flow and flame structures. The temperature distribution, along with cross-sectional averaged temperature and flame structure, are compared for fuel/air injection strategies. The temperature field reveals that configurations in which both air and fuel jets are located at the cavity-walls midpoint or adjacent to the cavity inferior wall, lead to a more uniform temperature distribution and lower maximum temperature with the latter configuration performing slightly better. While, the former configuration provides the closest cross-sectional averaged temperature to the adiabatic flame temperature. The reaction rate distributions show that the configurations mentioned above lead to a more contained flame, chiefly due to more efficient fuel-air mixing at lower regions of the cavity.}, keywords = {Trapped Vortex Combustor,Large Eddy Simulation,temperature distribution,Flame Structure}, url = {https://www.energyequipsys.com/article_43225.html}, eprint = {https://www.energyequipsys.com/article_43225_f42544f00249b6bd96441cf3bf79c4db.pdf} } @article { author = {Farzan, Hadi}, title = {Comparative performance assessment of flat plate and evacuated tube collectors for domestic water heating systems in Kerman, Iran}, journal = {Energy Equipment and Systems}, volume = {8}, number = {2}, pages = {143-152}, year = {2020}, publisher = {University of Tehran}, issn = {2383-1111}, eissn = {2345-251X}, doi = {10.22059/ees.2020.43226}, abstract = {This study represents a year-round energy performance of two solar water heating (SWH) systems with a 4m2 flat plate collector (FPC) and an evacuated tube collector (ETC) operating under the same weather conditions. The energy performance of the two considered systems was compared on a monthly and yearly basis. The obtained results showed that for an annual total solar insolation of 2056kW.h.m-2, a total of 3577kW.h.y-1 and 4201kW.h.y-1 of heat energy were collected by 4m2 FPC and, ETC systems, respectively. The annual average energy efficiency by the FPC system was 43%, while its annual solar fraction was 50%. The ETC system had 51% energy efficiency with 58% solar fraction. The economic analysis showed that both solar water heating systems are not economically viable under prevailing costs in Iran. Furthermore, according to the obtained results, the FPCs are more favorable than the ETCs due to its economic analysis and energy performance. These results provide useful information for households and policymakers.}, keywords = {Plat Plate Collector,Evacuated Tube Collector,Energy Performance Analysis,Economic Analysis,Solar Water Heater}, url = {https://www.energyequipsys.com/article_43226.html}, eprint = {https://www.energyequipsys.com/article_43226_eee4ec9ed37ec24da8d4df83734eb71d.pdf} } @article { author = {Hajabdollahi, Hassan and Hosseini, Zahra}, title = {Dynamical modeling and thermo-economic optimization of a cold room assisted vapor-compression refrigeration cycle}, journal = {Energy Equipment and Systems}, volume = {8}, number = {2}, pages = {153-167}, year = {2020}, publisher = {University of Tehran}, issn = {2383-1111}, eissn = {2345-251X}, doi = {10.22059/ees.2020.43227}, abstract = {A cold room assisted vapor-compression refrigeration cycle is dynamically modeled in a year and optimized. Total annual cost (TACO) and coefficient of performance (COP) are selected as two objective functions. Both cold room and refrigeration cycle parameters are considered as design variables. Moreover, three working fluids included R22, R134a and R407c are examined. The optimum Pareto front reveals that unlike the thermal system such as heat exchanger and power plant, the objective functions are not conflicted in the optimum situation. The optimum solutions show that R407c is the best refrigerant in both thermodynamics and economics viewpoints with 9148.2 $/year as total annual cost and 6.12 for COP. The optimum result of R407c showed that the total annual cost improved by 50.74% and 8.68% in comparison with R134a and R22, respectively. Furthermore, COP improved 9.97% and 13.72% in R407c compared with R134a and R22, respectively.}, keywords = {Cold Room,Working Fluid,Multi-objective optimization,Total Annual Cost,Coefficient of performance}, url = {https://www.energyequipsys.com/article_43227.html}, eprint = {https://www.energyequipsys.com/article_43227_19e285ee794ae4b918bc437b3222df6a.pdf} } @article { author = {Karimi, Delara and Ghorbani, Babak and Momen, Mahyar}, title = {Net zero energy buildings in semi-arid climates: An analysis on 3 case studies in Tehran, Iran}, journal = {Energy Equipment and Systems}, volume = {8}, number = {2}, pages = {169-178}, year = {2020}, publisher = {University of Tehran}, issn = {2383-1111}, eissn = {2345-251X}, doi = {10.22059/ees.2020.43228}, abstract = {This paper analyzes utilization of renewable energy systems and efficient building envelopes in the semi-arid climate. The proposed model evaluates renewable energy systems solutions as well as economic- and energy-efficient construction materials for the net zero-energy buildings (NZEB) in semi-arid climates. The objective of this paper is to optimize total energy cost and environmental impacts in NZEB. Three real case studies in Tehran, Iran, are used for this analysis. Different potential renewable energy systems, including PV panels, solar thermosiphon systems, geothermal heat pumps, and their combinations, are investigated in two residential buildings and a commercial building. Moreover, analyzing building envelopes using thermodynamic characteristics of building surfaces is done. The results show that the implementation of the proposed model in the buildings in semi-arid climates significantly reduces the negative environmental impacts for both residential and commercial buildings, and also increasing their energy efficiency up to 63% and 38%, respectively.}, keywords = {Net Zero Energy Buildings,Renewable Energy,Building Envelope,Energy Efficiency,Environmental Impacts}, url = {https://www.energyequipsys.com/article_43228.html}, eprint = {https://www.energyequipsys.com/article_43228_defedc624f57d0b57759ee45d877e384.pdf} } @article { author = {Rezaie, Behnaz and Rosen, Marc. A.}, title = {The food-energy-water nexus: A framework for sustainable development modeling}, journal = {Energy Equipment and Systems}, volume = {8}, number = {2}, pages = {179-201}, year = {2020}, publisher = {University of Tehran}, issn = {2383-1111}, eissn = {2345-251X}, doi = {10.22059/ees.2020.43229}, abstract = {Energy, water, and food are facing present and future challenges triggered by climate change, population growth, human behavior, and economics. Management strategies for energy, water, and food are possible through policies, technology, and related education. However, the links between resources (energy, water, and food) and impacting factors (population increase, human behavior, economics, and global warming) need to be developed. Holistic modeling is needed to supply and demand energy, water, and food. That type of modeling explores the energy-water-food nexus. The framework for such modeling is described in this study, and previous frameworks are reviewed. Recommendations for addressing energy, water, and food challenges, before and after completing the energy-water-food nexus modeling, involve the following: modifying processes, modifying products, innovative processes, and innovative products. With an energy water-food-nexus model, the impact of any changes on resources can be measured and quantified.}, keywords = {Energy-Food-Water Nexus,FEW Nexus Modeling,Climate change,Sustainable development,Technical Innovation}, url = {https://www.energyequipsys.com/article_43229.html}, eprint = {https://www.energyequipsys.com/article_43229_be6ba068617e62eb8b182202a74545ef.pdf} }