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Saffari M.,University of Lleida | De Gracia A.,University of Antofagasta | Ushak S.,University of Antofagasta | Ushak S.,Solar Energy Research Center | Cabeza L.F.,University of Lleida
Energy and Buildings | Year: 2016

In buildings, HVAC systems consume a high amount of energy to provide thermal comfort for occupants. A methodology is presented in this paper to control thermostat operation of the buildings considering the effects of indoor and outdoor boundary conditions and phase change material (PCM) characteristics. EnergyPlus v8.1 building energy simulation software was used to analyze the energy performance of the PCM incorporated building models and to implement Fanger model to control HVAC thermostat operation according to BS EN 15251:2007 thermal comfort categories. Three types of building HVAC schedule, PCM with different melting points and layer thicknesses were studied for Madrid climate zone. Moreover, the impact of occupants clothing on the energy consumption was investigated. Furthermore, payback analysis was conducted to find out the economic benefits of PCM integration into the building envelopes. Application of PCM improved the cooling and heating energy performances except for the office model in winter (heating period). Additionally, higher energy savings and lower payback periods were observed when PCM with higher melting point was applied to the buildings. Eventually, energy savings in PCM incorporated models were found to improve further when occupants changed their clothing behavior in winter. © 2015 Elsevier B.V. All rights reserved.

Mustafa F.I.,Solar Energy Research Center | Gupta S.,Panjab University | Goyal N.,Panjab University | Tripathi S.K.,Panjab University
AIP Conference Proceedings | Year: 2011

We have made diodes consisting of the same alloy i.e. SbxSe 1-x (x=0.4, 0.5, 0.6 and 0.7), but change the concentration of Sb metal from 40% to 70% atomic weight percentage. It is observed from the Hall measurements that the nature of charge carriers have changed from p- to n-type at x=0.6 for SbxSe1-x. We have measured I-V characteristics of four p-n junction diodes i.e. p-Sb2Se 3/n-Sb3Se2, p-Sb2Se 3/n-Sb7Se3, p-SbSe/n-Sb3Se 2, p-SbSe/n-Sb7Se3. From the I-V plots we have calculated the parameters as built-in voltage (Vbi), forward resistance (Rf), ideal factor (n), saturation current (I o), breakdown current (IBd) and breakdown voltage (V Bd). © 2011 American Institute of Physics.

Han I.-S.,Energy Materials and Convergence Research Center | Seo D.-W.,Energy Materials and Convergence Research Center | Kim S.-Y.,Energy Materials and Convergence Research Center | Woo S.-K.,Energy Materials and Convergence Research Center | And 2 more authors.
Nippon Seramikkusu Kyokai Gakujutsu Ronbunshi/Journal of the Ceramic Society of Japan | Year: 2014

Reaction sintered Si/SiC composite was fabricated to apply to a solar absorber and the fabricated material was evaluated on its basic properties and performance. SiC and carbon black were mixed to shape a honeycomb with a multi-channel via vacuum extrusion process. The Si/SiC honeycomb material was also fabricated with less than 5% of pores by molten silicon infiltration in vacuum. The sintered density and porosity of the fabricated material, and the 3-point bending strength at room temperature and high temperature (11001300° C) were measured and the thermal conductivity at room temperature and 1100°C were also analyzed. In addition, the fabricated honeycomb material was modulized and installed to a solar absorber system to measure the outlet air temperature and thermal efficiency and evaluate the performance of honeycomb material as a solar absorber material. © 2014 The Ceramic Society of Japan.

Al-Ammri A.S.,University of Baghdad | Ghazi A.,University of Baghdad | Mustafa F.,Solar Energy Research Center
Proceedings of 2013 International Renewable and Sustainable Energy Conference, IRSEC 2013 | Year: 2013

This paper deals with the study of the dust characteristics and its effect on the performance of street photovoltaic cells in Baghdad-Iraq. Sample of accumulated dust on the surface of the solar panels at height 26 meters have been microscopy examined with 100x magnification. The results show that, varies in size, shape and disruption. The morphology of dust particles has irregular forms, tends to be spherical and not all of them are completely opaque. VOC (group of carbon-based chemicals that easily evaporate at room temperature), which is most of them comes from the refineries causes a large adhesion to the dust particles in the installed solar panel. © 2013 IEEE.

Maestre J.M.,University of Seville | Ridao M.A.,University of Seville | Kozma A.,Catholic University of Leuven | Savorgnan C.,Catholic University of Leuven | And 10 more authors.
Optimal Control Applications and Methods | Year: 2015

SUMMARY In this paper, we analyze and compare five distributed model predictive control (DMPC) schemes using a hydro-power plant benchmark. Besides being one of the most important sources of renewable power, hydro-power plants present very interesting control challenges. The operation of a hydro-power valley involves the coordination of several subsystems over a large geographical area in order to produce the demanded energy while satisfying constraints on water levels and flows. In particular, we test the different DMPC algorithms using a 24-h power tracking scenario in which the hydro-power plant is simulated with an accurate nonlinear model. In this way, it is possible to provide qualitative and quantitative comparisons between different DMPC schemes implemented on a common benchmark, which is a type of assessment rare in the literature. Copyright © 2014 John Wiley & Sons, Ltd.

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