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CONTENTS
Volume 8, Number 1, March 2021
 


Abstract
The application of Photovoltaic (PV) power in the building sector, is expanding as part of the ongoing energy transition into renewables. The article addresses the question of sustainability of energy generated from PVs through an environmental assessment of a building-integrated PV system (BIPV) connected to the grid through net metering. Employing retrospective life cycle analysis (LCA), with the CCaLC2 software and ecoinvent data, the article shows that the carrying structure and other balance of system (BOS) components are responsible for a three times higher energy payback time than the literature average. However, total environmental impact can be lowered through reuse or reinstallation of PVs on the same building structure after the 30-year interval. Further ways to improve environmental efficiency include identifying the most polluting materials for each LCA parameter. The results of this study are of interest to researchers and producers of PVs and organizations investing and promoting decentralized power production through PVs.

Key Words
building-integrated photovoltaic systems; life cycle analysis; CO2 emissions; EPBT; sustainability

Address
Demetrios N. Papadopoulos, Constantinos N. Antonopoulos and Vagelis G. Papadakis: Department of Environmental Engineering, School of Engineering,University of Patras, Seferi Str 2, 30100, Agrinio, Greece


Abstract
In this study, the first law of thermodynamics was used to establish a one-dimensional (1-D) thermal model for parabolic trough receiver (PTR) taking into account the pressure drop and kinetic energy loss effects of the heat transfer fluid (HTF) flowing inside the absorber tube. The validation of the thermal model with data from the SEGS-LS2 solar collector-test showed a good agreement, which is consistent with the previously established models for the conventional straight and smooth (CSS) receiver where the effects of pressure drop and kinetic energy loss were neglected. Based on the developed model and code, a comparative study of the newly designed parabolic trough Scurved receiver versus the CSS receiver was conducted and solar unit's performances were analyzed. Without any supplementary devices, the S-curved receiver enhances the performance of the parabolic trough module, with a maximum of 0.16% compared to CSS receiver with the same sizes and mass flow rates. Thermal losses were reduced by 7% due to the decrease in the temperature of the outer surface of the receiver tube. In addition, it has been shown that from a mass flow rate of 9.5 kg/s the heat losses of the S-curved receiver remain unchanged despite the improvement in the heat transfer rate.

Key Words
1-D thermal model; conventional straight receiver; kinetic energy loss; pressure drop; S-curved receiver

Address
Yassine Demagh: LESEI, Mechanical Department, University of Batna 2, 05000 Batna, Algeria

Abstract
Electrochemical double-layer capacitors (EDLCs) based on solid polymer electrolytes (SPEs) have gained an immense recognition in the present world due to their unique properties. This study is about preparing and characterizing EDLCs using a natural rubber (NR) based SPE with natural graphite (NG) electrodes. NR electrolyte was consisted with 49% methyl grafted natural rubber (MG49) and zinc trifluoromethanesulfonate ((Zn(CF3SO3)2-ZnTF). It was characterized using electrochemical impedance spectroscopy (EIS) test, dc polarization test and linear sweep voltammetry (LSV) test. NG electrodes were made using a slurry of NG and acetone. EIS test, cyclic voltammetry (CV) test and galvanostatic charge discharge (GCD) test have been done to characterize the EDLC. Optimized electrolyte composition with NR: 0.6 ZnTF (weight basis) exhibited a conductivity of 0.6 x 10-4 Scm-1 at room temperature. Conductivity was predominantly due to ions. The electrochemical stability window was found to be from 0.25 V to 2.500 V. Electrolyte was sandwiched between two identical NG electrodes to fabricate an EDLC. Single electrode specific capacitance was about 2.26 Fg-1 whereas the single electrode discharge capacitance was about 1.17 Fg-1. The EDLC with this novel NR-ZnTF based SPE evidences its suitability to be used for different applications with further improvement.

Key Words
electrochemical double-layer capacitors; natural graphite; natural rubber; single electrode specific capacitance; solid polymer electrolytes

Address
Nanditha Rajapaksha, Kumudu S. Perera and Kamal P. Vidanapathirana: Polymer Electronics Research Group, Department of Electronics, Wayamba University of Sri Lanka, Kuliyapitiya, Sri Lanka


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