jtire
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Abstract: This paper reports on the effect of reverse bias (RB) on dye-sensitized solar cells (DSSCs) that were investigated outdoor in Wajir (1o44’50’’ North, 40o 4’ 8’’ East), Vihiga (35o0’ East, 0o15’ North), Kitui (3o 0’ South, 37o 50’ East) and Kajiado (360o 5’ East, 30o 0’ South) in Kenya. The DSSCs’ J-V characteristics, namely, Voc, Jsc, FF and η, were studied under varied RB potentials. This was achieved through partial, as well as complete shading of the DSSCs during their operation in the study sites, using a thick piece of black cloth, and measuring the obtaining J-V characteristics. Findings of the study reveal that subjecting the DSSC module that was investigated in Wajir to RB of between 1V and 4V triggered between 25.53% and 23.53% drop in the module’s efficiency (η), followed by its total breakdown thereafter. The modules studied in Vihiga, Kitui and Kajiado exhibited a similar trend, but with variations in η under the different RB regimes. The DSSCs’ breakdown under RB regimes of over half their voltage ratings could be attributed to the damaging of their dye constituents. These findings are important for context-informed DSSC dye choices, as well as DSSC-integrated designs that appeal to local cultural textile fabrics, like shawls, kanzu (long robes) and light coats that women and men dress in, respectively, in Wajir, and blankets that both men and women wrap around their shoulders in Kajiado, as well as in local architectures. The findings underscore the existence of vast prospects for localized industries that innovate in DSSC-integrated designs for local espousal. They could form foundations for programs that mentor people, especially children and youths at local levels to engage in climate change-mitigating enterprises. Keywords: Dye sensitized, shading, textile fabrics, architecture. |
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Abstract: Carbon black (CB) and multi-wall carbon nanotube (MWCNTs) supported cobalt, namely, CoPc/CB and CoPc/MWCNTs, respectively, with different metal loads was synthesized and used as the cathode catalyst for anion exchange membrane fuel cells. The prepared catalysts were characterized using X-ray diffraction and scanning electron microscopy. The surface morphology analysis revealed heterogeneous cobalt distribution on the carbon support. Cyclic Voltammetry was also studied to investigate the best combination ratio. The results indicated that the electrochemically largest active surface area was observed when 30 and 40 wt% cobalt was combined with 70 wt% CB and 60 wt% MWCNTs, respectively. The anion exchange membrane fuel cell performance showed that both cathode catalysts exhibited the highest peak power density at 40 wt%t. Co load. The peak power density of 55 mW/cm2 at 0.4 volts was obtained using CoPc/CB. Meanwhile, the promising catalyst CoPc/MWCNTs only produced 35mW/cm2, which did not meet the expectation. According to some references, the alkaline fuel cell performance might be bothered by the acid residues, sulfates and nitrates produced by the MWCNT purification process. Keywords: Anion Exchange Membrane Fuel Cell, multi-walled carbon nanotubes, carbon black, cobalt phthalocyanine, catalyst. |
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Abstract: Solar Chimney Power Plants (SCPP) – also known as Solar Updraft Power Plants – consists in a structure composed by a glass collector, placed in a few meters from the ground, with a chimney in its center, in order to promote a pressure differential and consequently a heated air flow. On the bottom of the chimney, a turbine convert the kinetic energy from the heated airflow in electric power. Many mathematical and numerical methods for predict the performance of this kind of renewable energy plant have been conducted, but always with a divergence among them. The main objective of this work is to compare the mathematical methods of evaluation the overall performance, as well to propose a more accurate mathematical method, comparing all results with Manzanares Plant and other methods in the literature. Two approaches were studied and then modified: one based on continuity and momentum equation and the other based on the sum of all pressure drops along the system. The main reasons of the difference between the models analyzed are highlighted. The results shows that one of the proposed methods leads to a divergence of only 1.3% when compared to Manzanares pilot plant, i.e., with an excellent agreement with experimental data. Keywords: Solar chimney, Solar energy, Renewable energy, Heat transfer, Solar tower. |
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Abstract: Fungi have a prominent status in fermentation for the production of different bio-products. Endophytic fungi isolated from medicinal plants are particularly formidable in their adaptability to solid state fermentation as an extension of its natural habitat and are also a potent source of broad-spectrum cellulolytic enzymes. We report for the first time the use of endophytic fungus isolated from Aegle marmelos for enhanced cellulolytic enzymes production from groundnut shell (GNS) as substrate. ImageJ software identified Trichoderma harzianum as an endophytic fungus having maximum radial growth rate. A systematic comparison of the endophytic fungus with Aspergillus oryzae, under solid state fermentation (SSF) and submerged fermentation (SmF) conditions was performed and enhanced cellulase production was observed by the endophytic fungus (4.27 FPU/ml) under SSF environment compared to SmF (2.35 FPU/ml). A comprehensive understanding of the systemic breakdown in the structural integrity of the biomass has been achieved using a synergy of enzyme assay protocols, spectral and thermal based techniques. The use of endophytic fungi in SSF systems in our study lays the basis for the production of other industrially important enzymes. The present study opens the door for the synergistic use of endophytic and epiphytic fungi for the production of cellulolytic enzyme. Keywords: Fermentation, Biomass, Fungi, Extraction, Agricultural Wastes. |
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Abstract: The electrical power output of photovoltaic (PV) cell depends on its operating temperature during its absorption of solar radiation and conversion of solar energy to electrical energy. The increase in PV panel temperature due to overheating negates its electrical yield and efficiency. In addition, overheating causes hot spots, failure of adhesive seals and delamination. An effective way to combat this problem is to reduce the operating temperature of PV panel by cooling. In the present work, a novel thermal management technique for improved cooling of flat PV panel is proposed with the use of serrated fins rather than straight fins. For this reason, the thermal and electrical performance of the flat PV panel with cooling system consisting of duct, brushless DC cooling fan, a plate fin and serrated fins of varying angles (30˚, 45˚and 60˚) made up of aluminium were investigated experimentally. Experiments were conducted at constant wind velocity (1 m/s) with the developed technique in the location of Tiruchirappalli (78.6 E to 10.8 N), Tamil Nadu, India with flat 10 W PV panel. By using serrated fins of varying angles of 30˚, 45˚, 60˚ and plate fin (90°), the temperature of the PV panel decreased by a maximum of 4˚C, 7˚C, 6˚C and 3˚C respectively. Similarly the PV power increased in the range of 15.38%, 61.53%, 41.53% and 7.69% for 30˚, 45˚, 60˚ and plate fin (90°) respectively. It is concluded that 45˚ angled serrated fin is more efficient in providing the cooling effect than the other angles of serrated fins considered. Keywords: Photovoltaic, serrated fin, thermal management, heat transfer, IV characteristics. |