Renewable Energy Resources and Technologies
Tsutomu Dei; Hossen Iddi Kayumba; Julius Agaka Yusufu
Abstract
This research explores biomass gasification for power generation in rural areas of developing countries, utilizing a 20 kW U-flow-shaped gasification system developed at Ashikaga University. While small-scale power systems typically rely on reciprocating or modified diesel engines, which face issues ...
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This research explores biomass gasification for power generation in rural areas of developing countries, utilizing a 20 kW U-flow-shaped gasification system developed at Ashikaga University. While small-scale power systems typically rely on reciprocating or modified diesel engines, which face issues due to tar produced by biomass gasifiers, this study employed a piston-less rotary engine. Performance evaluations were conducted at various engine speeds and gasifier operational modes, demonstrating continuous power generation for approximately six hours. Improved maintenance of rotary engines could benefit rural users, with potential efficiency gains through thermal energy recovery, although tar filtration needs enhancement. The experimental findings reveal continuous power generation for approximately six hours under both operational conditions, with the closed-top operation outperforming the open-top counterpart in terms of power output. However, control over power output and gasifier temperatures is more straightforward in the open-top operation. Gasifier performance was assessed based on fuel consumption rate and system efficiency, with consumption rates varying by rotary engine speed, measuring 2.0 kWh/kg at 2800 rpm and 2.3 kWh/kg at 3200 rpm, and 2.9 kWh/kg at 3600 rpm. Cold gas efficiency of the U-shaped gasifier was 63.4%, and energy conversion efficiency reached 9.4% at 2800 rpm operation. At 3200 rpm operation, cold gas efficiency improved to 79.8%, but energy conversion efficiency decreased to 7.3%. The rotary engine's energy conversion efficiency was lower than that of a gas engine. Nonetheless, if the rotary engine reduces maintenance needs, it could benefit rural users. Efficiency can be improved through thermal energy recovery.
Renewable Energy Resources and Technologies
Ahmed H. Mohammed; Ahmed N. Shmroukh; Nouby M. Ghazaly; Abd Elnaby Kabeel
Abstract
investigated in the weather conditions of Qena, Egypt, at a location of (Latitude: 26.16°, Longitude: 32.71°). Boosting the output of the pyramid solar still is the primary focus of the proposed strategy. To achieve this, four basins were built and integrated into the pyramid solar still, with ...
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investigated in the weather conditions of Qena, Egypt, at a location of (Latitude: 26.16°, Longitude: 32.71°). Boosting the output of the pyramid solar still is the primary focus of the proposed strategy. To achieve this, four basins were built and integrated into the pyramid solar still, with their size increasing in proportion to the surface area of the condensing glass. A 25% increase in basin area per square meter of solar still was achieved compared to conventional pyramid solar still (CPSS) with the same condensing cover area. The thermal performance and productivity of the suggested solar still were demonstrated by developing energy balance equations for temperature components and then analytically computing their solutions. The results showed compatibility between theoretical and experimental results. The highest yields for CPSS were 2524 mL/m2, and for MPSS, they were 3415 mL/m2. The stepped area enhanced the yield by 35.3% compared with CPSS. Moreover, the efficiency of CPSS and MPSS was recorded as 23.5% and 31.7%, respectively. Furthermore, the maximum yield of freshwater was obtained for the northern condensing cover, with the recorded value reaching 1174 mL/m2. Distilled water under the proposed system would cost $0.0179 per liter. Finally, the TDS and pH levels are in accordance with WHO recommendations for the quality of drinking water.
Renewable Energy Resources and Technologies
Armin Motamed Sadr; Mehran Ameri Mahabadi; ٍٍEbrahim Jahanshahi Javaran
Abstract
In this research, the performance of an asphalt solar air collector was experimentally tested and the daily thermal and exergy efficiencies of the collector were analyzed. The sun's radiant energy is absorbed by asphalt and converted into thermal energy. Then, it is transmitted to aluminum pipes buried ...
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In this research, the performance of an asphalt solar air collector was experimentally tested and the daily thermal and exergy efficiencies of the collector were analyzed. The sun's radiant energy is absorbed by asphalt and converted into thermal energy. Then, it is transmitted to aluminum pipes buried under the asphalt and, finally, to the air passing through the pipes. A suction fan induces the ambient air to the collector. The experimental results show that the daily thermal efficiencies at mass flow rates of 0.007 (kg/s) and 0.014 (kg/s) are 11.98 % and 24.10 % and daily exergy efficiencies are 0.34 % and 0.66 %, respectively, showing the increase in daily energy and exergy efficiencies with increasing the air mass flow rate. In addition, results show that as the flow rate increases, the outlet air temperature decreases. The presence of temperature difference between the inlet and outlet of the collector in the last hours of the day, when the sun's radiation islow, indicates that asphalt acts as a thermal energy storage medium.
Renewable Energy Resources and Technologies
Mohammad Reza Shekari; Seyed Mohammad Sadeghzadeh; Mahdi Golriz
Abstract
In recent decade, Perovskite Solar Cells (PSCs) have received considerable attention compared to other photovoltaic technologies. Despite the improvement of Power Conversion Efficiency (PCE) of PSCs, the chemical instability problem is still a matter of challenge. In this study, we have fabricated two ...
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In recent decade, Perovskite Solar Cells (PSCs) have received considerable attention compared to other photovoltaic technologies. Despite the improvement of Power Conversion Efficiency (PCE) of PSCs, the chemical instability problem is still a matter of challenge. In this study, we have fabricated two kinds of PSCs based on gold and carbon electrodes with the optimal PCE of about 15 % and 10.2 %, respectively. We prepared a novel carbon electrode using carbon black nanopowder and natural graphite flaky powder for Hole Transport Material (HTM) free carbon-based PSC (C-PSC). Current density-voltage characteristics over time were measured to compare the stability of devices. Scanning Electron Microscope (SEM) and Energy-dispersive X-ray Spectroscopy (EDS) analyses were carried out to study applied materials, layer, and surface structures of the cells. The crystal structure of perovskite and its association with the stability of PSCs were analyzed using an obtained X-ray diffraction (XRD) pattern. As a result, the constructed HTM-free C-PSC demonstrated high stability against air, retaining up to 90 % of its optimal efficiency after 2000 h in the dark under ambient conditions (relative humidity of (50 ± 5); average room temperature of 25 °C) in comparison to constructed gold-based PSCs (Gold-PSC) which are not stable at times. The experimental results show that novel low-cost and low-temperature carbon electrode could represent a wider prospect of reaching better stability for PSCs in the future.
Renewable Energy Resources and Technologies
Mojtaba Moravej; Fatemeh Namdarnia
Abstract
Solar water heaters are good tools for saving fuel. The main component of these water heaters is collectors, which are responsible for absorbing solar energy and transferring it to the working fluid with the least heat dissipation. The present study is an experimental study of the performance of the ...
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Solar water heaters are good tools for saving fuel. The main component of these water heaters is collectors, which are responsible for absorbing solar energy and transferring it to the working fluid with the least heat dissipation. The present study is an experimental study of the performance of the solar semispherical collector with 1 m2 of absorber area at different volumetric flow rates. Water was used as the working fluid with the volumetric flow rate between 0.005-0.0166 kg/s, and the experiment was conducted in the ASHRAE 93 standard conditions. The results showed that the efficiency of semispherical solar collector increased as the flow rate of the working fluid increased, such that the highest efficiency, which is 67%, belonged to mass flow rate 0.0166 kg/s. In addition, the difference between outlet and inlet temperatures decreased due to the system being closed during the test. In addition, according to the experiments, the reduction of radiation and wind speed did not have any significant effect on the efficiency and outlet temperature of the collector. Finally, parameters such as inlet and outlet temperature of collector, ambient temperature, ambient radiation intensity and their effect have been investigated empirically on the collector efficiency graph.
