Abstract: In this study, the effects of the positions of inlet and outlet in a single-flow flat plate rectangular box active solar air heater due to convective heat transfer were designed, constructed, theoretically investigated using CFD fluid flow (fluent) software, and experimentally examined. The internal dimensions of the solar air heater are length and width of 100 cm and 50 cm, respectively, and the air gap between absorber plate and glazing glass is 9 cm. The solar air heaters are constructed with 18 mm thickness plywood, 4 mm thickness glazing glass, and 1 mm thickness aluminium sheet metal. Except for the glazing glass, other construction materials are painted black to absorb solar radiation. The positions of the inlet and outlet depend on the fraction of the width of the solar air heater. Based on the three-day average outlet temperature of the solar air heaters, solar air heater B has the highest average outlet temperature compared with other active solar air heaters and ambient air temperatures. Based on the three-day average outlet temperature of solar air heaters and ambient air temperatures, the active solar air heater B outlet temperature is 33.83 percent greater than the ambient air average temperature. The average outlet temperature of the air in passive solar air heaters increased by 17% and 4.43% compared to ambient air and active solar air heaters outlet air temperatures, respectively, due to the speed of the air in the solar air heater. The uncertainty of the instruments to measure the temperature of the air is 0.289°C, and the uncertainty of the solar air heater is 0.462°C. A higher average air outlet temperature was achieved in March at a tilt angle of 12° at a latitude of 8.89°. The negative tilt angle in May at a latitude of 8.89° indicates the south-facing orientation of solar air heaters is better. The passive solar air heater and ambient air temperature have a higher air temperature fluctuation than the active solar air collector. PubDate: Fri, 06 Oct 2023 06:50:01 +000
Abstract: The study intends to present the bioenergy potential in Ethiopia using major sources of biomass generation. The study utilized data from secondary sources to generate the potential using the available biomass sources within the country. In order to determine the bioenergy potential, four residue biomass sources, including livestock manure, crop residues, forest residues, and municipal solid waste (MSW) from major cities, were considered. The Food and Agriculture Organization Corporate Statistical (FAOSTAT) Database as well as national and local reports were used to compile information on crops, forests, animals, and human populations. The potential of each source is estimated for 2020-21 as the base year. The total bioenergy potential of the country is estimated to be 2955 petajoule (PJ) per year, with 56.01% of it coming from forest residue, 28.29% from crop residue, 15.36% from livestock waste, and 0.33% from MSW. In addition, it is estimated that 819.7 terawatt hours (TWh) of electricity may be generated from all sources yearly. This is equivalent to around 8, 58, and 89 times Ethiopia’s total primary energy consumption, electricity production, and electricity net consumption in 2020, respectively. Results also demonstrated that the total potential (819.7 TWh·y−1) is roughly 56% greater than the forest residues’ potential alone (459 TWh·y−1). This implies that biomass resources might be crucial in assisting Ethiopia to fulfill its future energy needs. To fully realize the availability of biomass energy, the study suggests performing integrated development research, choosing the best feedstock and value chains for bioenergy, and creating a bioenergy database. PubDate: Fri, 11 Aug 2023 06:20:01 +000
Abstract: This work evaluates the performance of optimal hybrid PV/battery and PV/diesel generator renewable energy systems for a remote village in Burkina Faso. Based on socioeconomic data and the household sample survey, a technoeconomic simulation and optimization model of electrical loading are presented. Ant colony optimization (ACO) and the loss of power supply probability (LPSP) algorithms were used for the search of the optimal hybrid power system. For the selected village location, the results have shown that the hybrid PV/battery system represents the best renewable energy solution due to abundant solar irradiation and carbon emission free compared to the conventional diesel generator (DG) or PV/DG system. To reach the estimated load power demand of 2150 kWh for the studied location, optimized PV/battery configuration sizing required 650 PV modules of 250 W and 715 batteries of 300 Ah. The economical evaluation reveals a cost investment of about 1,293 025.7 USD for a lifetime of 25 years in comparison of that of PV/DG and DG systems, which are 1,088 701.9 USD and 1,682 850.6 USD, respectively. However, environmental and atmospheric pollution is minimized with a saving of more than 17943 tons of CO2. Therefore, the production of electricity from the PV/battery system leads to better competitiveness reliability for a socioeconomic development of studied remote villages. PubDate: Sat, 27 May 2023 08:50:00 +000
Abstract: The increased electricity demand amidst inadequate electricity generation in South Africa has plunged the country into frequent power outages and load shedding. However, the country still has the lowest electricity transmission and distribution losses in sub-Saharan Africa. Despite low losses, there is still an opportunity to reduce losses further and reduce power outages and load shedding. This study examines the determinants of electricity transmission and distribution losses in South Africa. The results will inform policymakers on avoiding higher electricity transmission losses to alleviate the current electricity shortfall. Using the time-series data from 1971–2020 and the autoregressive distributed-lag (ARDL) bounds testing approach to cointegration, the study confirmed a long-run relationship between electricity transmission, distribution losses, and income, price, investment, political regime, and economic integration. Regression analysis from the ARDL methods revealed that investments, political administration, and economic integration positively influence electricity transmission and distribution losses. At the same time, income reduces electricity transmission and distribution losses in the long run. However, income, price, and economic integration minimize electricity transmission losses in the short run while the remaining variables maintained their positive effects. The implication is that without proper checks in place, an expansion in South Africa’s economic integration, investment, and democracy may negatively affect the electricity sector of the country through an increase in electric power losses, while higher income will help the industry via lower electric power losses. The paper, among other things, recommends building a robust economy to ensure lower levels of electricity transmission and distribution losses. PubDate: Sat, 13 May 2023 06:20:00 +000
Abstract: The standalone vapour-based multistage solar still with stacked stages (MSS-SS) belongs to a pool of widely studied small-scale water desalination devices through solar thermal energy. This work contributes to the body of knowledge by presenting a system with new configurations. There is a need to develop small-scale systems to be reliable devices for freshwater provision, as brackish water is available for processing. The experimental study was conducted in a field under actual weather conditions, with the data logged and analysed to study the systems’ behaviour under varying meteorological conditions. A maximum distillate yield of 7790 ml, corresponded to a maximum daily average solar radiation at high range. There was a 21.8% decrease to 6090 ml at moderate daily average range and a further decline of 80.5% to 1190 ml in the low daily average range, representing a significant drop in the distillate yield caused by the insufficient heat collection at low range. The high, moderate, and low ranges corresponded to summer, spring and autumn, and winter, respectively. The lower values of the moderate range were the most optimum operationally. The impulsive modes were ideal for high rates of the heat inputs, while the continuous were for low rates. The assumption of a continuous mode and a further increase in the rate of thermal energy input caused thermal damage necessitating the augmentation of the thermal energy storage (TES) device due to a larger collector-to-basin area (CBA) ratio. The distillate yield trends from the stages were dynamic and were the inverse of the stage temperature, which was dictated by the mode and rate of the thermal energy input. These trends were such that stage 5 > 3 > 2 > 1 > 4 at moderate to high ranges and changed a low range. The summer season enhanced the cumulative saline water (SW) preheating and heat recovery to 66.8°C. The economic analysis found that at its most productive level, the cost of producing water per litre (CPL) from the vapour-based MSS-SS was R 4.05. The small-scale water purification systems are helpful, especially in remote areas. PubDate: Tue, 28 Mar 2023 10:20:01 +000
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