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Item Synthesis of Crystalline Nanocellulose Its Effect on the Mechanical Properties of E-Glass Fiber-Epoxy Composite for Prosthetic Shank Applications(Addis Ababa University, 2023-03) Betselot Tesfaye; Desalegn Wogaso (PhD); Eyobel Mulugeta (PhD) Co-AdvisorProsthetic shank is one of the prominent parts of prosthetic leg that transfers load from prosthetic socket to the foot section. Nowadays, it is common to use composite materials for prosthetics and orthotics applications. This research focuses on the synthesis and characterization of properties of crystalline nanocellulose (CNC) powder and investigating its effect on the mechanical and physical properties of E-glass fiber - epoxy composite for prosthetic shank applications. Different properties including tensile, impact, flexural, water absorption, thermographic, density and surface morphology of a hybrid composite are investigated. The research further targets to test the suitability of developed composite material for prosthetic shank applications. Extraction of CNC powder is performed using chemical extraction technique which involves alkali treatment, delignification, bleaching and acid hydrolysis. Crystallinity of CNC particles are determined at 2 values of 19.890, 44.040, 64.340 and 77.510. Crystallite size of these powders is found to be approximately 13 nm by x’pert high score software from the XRD analysis. FT-IR was conducted to determine fiber-fiber and fiber-epoxy chemical bonding interaction. Thermal properties of CNCs are examined using thermographic analysis (TGA) approch and the result reveals a three-stage decomposition of CNC powders in temperature ranges of 62-240 oC, 240-360 oC, and 360-625 oC, respectively. Hand layup method with light load compression is employed to fabricate hybrid composite specimens with different % CNC powder. Mechanical and physical tests are carried out to determine the composite’s performance according to ASTM standards. The results reveal addition of CNC powder enhances the overall performance of the composite, and composite specimen with 8wt% CNC powder shows superior mechanical and physical properties. The numerical values obtained was tensile strength of 127.8Mpa, compression strength of 91.1Mpa, flexural strength of 251Mpa, and impact energy of 6.83J. Further, selected composite is modeled for the prosthetic shank application using finite element software, ANSYS 2022, and maximum equivalent von Mise’s stress of 0.82598 MPa and deformation of 0.054065 mm are obtained. Based on the overall findings and analysis, it is highly recommended to develop and use hybrid E-glass fiber – CNC - epoxy composite as a substitute material for prosthetic shank applications.Item Investigation of Electric Injera Mitad with Copper Wire Embeddings for Performance Improvement(Addis Ababa University, 0202-11) Daniel Asrat; Abdulkadir Aman (PhD)Ethiopians make injera, a staple food, on a clay baking pan, mitad, with either biomass or electricity as the energy source. The existing electric mitads in the country are highly inefficient, demand high power, and consume significant energy. The clay plate of the appliance is produced and assembled traditionally and its poor thermal performance created overloading of the electric power distribution network and introduced high energy consumption to the consumer and the nation. Efforts to enhance the thermal properties of the clay plate are yet to address the practicability of casting and producing improved clay plates at the level of local producers. This study examines the effect of copper wire embeddings in the clay plate of electric injera mitad to improve its performance. The study investigated the development of a CuWE clay plate of electric mitad, determined its effect on performance, and compared this performance with other similar studies. The traditional methods of clay plate production were identified and the Controlled Cooking Tests were conducted. The investigation revealed that, for a triple baking test, 30 injera per baking test, the CuWE clay plate electric mitad's heat-up time, the maximum-to-minimum heat-up temperature difference, and energy consumption were reduced by 3 min, from 64.3 °C to 36.9 °C, and 110 Wh, respectively. Energy efficiency was improved by 10.8% as compared to the base case electric mitad; the cyclic baking time per injera was decreased by 0.6 minutes; the overall baking period, including heat-up time; the specific energy consumption; and the total energy consumption were reduced by 21 minutes, 0.09 kWh/kg of injera, 1.0 kWh, or 15.4%, respectively. It was revealed in the study that embedding copper wire in the clay plate of electric injera mitad improved baking surface temperature uniformity and injera quality; reduced energy consumption and time to bake. Local manufacturers can produce CuWE electric mitads without the aid of any special equipment or production techniques to reduce the huge impact of electric injera mitads on the power and energy demand of the country.Item Experimental Analysis of Biogas Production from Seven Types of Feedstocks (Mown Grass, Food Waste, Chicken Manure, Cattle Blood, Cattle Rumen Content, Pig Manure, and Cow Dung)(Addis Ababa University, 2023-07) Henok Girma; Ebrahim Tilahun (PhD)The significance and role of biogas in energy production and waste management are growing fast. The most determining factor for the gas composition and microorganism community in biogas production is the type of feedstock used. Biomass such as agricultural residues and livestock wastes are the major feedstocks for producing biogas. Ethiopia is one of the leading potential sources of agricultural and livestock wastes in Africa. Regardless of these resources, the majority of Ethiopians still lack access to clean energy. The feedstocks in most domestic biogas digesters constructed by the national biogas program of Ethiopia were mostly livestock (cattle) wastes. This study was conducted to assess the biogas potential of seven feedstocks that were as mown grass, food waste, chicken manure, cattle blood, cattle rumen content, pig manure, and cow dung under a controlled temperature of 40 ± 0.2 in a 500-mL laboratory scale batch digester. The feedstocks used in this experiment were subjected to characterization before and after digestion and the methane production was measured and normalized on a volatile solids basis. The maximum specific methane yield (mL/g VS) and methane percentages of the mown grass, food waste, chicken manure, cattle blood, cattle rumen content, pig manure, and cow dung were 231 and 79.4%, 82.12 and 67.9%, 177.99 and 77.8%, 173.06 and 68.6%, 350.3 and 77.1%, 127.05 and 77.6%, 32.88 and 69.9%, respectively. The chicken manure and cattle blood had the highest concentrations of hydrogen sulfide, producing 1249 and 1102 ppm, respectively. The grass, food waste and inoculum I also generated 805, 170, and 52 ppm of H2S within 28 days of the HRT. The obtained results showed that utilizing feedstocks beside cow dung could increase the quality and quantity of biogas production.Item Numerical Simulation and Performance Investigation of Bubble Pump Refrigerator(Addis Ababa University, 2023-10) Henok Habte; Solomon Teklemariam (PhD)Approximately 30% of the primary energy consumed worldwide is used for refrigeration. In light of the global search for sustainable energy sources and energy-efficient methods of operation, solar-powered bubble pump refrigeration systems have gained traction as an alternative means of satisfying cooling requirements. Diffusion absorption refrigerators, sometimes referred to as bubble pump refrigerators, are driven by low-grade energy sources such as solar, waste heat, and recovery heat and do not require any mechanical moving components. However, in comparison to other cooling options, this system's coefficient of performance (COP) has been low. To increase the system's efficiency, more research on the effects of various parameters is required. The objective of this study is to enhance understanding of the behavior of the system through an examination of the impact of several critical factors. Using the programs ASPEN PLUS and EES, a thorough numerical simulation was conducted after a thermodynamic and system model was created. Every simulation was run with a standard total pressure of 25 bars. The model was used to forecast how different factors, such as generator heat, concentration of the refrigerant in a rich solution, and refrigerant purity, would affect the system's performance. The significant impact of refrigerant purity at the rectifier's outlet on coefficient of performance (COP) was one of the key finding. It was discovered that the COP rose from 0.15 to 0.36 as the purity improved from 0.950 to 0.999. It was also noted that a generator temperature of 200oC at 240W of thermal input was optimal at 25 bars of total system pressure. Additional heat rises did not appear to have a noticeable impact on the performance of the system. The one thing that makes this research stand out is the study of the effect of hydrogen on the COP of the system. It was observed that both heat absorbed at the evaporator (Qevap) and COP increased steadily and with similar degree of increments as hydrogen mass fraction increased from 0.5 to 0.95. This is due to the higher reduction of the partial of the refrigerant at evaporator inlet causing the refrigerant to lower its temperature further. Generally speaking, with more research done, the bubble pump refrigeration holds a lot of potential to take the place of traditional cooling technologies.Item Parabolic Trough Solar Collector Design, Modeling and Simulation for the Application of Industrial Parks: A Case Study of Bole Lemi Industrial Park(Addis Ababa University, 2022-07) Mengesha Abreha; Tilahun Nigussie (PhD)Despite the need for additional research to bring concentrator solar plants up to a competitive economic level, molten salt integrated parabolic trough solar collector plants produce essentially lower levels of carbon dioxide than conventional power systems. Priority study areas in the thermal engineering applications for the textile industry include the optimal design, mathematical modeling, performance simulation, and cost investigation of parabolic trough solar power plants. This thesis is concentrated on the dynamic modeling of 50 MWe parabolic solar trough collector up-scaled versions for power supplies in Bole Lemi Industrial Park. Prior evaluations was carried out to choose the finest collector and receiver geometry, heat transfer fluid ,solar field design points and energy storage systems based on diverse determination criteria. In addition to satellite driven solar resource data collected from NASA, direct normal irradiance (DNI) on daily and monthly basis were measured using Payranometer.The solar field components then coordinated into power generating module and the systems performance was simulated to create genuine working environment. The input parameters such as declination angle, azimuth angle, hour angle and equation of time were analyzed using empirical equations. Assessment of daily global solar radiation and sun shine duration at the case study area was conducted using Meteonorm8 .Taking all the collected primary and secondary data, comprehensive numerical simulation of parabolic trough solar power plant employing System Advisor Model (SAM) was developed. The average monthly DNI as function of thermal power produced on the field, monthly energy generation, thermal cycle efficiency and levelized cost of energy with solar multiple were plotted in order to investigate their correlation pattern. The simulated time series yield showed that maximum annual power cycle efficiency of the system to be 25.5% and the maximum average thermal power output occurred in the months of January through April and November through December. The findings were further cross checked with similar previous scientific works using common parameters and fair agreement has been achieved, illustrating the proposed technology is applicable for any industrial application.Item Bussing Machine Improvement of 20MW/Year Solar Panel Production Line: A case study of Ethiopian Power Engineering Industry (Sandafa)(Addis Ababa University, 2022-09) Samrawit Temesgen; Kassahun Yimer (PhD)Ethiopia has plenty of sunshine months compared to the developed world and other African countries by recording 80% of solar energy potential. However, currently the one and only renewable energy industry is the “Ethiopian Power Engineering Industry” that stopped the production of the PV panels, due to lack of management skills and economic problems to be competitive on the PV market in assembling the solar cell in the industry continuously. On this research, knowledge based technical solutions given to the management and the supervisor of the industry, while the industry has faced a technical problem on the solar cell connecting machine/bussing machine which means the machine has stopped connecting the solar cells. Data collected from the internet, site survey and questionnaire in order to analyze the problems. Based on the data collected this paper presents innovative solutions with three solar cell connecting technology for the technical problem of the bussing/solar cell connecting machine of the 20MW/year PV panel production line in the industry. By comparing these innovative solar cell connecting technologies for the bussing machines simulation run with the software Griddler 2.5 for the bus bars variations the I-V characteristics, power output and the Fill Factor effect of the solar cells simulated. However, currently the industry is using the 2 Bus Bars (2BB) technology produced by the bussing machine but from the output of the software smart wire solar cell connecting technology is preferable. A recommendation was made for the industry economically to apply the smart wire solar cell connecting technology and it is recommended that to do more researches on this technology.Item Adama II Wind Farm Long-Term Power Generation Forecasting Based on Machine Learning Models(Addis Ababa University, 2022-08) Solomon Terefe; Mesfin Belayneh (PhD)Currently, renewable energy production from wind farms with hundreds of megawatts connected to the grid is increasing. Wind energy is intermittent and random due to being highly dependent on wind speed nature, hence grid interconnection among nations of the Eastern Africa region plans face reliability issues. Accordingly, Ethiopian Electric Power needs to diligently plan ahead of time the allocation of generating units in its power plants to match its national and regional energy demand (MW) because if the demand is higher than the generation it can cause several blackouts resulting in a huge loss to the economy; on the other hand, if the generation is higher than the demand the extra electricity will be wasted and it can also create an unnecessary load on the transmission lines. This thesis studies the power production performance analysis of the Adama II wind farm using MATLAB SIMULINK with scenarios of fault ride-through capability, short circuit fault, control fault, and wind speed variation impact. Furthermore, conducting long-term wind power forecasting to safely national and regional grid integration by applying basic time series models SARIMA and then extended to linear regression, random forests, and XGBoost to accurately forecast the Power output of the wind turbine. Impact and performance analysis result has observed a short circuit and control fault on the grid interconnection point occur will bring a grid disturbance to the power system. But a rapid speed variation will be composited by the farm’s reactive power supply. Moreover, Adama II wind farm delivery 0MW upto 153MW power to gird, during maintenance and some grid and turbine faults it failed to delivery as its capacity. Main reason to downtime is due to grid fault, night time due to light load at night Adama II wind farm don’t have voltage regulator to cop up its power fluctuation. Furthermore, the thesis developed a one-year ahead forecasting model to improve the Adama II wind power plant grid integration impact for reliable plant operation and maintenance schedule. The study tests 1 hour, 1 week, and 12 months. 1-hour ahead and 1-week ahead forecasting using SARIMAX, Elastic net, and Random Forest regression give around 90% R2 score and 2~4% MAPE using lag variables for short-term 1-hour ahead and 1-week ahead forecasts. But for more than 1 month ahead forecasting XGBoost (with Fourier terms for seasonality) performs very well for longer forecast windows.Item Field-Based Performance Evaluation of Three Household Biogas Digesters: the Case of Holeta, West of Addis Ababa, Ethiopia(Addis Ababa University, 2022-11) Tariku Messele; Ebrahim Tilahun (PhD)Biogas is one of clean, and alternative renewable energy source obtained through anaerobic digestion of readily available organic waste materials. Ethiopian government have been actively engaged in disseminating biogas technologies into the country science 2009. Until Jan, 2022, total of 35,626 domestic biogas digesters were constructed through consecutive three phases. The biogas digester functionality rate is 79%, however only 30% of the constructed biogas digesters were functioning without significant problem. The performance of a biogas plant is mainly dependent on the input feedstock characteristics, the microbial activity (condition inside the bio-digester), and process conditions and parameters including pH., temperature, and etc. This study evaluated the performance of three household anaerobic bio-digester to which generates biogas from cattle dung. The bio-digesters selected through purposive sampling in Holeta west of Addis Ababa. The finding of the study indicated that the biochemical theoretical methane potential was 60%, while the actual methane percentage was 51%. The total solid, volatile solid, and chemical oxygen demand removals resulted as 37.7%, 26.7%, and 70.7%, respectively. The result shows lower digestibility, this is due to unstable alkalinity, temperature, and pH level. Sulfate-reducing bacteria had also an effects in the methanogenic bacteria’s performance. The maximum hydrogen sulphide amount contained in the biogas was 651 ppmv, which is caused by high sulfur content on the feedstock. The study concluded that improper management, lack of monitoring of installed biogas digesters, poor construction quality, are among the challenges that have derailed the sustainable implementation of, and household biogas production in the country. Unless these problems are addressed, the functionality rate of bio-digesters in Ethiopia could not been improved.Item Assessment of Energy Consumption in Brewery Industry: Case Study in Dashen Brewery(Addis Ababa University, 2022-10) Zewge Worku; Solomon TekleMariam (PhD)Dashen Brewery factory is one of the biggest energy consuming brewery factory in Ethiopia. There are many processes involved in the manufacture of beer and these processes involve the use of thermal energy generated with heavy fuel oil and also electricity to drive pumps, motors, compressors, lighting and others. The 2019 of the factory energy bill data showed that the total electricity consumption of factory was around 36.2GWh and a thermal energy (heavy fuel oil) consumption of 96346.5GJ. The specific energy consumption of the factory for both thermal and electricity has been analyzed and compared with the international best performed factories. This has been done by collecting the historical energy consumption and production data of the factory. The purpose of this assessment is to identify energy saving opportunities and to recommend possible measures with their technical and financial feasibilities. To conduct this assessment different similar studies on breweries were assessed and detail analysis were not observed in many of the researches especially on leakage testing on air compressors, saving calculations from heat loss on valves and flanges, and heat recovery system on flue gas. In this study, the above research gaps have been addressed and saving potentials also been estimated. According to the preliminary analysis, the average total specific energy consumption of the plant is 98.14kWh/HL which is higher than the recommended international bench mark by 42kWh/HL. This initiates the researcher to conduct a detail energy consumption assessment on selected on major energy consuming devices like compressor, boilers, electric motors, and lightings. To conduct the assessment, historical data of the factory were collected and measurement was also taken for detail assessment by using portable instruments. Energy conservation measures have been identified and their saving potentials have also been estimated. Optimizing the compressed air usages and arresting the leakage a total annual electric energy of around 337,104kWh can be saved. This is equivalent to a monetary annual saving of 404000Birr. The energy consumption assessment study on one of the boilers indicated that, reducing the excess air, insulating the valves and flanges, and installing economizer at the stack, an annual fuel and cost saving of around 235,200 litter and 838,764 birr can be achieved respectively. The envisaged annual energy saving potential by retrofitting inefficient lightings by light emitting diode, LED, is 221,000 kWh per year equivalent to a monetary saving of about Birr 265,849 per year. Finally, the efficiency reduction due to under loading of electric motor was analyzed and some of them were found to be a loading of 50% and below. This efficiency reduction can be improved by installing variable frequency drive,VFD or other means. Improving the loading on electric motors, an annual energy saving of 80,800kWh and equivalent cost saving of 96,900 Birr can be achieved. Generally the study on the selected areas of the factory indicates that a total of 639428kWh electricity and 235249 litter of heavy fuel oil can be saved if the recommended energy conservation measures in each area are implemented. Additional energy might be saved by conducting energy consumption assessment on other sections other than the selected focus areas such as detail studies on pumps, cooling sections, cooling tower, waste water treatment, and on other remaining areas. Additional benefits of implementing the energy saving opportunities come from decreasing environmental impacts, improving working conditions of the plant employees and higher energy security at the plant.Item Functionality Test of DC Powered Induction Cook Stove Design(Addis Ababa University, 2024-10) Meron Alemu; Mesfin Belayneh (PhD)Solar energy is widely recognized as a clean, reliable, and promising power source for the future. This study is centered on conducting a functional evaluation of a DC-sourced induction cooking system. It analyzed household electric cooking demands and developed a DC-based system analogous to fulfilling these energy requirements. Induction heating was chosen for its efficiency compared to conventional electrical stoves available in the market, operating on the principle of electromagnetic induction. The magnetic field generated by the current flow induces heat in a resistive cooking pan. Tailored to Ethiopian urban cooking habits, a 500-watt induction stove design was crafted to meet the cooking needs of an average family of five, accounting for 3.5 hours of cooking per day. The PV system/DC source design comprised two parallel-connected 12V, 250W panels, and three parallel-connected 12V, 150Ah batteries, ensuring a reliable power supply to the induction cooker. Through the integration of Proteus software and laboratory simulations, the operationalization of an induction cooking system powered by a DC source was successfully demonstrated. This system utilized astable multivibrator and half-bridge topologies, with wireless electric conduction enabling LED lighting without direct contact. The variation in light intensity with height was attributed to voltage and current fluctuations caused by magnetic field variations. The addition of extra current, resulted in a buzzing noise due to magnetostriction. Experimental testing of the developed induction cook stove, using a small 24V panel and a voltage divider, exhibited similar output characteristics in terms of LED illumination and current flow, a maximum of 105 Vpp voltage was achieved at the cooking coil. Ansys simulations provided crucial insights into current flow direction, magnetic field density, field intensity, and their effects on the coil, mirror, and pan. Energy conduction was noted to be influenced by the current and frequency passing through the coil, while magnetic flux density impacted total energy transfer based on the distance between the pan and the coil. An examination of the interaction between the cookware and cooking coil was conducted for various values of operating currents (5A, 15A, and 30A) and frequencies (25kHz, 50kHz, and 75kHz). The magnetic field intensity was observed to be influenced by both the operating current and frequency. Notably, the pan exhibited quicker heating as the magnetic flux density increased. This study contributes to enhancing the understanding and implementation of DC-powered induction cooking systems, highlighting their potential for sustainable cooking solutions and promoting the adoption of clean energy practicesSolar energy is widely recognized as a clean, reliable, and promising power source for the future. This study is centered on conducting a functional evaluation of a DC-sourced induction cooking system. It analyzed household electric cooking demands and developed a DC-based system analogous to fulfilling these energy requirements. Induction heating was chosen for its efficiency compared to conventional electrical stoves available in the market, operating on the principle of electromagnetic induction. The magnetic field generated by the current flow induces heat in a resistive cooking pan. Tailored to Ethiopian urban cooking habits, a 500-watt induction stove design was crafted to meet the cooking needs of an average family of five, accounting for 3.5 hours of cooking per day. The PV system/DC source design comprised two parallel-connected 12V, 250W panels, and three parallel-connected 12V, 150Ah batteries, ensuring a reliable power supply to the induction cooker. Through the integration of Proteus software and laboratory simulations, the operationalization of an induction cooking system powered by a DC source was successfully demonstrated. This system utilized astable multivibrator and half-bridge topologies, with wireless electric conduction enabling LED lighting without direct contact. The variation in light intensity with height was attributed to voltage and current fluctuations caused by magnetic field variations. The addition of extra current, resulted in a buzzing noise due to magnetostriction. Experimental testing of the developed induction cook stove, using a small 24V panel and a voltage divider, exhibited similar output characteristics in terms of LED illumination and current flow, a maximum of 105 Vpp voltage was achieved at the cooking coil. Ansys simulations provided crucial insights into current flow direction, magnetic field density, field intensity, and their effects on the coil, mirror, and pan. Energy conduction was noted to be influenced by the current and frequency passing through the coil, while magnetic flux density impacted total energy transfer based on the distance between the pan and the coil. An examination of the interaction between the cookware and cooking coil was conducted for various values of operating currents (5A, 15A, and 30A) and frequencies (25kHz, 50kHz, and 75kHz). The magnetic field intensity was observed to be influenced by both the operating current and frequency. Notably, the pan exhibited quicker heating as the magnetic flux density increased. This study contributes to enhancing the understanding and implementation of DC-powered induction cooking systems, highlighting their potential for sustainable cooking solutions and promoting the adoption of clean energy practicesItem Design and Analysis of A Stand-Alone Solar Photovoltaic (PV) System For Electrification of A Rural Health Centers in Ethiopia: The Case Study of Lemba Health Center(Addis Ababa University, 2024-12) Hermela Estifanos; Tilahun Nigussie (PhD)In many rural and remote regions of Ethiopia where healthcare facilities are situated far from the power grid, there is a pressing need for a sustainable and environmentally friendly energy source to meet crucial electricity demands for lighting, communication, refrigeration, and essential medical equipment. Leveraging solar photovoltaic (PV) systems that harness abundant year-round sunlight as their sole input, offers a silent, safe, clean, and renewable energy solution. This thesis delves into a meticulous examination, design, and optimization of an independent photovoltaic system tailored to cater to the energy requirements of the Lemba Health Center on a daily basis. A comprehensive methodology is outlined, detailing the specification of each system component in alignment with the typical energy consumption patterns at the designated site. Utilizing sophisticated tools such as HOMER PRO and RETScreen Expert software, the study conducts a thorough performance and economic evaluation to determine the power output of the proposed solar photovoltaic system and assess the associated costs. The findings of the analysis underscore that the sizing of the standalone photovoltaic system hinges on factors such as load profile data, solar radiation levels, and the costs of system components. The HOMER analysis underscores the significant benefits and cost-effectiveness associated with deploying a photovoltaic system to power the health center, highlighting its superiority over traditional off-grid power systems and underscoring its positive impact on environmental conservation. Notably, the evaluation reveals that even during months with the lowest solar radiation, such as July, the system can meet the average energy demand, with a projected net present cost (NPC) of $68,155.56. Notably, this involves the installation of 15.3 kW peak power solar panels rated at 300W each.Item Design and Experimental Investigation of New Manual Solar Tracking for Water Pumping System(Addis Ababa University, 2024-12) Teklemariam Gochem; Ebrahim Tilahun (PhD)Ethiopia has abundant solar energy and irrigation potential which if exploited properly would contribute a great significance to the economic development of the country. Eventhough solar energy for water pumping is the most promising technology in Ethiopia, still less than 1% of 5.2 kWh/𝑚2has been exploited per day. Due to low system efficiency of conventional solar water pumping system, the initial cost of the system remained very high. Therefore, the main objective of this research is to design, manufacture and investigate an innovative solar tracking system for water pumping. The system designed by solid work software after sizing of solar water pumping system and determination of the different solar angles. Based on the design the new manual solar tracking system manufactured and assembled in Ethiopia Water Technology Institute. The new design has three solar panel (having voltage of 28.78 V, current 6.6A and power 190 W each) only the two panels move easily to track the sun manually. During experimental investigation, two solar tracking system (fixed and manual) were compared based on their efficiency. The result shows that the solar irradiance loss in the newly designed manual solar tracking system was reduced by 22% while the efficiency increased by 16% than the fixed axis solar collector. The result also revealed that, the manual tracking system took 7.5 hours to pump 30 𝑚3of water whereas the fixed axis collector requires 8.3 hours to pump the same volume of water. This difference came due to making the two solar panel faced towards the direction of the sun especially in the early morning and late afternoon. Therefore, disseminating this new manual solar tracking system able to, maximize crop productivity; reduce initial cost used in conventional solar water pumping system. Hence, the novel manual tracking system developed in this study is cost effective and robust alternative to conventional solar water pumping system.Item Experimental Investigation on Cylindrical and Divergent Solar Chimney Power Plants(Addis Ababa University, 2024-01) Hana Gebremariam; Solomon Tesfamariam (PhD)The solar updraft tower (SUT) is an innovative renewable energy power plant that converts low-temperature solar heat into electricity. This system operates by heating air beneath a large, greenhouse-style roof, which surrounds the base of a tall chimney. The heated air rises through the chimney, creating an updraft that drives wind turbines to generate electricity. This research evaluates the performance of a small-scale solar chimney power plant (SCPP) by developing two prototypes: one with a cylindrical chimney and another with a divergent chimney. The study focuses on analyzing the impact of chimney design on power output and efficiency using local solar radiation data. Experimental results reveal that the average power outputs for the cylindrical and divergent chimneys were 5.29 W and 23.6 W, respectively. The divergent chimney with a 2° angle achieved an efficiency of 1.9%, which is significantly higher than the 0.44% efficiency of the cylindrical chimney. These findings indicate that the area ratio and air velocity substantially influence the power plant's performance. Furthermore, theoretical calculations showed that increasing the chimney height from 1.5 meters to 2.5 meters led to a 66.6% increase in power output for both chimney types, while increasing the height from 2.5 meters to 3.5 meters resulted in a 40% increase. A 2.5-meter-high divergent chimney produced 3.1 times the power output compared to a 3.5-meter cylindrical chimney, and a 1.5-meter divergent chimney exhibited an 86.46% increase in power output compared to a 3.5-meter cylindrical chimney. Overall, the divergent chimneys enhanced power output by 335.4% at the same height, demonstrating the significant impact of chimney configuration.Item Roof Top Photovoltaic Energy Potential Mapping. Case Study of Jemo-1 Condominium Site; Addis Ababa, Ethiopia(Addis Ababa University, 2024-07) Efrem Negussie; Tilahun Nigussie (PhD)This study addresses energy potential mapping from photovoltaic panels on rooftops, focusing on geographic, physical, technical, and economic constraints for viable energy prediction. The research was conducted in Jemo condominium housing, representing typical living conditions. Geographic location potential, rooftop orientation for solar insolation, and technical potential aligned with energy demand scenarios were analyzed. Economic potential was also assessed. The adoption of solar PV systems in urban residential houses promises sustainable energy provision. This study evaluates solar energy feasibility through PV applications on rooftops, aiming for self-sufficiency in electrical energy, reduced carbon emissions, and alleviated energy scarcity. Secondary data were used to predict energy potentials via empirical formulations, spreadsheets, graphical analyses, and simulations. Optimal PV system performance was analyzed by incidence angle, azimuth classes, and roof slope. Google Earth was used to quantify physical potential by scanning rooftop orientations and directions. Technical potential was assessed by considering specific modules and their characteristics. Scenarios related to demand, supply, and backup were examined to predict optimums. Economic potential analysis concluded that a building block in Jemo-1 can pay 19,864.00 ETB per month for PV electric service. With a 143 m² rooftop area, 108 solar panels (1.31 m² each) and 7.2 kWhr additional power from storage equipment were determined. The capital investment for this setup is 1,462,406.40 ETB for a demand size of 14.26 kWhr/day or 5,205 kWhr annually. A 15-year life cycle and future worth assessment at local interest conditions suggest a capital investment of 805,649.00 ETB. A GHG effect analysis showed an annual emission of 1,077 kg CO2 from the conventional grid and 1,540 kg CO2 from the PV system, a 42% increase for the PV system.Item Numerical Simulation and Performance Investigation of Bubble Pump Refrigerator(Addis Abab University, 2023-10) Henok Habte; Solomon Teklemariam (PhD)Approximately 30% of the primary energy consumed worldwide is used for refrigeration. In light of the global search for sustainable energy sources and energy-efficient methods of operation, solar-powered bubble pump refrigeration systems have gained traction as an alternative means of satisfying cooling requirements. Diffusion absorption refrigerators, sometimes referred to as bubble pump refrigerators, are driven by low-grade energy sources such as solar, waste heat, and recovery heat and do not require any mechanical moving components. However, in comparison to other cooling options, this system's coefficient of performance (COP) has been low. To increase the system's efficiency, more research on the effects of various parameters is required. The objective of this study is to enhance understanding of the behavior of the system through an examination of the impact of several critical factors. Using the programs ASPEN PLUS and EES, a thorough numerical simulation was conducted after a thermodynamic and system model was created. Every simulation was run with a standard total pressure of 25 bars. The model was used to forecast how different factors, such as generator heat, concentration of the refrigerant in a rich solution, and refrigerant purity, would affect the system's performance. The significant impact of refrigerant purity at the rectifier's outlet on coefficient of performance (COP) was one of the key finding. It was discovered that the COP rose from 0.15 to 0.36 as the purity improved from 0.950 to 0.999. It was also noted that a generator temperature of 200oC at 240W of thermal input was optimal at 25 bars of total system pressure. Additional heat rises did not appear to have a noticeable impact on the performance of the system. The one thing that makes this research stand out is the study of the effect of hydrogen on the COP of the system. It was observed that both heat absorbed at the evaporator (Qevap) and COP increased steadily and with similar degree of increments as hydrogen mass fraction increased from 0.5 to 0.95. This is due to the higher reduction of the partial of the refrigerant at evaporator inlet causing the refrigerant to lower its temperature further. Generally speaking, with more research done, the bubble pump refrigeration holds a lot of potential to take the place of traditional cooling technologies.Item Testing of Improved Biomass Cook stove (Tikikil and Mirt) in Rural Households of Southern Ethiopia Using the New Field Testing Standard: The Case of Gamo Zone(Addis Ababa University, 2023-07) Dawit Tibebu; Kamil Dino (PhD)This study has been carried out in the Gamo Zone of Ethiopia with the aim of evaluating the performance of household biomass cookstoves in actual field settings in kitchens. Both Tikikil and Mirt cookstoves were distributed to 38 households to evaluate the daily fuelwood consumption, PM2.5 emissions, and the overall usability of these stoves by comparing them to the Choche cooking stoves which is practiced in the community by applying the newly developed ISO 19869:2019 field standard procedure. Data on daily fuelwood and energy consumption, as well as user preferences, were collected through before-and-after surveys of randomly selected households. Direct field examination of seven home-specific fuel use for baking injera for three replication and monitoring PM2.5 emissions over 24 hour in 20 household kitchens using both Choche and the improved cookstoves (Tikikil and Mirt). The cooking tests and kitchen performance assessments were carried out using Excel-based data and calculation tools developed by the Shell Foundation. Descriptive statistics and paired t-tests for mean differences were performed using SPSS software. The concentration of PM over a 24-hour period in households was calculated using PICA software. The study finds that, the mean daily fuel use for Choche cooking stove was 8.72 kg (SD = 2.26), and the mean daily fuel use for improved cook stoves was 5.80 kg (SD = 2.06). The paired differences between the two means were 2.91 kg (SD = 2.65), which was statistically significant (p < .001) ICS in this study reduced fuelwood use on average by 33.3%. A household in the locality would emit, 5,858.9 kg and 3,898.89 kg CO2e per year from using the Choche, and ICS (Tikikil and Mirt) stoves, respectively. The difference between the two types of stoves in CO2 emissions is 1.96 metric tons per year per household. The mean specific fuel consumption for Choche and Mirt stoves was 609.52 g/kg (SD= 65.83), and 444.95 g/kg (SD= 59.48), respectively. The mean total cooking time for Choche and Mirt stoves was 99.90 minutes (SD=4.51) and 95.47 minutes (SD=7.51), respectively, the paired differences between the two cooking methods was 4.42 minutes (SD= 5.88). The average PM2.5 concentration with the Chocho stove is 1102±408.6 μg/m3, while for Tikikil and Mirt stoves was 749.6±225.1 μg/m3 , This figure is about 45 times and 30 times above the WHO 24-hour guideline of 25 μg/m3 of household air pollution. The relative difference in mean between the two stove types is 32.6 % emission reduction by Tikikil and Mirt stoves. The performance of the Tikikil and Mirt improved cookstoves demonstrates their enhanced efficiency compared to the Choche stove. As a result, these improved cookstoves have a positive impact on better fuel utilization, reducing cooking time household health by reducing exposure to indoor air pollution. The finding majorly suggests that further studies need to be conducted in depth on the traditional cooking practice of the rural community and try to engage them in designing the alternative technologies, awareness creation should be in place for the adoption of improved cookstoves and enhance collaborative efforts among the government, non-government, and private sectors for the success of large-scale dissemination. In view of this, important lessons could be drawn from this case study and local household cooking practice for future interventions.Item Investigation of Combined Treatment Methods on Biogas Slurry (BGS) Concentration and Nutrient Recovery(Addis Ababa University, 2023-12) Eniyew Abebaw; Ebrahim Tilahun (PhD)Biogas slurry (BGS) is generated as byproduct during biogas production and can be used as organic fertilizer. However, Biogas slurry (BGS) application is limited due to its bulkiness and nutrient volatilization in the form of ammonia. Hybrid treatment methods which include chemical treatment, physical separator and evaporation process were used to concentrate bulky biogas slurry. Principal nutrients (P, and NH4-N) distribution in solid and liquid fraction of BGS was examined after chemically treated with the addition of coagulant and flocculant and physical separations by using vibrating screen. The result showed that significant portion of readily available soluble ammonium (NH4-N) was presented in liquid fraction with distribution share of 91% and a significant amount of phosphorous, P (68.2%) found in solid fraction. The influences of heating time (30, 45, and 60 minutes), heating temperature (65, 75 and 85 0C) and pH (7.76, 7 and 6) on water removal (WR) efficiency during evaporation of BGS liquid fraction was investigated. The highest WR efficiency (55%) was obtained at 75 oC, 45 minute and pH of 7. The effectiveness of NH4-N recovery was examined at different pH (6, 7 and 7.76) and maximum NH4-N (95.1% ) recovery were achieved at heating time of 45 min., temperature of 75 oC and pH of 6. The final concentrate biogas slurry (CBGS) had a higher nutritional concentration and was less bulky than the raw biogas slurry. This effort helps to prevent the challenge faced associated with transporting of bulky BGS from biogas digester to application sites, reduce imported chemical fertilizer dependency and promote sustainable farming.Item Techno Economic Feasibility Analysis of Mini-Grid Using Hybrid Renewable Energy System for Off-grid Community: a case of Shima Kebele North Shoa Ethiopia(Addis Ababa University, 2024-06) Mekdem Tesfamariama; Fitsum Salehu (PhD)Lack of clean and sustainable energy access is the biggest challenge for developing countries like Ethiopia. Many Ethiopian rural areas are not suitable for grid connections due to their geographical location and low number of residents. Rural communities utilize kerosene and biomass resources to meet their household energy demand, and the farmers employ large-scale irrigation schemes using diesel pumps. This causes a reduction in their profit gain and increases their expenses, including the cost of diesel pump maintenance and diesel oil transport. This study aims to assess the techno-economic feasibility of mini-grid solar energy for Shima Kebele, North Shoa, Ethiopia, which can provide reliable energy to the village. The energy demand of the study area is determined by conducting a questionnaire, a site visit, and using CROPWAT 8.0 software to determine the water requirement for irrigation. Onion water requirement is 8.65 mm/day and Tomatoes water requirement is 11.04 mm/day, which is equivalent to 4,922.5 m3/day required to irrigate 50 hectares. HOMER software is used to compute the techno-economics of various system configurations. The daily energy demand of the kebele is 1,568 kWh, where, around 67 % of the load is irrigation. The proposed optimal system consists of 343 kW of solar PV and a 60 kW generator. The proposed system NPC is USD 494,107 and the COE is USD 0.0885/kWh. The cost benefit analysis for irrigation was also done. The electricity saves around $36,000 per annum when compared to diesel. The system will improve the lives of rural communities in several ways. The result of the study can help encourage the different stakeholders to invest in mini-grids to tackle the socio-economic problems of the rural community, which will be a feasible and environmentally friendly solution.Item Parabolic Trough Solar Collector Design, Modeling and Simulation for the Application of Industrial Parks: A Case Study of Bole Lemi Industrial Park(Addis Ababa University, 2022-07) Mengesha Abreha; Tilahun Nigussie (PhD)Despite the need for additional research to bring concentrator solar plants up to a competitive economic level, molten salt integrated parabolic trough solar collector plants produce essentially lower levels of carbon dioxide than conventional power systems. Priority study areas in the thermal engineering applications for the textile industry include the optimal design, mathematical modeling, performance simulation, and cost investigation of parabolic trough solar power plants. This thesis is concentrated on the dynamic modeling of 50 MWe parabolic solar trough collector up-scaled versions for power supplies in Bole Lemi Industrial Park. Prior evaluations was carried out to choose the finest collector and receiver geometry, heat transfer fluid ,solar field design points and energy storage systems based on diverse determination criteria. In addition to satellite driven solar resource data collected from NASA, direct normal irradiance (DNI) on daily and monthly basis were measured using Payranometer.The solar field components then coordinated into power generating module and the systems performance was simulated to create genuine working environment. The input parameters such as declination angle, azimuth angle, hour angle and equation of time were analyzed using empirical equations. Assessment of daily global solar radiation and sun shine duration at the case study area was conducted using Meteonorm8 .Taking all the collected primary and secondary data, comprehensive numerical simulation of parabolic trough solar power plant employing System Advisor Model (SAM) was developed. The average monthly DNI as function of thermal power produced on the field, monthly energy generation, thermal cycle efficiency and levelized cost of energy with solar multiple were plotted in order to investigate their correlation pattern. The simulated time series yield showed that maximum annual power cycle efficiency of the system to be 25.5% and the maximum average thermal power output occurred in the months of January through April and November through December. The findings were further cross checked with similar previous scientific works using common parameters and fair agreement has been achieved, illustrating the proposed technology is applicable for any industrial application.Item Investigation of Combined Treatment Methods on Biogas Slurry (BGS) Concentration and Nutrient Recovery(Addis Ababa University, 2023-12) Eniyew Abebaw; Ebrahim Tilahun (PhD)Biogas slurry (BGS) is generated as byproduct during biogas production and can be used as organic fertilizer. However, Biogas slurry (BGS) application is limited due to its bulkiness and nutrient volatilization in the form of ammonia. Hybrid treatment methods which include chemical treatment, physical separator and evaporation process were used to concentrate bulky biogas slurry. Principal nutrients (P, and NH4-N) distribution in solid and liquid fraction of BGS was examined after chemically treated with the addition of coagulant and flocculant and physical separations by using vibrating screen. The result showed that significant portion of readily available soluble ammonium (NH4-N) was presented in liquid fraction with distribution share of 91% and a significant amount of phosphorous, P (68.2%) found in solid fraction. The influences of heating time (30, 45, and 60 minutes), heating temperature (65, 75 and 85 0C) and pH (7.76, 7 and 6) on water removal (WR) efficiency during evaporation of BGS liquid fraction was investigated. The highest WR efficiency (55%) was obtained at 75 oC, 45 minute and pH of 7. The effectiveness of NH4-N recovery was examined at different pH (6, 7 and 7.76) and maximum NH4-N (95.1% ) recovery were achieved at heating time of 45 min., temperature of 75 oC and pH of 6. The final concentrate biogas slurry (CBGS) had a higher nutritional concentration and was less bulky than the raw biogas slurry. This effort helps to prevent the challenge faced associated with transporting of bulky BGS from biogas digester to application sites, reduce imported chemical fertilizer dependency and promote sustainable farming.