Energy Technology

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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.
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.
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.
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.
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.
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.
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.
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.
Techno-economic Investigation of a Micro Hydro Power System for Rural Electrification: A Case Study of Lemere River, Hadya Zone, Ghibe Wereda
(Addis Ababa University, 2022-04) Frahiwot, Midaksa; Tilahun, Nigussie (PhD)
Ethiopia has a huge hydroelectric power generation potential due to the abundant water resources in the country. It is, therefore, necessary to use efficiently the sources in the country for the enhancement of electrical energy. The main purpose of this thesis is to investigate the viability of a standalone Micro Hydro Power plant from Lemere River in Hadya Zone, Ghibe Wereda. The power produced from the proposed plant is supplied to Geseda village to power home appliances, community service centers, churches and micro enterprises. The power demand of the village studied in detail. The study shows that a minimum load of 0.06 KW between 12:00 – 5:00 AM and a maximum load of 46.9 KW between 4:00 – 5:00 PM. The data required for the potential assessment of rivers were collected from the respective organization. Accordingly, the gross head, the design flow rate and power output of the site is found out to be 22m, 0.352m3/s, and 48KW respectively. The design of civil structures, selection of electromechanical equipment’s and also design of transmission system have been done. Additionally, the analysis and testing of this study were performed using RETScreen software tool to analyze and determine the Energy Model, Hydrology and load, flow duration curve of this potential site. The study is concluded by a sensitivity analysis properly adapted for the local market financial situation, in order to enlighten the decision makers on the expected profitability of the capital to be invested. According to the results obtained: The forebay was 12m in length and 1.2m in depth. Then finally penstock was 28m long with diameter of 386mm. The total cost of project was found to be 565,200USD, B/C ratio 6.2 and payback period 6.6 years. The result showed the viability of micro hydro power construction from the selected river Lemere.
Model Based Design of HAWT and its Control System under Simulink Environment
(Addis Ababa University, 2021-08) Tewodros, Walle; Abebayehu, Assefa (PhD)
This project addresses the model based design of a horizontal axis wind turbine simulation using MATLAB/Simulink. Wind turbine consists of different subsystems that use different technologies. Usually different teams develop each subsystem in separate environments, integrate and test it after developing a prototype. This project, however, starts with specifications and requirement of the model to model the wholes system, integrate the system and test it in single environment before a prototype is developed. In order to analyze the dynamic and/or steady state behavior of a wind turbine, the basic components of a wind turbine are structured in several libraries. Mechanical components, electrical machinery, power converters, common models, transformers, measurements and control, for studying the whole system and the effect of the change of one of the wind turbine components in the wind turbine efficiency are presented. Basic blade geometry, force and moment equation of the wind turbine model component are presented as embedded system in the model. Each equation of the control system converted into block diagram for integrating with Simulink environment for each control system of the model compensator design optimization is done. The NACA four-digit airfoil profile generated based on the recommended analytical equations of NACA aerodynamics blade profile. The profile is changed into MATLAB code to BE embedded in Simulink environment. 3D animations of wind turbine and its component models are developed to show its motion and response for the various operating condition of the system. A graphical user interface (GUI) is built which makes any user of this model to test the power output and the various operating condition for the data of selected site that a user wants. For each control system of the model compensator design optimization is done. Results of the system simulation are presented in graphical form suitable for system performance determination. From the power output, pitch actuator force, pitch actuator torque, Yaw actuator torque and wind turbine parameters, the useful energy and power output are determined.
Performance Evaluation of Solar Photovoltaic Power Supply System the Case of Ethiopian Civil Aviation, Arbaminch site
(Addis Ababa University, 2021-12) Mesfin, Behailu; Kamil, Dino (PhD)
The research work targeted on performance evaluation of power generated from solar source in the case of Ethiopian Civil Aviation Authority, at a specific location of Arbaminch, southern Ethiopia. All the Authority electronic equipment that are used for communication, demands a reliable and stable source of electrical energy to function. Especially ground to air and air to ground radio voice and signal communication requires the highest level of power quality and security. Hence, the quest for obtaining this source of energy from different means is mandatory. The communication equipments are installed at remote areas, on top of mountains, to avoid communication obstacles and to attain quality signal strength, where there is no reliable conventional power supply. But today other forms of energy are being harnessed, so as to convert to electrical energy, solar energy. The solar Arrays of Arbaminch were faded, shaded with dust and tree as a result the PV arrays can‟t deliver the required power in order to charge solar batteries, so that the batteries frequently discharged and eventually discarded before the service year. Twelve solar batteries each 2V/3266AH was purchased with more than one million birr and installed for Arbaminch solar site. The performance evaluation was made on panels, storage battery, solar charger, inverter and the connecting cable. The evaluation were done based on the literature review of similar plants, actual site observation, technical and meteorological data collected, then the measurement and the PVsyst software result were compared and discussed. PV power supply system performance losses were considered. Effect of temperature, shad and dust, improper sizing, tilt angle, and effect of irradiance were considered. Based on the name plate data of the component the total power generated from the PV Array were 2.72kW before loss and minimum energy 13kWh/day with inverter and charge controller power capacity of 3kW but only 0.56kW were supplied to the load and the rest wasted. The PV syst simulation results are indicator parameters whether the PV can charge the battery effectively or not. Based on other countries, the expected performance Ratio (PR) value were more than 0.7 but in the case of Arbaminch the Ratio achieved were below 0.5 and this shows that there is a minimum loss of 0.2 (20%). Moreover, the fill factor value obtained 0.62 but the expected value is 0.8 and more, this shows that there is a loss. The optimal power sources interfacing mechanism and the best performance up grading means in terms of technical and economical benefits was recommended.
Experimental Analysis of Coal Upgrading: The Case of Dawuro, Southern, Ethiopia
(Addis Ababa University, 2021-09) Muluken, Filmon; Wondoson, Bogale (PhD)
Coal has been major energy source for cement, steel and chemical industry in Ethiopia and also the country has high coal deposit. However, Ethiopian Coal is low in quality and calorific value and high sulfur, ash, and volatile content. Due to this, almost all local and international industries do not like to use Ethiopian coal. Hence, this study experiment on the ways of upgrading or enhancing the low quality of Ethiopian coal to high quality. Fluidized bed or dry cleaning is used to separate impurities from raw coal based on density difference, and chemical cleaning method is used to remove sulfur content by leaching with hot alkaline solution. The experimental result shows that Fluidized bed and washing machine have a capacity to upgrade its calorific value from 3000kcal/kg to 6,600kcal/kg, reduce moisture content from 37% to 5%, ash content, 27% to 4%, volatile matter 8% to 3.43%, reduce Sulfur content from 1.5% to 0.45%. Chemical cleaning effectively removes almost all sulfur up to 99% but high cost. Physical cleaning is effective in cost rather than chemical cleaning. This shows that it’s possible to use low graded coal by upgrading its qualities.
Development and Experimental Investigation of Electricity Generation from Hydraulic System Speed Breaker
(Addis Ababa University, 2020-12) Zerom, Kahsay; Abdulkadir, Aman (PhD)
Energy is among the key elements for the economic and social developments of one country due to that an effort was made to capture the energy wasted when the vehicle passes through the speed breaker. Different mechanisms are used to convert the kinetic energy of the vehicles over the speed breaker in to electricity but in this paper, a prototype is proposed in order to convert the weight of the vehicle in to electricity. This technology is used as energy recovery and reducing dependence on the conventional sources of energy, which focused on the electricity generation from hydraulic system speed breaker. In the rural part of Ethiopia, the generated electricity is used to charge the rechargeable torch for the purpose of light. Also in the urban areas of Ethiopia even there is access of electricity but still the government is unable to supply a steady power. Objective of this research is to increase the efficiency of the existing technology by replacing the traditional one with simple hydraulic type speed breaker. This paper presents detail design and modeling, simulation analysis using ANSYS workbenches and experimental investigation of electricity generation from the prototype by developing a prototype. The new prototype have two-power generation station known as ��1 and ��2. ��1 Used to convert the weight of the vehicle from 1000Kg to 2000Kg and ��2 converts from 2000Kg to 7000Kg weight of the vehicle in to electricity using DC generator and stored using battery. The prototype was tested by applying load (5Kg, 10Kg, 18Kg, 20Kg and 30Kg) on the dome and the average output voltage with load condition (5-watt lamp) is 2.36, 6.46, 12.66, 14.42 and 18.74 volt respectively and the observed average current output is 0.125, 0.156, 0.168, 0.204 and 0.231 Amp respectively. The result power output observed from the prototype with load condition (5-watt lamp) by applying the above weights over the dome is 0.3, 1, 2.1, 2.9 and 4.3 watts and from the simulation result, the power output is 1.03, 2.5, 4.8, 5.4 and 8.3 respectively. Finally, the finding from the prototype of the model and simulation study is discussed in this paper. Therefore, from the result, observed weight of the vehicle applying over the prototype is direct proportional to the power output and this method of electricity generation is eco-friendly to the environment.
Electrical Energy Audit of Walia Steel Industry
(Addis Ababa University, 2020-11) Getachew, Adane; Yilma, Tadesse (PhD)
As the energy demands rise and the pollution levels grow, it becomes imperative to save the energy in all fields in which it is used therefore the subject of energy conservation is a big concern for industries in general and steel industries in particular where energy is intensively used but not properly managed. And when it comes to the energy usage of Walia Steel Industry the inefficient energy usage of the factory can be seen from the average power factor value of 0.48, from its poor monthly average load factor of 31.80%, high specific energy consumptions as compared with international benchmarks, under-loaded motors, transformer, and cable losses, oversized installed capacities of distribution transformers and from the monthly average penalties for maximum demand and power factor which is of 81,564.67ETB. Hence the purpose of this thesis is to address the energy inefficiency problems of the industry through conducting detailed energy audits of the factory and recommend energy conserving measures to alleviate the identified inefficiency reasons for the factory. Accordingly, the energy audit of the major energy-consuming systems of the factory has been done and for the analysis of the audit historical data of energy consumption and production data of 23 months, measurement data of motors, power distribution lines data has been collected for analysis, modeling, and simulation work using motor master+ international and ETAP 16.0.0 software packages. From the detailed audit by replacing the under loaded motors with proper sizes of motors can save 705,210.25ETB annually, and by correcting the power factor of the system and reconfiguring the network the energy loss has decreased by 69.1% and the annual cost saving of 167,690.43ETB can be gained from the avoided loss, from avoided demand charge is of 84,253.80ETB and from the avoided power factor penalty is 2,835,000.00ETB. Finally to mitigate the energy inefficiency of the factory resizing the motors and installing power factor correctors in the power system of the factory has been recommended.
Small Wind Turbine Blade Optimization for Smooth Starting Performance in Low Wind Speed Regions
(Addis Ababa University, 2021-02) Tewodros, Driba; Wondwossen, Bogale (Assoc. Prof.)
Access of electricity in the developing country is a big issue that the government highly concerned. Small wind turbines are one of the alternative the government have in order to address electricity specially in rural areas. Wind turbines are highly dependent on wind speed, hence the areas with low wind speed region can not access the electricity as expected. This is because the turbine works in low wind speed range which gives the annual energy production more less than the desired output.This thesis investigate the way how to get the optimum energy output from small wind turbines by lowering the time at which the wind turbine starts rotating and generating electricity with out decreasing performance of the turbine. The main objectives of the thesis were starting time and coe cient of performance and the parameters used for the optimization processes were chord value, twist value and type of airfoil. Two non optimized blade with single and mixed airfoil section are designed with usual designing procedure by using horizontal axis wind turbine design code credited to Oboe Daniele and Marinoni Andrea. Three optimized blade which have 0.8466m, 0.5m, and 0.5m radius with the rst two blades have SG6043 airfoil section and the third one has SD7062 airfoil section are designed. The optimization is taken by multi objective genetic algorithm and di erent input criteria like airfoil type, blade number, starting wind speed, resistive torque is taken for a better investigation. Beside to analysis of the optimized and non optimized blade, the e ect of weight given to starting, genetic algorithm parameters, limiting the boundary of twist and chord value, airfoil, designing the blade with single and mixed airfoil, blade number, and starting data are well investigated. Non optimized 3-bladed, SD7062 airfoil section blade starts in 16.3sec at 5m s wind speed while the Optimized blade with the same blade speci cation starts at 8.63 second which means there is 88.8% improvement in starting time but the coe cient of performance only decreases from 0.34 to 0.335, which means its percent reduction is 1.49% . From previously conducted research on starting performance with the same input criteria with this thesis by (1) which gets 87% improvement in starting time and 1.6% reduction in coe cient of performance. This research shows improvement by altering airfoil type, chord and twist value. The optimum blade which have lowest starting time and better power performance was manufactured from Australian timber by Computer numerical control machine and experimental testing was conducted. In order to get constant wind speed ow, a controlled moving vehicle was used for the experimentation process. The starting time and coe cient of performance of the blade from the software were 8.63sec and 0.335, while the experimental result gives 9sec and 0.3228. This shows there is a 3.61% and 4.2% error while testing in Cp and starting time respectively. Value of errors comes from rst the generator, since it needs to be excited it makes some delay on recording some seconds as it starts generating electricity.Beside to excitation the generator is used and maintained repeatedly, this makes it to do not perform as it is rst manufactured. There is also some manufacturing and assembling di culties while making parts and assembling the wind turbine which add some contribution on the performance of blade under experimental testing. Finally the manufactured wind turbine produce 19.4W electrical power at 5 m sec which is the frequent available wind speed in low wind speed region(2).
Design and Development of Three Small Generators Operated Micro Wind Turbine
(Addis Ababa University, 2021-02) Tekalegn, Amanuel; Abdulkadir, Aman (PhD)
World is struggling to mitigate climate change due to uses of fossil fuel for energy gen- eration and also searching substitution for fossil fuel in energy sector. Wind energy is one of the lowest environmental impact forms of clean energy available today. In order to convert wind in to energy many technologies are used up to know from small o grid to large wind farm wind turbine. However, it's di cult to nd cost e ective and durable Micro wind turbine for o grid use to generate electricity in rural part of Ethiopia which is in dark for a long period of time. This study aims to Design And develop Three Small Generators operated Micro Wind Turbine with production capacity of 2:4KW, to o -grid use for rural part of Ethiopia with durability and low cost relatively to current Micro wind turbine. Polyvinyl chloride (PVC) is used to manufacture the small wind turbine blade and Three small generator are driven by direct coupled external ring gear with turbine axle. PVC blade is manufactured with best twist angle through the radius of blade for better direct wind contact to get better energy extraction from low wind speed. This Three Small Generators operated Micro Wind Turbine development costs took up to 28,885 ETB. At the end of this research is done and commercialized the electricity demand can de- crease in o grid users, the electricity coverage can cover rural (remote) area of Ethiopia around 30 Percent of the rural population which is in need of electricity.
Design of Solar Photovoltaic System to Power Air Conditioning Unit for A Light City Train (Case Study on Addis Ababa Light Rail)
(Addis Ababa University, 2020-10) Rukia, Hassen; Solomon, Tesfamariam (PhD); Fitsum, Sahilu (Mr.)
Energy is the basic utility required to drive trains. Trains use either fossil fuel or electricity to energize the system. The Addis Ababa city light rail has two routes namely: the North-south Line (MENILIK II Square to KALITI Route) and the East-west Line. The train gets electricity from the grid. Electrical energy coming from the grid enters the control unit from where to be supplied to different units. One of the energy-intensive units is the air-conditioning system. This research work focused on designing a rooftop solar photovoltaic system to provide the energy required for the air conditioning units of the 17.1 kilometers from Ayat to Torhailoch Route. The data collected from the Ethiopian Methodology Agency, NASA, and PVGIS showed the sun can be provided at minimum solar insolation of 4.8 kWh/m²/day to the route line. The air conditioning system of the train is a DLD25 type air conditioning unit. The cooling capacity is 6 kW and power of 2.25 kW for each AC, the air supply volume is 1300m3/h, and the total electrical power is 9 kW for 4 air conditioner. The train travels at an average speed of 70 km/h without significantly changing its direction from East to West and vice versa. In a coach, 36 photovoltaic modules (having a 66.35 m2 aperture area) can be installed in an effective rooftop area of 71.6 m2. The battery size is 150Ah, 12V controller size of 80 A, 220V, and 30 KW of inverter size. The PVSYST and MATLAB software simulation results projected within different months electrical energy varying between 11.48 kW and 14.45 kW can be generated. The train in general requires 260 kW of electricity. Of this 9 kW or 3.5 % amount of energy is consumed by the air conditioner. Hence, by supplementing the locomotive with solar PV modules 1034775 Birr can be substitute per annum. As compared to other researches, this thesis work is to simplify the mounting of the solar PV modules by considered the solar insolation variation within the route to know the performance of the system. Hence it is recommended to Addis Ababa Light Rail Train to apply this solar-powered air conditioning system.
Designing, Simulating and Manufacturing of Improved Charcoal Stove
(Addis Ababa University, 2020-12) Lemma, Kahsay; Kamil, Dino (PhD)
Nearly 2.7 billion people in the world depend on biomass for cooking. Charcoal fuel is a solid biomass fuel which is widely used in urban and semi-urban areas of Ethiopia. However, these fuels are combusted inside thermally inefficient stoves. One solution to such problem could be designing, manufacturing and disseminating improved stoves. Thus, this study aims at designing, simulating and manufacturing an improved charcoal stove to maximize the thermal performance. Designing the stove has been performed by solid work. Besides, simulation has been performed by CFD module which is found in COMSOL Multiphysics software. This module includes coupled sub models representing fluid flow and heat transfer. From the simulation temperature distribution, velocity distribution and pressure distribution in the grate holes and on the combustion chamber of the stove were analyzed. The simulation shows that the increased temperature results in higher firepower, which leads to higher thermal performance of the stove. The prototype was tested using the Water Boiling Test (WBT) protocol. The simulation results were compared and validated with experimental results. Based on simulation thermal efficiency obtained was 34.7%. With regard to experimental investigation, the thermal efficiency of the stove is 32.6% and its specific fuel consumption is 56 g of fuel/ liter of water. The study showed an improvement in thermal performance of the charcoal stove. The specific fuel consumption of the prototype charcoal stove shows 70% improvement compared to the three-stone fire. Generally, the new prototype charcoal stove has better thermal performance compared to the previous designs proposed by other researchers. Therefore, disseminating our improved charcoal stove at a larger scale in Ethiopia will be beneficial in preservation of forests and associated ecosystem services and will improve health for households.
Design and Experimental Analysis of Charcoal Production from Maize Waste (Corncob)
(Addis Ababa University, 2020-10) Geda, Feyera; Wondwossen, Bogale (PhD)
Maize is the second dominant crop that is used as a food next to Teff in Ethiopia. However, there is much left-over corncob after harvest and during processing. Some peoples need the waste of this corn for cooking purposes and baking Injera. Pyrolysis is the process at which charcoal is produced within low oxygen environmental conditions. Developing an innovative pyrolysis system for the production of charcoal from corncob that is economical, efficient, and environmentally friendly is very important. The main objective of this research work to design and experimental analysis of charcoal production from corncob by slow pyrolysis. The continuous pyrolysis system has been designed, manufactured, and tested. Data collection, characterization of corncob, and charcoal analysis were done. The physical characterizations of the corncobs have also been done by estimating the proximate analysis. Bomb calorimeter was used to measure the energy content of the corncobs and the produced charcoal. As the quality properties and chemical composition of plant material are one of the most important indicators of how much waste can be used in charcoal production the characterizes of moisture content, Volatile matter content, fixed carbon content, and an ash content of the corncob were found as 9.11%, 65.84%, 15.76%, 9.28% respectively. Based on the experimental result the corncobs charcoal was 1.55% of moisture, 13.65% of Volatile matter, 65.64% of fixed carbon and 18.26% of ash contents were observed. Based on the result, 2.1 kg of biochar is produced from 3kg of corncobs at rpm of 12.5 and 24℃/min of residence time at the temperature of 600℃. This implies a product yield of 70 % has been found. The parameters like temperature, rotation of the motor, and moisture contents of the waste have effects on the production of the charcoal from corncobs using this machine. Based on the experimental result, the lower heating values of the corncobs and its charcoal were found to be 16.97 MJ/kg and 27.43 MJ/kg respectively. Thus, by using this machine
Characterization and Experimental Analysis of Biodiesel Extracted from Sclerocarya Birrea (Marula) Fruit Using Catalyst
(Addis Ababa University, 2021-01) Bikila, Gebeyehu; Solomon, Kiros (Ass. Prof.)
The investigation of indigenous resources as alternative energy is the reasonable solution for the diminishing of naturally existing materials for production of fuel from crude oil, environmental concern. Many researchers have been involved in producing a low-price fuel from naturally existing raw materials. Thus, in this specific work biodiesel production was examined from Marula seed. The seeds were collected from Arba Minch Nech Sar National Park and the seeds Proximate analysis has been conducted to determine moisture content, ash content, crude fiber content and fat contents. The result found was 5.90%, 4.27%, 11.84% and 47.66% respectively. The extraction of the oil was performed by solvent method using n-hexane as solvent through Soxhlet apparatus and fixing the extraction time. This study aimed to extract a biodiesel from sclerocarya birrea by examining the physio-chemical properties, and the biodiesel production was optimized for pre-determined parameters such as Catalyst Concentration (CC), Reaction Temperature (RT) and Methanol to Oil Ratio (MOR) by implementing Design Expert Software (DES). The optimum conversion efficiency of marula oil to Fatty Acid Methyl Ether (FAME) was 93.45% at optimal condition of 9:1 methanol to oil ratio for 1.75%of catalyst loading at 60oC of reaction temperature. The properties of sclerocaryabirrea which were determined exist in the recommended standards. The oil content of the seed was found 41.57%. The values of the physiochemical properties of the oil were viscosity 92.8mpas, specific density 0.923, acid value 7.51, Saponification value 229miligrams and free fatty acid 3.8% and the biodiesel were characterized as of its calorific value (CV) which was 42.56 MJ/Kg, viscosity of 11.3mpas, iodine value of 115 I2/gm, and flash point of 235oC. In this thesis work, it was concluded that Sclerocaryabirrea can be a possible input for biodiesel production which in turn minimize the dependency on fossil fuels.

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