Energy Technology

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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.
Design, and Development and Performance Evaluation of Thermoelectric Stove using CFD
(Addis Ababa University, 2020-05) Abraham, Mohammed; Wondwossen, Bogale
Thermoelectric stove is kind of improved cooking stove, can able to reduce the wastage of energy, reduce fuel consumption. Thermoelectric stoves able to convert partially wasted energy in to useful electrical energy in stove. They are designed and developed to harvest energy for home-made utilization. The utilized energy used for lighting application, phone charging, radios, and other home utilities. Due to essentiality of improving cooking stove to minimize wasted energy, and the limitation access of electrical energy, thermoelectric stove is one option cup up such problems. Design, development and performance evaluation of thermoelectric stove is able to generate energy for the one family members, which live in rural community. The conducted computational fluid dynamics (CFD) in stove and thermoelectric module (TE) improves efficiency of stove and the performance of thermoelectric module (TE) significantly. This research work focused on the development and performance evaluation of thermoelectric stove by computational fluid dynamics (CFD), development of performance evaluation includes; specifying size of stove, optimizing of air gap, and determining of location thermoelectric generator (TEG) in stove. This design and development prime concern is to increase performance of stove and performance of thermoelectric module (TE). In this research, size parameters of stove are (��cham..wall=150mm,ℎ��ℎ��.��=205mm,ℎ�� =25mm, ��pot=160mm, R flame =89mm, L flame =25mm),and size parameters of thermoelectric module are:( ��1=326 0C, ��2= 88 0C, ��= 298.9 0C, ��= ��= 0.056×0.056 ��2, �� = �� = 0.04×0.04 ��2).Some tools were used to conduct simulations. Solid work 2019 used to draw solid 3D model for both stove and thermoelectric module. ANSYS 2019 used to conduct CFD simulation heat transfer analysis in stove and for meshing, temperature distribution simulation, numerical temperature distribution. Thermoelectric simulation used to conduct thermoelectric heat transfer analysis, voltage developed ( ��) and Power developed (��). Research results show that 3.133W of electrical power is developed with 27% thermal efficiency of stove. The obtained improved air gap that leading increment of performance of the thermoelectric stove. The results obtained from simulations were discussed in accordance with temperature distribution and power developed per module.
Performance Simulation of Solar Adsorption Cooler with Activated Carbon-R134a pairs (ACF-A20, Granular AC and Maxsorb III)
(Addis Ababa University, 2020-06) Samuel, Teka; Solomon, Tesfamariam (PhD)
Solar thermal energy can be used to drive sorption coolers. Some of the sorption cooling systems are absorption, adsorption and desiccant systems. This research paper focuses on the performance analysis of adsorption refrigeration system that utilizes activated carbon-R134a pairs. To this end, three variants of activated carbon were assessed for their performance. These types of activated carbon are: ACA-F20, Granular activated carbon and Maxsorb III. These adsorbent materials have varying pore diameter, surface property and adsorption capacities. The solar adsorption system is highly dependent on pressure, temperature and concentration of the adsorbate on the surface of the adsorbent material. Based on the pore diameter of activated carbon Dubinin-Astakhov equation was selected to characterize the adsorption pairs and simulate using MATLAB. For the Dubinin-Astakhov equation, values of characteristic energy, maximum adsorption capacity and exponential constant were adopted from the works of other researchers: Loh and Askalany. The coefficient of performance values of ACA-F20-R134a, Granular-R134a and Maxsorb IIIR134a were found to be 0.27, 0.2908 and 0.311 respectively at bed temperature of 280K. The specific cooling power values for these pairs were 39.29, 49.03 and 62.09 W/kg respectively. Some researchers proposed complex system and found performance values with coefficient of performance values ranging between 0.38-0.7. In this specific research lower values were attained using solar energy unlike the other research works that focused on performance analysis of activated carbon and R134a using waste heat and two stage processes that tend to give higher the cooling effect obtainable by refrigerant R134a. As a result the coefficient of performance values were higher than the one obtained in this research.
Experimental Analysis of Solar Thermal Tea Dryer
(Addis Ababa University, 2020-07) Miskir, Teffera; Kamil, Dino (PhD)
The tea drying is a heat transfer between the product and the surrounding to dry the leaf and make ready for market. Conventional tea dryer consumes too much energy since the water will be heated using the electric boiler. The main objectives of this research are to design, manufacture and test the performance of solar thermal tea dryer. The solar dryer was mathematically designed using the data gathered from the National Metrological Agency. The solar dryer was sketched on the solid work before it goes to the workshop for construction. The construction of the dyer was done in Addis Ababa Institute of Technology, Mechanical Engineering workshop. The designed dryer has a collector area of 1.3 and a ventilation area of 0.1 . The assessment has been done with scientific experiment using different measuring methods and tools at Addis Ababa Institute of Technology, Addis Ababa University, and Addis Ababa, Ethiopia. The solar radiation on the collector, the ambient temperature, the temperature on the solar collector, and inside the dryer chamber, including the wind speed were measured and analyzed. The sample products used to measure the performance of the dryer are Moringa (drumstick tree) and Ginger. Due to a problem countered in bringing tea leaves without losing moisture. The initial moisture content of the Moringa (drumstick tree) leaf was 50% and the final moisture content was 5.1%, and for Ginger the initial moisture content was 68% and the final moisture content was 13.1%. The total moisture removed from the sample products was 44.9 % and 43.9 % for Moringa and Ginger respectively. The drying rate for Moringa and Ginger is 0.27 ⁄ and 0.25 ⁄, respectively. The average collector efficiency is 36.3% and 22.1% with no load and with load, respectively. The total time taken to dry the products is 6 h. Finally, the overall efficiency of the dryer for drying Moringa and Ginger is 23.8% and 21.5%, respectively. The solar dryer could be used for drying other agricultural products after testing at different seasons especially when there is a high and low solar radiation and temperature to see the maximum and minimum performance of the dryer.
Development and Experimental Testing of Thermal Storage System for Solar Parabolic Dish Concentrator
(Addis Ababa University, 2020-05) Melaku, Wolde; Solomon, Tesfamariam (PhD)
Ethiopia is one of the developing countries in the world, about 79.4% of people live in the rural area and 55.7 % live without electricity. Peoples who live in a rural area mostly use firewood for cooking and heating purpose. Renewable energy sources can be used as alternatives to substitute the firewood in rural areas. Parabolic dish solar collector has a relatively bigger aperture area to focus the solar rays in the limited receiver space and delivers high temperatures. This study deals with the development and experimentation of thermal storage system for solar parabolic dish concentrator. A phase change material, magnesium chloride hexahydrate was used to store the thermal energy since it is easily available in the local market. The heater (receiver) is portable because it can be easily dismounted from the collector. During sunshine it can be used as it is, whereas after sunset the receiver can be easily dismantled from the dish and kept indoor with an insulting vessel to minimize heat loss from the receiver’s outer surface. The aperture area of the parabolic dish is 0.2160 m2. The space occupied by the cylindrical phase change material container is 0.003083 m3. The volume of the phase change material is 0.002853 m3. Rod type fins are integrated to enhance heat transfer. To minimize heat loss by convection the storage system has glazing material. The glazing (cover) minimized the heat loss by 10.1%. The phase change material was heated up to 119oC. This ensures that the phase change material was completely melted since its melting point was not exceeding 117oC. One litter of water was heat from 22oC to 92oC. The overall efficiency of the concentrator is 75.9 % with the glazing system and 65.9 % without glazing system. As compared to the reviewed results of other researchers with similar aperture area of box type solar cooker, 400 g of water was heated from 25 oC to 78 oC with in the time of 2 hours. But in this research 1000 g of water was heated from 22 oC to 92 oC with in 2.67 hours. Hence, parabolic dish solar water heater with storage and glazing systems may comfortably be used in rural areas to warm food and boil water.
Techno – Economic Feasibility Study of Solar and Wind Energy Potential for Kombolcha Industrial Park
(Addis Ababa University, 2020-03) Mekdes, Paulos; Kamil, Dino (PhD); Solomon, Tesfamariam (Mr.) Co-Advisor
Ethiopia being one of the developing countries, industrial park is one of the options it has chosen to improve its economy. While the country is involved in works of different sectors, nationwide electricity access is still a major challenge. With the problem of lack of sufficient electricity, industrial parks also face challenges in blackout and interruption of electricity. This thesis is basically a case study addressing the techno-economic feasibility study of solar and wind energy potential for Kombolcha Industrial Park (KIP) as an off-grid system. With different methods starting from data collection incorporating site visit, qualitative data of interview, questionnaire, data collection from different governmental office the analysis was begun. Further analysis was done using Matlab and HOMER to model, simulate, and state the most optimized system. The viability of solar and wind energy system was analyzed using data collected from National Metrology Agency as a primary input. With the utilization of Matlab, a specific solar PV was chosen along with the site data of solar irradiation, it was simulated to give a viable outcome. The wind energy viability was also assessed to give a positive output. This being said the current energy demand of KIP is 2.8 MW. At present, to withstand the challenge, the industrial park uses diesel generators to cover their energy demand. The solar and wind potential was predicted using HOMER software taking the collected data as an input. The economical and emission reduction aspect was also estimated using HOMER. One of the best options of the technology mix was to generate the required 2.8 MW of electrical power by combing 69% (1.8 MW) of PV modules with 31% (1.0 MW) of wind turbine with cost of energy of USD 0.198/ kWh. However, this costs around USD 19 million. It has been with much cheaper cost of USD 6.65 million is required the 2.8 MW using only PV modules with battery and cost of energy of USD 0.07/kWh. The total free rooftop area of the park is around 43.3 thousand square meters. All the seven park's sheds have V-shaped ceilings. One side of the ceiling is facing towards the south and the other half is facing toward the north. Totally 14,250 - PV modules have to be mounted to generate the designed power on the south facing rooftop occupant 20 thousand square meter. The park uses a total amount of 1,080 liters of diesel per month to run a generator when interruption of power occurs. Emitting a total estimated emission of 24 tCO2 e per annum.
Sustainability and Optimal Design of Small-scale Photovoltaic Systems for Rural Applications in Ethiopia
(Addis Ababa University, 2017-10) Lemu, Kebede; Solomon, Abebe (PhD)
The government of Ethiopia placed a high priority on providing access to energy for remote locations. Despite this policy and the expenditure of millions of birr, the majority of the population still remains without access to electricity services today. To meet the lighting and other basic energy needs, many households continue to depend on polluting and non-efficient energy means such as kerosene and dry cell batteries. Electrification through grid extension was the only electrification options available to the rural population in this country. More recently, there is a dramatic increase in the use of renewable energy solutions, mostly off-grid solar PV systems by governmental and non-governmental organizations. Off-grid solar photovoltaic (PV) system is an obvious choice for bringing modern energy supply to the remote Ethiopian communities. In the past ten years, different governmental as well as nongovernmental organizations in Ethiopia have implemented thousands of solar photovoltaic systems for homes and institutions across the four regions in Amhara, Oromia, SNNP and Tigray regions of Ethiopia. However, to date there has not been a major study conducted in regards to the sustainability and PV systems design considerations. Accordingly, this study assessed the different systems implemented in the four regions (Amhara, Oromia, SNNP and Tigray regions) with the main objective to identify factors affecting the sustainability of solar PV system dissemination thereby suggesting best ways for designing stand-alone solar PV systems for rural applications. In order to meet these objectives, scientific methodologies were followed which include literature review, site visit, data collection and analysis. All the necessary data were collected by conducting surveys of solar PV systems installed in the selected sample Woredas of the four regions, and also by conducting interviews of PV system users and energy experts working in the respective Woredas, Zones and Regions. The thesis presents the major findings from the result of the data analysis which is evaluated in order to summarize the sustainability aspects of solar PV systems dissemination and to propose the most feasible solutions for the problems raised by the study. Based on the survey data analysis result, load estimations were done for homes and institutions found in off-grid areas. The solar radiation data of the regional capitals were retrieved from NASA which has been taken as an input for an optimized PV module and battery design that is simulated using PVSyst. This thesis also examines issues of optimal designing and as such provides optimum sizes of photovoltaic panels and batteries for two types of homes with different load considerations, and for institutions such as schools and health facilities. The findings show that there are different system sizes that exist for the same kinds of institutions. In addition, similar sized systems were supplied and installed for all regions. The simulated system using PVSyst shows, for Adama (Oromia region) and Mekele (Tigray region), smaller PV size is needed as compared to Bahir dar (Amhara region) and Hawassa (SNNPR).
Analysis and Performance Simulation of Solar Powered Water Pumping System: A Case Study in Jigjiga
(Addis Ababa University, 2019-06) Sofiya, Hussein; Yilma, Tadesse (PhD)
In most regions of Ethiopia groundwater is the major source of freshwater for drinking and agriculture, almost all groundwater is obtained from shallow to moderately deep wells. Whether we use diesel generators to generate power or electricity from the grid, the energy consumption is high and also using diesel energy which is one of the major causes of air pollution. The possible solution to minimize this problem is using renewable energy system. In this research the performance analysis of photovoltaic powered water pumping (PVPWP) system with maximum power point tracking (MPPT) controller was carried out under climate condition of Jigjiga. In this research a detailed electrical characteristics of 1800Watt non-tracking PV array (with 6Sx4P configuration) was determined on current vs. voltage as well as power vs. voltage plane by taking manufacturer’s data sheet of the PV module as input. A polynomial performance equation (which relates output flow rate of the pump with the input power and system head) was obtained with curve fitting technique, after performance points of the pump had been taken from the performance curve. Hence the hourly performance variation of the PVPWP system was predicted from the electrical characteristics of the PV array and the performance equation for (50, 60, 70, 80, and 90 meters of pumping heads). The modeled system gives a flow rate of 20-30 m /day for sunny days for the total dynamic head of 80m and solar irradiation of 5000-7000 Wh/m 3 2 /day

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