Energy Technology

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Browsing Energy Technology by Author "Alemu, Demiss(PhD)"

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    Comparative Analysis of Briquetting Most Viable Biomass Waste to Substitute Charcoal in Ethiopia
    (Addis Ababa University, 2014-04) Belay, Anteneh; Alemu, Demiss(PhD)
    Agricultural residues seem to be the most promising energy resources for developing countries. However, the majority of them have low energy density. One of the favorable technologies for enhancing that property is charcoal Briquetting. A large amount of agricultural and solid wastes are left in the field after harvest. The primary objective of the study was to investigate the comparative analysis of resource availability, physico-chemical properties and performance of biomass charcoal produce from the most promising wastes. Specific objective were to develop and characterizing composite charcoal briquettes, investigate factors affecting densification of composite charcoal briquettes and compare resources availability, physic-chemical property and performance of charcoal briquettes with wood charcoal. The composite charcoal briquettes were produced using ASTM standard by a combination of process factors. The three process factors were dwell time, clay binder ratio and pressure. Design expert software, Box-Henken model were employed to investigate the effect of process factors. The Density was found in the range of 783.00-1,187.00 kg/m^3. The coefficient of multiple determinations for prediction of the proposed density model was about 95.7%. The effect of the three variables against density was investigated. When every two combinations of the above variables were increased, density of briquettes was also found to increase. Optimum point of dwell time, pressure and clay binder concentration was found at 3.6 minute, 45 bars and 18.27% respectively. The optimal point was validated. The Production of 1300 tones/yr briquettes plant was evaluated. The total investment cost was found to be 1.9137milloion birr. The net present value and the internal rate of return of the project were 2,753,976 Birr and 19% respectively it implies the project was feasible. Base on the resource estimation using production to residue ratio, the quantity of available agricultural residue, cotton stalk, coffee husk, bamboo residue and jatropha press cake in Ethiopia was approximately 4,655.887, 219.933, 109.757, 109.757,1,000 and 0.228Ktones/yr respectively. When the fixed carbon of charcoal made from bamboo, cotton stalk, coffee residue and composite with that of Acacia charcoal, 60.85, 58.4, 63.9, 68.25 and 69.74w/w % were found respectively. The above value all had relatively similar which makes it possible to substitute wood charcoal. Regarding heating values of briquettes produced from bamboo, cotton Comparative Analysis of Briquetting Most Viable Biomass Waste to Substitute Charcoal in Ethiopia AAU, AAiT, M.Sc. Thesis by Anteneh B. xiv stalk, coffee residue, composite and Acacia spp. charcoal were 29135.94KJ/Kg, 19209.03KJ/Kg, 11710.48KJ/Kg , 23446.08KJ/Kg and 32573.304 KJ/Kg respectively. But all the heat values of briquettes were lower than that of charcoal. If the country substitutes wood charcoal by charcoal briquettes, it will reduce 47.06 CH4 / year and 1530.383 Co2/year for every production of 1300 tons per year. The study showed that charcoal from bamboo; cotton stalk, coffee residue and agricultural residue could be used as substitutes for Acacia charcoal as they had comparable potential energy. But jatropha press cake currently had a low possibility to be use in our scenario. Generally, this research concludes that the biomass charcoal had positive value of production method, fixed carbon and performance, but one negative value was obtained from calorific value. With ¾ positive values, these biomass wastes can substitute wood charcoal in Ethiopia.
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    Design of Coolant Heater For An Emergency ELECTRIC Generator Drive Diesel Engine By Solar Energy For A Cement Industry
    (Addis Ababa University, 2016-12) Meleta, Tadesse; Alemu, Demiss(PhD)
    coolant and lubricant to attain the optimum operating temperature without delay in an industry using diesel engine to drive emergency electric generator in attaining its rated power capacity for one of the diesel engine driven emergency electric generator installed for Mugher Cement Factory. The result will serve for avoiding the cement production equipment of the rotary kiln and related drive systems from thermal gradient deformation immediately after unexpected main grid failure. In order to improve the circulating coolant temperature and the pre-heating time requirement, electric heater has been installed. To measure the improvement of engine efficiency during starting up period after main grid failure, temperature data are collected from the generator set controller and measuring instruments both before and after installation of electric heater. These data have been collected when this experiment was made on site in Mugher Cement Factory. The data contain readings of temperatures [°C] obtained from measuring instruments and installed controller. The analysis of the system has been done by using controller performance display readings and performance measuring instruments. Besides, temperature reading data has been analyzed by using some statistical methods, particularly to investigate the improvements achieved or the severity of the existing problem. From the performance improvements, the results computed from observed data as well as from test instruments, the generator set shows that its performance has been clearly improved by using heater to heat the coolant. Besides these, it can be deduced, even if not tested, that coupling of the solar thermal technology can further improve its performance. Based on these preliminary results, a solar water heater of 100 litre capacity, with provision of auxiliary electrical heater in addition to solar heater, in comparison with the cases of electrical heater, is designed in detail to be locally fabricated and installed for the case of Mugher Cement Factory. Generally, selecting and adopting proper solar water heating technology for the circulating coolant of emergency electric generator drive diesel engine has improved preheating time in attaining engines thermostat opening temperature in a lesser time to avoid the rotary kiln and related drive-driven systems thermal gradient deformation immediately after the main grid failure of a cement industry. This is an indication of the applicability of the result of this thesis. xvii The output of the research shall contribute reliability for industry’s production processing equipment, especially the key equipment that operate at high process temperature, by avoiding rapid cooling that causes the thermal gradient deformation and leads to complete equipment damage and consequently loss of production, revenue and employee lay off due to inefficiency of the engine. The finding of this research can be used as the potential of making the diesel engine driven electric generator that enable to attain its full load immediately by adopting similar technologies for institutions that require immediate back up. Furthermore, it creates an opportunity in looking at heating water by harnessing energy from the sun for industrial and commercial firms in order to overcome the rising of oil prices as well as utilization of environmental-friendly alternative sources of energy, specifically renewable energy technologies and promoting green energy technology. Key words: Engine coolant, heating time, delay time, heater, emergency generator, kiln, cooler, solar radiation, solar collector.