Engineering and Technology

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Browsing Engineering and Technology by Author "Biira, Saphina"

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    Quantification and characterization of cocoa pod husks for electricity generation in Uganda
    (Sustainability and Society, 2019) Kilama, George; Lating, Peter O.; Byaruhanga, Joseph; Biira, Saphina
    Due to limited coverage, the electricity power supply in Uganda is an obstacle to the country’s economic development. Utility firms in Uganda either lack the financial capacity to expand their grids to isolated rural areas or choose not to do so due to the low return on investment. Therefore, connecting households to minigrids represents an effective solution to providing power to remote/rural areas. This study evaluates the resource and technology of generating electrical energy from cocoa pod husks (CPHs), an agricultural residue/waste, generated in Uganda. The use of agricultural waste for energy generation is the most suitable option for the rural population in Uganda because of the availability of a raw material (biomass) for its production, which is pollutionfree (renewable and clean) and does not have competition for use. The inability to convert these solid wastes into useful products culminates into environmental related challenges, such as landfilling, climate change, pests, and diseases. Therefore, the aim of this study is to quantify the amount of generated CPHs and evaluate its potential for electricity generation in Uganda. Subsequently, we have been looking into the potential of CPHs as a feedstock for a thermochemical conversion process and the feasibility of a direct combustion technology. Results: The amount of CPHs generated in Uganda has been estimated. The physiochemical analysis has shown that the proportion of CPHs in the fresh pods is about 74%, which is nearly the same as in other studies. The dry matter content of CPHs has been found to be on an average of 19%, whereas ash content, moisture content, and the gross caloric value have been recorded to be 12.3%, 12.58%, and 17.5%, respectively. It seems therefore likely that 41.7 GJ of energy might be produced each year from CPHs in Uganda. Conclusion: This study has demonstrated that the CPHs are an important energy source. As there is an increasing trend in cocoa and CPH production in Uganda per year, the electricity production based on CPHs is sustainable and can be upgraded. The use of CPHs for energy conversion is therefore feasible, cost-efficient, and a solution to some environmental challenges.
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    Thermal Performance Evaluation of the Funnel Solar Cooker of Different Funnel Lengths Implemented in Nagongera, Uganda
    (Tanzania Journal of Science, 2020) Chepkurui, Jonah; Biira, Saphina
    The aim of this study was to evaluate the thermal performance of a funnel solar cooker with different funnel lengths. Four funnel solar cookers of varying funnel lengths were constructed at Nagongera, in Tororo District, Uganda from cheap locally available materials. After construction, four blacked cooking pots of the same size filled with 1 kg of water were each placed in a cooker from 09:00 to 17:00 hrs. The temperature of the water in the pots was recorded after every 2 hours. The maximum temperatures of 93 °C, 84 °C, 68 °C and 58 °C for the funnel lengths of 50 cm, 42.6 cm, 32 cm and 23.3 cm, respectively were achieved at 13: 00 hrs for the average solar intensity of 684 W/m2 and ambient temperature of 27.9 °C. Similarly, as the funnel lengths increased from 23.3 cm to 50 cm, the thermal efficiency of the cooker increased from to 29.2% to 33.2% due to increased solar collecting surface. This indicates that the cooking temperature and thermal efficiency depended on the funnel lengths of the cooker and the time of the day. The results obtained were suitable and therefore the funnel solar cooker can be introduced to the community.
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    Thermodynamics kinetics of boron carbide under gamma irradiation dose
    (International Journal of Modern Physics B, 2019) Mirzayev, Matlab; Demir, Ertugrul; Mammadov, Khagani; Mehdiyeva, Ravan; Jabarov, Sakin; Tugrul, A. Beril; Biira, Saphina; Tiep, Nguyen; Thabethe, Thabsile
    In this paper, high purity boron carbide samples were irradiated by 60Co gamma radioisotope source (0.27 Gy/s dose rate) with 50, 100, 150 and 200 irradiation hours at room-temperature. The unirradiated and irradiated boron carbide samples were heated from 30 C to 1000 C at a heating rate of 5 C/min under the argon gas atmosphere of ow rate 20 ml/min. Thermogravimetric (TG) and Differential Scanning Calorimetry (DSC) were carried out in order to understand the thermodynamic kinetics of boron carbide samples. The weight kinetics, activation energy and specific heat capacity of the unirradiated and irradiated boron carbide samples were examined in two parts, T 650 C and T 650 C, according to the temperature. The dynamic of quantitative changes in both ranges is different depending on the irradiation time. While the phase transition of unirradiated boron carbide samples occurs at 902 C, this value shifts upto 940 C in irradiated samples depending on the irradiation time. The activation energy of the unirradiated boron carbide samples decreased from 214 to 46 J/mol in the result of 200 h gamma irradiation. The reduction of the activation energy after the irradiation compared to the initial state shows that the dielectric properties of the irradiated boron carbide samples have been improved. After the gamma irradiation, two energy barrier states depending on the absorption dose of samples were formed in the irradiated samples. The rest and second energy barriers occurred in 0.56{0.80 and 0.23{0.36 eV energy intervals, respectively. The existence of two energy levels in the irradiated boron carbide indicates that the point defects are at deep levels, close to the valence band.
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    Trends and status of women in physics in Uganda
    (AIP Publishing LLC, 2019) D’ujanga, Florence M.; Biira, Saphina; Akoba, Rashida
    Most women in Uganda with an advanced degree in physics find employment at a university, teaching and conducting research. Very few take jobs in by industry or at government research laboratories. This paper discusses the trends in Uganda in women’s participation in the field of physics and their status. The paper also highlights factors that hinder girls from pursuing the study of physics and describes interventions the government is initiating to alleviate the situation.