Browsing by Author "Sebbit, Adam"

Now showing 1 - 6 of 6
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    Improving reliability and functional sustainability of groundwater handpumps by coating the rubber piston seals with diamond-like carbon
    (Honor, 2015) Lubwama, Michael; Corcoran, Brian; Kirabira, John Baptist; Sebbit, Adam; Sayers, Kimmitt
    In many rural communities, handpumps are essential in order to provide access to safe drinking water from groundwater sources. The functional sustainability of handpumps is poor, however, and most maintenance issues in handpumps are caused by wear of the nitrile rubber piston seals. This study identified handpump problems faced by a rural community in southern Uganda, specifically related to wear of piston seals. We investigated a novel surface-engineering approach to improve the wear resistance of piston seals by depositing diamond-like carbon (DLC), and silicon (Si) doped DLC onto the seals. Wear mechanisms for the coated seals were determined using a piston seal wear test rig. Tests were undertaken with clean normal water, and water seeded with sand particles. Wear mechanisms identified included adhesion, abrasion, and fatigue. For the DLC and Si-DLC coated piston seals the dominant wear mechanism was abrasion, with minimal fatigue wear. Adhesive wear on the coated piston seals is explained by the generation and transfer of a tribo-layer, which increases wear resistance and functional sustainability of the piston seal. Wear resistant seals could significantly reduce the maintenance costs of existing handpump designs, and improve their functional sustainability.
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    Macroeconomic effects of a low carbon electrification of greater Kampala Metropolitan area energy policy: A computable general equilibrium analysis
    (Energy Strategy Reviews, 2022) Kimuli, Ismail; Lubwama, Michael; Sebbit, Adam; Kirabira, John Baptist
    Greater Kampala Metropolitan Area (GKMA) is Uganda’s capital facing increasing pressures to raise electricity generation and also mitigate CO2 emissions. A low-carbon electrification of the GKMA energy policy is proposed for sustainability. But the macroeconomic effects of this policy are unknown. The study uses a multi-sector, single region, static GKMA-CGE model to address the knowledge gap in 4 scenarios. BAU is the baseline against which comparisons with Kabejja (20% CO2 abatement); Carbon-Tax ($100/ton) and Lutta scenarios (95% CO2 abatement) are made. The results indicate GDP increased by Kabejja:0.7%; Carbon-Tax:1.3%; Lutta:1.56% with respect to BAU. Equivalent variation also increased compared to BAU. Energy & CO2 intensities of GDP decreased in all scenarios. The study recommends Lutta for a sustainable 2050.
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    Small-scale CHP for Rural Electrification in Uganda – The State-ofthe- art and Prospective Development
    (In Second International Conference on Advances in Engineering and Technology, Working Paper., 2011) Musinguzi, Wilson B.; Okure, Mackay A.E.; Sebbit, Adam; Løvås, Terese
    Worldover, small-scale CHP systems are undergoing rapid development, and are emerging on the market with promising prospects for the near future. The choice of a suitable CHP system is driven by the need and local conditions at the target end user, keeping in mind that the system integration should have a good balance of being most efficient, reliable, cost effective, socially beneficial, least polluting and sustainable in the long run. In developing countries, small-scale biomass-fuelled CHP systems have a particular strong relevance in improving the quality of life, especially among rural communities. This paper presents the recent advances in small scale CHP process integration for decentralized power generation. It also presents an exergy analysis of a prospective CHP system that has the potential of providing relatively higher efficiency and minimal operational difficulties and thus attractive for rural electrification in Uganda. The target generation capacity is 100 kWe sufficient to meet electricity needs of a rural community of 250 households. Stepwise procedure with simulation using Aspen Plus is used in the analysis of this CHP cycle. The results show that the proposed process integration has the promise of efficiently utilizing the exergy generated.
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    A sustainable energy portfolio for Greater Kampala Metropolitan Area towards the mid-century
    (Heliyon, 2022) Kimuli, Ismail; Lubwama, Michael; Kirabira, John Bosco; Sebbit, Adam
    With steadfast economic development, the Greater Kampala Metropolitan Area (GKMA) faces increasing pressures to raise low-carbon electricity in the energy consumption by fuel type, abate CO2 emissions, and also restructure transportation for sustainability. GKMA is Uganda’s capital with rampant anthropogenic interference that causes climate change. A sustainable energy portfolio is a low-carbon scenario endowed with CO2 emissions abatement strategies for GKMA towards 2050. Using TIMES-VEDA to address the knowledge gap, the study develops and examines a sustainable energy portfolio for GKMA. TIMES-VEDA is an engineering model generator with a bottom-up approach, paying in-depth attention to low-carbon themes while optimizing energy management systems. The analysis shows that sustainability is plausible by optimizing the total primary energy supply, electrical power production from PV-solar & hydropower technologies, and switching 90% of passengers of the road category to the Kampala metro.
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    Thermal characterization of Uganda's Acacia hockii, Combretum molle, Eucalyptus grandis and Terminalia glaucescens for gasification
    (Biomass and Bioenergy, 2012) Musinguzi, Wilson B.; Okure, Mackay A.E.; Wang, Liang; Sebbit, Adam; Løvås, Terese
    In this paper, thermal characterization of four Ugandan woody biomass species was carried out in order to ascertain their suitability for gasification for small-scale biopower generation. The analyses and tests covered the aspects of proximate analysis, ultimate analysis, heating value, Thermogravimetric Analyses (TGA), ash melting and chemical composition. Eucalyptus grandis revealed ideal properties that make it the most promising wood specie for gasification applications. Furthermore, the low ash content in E. grandis significantly minimizes the possibilities of ash deposits on the gasifier and heat exchanger surfaces. The high fixed carbon in Terminalia glaucescens, Acacia hockii and Combretum molle makes these species ideal for charcoal making (pyrolysis). Due to high ash melting temperatures demonstrated by these samples, their pyrolysis and gasification can therefore take place with minimal worry of the ash related problems.
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    Thermodynamic Modeling of Allothermal Steam Gasification in a Downdraft Fixed-bed Gasifier
    (Trans Tech Publications Ltd., 2014) Musinguzi, Wilson B.; Okure, Mackay A.E.; Sebbit, Adam; Løvås, Terese; Silva, Izael Da
    A process of converting a solid carbonaceous fuel into a gaseous energy carrier in presence of a gasifying medium at high temperature is called gasification. The resulting gaseous energy carrier, known as producer gas, is more versatile in its use than the original solid fuel. Gasification is widely considered as a more efficient and less polluting initial thermochemical upstream process of converting biomass to electricity. The objective of this study was to investigate the process of allothermal steam gasification in a fixed-bed downdraft gasifier for improved quality (HHV, high hydrogen content) of the producer gas generated. The study involved thermodynamic equilibrium modeling based on equilibrium approach in which the concentrations of the gaseous components in the producer gas at equilibrium temperature are determined based on balancing the moles in the overall gasification equation. The results obtained suggest that the maximum equilibrium yield of producer gas with high energy density is attained at a gasification temperature of around 820oC and a steam/biomass ratio of 0.825 mol/mol. The equilibrium yield was richer in hydrogen at 52.23%vol, and with a higher heating value of 11.6 MJ/Nm3. Preliminary validation of the model results using experimental data from literature shows a close relationship. The study has further shown the advantage of using steam as a gasifying medium towards the improved quality of the producer gas generated.