Browsing by Author "Ambusso, Willis J."

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    Evaluation of Energy Efficiencies in a Varied Steam Release Domestic Pressure Cooker
    (Journal of Thermal Engineering, 2025-07) Ayub, Hesborn R.; Ambusso, Willis J.; Nyanga, Daudi M.
    Despite its efficiency, pressure cooking is characterized by two primary energy losses: direct steam release during whistling and convection heat loss to the surroundings. The study focused on reducing energy losses during pressure cooking. The study experimented to determine the effect of each modification on pressure cooker energy efficiency. Ceramic wool insulation and automation for zero steam release modifications to an ordinary pressure cooker were used interchangeably. The experiment’s controls were an ordinary induction-powered pressure cooker and an electric pressure cooker powered with a resistive element. The energy consumption and standby cooking time were measured, and efficiency was calculated. Insulation improved standby cooking time and energy efficiency by 100% and 3.3%, respectively, whereas automation alone increased energy efficiency by 196%. Combining insulation and automation increased energy efficiency by 200%. The insulated automated pressure cooker had an efficiency of 93%, which was close to the electric pressure cooker’s 95%; both combined insulation and automation. It was discovered that a combination of insulation and automation eliminates major pressure-cooking losses, including convection and direct steam thermal energy. This reduces the amount of energy consumed while cooking, thereby increasing energy efficiency. This will significantly reduce the cooking carbon footprint, reducing the demand for fuel wood from forests. This will save forests, thereby combating climate change and improving environmental sustainability. The novel aspect of this study is that it investigated each effect of zero-steam release and thermal insulation pressure cooker modification on energy efficiency. This has reduced thermal energy waste and increased energy efficiency, adding to the body of research knowledge in the field of thermal engineering. This study is significant because it will spur efforts to improve energy efficiency in cooking, lowering the carbon footprint.
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    Fluoride adsorption onto an acid treated lateritic mineral from Kenya: Equilibrium studies
    (Academic Journals, 2012) Wambu, Enos W.; Onindo, Charles O.; Ambusso, Willis J.; Muthakia, Gerald K.
    Adsorption of fluoride (F) ions from water using acid treated lateritic mineral (LM-1) from Kenya was studied by batch experiments. The effect of acid-treatment of adsorbent and change in temperature, mass of LM-1, pH and selected competing ions was evaluated. The adsorption process was strongly influenced by temperature, pH and adsorbent dosage. The percentage F removal increased the presence of the nitrate and the chlorate ions but decreased the presence of sulphates, chloride and phosphate ions. Adsorption isotherms were classified according to Giles’ classification and the adsorption data validated using Langmuir and Freundlich isotherms. The data correlated to both the Langmuir and Freundlich isotherms although the data fit to the Freundlich model was somehow better. This showed that F adsorption onto LM-1 followed a mixed adsorption mechanism in which physisorption reactions involving intra-particle diffusion of F into mesoporous sites in LM-1 became increasingly important at higher concentrations and temperatures whereas ion-exchange mechanism involving surface OH- appear to dominate at low surface coverage in more alkaline conditions. With maximum adsorption capacity of 10.5 mg/g, LM-1 could be used to remove F water.
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    Numerical Simulation of Fluid Flow in a Dual Porosity Geothermal System with a Thin Zone of High Horizontal Permeability
    (Kenyatta University, 2007) Ambusso, Willis J.
    A numerical simulator capable of mode ling fluid flow in layered dual porosity geothermal systems with high horizontal permeability has been developed. The simulator can match multiple-peaked tracer profiles from injection tests and reliably predict temperature and pressure changes caused by injection of brine in these systems. The simulator was tested and validated using data from Svartsengi geothermal field in Iceland, a non-layered geothermal field, and Olkaria geothermal field in Kenya, a layered geothermal reservoir. Simulated results show significant improvement over regular geothermal simulators and indicate that fluid flow within the horizontal layers with high permeability are best represented by fracture flow theory where fluid flow between the matrix-fracture network occurs in both directions rather than what is normally assumed that fluid flow is governed purely by dual porosity model where fluid flow occurs only from the matrix to the fracture. The study shows that fluid movement in horizontal fractures will dominate main fluid flow features in the reservoir and shall uniquely modify tracer profiles. These horizontal fractures will also lead to high returns of injected fluid at relatively low speeds in reservoirs with moderate permeability as has been noted in Olkaria. This simulator makes it possible to extract quantitative values of the hydrologic parameters of the respective layers. This should lead to better planned and managed brine injection programs.