Browsing by Author "Nyaanga, David"

Now showing 1 - 3 of 3
  • Publication
    Publication
    Effect of Process Techniques on Three Feedstocks Mix on Briquette Performance Properties
    (Journal of Energy, Environmental & Chemical Engineering, 2022-02-16) Okwara, Wilberforce; Nyaanga, David; Aguko, Kabok; Nyaanga, Jane
    Energy availability at domestic level is a challenge across the world and especially in Africa. Firewood is the major source of energy for cooking for households in Kenya and there is need for a friendly sustainable environmental fuel. Carbonized biomass materials (briquettes) are considered a substitute. This study thus evaluated effect of selected briquetting techniques on briquettes’ performance properties. Milled charcoal dusts mixed in a ratio of 1:1:1 (Rice husk, maize cob, and sugarcane bagasse) with molasses binder in the ratio of 6:1 was hence ready for densification and agglomeration. The Water Boiling Test was used in determination of the briquette’s performance characteristics for various parameters. High (screw press); and low (drum agglomerator and hand making) pressure briquetting techniques were distinctly different in ignition time (minutes), time to boil (minutes) burning rate (g/min), specific fuel consumption (g/ml) and power output (kW) values as (4, 3, 3; 14, 12, 11: 0.8, 1.1, 1.3; 0.11, 0.13, 0.15; and 1.8, 1.4, 0.75). Diversified briquetting techniques, number and type of feedstocks are thus factors that influence performance characteristics of briquettes in converting the agricultural and or other wastes for useful energy application. This knowledge should enable users to make choices on techniques for optimum efficiency towards realization of Sustainable Development Goal Number #7 on affordable and clean energy.
  • Publication
    Publication
    Effect of Total Solids on Biogas Production in a Fixed Dome Laboratory Digester under Mesophilic Temperature
    (Annals of Advanced Agricultural Sciences, 2020-05) Barasa, Henry; Nyaanga, David; Njue, Musa; Matofari, Joseph
    An investigation on the effect of total solids on biogas production was done using a laboratory scale batch reactor of 0.15 m3 capacity. The feedstock was dung from dairy cows managed under a free-range system. Experiments were done on a substrate having total solids of 6%, 7%, 8%, 9%, and 10% at a constant temperature of 35°C; and the mean biogas production was 0.249, 0.304, 0.487, 0.287, and 0.244 m3 of biogas per m3 of digester volume per day (m3/m3d), respectively. It was concluded that the highest average biogas production of 0.487 m3/m3d is attained at total solids of 8%.
  • Publication
    Publication
    Optimization of Biogas Production in a Batch Laboratory Digester Using Total Solids, Substrate Retention Time, and Mesophilic Temperature
    (International Journal of Power and Energy Research, 2020-07) Barasa, Henry; Nyaanga, David; Njue, Musa; Matofari, Joseph
    Optimization was done by investigating the interaction effects of total solids, mesophilic temperature, and substrate retention time on biogas production in a batch biodigester. The volume of the biodigester was 0.15m3. Central composite design of Response Surface Methodology was used to design the experiment. Total solid levels were varied from 6.31% to 9.68%, temperature was from 26.59°C to 43.41°C, and substrate retention time was from 9.95 to 20.04 days. Analysis of results was done using Design Expert software statistical package (version 10.0.0.3). It gave a coefficient of determination of 0.9665 which indicated a high correlation between the variables. All the variables had a significant effect. The highest biogas production rate of 75.41litres/day (or 0.50 m3 of biogas per m3 of digester volume per day, m3/m3d) was achieved at a level of 8% total solids, a temperature of 43.41°C, and a substrate retention time of 15 days.