Browsing by Author "Kivevele, Thomas T."

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Effect of Antioxidants Extracted from Clove Wastes and Babul Tree Barks on the Oxidation Stability of Biodiesel made from Water Hyacinth of Lake Victoria Origin
(Springer Nature Switzerland AG, 2019-11-04) Waweru, Emmanuel J.; Pogrebnaya, Tatiana; Kivevele, Thomas T.
Biodiesel from water hyacinth has shown to have poor oxidative stability due to the presence of significant amounts of unsaturated fatty acids. Most studies have been using synthetic antioxidants to improve oxidation stability of biodiesel but they are expensive and proved to be toxic at higher concentrations. This study assessed the possibility of using natural antioxidants extracted from clove wastes and babul tree barks since they are cheap, easy to extract and locally available and blends of these with synthetic antioxidant such as 1,2,3-trihydroxybenzene (Pyrogallol, PY) in improving the oxidation stability of biodiesel. Non-edible water hyacinth collected from Lake Victoria Tanzania was used as feedstock for biodiesel production. The biodiesel was analyzed for physicochemical properties and fatty acid composition. Most of the physicochemical properties were within the acceptable limits for ASTM D6751 and EN 14214 except for oxidation stability which recorded 2.4 h and was below limits. Fatty acid analysis showed the presence of unsaturated fatty acids at 42% which contributed to the poor oxidation stability of the biodiesel. Clove waste and babul barks displayed significant total phenolic contents of 220.0 ± 0.1 and 48.0 ± 0.2 mg GAE/g, respectively. Clove antioxidant displayed an improvement of 153% in oxidation stability at 1000 ppm while babul improved by 236% at 800 ppm. Blends of clove with PY displayed much higher improvements in oxidation stability by 398% at 800 ppm while babul with pyrogallol showed a general decrease in performance by 46%.
Tamarindus Indica fruit shell ash: a low cost and effective catalyst for biodiesel production from Parinari curatellifolia seeds oil
(Springer Nature Switzerland AG., 2019-02-21) Nabora, Christian S.; Kingondu, Cecil K.; Kivevele, Thomas T.
The study evaluated the potential use of agricultural waste, Tamarindus indica fruit shell ash, as a solid base catalyst for production of biodiesel. The catalyst was prepared by calcination of T. indica fruit shell at 800 °C in mufe furnace for 3 h. Branauer-Emmett-Teller, thermal gravimetric analysis, X-ray difraction, scanning electron microscope, X-ray forescence, and Hammett indicator techniques were used to characterize the physicochemical properties of the produced catalyst. The catalyst had basic strength of greater than 9.7 and mesoporous structure with pore size d=3.2 nm. The crystalline phase was made up of calcium oxide, potassium oxide, and magnesium oxide. The catalyst was tested for biodiesel production using Parinari curatellifolia seeds oil. The results showed that the best operating parameters for the production of biodiesel were 9:1 methanol to oil molar ratio, 125 mg catalyst (5 wt% of oil), 2 h reaction time, and 60 °C reaction temperature. These optimized operating parameters aforded a maximum yield of 96.2%. Also, fuel properties of biodiesel: acid value, viscosity, and fash, pour, and cloud points were investigated and compared to the ASTM standards limits D6751. The results were observed to be in good agreement with the ASTM standards limits for biodiesel. In addition, the catalyst was easily separated and subsequently reused for four runs in biodiesel production. Thus, Tamarind fruit shell derived catalyst is very promising for the production of biodiesel due to its high performance, low-cost, easy preparation and availability
Theoretical and Experimental Performance Analysis of a Novel Domestic Biogas Burner
(Hindawi, 2020-09-16) Petro, Lucia M.; Machunda, Revocatus; Tumbo, Siza; Kivevele, Thomas T.
The inefficient indoor burning of fuelwood on traditional cookstoves generates pollutants, primarily carbon monoxide and many other human health-damaging emissions. It is from this risk that it is necessary to have an immediate shift to alternative cleaner fuel sources. Biogas, which is among the biofuels from biomass, is one of the resources that play a considerable part in a more diverse and sustainable global energy mix. For domestic purposes in rural areas of Tanzania, biogas provides a better option that can supplement the use of fossil fuels such as wood, charcoal, and kerosene, which is nonrenewable. However, the low efficiency experienced in the locally made biogas burners hinders the large-scale use of biogas among the population in the country. With the locally made burners, the users of biogas for the domestic application face problems including heat loss and high gas consumption which affects the whole cooking process. It is against this backdrop that the current study objectives incline on designing and improving the efficiency of the locally manufactured burners to achieve the uniform flow of fuel in the mixing chamber, which will result to the consistent heat distribution around the cooking pot. The optimization of the burner was done by using computational fluid dynamics (CFD) through varying the number of flame portholes and air holes as well as the size of the jet before fabrication. The increased efficiency of the burner has also contributed by the addition of the fuel distributor. The results showed that the optimum hole diameter of the jet was 2.5 mm and that of the manifold was 100 mm. The currently developed biogas burner was tested and compared with the other two locally made burners. The water boiling test (WBT) on these three burners showed that the developed burner has a thermal efficiency of 67.01% against 54.61% and 58.82% of the Centre for Agricultural Mechanization and Rural Technology (CARMATEC) and Simgas, respectively. Additionally, the fuel consumption of the developed burner was 736 g/L as compared to 920 g/L for CARMARTEC and 833 g/L for that of Simgas. The developed burner and its corresponding cookstove are both environmentally friendly and economical for household utilization in Tanzania and other developing countries.