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Optimization of the Angle of Frog in Mouldboard Tillage Operations in Sandy Clay Soil

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Open Journal of Optimization 2015年第4期4卷 131-140页

作者： Angela Hiuhu ayub Njoroge gitau Duncan Onyango Mbuge John Ndisya Mulwa Department of Biosystems Engineering University of Nairobi Nairobi Kenya

This paper investigated the effect of three independent variables including: tillage speed (ranges of below 2.5 m/s and between 2.5 m/s and 5 m/s), tillage depth (range of 10 cm from 0 cm to 30 cm) and frog angle (30° 40°, and 50°) on draught forces. The experimental work was completed with determination of the draught forces using an analytical method (Saunders Equation). Numerical Simulation: Discrete Element Method (DEM) was used to verify the results obtained analytically. The results indicated that tillage depth has a stronger influence on the draught forces as compared to the tillage speed. Minimal draught forces can then be achieved through operating at shallow tillage depth and maintaining a frog angle of 30°. The results showed a variance of ±15.95% to the calculated values supporting DEM as a numerical method capable of predicting draft forces correctly, tillage power optimization and determination of optimal frog angle for the mouldboard plough.

关键词： DEM EDEM Soil-Cut Interactions Modelling Tillage Draught

Diesel Engine Emissions and Performance Characteristics under Cape Chestnut Biofuel

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Journal of Power and Energy Engineering 2013年第6期1卷 9-14页

作者： Jedidah W. Maina ayub N. gitau James A. Nyang’aya Department of Environmental and Biosystems Engineering University of Nairobi Nairobi Kenya Department of Mechanical and Manufacturing Engineering University of Nairobi Nairobi Kenya

Cape Chestnut oil was processed to biodiesel through transesterification. Cape Chestnut kennels are reported to have oil content of 60% - 63% [1]. Properties of biodiesel were determined and compared with those of diesel and engine tests done at a constant speed of 1500 RPM on the biodiesel blends to evaluate their performance and emissions characteristics. Performance evaluation was in terms of Brake Specific Fuel Consumption (BSFC), Brake Horse Power (BHP) and Brake Thermal Efficiency (ETE). The engine was initially run on diesel to establish the reference characteristics before running on biodiesel blends. The biodiesel was blended with diesel volumetrically to 80% (B80), 50% (B50), 20% (B20) and 5% (B5) the percentage being the volume of biodiesel in the blended fuel. Diesel fuel had the lowest BSFC followed by B5 whose BSFC was 7.3% higher than that of diesel. BTE for B100 was lower than that of diesel by 20.3% while that of B5 was 7.6% lower. Concentration of SO2 in B100 was 92.7% lower than that of diesel fuel while that of B20 was 24.7% lower. NO and NO2 concentrations for B100 were around 15% higher than that of diesel. Particulate matter of less than 10 μm diameter (PM10) for diesel was found to be 72% of the total collected from all the test fuels as compared to that of biodiesel blends at 28%. The study concluded that Cape Chestnut biodiesel blends containing up to 20% biodiesel can be used in an unmodified diesel engine since their performance and emission characteristics were very similar to that of diesel but with reduced toxic gas emissions therefore friendly to the environment.

关键词： Biodiesel Transesterification Performance Emissions Brake Specific Fuel Consumption Brake Horse Power Engine Thermal Efficiency

Evaluating Anaerobic Digestion Technology in Reducing the Quantity of Solid Waste: Case of Kigali Dumpsite

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Journal of Geoscience and Environment Protection 2020年第5期8卷 204-220页

作者： Nikuze Marie Joselyne Muthumbi Waweru ayub N. gitau Uliho Alphonse Munyensanga Patrick Department of Environmental and Biosystems Engineering University of Nairobi Nairobi Kenya Department of Civil Environmental and Geomatics Engineering University of Rwanda Kigali Rwanda Key Laboratory of Industrial Biotechnology Jiangnan University Wuxi China Department of Mechanical Engineering Diponegoro University Semarang Indonesia

Biodegradable organic matter constitutes a great portion of Municipal solid waste and comprises organic material which can be broken down by bacteria like paper, card, green waste, food waste, miscellaneous items with an organic element and fine materials. This paper mainly evaluated the potential of anaerobic digestion technology in reducing the quantity of solid waste destined to the dumpsite in Kigali city. The paper evaluates the viability of using biodegradable waste meant to the land where the biogas is produced and undertaking its cost & benefit analysis for chemical, physical and biological characteristics of municipal solids waste on anaerobic digestion technology. The quantity of municipal waste generated in Kigali city was used for designing the biodigester required. The paper indicates that the organic waste in Kigali city produces 457 L/kg DM of methane and the overall assessed value of methane was 51,384,375 L with the electricity derived from the methane of 180,873 KWh which is 54% of the daily demand in Kigali city. The volume of the biodigester was found to be 58,065 m3. Based on the energy recovered, revealed that cities will benefit this research for the population demand for the increased electricity.

关键词： Anaerobic Digestion Technology Biodegradable Waste Kigali Dumpsite Mu-nicipal Solid Waste Waste to Energy

Optimization of Specific Draft Requirement and Hitch Length for an Animal Drawn Sub-Soiler: A Case of Sandy Clay Loam Soils

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Open Journal of Optimization 2019年第3期8卷 83-99页

作者： Nicodemus K. Mwonga ayub N. gitau Joackim M. Mutua Simon T. Mwangi Department of Environmental and Biosystems Engineering University of Nairobi Nairobi Kenya

This study aimed at optimizing tillage depth and hitching length for optimal draft requirement in sandy clay loam soils for animal drawn subsoiler. Field experiments were conducted to collect draft datasets using the MSI 7300 digital dynamometer communicating remotely with MSI-8000 RF data logger connected to a laptop through the serial port. To determine the numeric values of soil parameters pertinent to subsoiling, field experiments, laboratory tests and numerical analysis techniques were employed. For a specified speed, a combination of three hitch lengths of 2.5 m, 3.0 m and 3.5 m and three depths from 0 cm to 30 cm with a range of 10 cm interval was used. Soil bulk density was found to vary between 1.52 to 1.37 g/cm3 and 1.44 to 1.67 g/cm3 for Machakos and Kitui experimental plots respectively. Soil moisture content increased with an increase in depth ranging from 3.53% to 9.94% for Machakos site and from 4.15% to 9.61% for Kitui site. Soil shear strength parameters ranged between 21.71 and 29.6 kPa between depths of 0 - 20 cm and decreased to 28.07 kPa for depths beyond 20 cm at Machakos experimental plot;while for Kitui experimental plot, it ranged between 30.02 and 39.29 kPa between depths of 0 - 30 cm. A second-order quadratic expression of the form y = ax2 + bx + c was obtained for the relationship between specific draft and depth at given hitching length as well as specific draft against hitching length at a given depth. The optimal hitching length and tillage depth for Machakos experimental plot were obtained as 2.9 m (~3 m) and 16.5 cm respectively. In Kitui experimental site, the optimal hitching length was obtained as 2.9 m (~3 m) and the optimal tillage depth was 15.4 cm.

关键词： Soil Resistance Specific Draft Hitching Length Subsoiling Depth Animal Power