Faculty of Engineering and Technology

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    Analysis of catchment hydrologic response under changing land use The case of upper Molo river catchment, Kenya
    (Egerton University, 2008-10) Kirui, Wesley K
    Change in land use has a direct effect in catchment hydrologic response. It is caused by human intervention to enhance and diversify their livelihood needs, and at the same time get economic benefits from the land resources. These interventions result in changes in surface runoff, soil erosion and sediment yield among others. If the change in land use is not well managed then it will affect the quantity and quality of water resources as well as production potential of the land. Based on this ground this study was formulated to investigate the effects of land use changes on catchment response, in particular surface runoff and sediment yield. Such a study required continuous hydrologic data such as stream flow and sediment yield for a number of gauging stations within the study catchment. However, most catchments in Kenya do not have adequate data to accomplish such study. In this study upper Molo River catchment in eastern Mau was used because of its consistent stream flow data. In this catchment there has been significant reduction in stream flow during dry season and flooding in the rainy season. This study investigated a modelling approach for predicting the changes in catchment response as a result of land use change. Soil and Water Assessment Tool (SWAT) was identified as suitable model and used to simulate the catchment response under different land use types. The input data used were digital elevation model (DEM), land cover, soils and rainfall. The DEM was processed in Arc View GIS and land cover maps derived from satellite image using ERDAS 8.5 imagine software. The land cover analysis results show that forest cover reduced by 48% as a result of increase in agricultural and settlement areas between the years 1986 to 2001. Simulation analysis carried out for 1986 and 1995 land cover maps, show an increase in surface runoff of 13.3%. In the simulation the data set was divided into two; 1980 to 1989 for calibration and 1991 to 2000 for validation. Conceptual parameters derived during calibration were used in the model to simulate streamflow for the two data sets and gave a Nash Sutcliffe coefficients of 0.87 and 0.72 respectively. The sediment yield values were 1.5t/ha for the calibration and 2.7t/ha for validation periods respectively. These results show insignificant change in the catchment response but demonstrated the effects of land use changes on catchment response. It is therefore concluded that land cover change of less 48% have insignificant change on catchment hydrologic response.
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    Evaluation of the impact of land use change on catchment hydrology: the case of Wundanyi river catchment in Taita Hills, Kenya
    (Egerton University, 2013-04) Mkaya, Dishon Mwawasi
    The conversion of forest land to agricultural land and urban settlement usually increases soil erosion, and volume of storm runoff in a catchment. In Kenya, the rural communities are encroaching into the humid and marginal areas to open up new lands for agricultural production and settlement. These changes have led to environmental degradation, which has negatively altered the hydrologic regimes of many catchments in Kenya. The Wundanyi River catchment is one of the catchments that have undergone rapid land use changes over the last 30 years. It requires intervention to improve and sustain hydrologic processes to prevent further degradation. However, the catchment lacks continuous records for hydrologic data that can be used. Therefore, there was need to apply remote sensing and modelling approach in getting hydrological data for this catchment for analysis and management. The study applied the Soil and Water Assessment Tool (SWAT) model to evaluate the impact of land use change on the catchment hydrology. The input data used included digital elevation model (DEM), land use maps, soil maps and rainfall. Changes of land use in the catchment were characterised and quantified using remote sensing and GIS. The land use evaluation results showed that the agricultural land and built up area increased by 10% and 156% respectively between 1975 and 2004, while the forest land cover reduced by 57%. Simulation of land use change scenes showed that average annual surface runoff and sediment yield increased from 8.74mm to 99.30mm and 0.43t/ha to 20.10t/ha, respectively. These findings can be used by catchment stakeholders and policy makers to address challenges resulting from catchment degradation. This research will further help in making informed decisions in selecting and developing viable catchment management options that will promote sustainable utilization of land and water resources within Wundanyi River Catchment.
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    Potential of sour plum (Ximenia americana l.) seed oil as a biofuel
    (Egerton University, 2014-02) Kibuge, Richard Minkech
    Energy systems based on fossil oil products have witnessed increased demand all over the world with prices reaching new peaks, and continue to further weaken African economies. Potential biofuel oil sources, production and their optimization in standard to fossil equivalent should be sought. Sour plum (Ximenia americana L.) seed oil as one potential biofuel was extracted from plant seeds using screw press then tests were carried out to evaluate its properties as substitute for kerosene. Fuel properties of the sour plum (Ximenia americana L.) seed oil that had less than 10% difference and therefore had insignificant difference from kerosene and Jatropha seed oil properties were: calorific value, specific gravity, pour point, sulfur content and acid value, while Density, kinematic viscosity, fire point, carbon residue, and ash content had difference above 10% from those of kerosene. The latter properties: Density, kinematic viscosity, fire point, carbon residue, and ash content were analyzed further to determine their effect on mass burned and flame height burning parameters when sour plum seed oil was unblended and blended with kerosene in ratio 50%, 40%, 30%, 20% and 10%. Pearson’s product correlation coefficient r = 0.975 between these parameters was obtained. Further, regression analysis done indicated that parameter values were influenced by the fuel properties: viscosity, density, fire point, carbon residue and ash content which were used as predictor variables. Analysis of burning the blended seed oils in modified wick stove showed Pearson’s product correlation coefficient r = 0.855 between the fuel energy and power produced and transfered. However, energy produced by the fuels differed significantly probably due to effect of the fuel properties. In conclusion, sour plum (Ximenia americana L.) seed oil when blended with kerosene in ratio above 10% had better burning characteristics and can supplement kerosene as biofuel.
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    Effects of selected roofing materials on air navigation signal propagation
    (Egerton University, 2016-01) Omusonga, Robert Jere
    The environment around radio navigation aids systems (navaids) includes buildings whose roofing materials interfere with signal propagation. This interference may cause partial loss of intelligence in communication between navaids and flying aircrafts. Buildings around airports have been restricted partly because they pose threats to flight navigation. This restriction as captured in the Laws of Kenya has not been supported by sufficient data. Previous studies have shown that about half of air accidents occur during landing. However, no data has been availed to determine the contribution of navaids to these accidents. The purpose of this research was to study effects of roofing materials on air navigation signal propagation. The method involved use of a 9.4GHz transmitter, a receiver and a computer to measure signal level transmitted through roofing materials at various angles of incidence. The study considered effects of decra (aluminum-zinc stone-chip coated steel), iron, steel, aluminum, plastic and clay materials on navaids signal strength, transmission distance and wave polarization. Decra gave the highest attenuation whereby 98% of the signal propagated was lost, out of which 53% was due to reflection. Decra also exhibited the lowest desired-to-undesired signal ratio of -27dB which was far below International Civil Aviation Organization recommended value of 20dB. Only iron and clay reported significant figures above the recommended value. Variation of signal strength with transmission distance depended on type of roofing material but generally a negative correlation was registered. Roofing materials had no significant effect on wave polarization. The study challenged flight navigation authorities and construction industry to isolate and develop a compromise roofing material that will have little effect on navaids signal propagation.
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    Investigation of mechanical and combustion characteristics of cashew nut and mango seed shells composite briquettes
    (Egerton University, 2016-04) Huko, Dickens Owino
    The ever increasing world energy demand, with over dependency on fossil fuel is hampered by adverse environmental effects due to global warming resulting from carbon dioxide emitted during combustion. Majority of Kenyans rely on biomass, whose sustainability is faced with diminishing forest cover, currently at 1.7 %. Hence, there is need to search for alternative environmentally friendly and accessible sources. Availability of mango seed and cashew nut shells, currently considered of no economic value, may be an option for alternative fuel. Although studies have been done on the mechanical and combustion characteristics of varieties of biomass, there is little information on composite briquette produced from the cashew nut and mango seed shells. This study focused on mechanical and combustion characteristics of cashew nut and mango seed shells composite briquette. Cashew nut and mango seed shells were collected, dried, hammer milled, carbonized in muffle furnace at 400oC for 5 mins and cooled. The carbonized shell fines were mixed at varying ratios and particle sizes and bonded with banana peels before compacting at different pressures. Resulting composite briquettes were dried and mechanical and combustion characteristics determined. Density of the briquettes varied from 381.3 Kg/m3, to 763.45 Kg/m3 at the mango: cashew nut shell ratios 5:0, 4:1, 3:2, 2.5:2.5, 2:3, 1:4, 0:5. Moisture content, ash content and calorific value increased from 7.30 %, 5.28 % 16.47 MJ/kg to 11.27 %, 10.37 % and 26.61 MJ/kg respectively as the cashew nut fines in the mix ratios was increased. Durability index, compressive strength and carbon monoxide rose from 95.59 %, 7.44 KN/m2,, 1.80 ppm to 99.1 % , 7.89 KN/m2 and 5.96 ppm respectively. As the particle sizes increased from 3mm to 11mm, the density, moisture, ash content reduced from 729.08 Kg/m3, 7.56 %, 5.94 % to 492.41Kg/m3, 6.88 %, 5.93 % respectively but no significant effect on calorific value. Durability index, compressive strength and carbon monoxide reduced significantly with change in particle sizes from 98.41 %, 7.75 KN/m2 and 5.64 ppm to 95.52 % , 6.37 KN/m2 and 5.21 ppm respectively. As the compaction pressure increased from 5 MPa to 11 MPa, the briquette density changed from 492.41Kg/m3 to 729.08 Kg/m3 but no significant reduction of ash content from 5.94 % to 5.92 %. Calorific value, Carbon Monoxide and durability index increased from 21.60 MJ/kg, 5.21 ppm, 97.14 % to 25.74 MJ/kg, 5.64 ppm and 98.87 % respectively which could be attributed to increased bonding of particles at higher pressure. The resulting briquettes had similar mechanical and combustion characteristics to wood and charcoal, hence could serve as alternative source of energy
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    Influence of air temperature, flow rate and sand layer thickness on the rate of charging sand
    (Egerton University, 2016-04) Gichichi, George Njuguna
    Solar thermal energy storage technology has made solar energy a potentially viable supplement for fossil fuels in much of the developing world. However one of the challenges in adopting the technology is the low efficiency of the storage media. Many thermal energy storage materials have difficulties and limitations such as handling, containment, storage and cost. Sand which is abundant, cheap, easy to handle and contain, can be used to alleviate the difficulties. Research carried out on sand as thermal energy storage material has been concentrated on the amount that can be stored. Literature on factors that influence the rate of charging sand thermal energy storage media could not be accessed. There is no existing information on the rate of charging various types of sand. The objective of this research was to determine the influence of air temperature and flow rate on the rate of charging different types of sand of different layer thicknesses. Sieve analysis was done on the sands to grade them in terms of particle size distribution. Air at temperatures of 40, 50, 60 and 70oC and flow rates of 0.0004, 0.0006, 0.0008 and 0.001m3/s was passed through a thermal energy storage tank containing four types of sand which were collected from Machakos, Mombasa, Kisumu and Nakuru. However electric heater was used to heat the air instead of a solar heating system. The Taguchi experimental design approach was used. The temperature rise for sand at intervals of 2.5 minutes was recorded. Data analysis was carried out by use of Excel Statistical Analysis Software (SAS). The result of the study showed that the rate of charging sand increases as temperature of air increases. The result also showed that the rate of charging sand increases slightly as flow rate of charging air increases. The rate of charging was inversely proportional to the sand layer thickness. The four types of sand showed different rate of charging with sand from Mombasa having the greatest charging rate at 1.14oC/min. This was followed by sand from Nakuru at a rate of 1.12oC/min, sand from Kisumu at 1.01oC/min and finally sand from Machakos at 0.9oC/min. The most influential factors on the rate of charging were sand layer thickness and charging air temperature and contributed 86.93% and 10.00% of the variation in the charging rate respectively. The air flow rate and type of sand had little influence on charging rate and contributed 2.23% and 0.49% of charging rate variation respectively. The optimum factors for the charging process were observed to be charging air temperature of 70oC, sand type from Mombasa, sand layer thickness of 0.01cm and flow rate of 0.001m3/s. A confirmation experiment proved the result to be correct by registering a charging rate of 3.60oC/min.
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    Development and testing of composite refractory bricks (a case study of selected Kenyan clays)
    (Egerton University, 2016-11) Keter, Charles Kimutai
    Refractory bricks (refractories) are used in the construction of furnaces and kiln internal linings that hold, melt and transfer raw materials being processed. Kenya imports refractories mainly for its cement, metal smelting and sugar processing industries. Kaolin, bauxite, salama, soapstone and ball clays exhibited Loss of Ignition of 7-15%, silica of 46-55% and alumina of 25-34%. Soapstone and salama clays exhibited high values of potassium (5.6%) and iron oxide (16%), while salama clay had low alumina of 20% disqualified as refractory clay material. Alumina, silica and iron oxides in kaolin, bauxite and ball clays made them suitable as composite refractory clays. The properties of the developed composite bricks were determined at different mix ratios and particle sizes and their results compared with American Society of Testing Materials (ASTM) standards. Kaolin and bauxite clays were mixed at different ratios with 10% binder (ball clay). Developed bricks were moulded to volumes of (70x70x70) mm, subjected to a pressure of 4.1N/m2 and dried at 110℃. The bricks were fired in the furnace at 200°C for 6 hours, 650°C for 3 hours, 950°C for 4 hours and 1250°C for 8 hours and left to cool to room temperature. They were then subjected to physical and thermal tests and data obtained analysed using Statistical Analysis Software at 5% level of significance. Cold crushing strength, thermal shock resistance and bulk density were directly proportional to the increase in kaolin ratio. Decrease in linear shrinkage and apparent porosity was directly proportional to bauxite ratio. As kaolin to bauxite ratio increased from 2:7:1 to 7:2:1, apparent porosity decreased from 38% to 29% and bulk density increased from 1.45g/cm3 to 1.61g/cm3, cold crushing strength increased from 2.2 to 3.3KN/m2, linear shrinkage decreased from 8.89% to 3.69%, and thermal shock resistance increased from 14 to 27 cycles. Bulk density, cold crushing strength, linear shrinkage and thermal shock resistance decreased with increase in particle sizes but apparent porosity increased with increase in particle size. As particle sizes increased from 150µm to 600µm, apparent porosity increased from 29% to 36%, bulk density decreased from 2.23g/cm3 to 1.166g/cm3, cold crushing strength decreased from 3.3 to 2.64MN/m2, linear shrinkage from 3.69% to 2.0%, and thermal shock resistance from 27 to 19 cycles. Particle sizes of 150µm at a mix ratio of 7:2:1 produced apparent porosity of 29%, bulk density of 2.23g/cm3, cold crushing strength of 3.3MN/m2, linear shrinkage of 3.69% and thermal shock resistance of 27 cycles which was suitable for commercial production. This study adds knowledge to existing literature on refractories local clays
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    Early and Rapid Detection of Human Immunodeficiency Virus in Blood Using Raman Spectroscopy
    (Egerton University, 2017-10) Otange, Ben Otieno
    Deaths due to Human Immunodeficiency Virus (HIV) related diseases are still very high, especially in Africa. This is mainly attributed to poor diagnosis and late detection of the virus at times when the virus has greatly multiplied within the human body. In an attempt to come up with early detection mechanisms of the virus, several investigations have been carried out. The current detection mechanisms are less rapid with some being. Here we report on the potential of Raman spectroscopy as an alternative optical method for early and rapid detection of HIV-1 p24 in plasma and HIV-1 in whole human blood and in plasma. Raman spectra of HIV-1 p24 antigen, HIV-1 positive (HIV+) and HIV-1 negative (HIV-) blood and plasma were analyzed in the fingerprint spectral range 400-1800 cm-1 after 785 nm excitation. The Raman spectra of HIV1-p24 antigen displayed characteristic Raman bands centered at 891, 967, 1004, 1080, 1170, 1200, 1270, 1335, 1449, 1486, 1609, 1656 and 1738 cm-1. Unique Raman bands were observed at around wavenumbers 928 cm-1and 1658 cm-1 for HIV- and at 1270 cm-1 and 1446 cm-1 for HIV+ plasma samples. The prominent Raman band at 1270 cm-1 and 1446 cm-1 in HIV+ samples were ascribed to vibrational state of amide III of α-helix and C-H bond bending vibrational mode in proteins and lipids components of plasma respectively. For multivariate analysis; Principal Component Analysis (PCA) and Artificial Neural Network (ANN) were used. PCA was able to differentiate clearly Raman spectral data from HIV- and HIV+ plasma samples with sensitivity of 100% and specificity of 89.28% as well as sensitivity of 83.3% and specificity of 100% for whole blood samples. Classification based on ANN applied on the entire spectral range of data sets gave high correlation coefficient R = 0.99798 and R = 0.99997 for HIV+ blood and plasma samples respectively. Similarly, quantification also resulted in a linear model with R2 = 0.9457 and R2 = 0.9959 based on unique HIV+ peak intensity centered at 1270 cm-1 and 1446 cm-1
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    Exhaust gases energy recoverable from compression ignition engine using diesel and biodiesel
    (2018-03) Orido., George Onyango
    The broad objective of this research was to recover exhaust gases thermal energy from internal combustion engines for use in other applications. The specific objectives were: to determine the amount of thermal energy lost through exhaust gases at various engine speeds and loads; to determine the amount of energy recovered from exhaust gases at various engine speeds and loads; and to simulate the amount of maize that could be dried with the recovered energy. The experimental set-up consisted of a single cylinder, four-stroke, multi-fuel engine connected to an eddy current dynamometer for loading. Thermocouple temperature sensors and transmitters were used to measure exhaust gas to calorimeter inlet temperature and exhaust gas from calorimeter outlet temperature. Exhaust gas mass flow rate and temperature measurements were used to determine lost and recoverable energy. For purposes of estimating the amount of maize that could be dried with the recovered energy, safe and recommended temperatures were used. The dryer had a rated capacity of 1900 kg/h. The instrumentation of the engine was mainly equipped with a data acquisition system and ICE software. In general, fuel energy was observed to initially increase with engine speed and later decrease at higher speeds for both fuels at constant loads. For example, at 6 Nm fuel energy increased from 50295 kJ/h at 1000 rpm to 84945 kJ/h at 1250 rpm and later decreased to 64680 kJ/h at 1500 rpm for diesel fuel. The same trend was observed for biodiesel at a constant load of 6 Nm. At constant speeds, heat energy lost through exhaust gases increased with increased engine loading for both fuels. Recovered heat energy from exhaust gases increased with increased loading up to 18 Nm at speeds of 1000 rpm and 1250 rpm, but later decreased at a load of 22 Nm for both fuels. Heat energy could not be recovered at a speed of 1500 rpm and loads of 18 Nm and 22 Nm because calorimeter outlet temperatures of exhaust gases equaled inlet temperatures for both fuels. The specific energy required to dry maize from a moisture content of 25% to 13% wet basis was found to be 1124 kJ/kg. In this study, 750 and 566 grams per hour of maize could be dried through simulation when the engine used biodiesel and diesel respectively at an engine speed of 1000 rpm and a load of 18 Nm.
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    Influence of temperature, air flow rate and slice thickness on egg drying rate and protein content under forced convection
    (Egerton University, 2018-11) Mecha, Peter
    The availability of egg products for consumption is hindered by spoilage and breakages during processing. Forced convection drying serves as one of the methods of solving these challenges. However, the influence of temperature, airflow rate and slice thickness on forced convection drying of eggs is inadequately documented. Therefore, drying of eggs was investigated under forced convection process. The mode of airflow and the food material was the continuous concurrent type. Raw eggs were boiled at 90oC for 17 minutes to harden them. The hardened eggs were deshelled and cut into 10 mm thick slices without separating the egg yolk and egg white. Forced convection drying of sliced hardened eggs was done at thicknesses of 10 mm, 20 mm and 30 mm. Drying temperatures were set at 35oC, 40oC and 45oC. Airflow rates were set at 0.09 m³/s, 0.12 m³/s and 0.15 m³/s. Protein content for each sample was determined using Kjeldahl method. L9 Taguchi orthogonal array technique was used to determine the optimal combination of airflow rate, drying temperature and egg slice thickness that gave the highest drying rate and protein content. Nine thin layer-drying models were fitted to the experimental data to determine the model that predicted drying process with minimal variations between experimental and predicted results. An analysis of variance at 5% level of significance showed that air drying temperature had significant influence on the drying rate and protein content. The drying rate increased with increased air drying temperature. The drying rate increased from 0.67 g/g min to 0.75 g/g min with rise in temperature from 35oC to 45oC respectively. Protein content dropped from 54.6% to 47.5% with increase in temperature. Increasing drying airflow rate increased drying rate from 0.67 g/g min to 0.76 g/g min at 0.09 m³/s and 0.15 m³/s. The protein content decreased from 54.4% to 48.3% at 0.09 m³/s and 0.15 m³/s. Increasing airflow rate had significant influence on protein content (p<0.05). Thickness increment led to decrease in drying rate from 0.72 g/g min to 0.68 g/g min at 10 mm and 30 mm. Lower slice thickness had lower protein content of 47.9% while the highest thickness had protein content of 53.8% due to high heat transfer in the lower thickness that thermally affect proteins. Increasing thickness had insignificant influence on protein content (p>0.05). The optimal combinations for drying rate were slice thickness of 10 mm, flow rate of 0.15 m³/s and temperature of 45oC. Slice thickness of 30 mm, airflow rate of 0.15 m³/s and temperature of 35oC were the optimal combinations for protein content. Page, Modified Page, and Aghbashlo et al. were found suitable for predicting drying processes of boiled eggs. However, Page model was most superior of the three with the highest R2 of 0.9991, lowest x2 and RMSE of 0.0001 and 0.0012 respectively.