COMPARATIVE ASSESSMENT OF GROUND AND SATELLITE AEROSOL OBSERVATIONS OVER LAGOS-NIGERIA

The performance of ground and satellite measuring sensors or devices in the West Africa climate system is worrisome. These challenges had resulted in the loss of large volume of useful data on notable database e.g. Aerosol Robotic Network (AERONET), Multi-angle Imaging SpectroRadiometer (MISR), Modern-Era Retrospective Analysis for Research and Applications (MERRA) e.t.c. With only about 47% of data available to scientists, it is evident that accurate nowcast or forecast can no longer be guaranteed. The frequent failures of ground measuring devices over West Africa are more systemic than error due to device fabrication. The optical state over Lagos-Nigeria was investigated using the aerosol model. Fourteen years aerosol dataset from MISR and two years aerosol dataset from AERONET were used for the study. The optical state over Lagos is significant due to the massive human population. Lagos is located within the latitude of 6.465 °N and longitude of 3.406 °E. The regression analysis and Mann-Kendall (MK) test show no significant trend and considerable relationship between satellite and ground data. The standard deviations of the optical state via satellite and ground observations are 0.131 and 0.233, respectively. The average optical state predictability of the satellite and ground observation was 14.2% and 53.1%, respectively. The atmospheric constants in Lagos are: a 1 = 1.175, a 2 = 0.8227, n 1 = 0.2926, n 2 = 0.3573, and a = b = π/2

Pyrolysis and Char Burnout Characteristics of Cassava Peelings as Potential Energy Source

The pyrolysis behaviour, kinetics and char burnout of cassava peelings as a potential source of energy has been investigated using TGA. Four heating rates: 5, 10, 15 and 20oC/min were used to evaluate the kinetic parameters of the thermal decomposition process using iso-conversional non-isothermal method. An isothermal method was used to evaluate the burnout behaviour of char produced at 20oC/min by adopting the Arrhenius equation. During the pyrolysis process, it was observed that two distinct peaks were identified during hemicellulose decomposition which could be due to component complexity of agricultural waste products. The activation energy at 20% conversion was found to be 164 KJ/mol which is higher than what was observed between 30-50% conversions (151-154 KJ/mol). However, as the conversion increased from 60-90% the activation energy also increased from 162-290KJ/mol which suggests that the pyrolysis reaction progressed through multi step kinetic process. It was observed that the burnout of the chars was found to decrease with increase in heating rate up to the char produced at 15oC/min. However, further increase in the heating rate to 20oC/min during the pyrolysis process produced char with faster burnout profile. This may be due to higher porosity of the chars formed at that heating rate. It was also observed that as the heating rate increased from 5-15oC/min during pyrolysis, the activation energy of the resultant chars reduced. Again, higher activation energy was observed for the char produced at 20oC/min implying that highly porous char structure can diminish mass transfer limitations during char combustion. The pyrolysis and char combustion kinetics will be useful for modelling and the design of thermo-chemical cassava peelings conversion systems Keywords: Biomass pyrolysis, heating rates, char burnout, kinetic

Development and application of heterogeneous catalysts for direct cracking of triglycerides for biodiesel production

PhD ThesisInterest in biodiesel has been growing due to its potential role in moderating global climate change by lowering net CO2 emissions from fuels used for transportation. Most biodiesel fuels are currently synthesized by transesterification using alkaline catalysts and methanol. Heterogeneous transesterification catalysts have begun to be considered as alternatives, but many drawbacks remain. The costs of production and environmental concerns resulting from the ester washing step: neutralization of residual catalyst, removal of soap, glycerol, methanol and absorbent in some cases have prompted the search for more environmentally friendly processes and solid catalysts. Therefore, it is desirable to replace homogeneous or heterogeneous transesterification with the use of heterogeneous catalysts in direct thermocatalytic cracking. In principle, this could reduce the cost of biodiesel production, as it removes the need for alcohol and numerous downstream processing steps which add to the substantial running costs of transesterification. In addition the problem of glycerol in the product is eliminated. Four sulphated zirconia catalysts were synthesized via conventional wet-precipitation and solvent-free methods with different molar ratios of the sulphating agent. Their activity for direct thermocatalytic cracking of rapeseed oil was evaluated at a temperature of 270oC and atmospheric pressure. The nature and concentration of the active Brønsted and Lewis acid sites on the catalysts were examined. Brønsted acid sites were found to be important in the catalytic reaction. The catalysts at this temperature exhibited different selectivities towards formation of saturated and unsaturated methyl esters. The solvent-free catalysts were more active with a conversion of 78% in 21/2 hours, while the wet-precipitated catalysts had a maximum of 66% conversion after two hours. The catalysts prepared by the solvent-free method had 59% yield for methyl ester, with 75% of these being unsaturated. The wet-precipitated catalysts exhibited a lower yield for methyl esters (maximum: 32%), but within this a greater proportion (68%) were saturated. After regeneration, the solvent-free catalysts regained their catalytic properties, whereas the conventional catalysts did not. Three of the catalysts exhibited substantial leaching, with one of the conventional catalysts losing 100% of the sulphate responsible for its activity. Thus, to improve their properties the catalysts were supported with meta-kaolin which resulted in higher Brønsted acidity and better stability.Nigerian government Petroleum Trust Development Fund (PTDF

Emission Comparison of Air-Fuel Mixtures for Pure Gasoline and Bioethanol Fuel Blend (E20) Combustion on Sparking-Ignition Engine

This study analyses and compared the exhaust gas emission of two different airfuel mixture, Pure Gasoline and Bioethanol Fuel blend (E10 and E20), in a spark-ignition (S.I.) engine. Proximate and ultimate analyses of pure gasoline and bioethanol blend were carried out for their respective percentage (%) elemental composition for each fuel (i.e., carbon, hydrogen, oxygen, sulphur, nitrogen, metals, and water). The analysis reveals that pure gasoline has high carbon (C) content of 86%, and bioethanol has a carbon content of 52.2%. Oxygen content stands at 33-35% and was carried out at varying load conditions. To ascertain their CO., CO2, HC., NO, lambda, and the calorific values of exhaust emission. The result clearly shows that bioethanol's calorific value is lower than that of gasoline, which gives a remarkable increase in mechanical efficiency, which was attributed to an increase in the oxygen content in bioethanol, ethanol blend during combustion gives an airfuel mixture lean in an unmodified engine. Hence the mixture strength (charge) burns more rapidly. Bioethanol blends in gasoline engines reduce CO. emissions, unlike gasoline, which gave higher CO emissions. The gas emission test was conducted on E10, and E20.and effective combustion was determined and completed much earlier in the expansion stroke, thereby decreasing the probability of CO emissions due to flame quenching. At the end of the investigation, it was found that bioethanol blend reduces CO and HC in exhaust stroke by 40% and gives a higher compression ratio (high speed) thus, causes a decrease in CO2 NOX. E20 for both idle and high speed recorded a remarkable reduction in comparison. Therefore, bioethanol fuel blends in gasoline engines are recommended as mitigation against the greenhouse gas effec

OPTIMAL DESIGN AND STRESS/STRAIN ANALYSIS OF WIND TURBINE BLADE FOR OPTIMUM PERFORMANCE IN ENERGY GENERATION VIA SIMULATION APPROACH

The blade is a significant part of a wind turbine, due to its role in the conversion process of the wind energy into mechanical energy. The blade during operation is being acted upon by different forces and pressures on high humidity, which gives rise to a high rate of failure of the blade. There is a great need to study these forces and constraints on the design shape of the material blade via a simulation approach. This research focusses on the optimal design and stress/strain analysis of a wind turbine blade for sustainable power generation. This is to enable the manufacturer and end-users of the wind turbine blade to understand how the blade material withstand the forces and pressures acting on the blade during operation in the form of displacement, stress, and strain in high humidity. The design and simulation software employed in this study is Solid Works Visualize 2018. The wind turbine blade is made of AL6061 alloy material. The blade is simulated under two forces, 1 N and 5 N, with the pressure at zero degree. The result from this analysis shows the maximum stress that causes the blade to experience failure during operation, and this failure occurs at 285.377 N/m^2 and 1426.83 N/m^2, respectively. The result from the simulation analysis shows the specific area were the deformation process, and possible failure will occur on the blades. This paper also gives reasonable suggestion for reinforcement of the wind blade during the maintainer's section, which can be applied to achieve optimum performance of the wind turbine blade

Municipal Solid Waste Conversion to Energy and Derived Chemicals using Pyrolysis

This research work evolved through the variables such as time and temperature to determine the highest bio-oil yields. Conventional pyrolysis was adopted in a drop type CVD pyrolyzer given the highest oil yields 32.50 %wt, at 500 0C for 30 min. The bio-oil properties (CHNS-O) at various temperatures were evaluated. Carbon, hydrogen, Nitrogen, sulphur and calorivic values were observed to increase as the temperatures increases, having highest values at 500 0C with a sudden decline at 550 0C. While oxygen, water contents, densities and pH values decreases as the temperature increases, with lowest values recorded at 500 0C and sharp increase at 550 0C. Hence, the degrees of de-oxygenation also increases as the temperature increases with 18.87 %wt. at 500 0C and decreased at 550 0C. The results of FTIR analysis of the bio-oils at 500 0C indicate functional groups such as alkyl/Aromatic substitute ether (C-O), Aromatic 10 amine (C-N), Phenol/30 Alkanol (O-H), alkenes (C=C), Nitriles (C-N) and amines (N-H) with their areas. Keywords: Pyrolysis, Bio-oil, Derived chemical, Energ

Emission Comparison of Air-Fuel Mixtures for Pure Gasoline and Bioethanol Fuel Blend (E20) Combustion on Sparking-Ignition Engine

This study analyses and compared the exhaust gas emission of two different airfuel mixture, Pure Gasoline and Bioethanol Fuel blend (E10 and E20), in a spark-ignition (S.I.) engine. Proximate and ultimate analyses of pure gasoline and bioethanol blend were carried out for their respective percentage (%) elemental composition for each fuel (i.e., carbon, hydrogen, oxygen, sulphur, nitrogen, metals, and water). The analysis reveals that pure gasoline has high carbon (C) content of 86%, and bioethanol has a carbon content of 52.2%. Oxygen content stands at 33-35% and was carried out at varying load conditions. To ascertain their CO., CO2, HC., NO, lambda, and the calorific values of exhaust emission. The result clearly shows that bioethanol's calorific value is lower than that of gasoline, which gives a remarkable increase in mechanical efficiency, which was attributed to an increase in the oxygen content in bioethanol, ethanol blend during combustion gives an airfuel mixture lean in an unmodified engine. Hence the mixture strength (charge) burns more rapidly. Bioethanol blends in gasoline engines reduce CO. emissions, unlike gasoline, which gave higher CO emissions. The gas emission test was conducted on E10, and E20.and effective combustion was determined and completed much earlier in the expansion stroke, thereby decreasing the probability of CO emissions due to flame quenching. At the end of the investigation, it was found that bioethanol blend reduces CO and HC in exhaust stroke by 40% and gives a higher compression ratio (high speed) thus, causes a decrease in CO2 NOX. E20 for both idle and high speed recorded a remarkable reduction in comparison. Therefore, bioethanol fuel blends in gasoline engines are recommended as mitigation against the greenhouse gas effec

Optimization of Process Parameters Influencing Biogas Production from Rumen and municipal waste: Analytical Approach

 Rumen waste with high carbohydrate, protein, and lipid content is considered as a suitable substrate for fermentation for methane gas. In this study, direct substrate and co-digestion of rumen waste (RW) and municipal waste (MW) were used. Samples (fresh cow rumen and food waste) were dried, grinded, and blended with water into a semi-solid to facilitate digestion. Central composite design (CCD) was applied to optimize parameters of co-digestion of RW and MW at a different temperature (29 – 33oC), initial pH values, agitation time (AGT), and carbon-nitrogen ratio (C/N). A comparative analysis was done using RSM in a predictive model of the experimental data obtained in accordance with the CCD. The combined effects of temperature, pH, AGT, and C/N as methane production by fermentation of RW and MW were investigated. Optimization using RSM showed a good fit between the experimental and the predicted data as elucidated by the coefficient of determination with R2 values of 0.9214. Quadratic RSM predicted the maximum yield to be 7764 mL CH4/g volatile solid (VS) at optimal conditions of 31°C; pH 7.05; 6s and C/N ratio 20.33. The maximum methane yield was 8550 mL CH4/g VS, at the optimal conditions for the experimental response obtained. The verification experiment successfully produced 8550 mL CH4/g VS within 30 days of incubation. This experiment indicated that the developed model was successfully and can be used for methane production from animal and municipal waste