Chibuikle Ononogbo | FEDERAL UNIVERSITY OF TECHNOLOGY, OWERRI (FUTO) (original) (raw)
Papers by Chibuikle Ononogbo
Journal of Thermal Engineering
In this work, an experiment-based study of a double-effect, single-slope active solar still (SSAS... more In this work, an experiment-based study of a double-effect, single-slope active solar still (SSASS) is presented. The system comprises an upper and a lower basin incorporated with a paraffin wax acting as a phase change material (PCM). The use of phase change materials is very important due to their high storage density and the isothermal nature of the storage pro-cess. Paraffin wax was selected based on its attractive thermo-physical properties. The thermal behaviours of the system during the diurnal and nocturnal phases in both compartments were explored. Experimental results showed that the upper basin’s yield contributed more to the overall distillate production over a 24-hour cycle while that of the lower basin predominated the diurnal production. Though the PCM served as an energy source during the nocturnal phase, it did not translate to significant improvement in the yield of the lower basin. The heat retention ability of the lower glazing retarded the condensation of the hu...
Energy Nexus, 2022
The demand for freshwater has continued to soar amidst an increasing population, industrializatio... more The demand for freshwater has continued to soar amidst an increasing population, industrialization, and environmental pollution. The continuous shrinkage of this important resource has necessitated the need for a concerted effort on seawater desalination. Solar-powered desalination occupies a strategic position in the water-energy nexus and offers an alternative to taking off pressure from the already stressed freshwater sources. A numerical study with experimental validation of a single-slope double-effect solar still integrated with paraffin wax is thus presented. A transient mathematical model considering the humid air media in the upper and lower chambers was developed. Previous works in this area ignored the thermal analysis of the humid air medium, and as such, adopted the evaporation theory in the estimation of the freshwater yield. However, this study considers the thermal resistance offered by the humid air in the computation of the yield using the condensation theory. The energy-balance equations were discretized using the finite element method and solved with the aid of version 7.12 of the FlexPDE numerical solver. The model was validated with data from the experimental study. The correlation coefficients between the predicted and experimental data showed good agreement with values in the range of 0. 97 ≤ ≤ 0. 99 , and values of root mean square percent deviation of 3. 2% ≤ ≤ 16. 8%. The system achieved its best performance in November with a daily yield of 4.06 kg/m 2 and a mean efficiency of 33.7%. The upper basin contributed an average of 52% of the total yield with a greater percentage of its yield occurring during the nocturnal phase. The effects of the upper basin and the PCM on the diurnal performance of the system were evaluated.
Research in Agricultural Engineering
The fracture resistance of food grains is an essential piece of information required for the opti... more The fracture resistance of food grains is an essential piece of information required for the optimum design and development of agricultural post-harvest machinery. In this study, the strength properties of two varieties of Bambara kernels (TVSU-1395 and TVSU-1353) were examined in terms of the mean rupture force, absorbed energy, and deformation as affected by the moisture content and kernel size. To achieve this, a quasi-compressive force was applied on the two varieties of Bambara kernels of varying moisture contents (5.43%, 7.24%, 9.01%, 11.54%, and 13.62% wb) and kernel sizes (small, medium, and large) in between the loading compartments of a universal Testometric device at a 20 mm/min loading rate. The experiments take ten treatments with 20 replications subjected factorially to a completely randomised design (CRD) into consideration. The results revealed that the force needed to initiate the kernel fracture increased with an increase in the kernel size and moisture content fro...
International Journal of Advanced Science and Engineering
The activities of industries such as those of bleaching, mining, printing, electroplating and met... more The activities of industries such as those of bleaching, mining, printing, electroplating and metallurgical industries, textile and dye producing industries are among the major industries that have a problem of water contamination [1]. Unlike the biological or organic pollutants which are biodegradable , heavy metals like Nickel (Ni) and Chromium (Cr) are non-biodegradable [2]. This makes them a source of great concern. Heavy metals accumulate in living organism to a level that causes toxicological effect. Human health and the entire ecosystem are at great risk, unless the water and land systems are effectively managed. For example, the dye industry is one of the known largest industries that consume water. And the effluent coming out of the dye industries is known to contain various metallic compounds, chemical compounds and colouring compounds, which require adequate treatment before discharge into any available water body [3]. However, dye-laden effluents are very difficult to treat to a satisfactory extent because they are highly varying in composition, unlike other industrial wastewaters that can be treated easily because they are just contaminated in some ways, by either anthropogenic, industrial or commercial activities prior to their release into the environment, or its reuse [4]. Though most industries produce some form of wet wastes, the recent trends in developed technologies would be either to minimize such production, or recycle the waste within the production process. However, many of the ABSTRACT: Watermelon seed chaff was used to treat industrial wastewater from a paint industry. The packed bed filtration method was adopted, as the effect of the bed height, together with the adsorbent particle size were monitored. Adsorbent particle sizes of 1.18mm, 0.60mm and 0.125mm were used to pack the glass column at varying heights of 4cm, 6cm, 8cm and 10cm, while 100mls of the wastewater was filtered through the packed bed for each of the twelve cases. The time taken for the filtration, the volume of the treated water recovered, and the volumetric flow rates were all recorded. In the end, the analysis of the water quality test parameters show that the filtration through the smallest adsorbent particle size of 0.125mm packed to the highest height of 10cm had the greatest effect on the wastewater purification by bringing most of the test parameters closer to the permissible limits; giving pH value of 7.00 which is within the Federal Environmental Protection Agency (FEPA) permissible limit of 6.9; Temperature value of 25.3 0 C within the limit of 20-30 0 C; Turbidity result of 201NTU as against the FEPA limit of 250NTU; Conductivity value of 52µs/cm against the specified value of 200µs/cm; TDS and TSS values of 33.8mg/L and 200mg/L against the specified limits of 50mg/L and 250mg/L respectively; and Calcium, Iron and Zinc values of 0.40ppm, 0.07ppm and 23.07ppm which are all within the specified limits of 0.75ppm, 0.3ppm and 50ppm respectively. It is inferred that filtration of wastewater through a packed bed of watermelon seed chaff is a good method of wastewater purification and can be adopted on an industrial scale.
International Journal of Advanced Science and Engineering
The performance evaluation of a dual flat-plate solar thermal collector suitable for diurnal heat... more The performance evaluation of a dual flat-plate solar thermal collector suitable for diurnal heating and nocturnal cooling applications is presented. Two collectors, each with estimated area of 0.784 m2 were designed, developed and experimentally investigated. The plates were made with mild steel and coated with matte black and polyethylene terephthalate (PET) powder. The results obtained showed that in the diurnal heating mode, the hybrid plate attained a maximum temperature of 68.8oC while the ambient temperature ranged from 25.3oC-30.4oC, at a peak insulation of 937.3W/m2during the test period. In the nocturnal cooling phase, the hybrid plate attained a minimum temperature of 21.3oC, while the ambient temperature ranged from 23.4oC-24.3oC. During the nocturnal phase at clear sky, the maximum water temperature drop recorded was about 10.3oC. Also,8oC difference in temperature occurred between the top water zone and the bottom zone in the tank, signifying a clear thermal stratification in the tank. The overall performance of the system revealed that the device is a promising technology in locations that have similar climatic conditions as Owerri; thus, showing a dual-purpose seasonal adaptability and energy saving capabilities. Therefore, an installation of the device into a building can ensure a supply of domestic hot water for domestic and other activities all year round. The system can also deliver heat for comfort heating in cold seasons or for comfort cooling during periods of elevated ambient temperatures, hence offsetting the seasonal energy bills in a building.
SSRN Electronic Journal, 2022
Biofuels, 2016
This paper represents the Performance operating characteristics of single cylinder diesel engine ... more This paper represents the Performance operating characteristics of single cylinder diesel engine using blend of chicken fat based Biodiesel at various loading conditions at constant speed. We compare the performance characteristics and smoke intensity of petroleum diesel with various blends of chicken fat based biodiesel with petroleum diesel.
Scientific Research Journal
Evaluation of the energy consumption during the thin-layer drying of yam slices in an exhaust gas... more Evaluation of the energy consumption during the thin-layer drying of yam slices in an exhaust gas waste heat recovery dryer is presented. The study took cognizance of some energy parameters such as the electric power consumption, thermal energy consumption and specific energy consumption during the drying process. Blanched white yam samples of different thicknesses were subjected to varying conditions of drying air temperatures and velocities of 55, 65, and 75°C; and 1.0, 1.5, and 2.0 m/s. The minimum value of electric power consumption (44.63 W-hr) was achieved at the drying air temperature and velocity of 75 ℃ and 1.0 m/s, and slice thickness of 1.0 cm; whereas a maximum value of 157.70 W-hr was obtained at the drying air temperature and velocity of 55 ℃, 2.0 m/s, and 1.0 cm slice thickness, respectively. The specific energy consumption values were in the range of 40.25 to 97.80, 52.33 to 108.79 and 58.77 to 124.16 kW-hr/kg, respectively for 1.0, 1.5 and 2.0 cm slice thicknesses. The results obtained revealed that the drying air temperature and velocity had an appreciable influence on the values of the energy consumption parameters of the dryer for the yam slice drying. It was observed that for all the experimental treatments, the higher the slice thickness of the yam samples, the higher the obtained energy consumption values.
This paper presents the energy parameters of corn drying in a convective crop dryer powered by ex... more This paper presents the energy parameters of corn drying in a convective crop dryer powered by exhaust gas waste heat. The empirical study was applied for drying 1,500 g batch size of an indigenous variety of maize grains (corn kernels). The study considered the impact of the drying air temperature and velocity on the energy indices (total and specific energy consumption, electric and thermal energy demand), drying rate, of the crop dryer, and the moisture diffusion coefficient of the studied samples. Tests were run at varying drying air temperatures (50, 55, and 60 °C) and air velocities (1.0, 1.5, and 2.0 m/s). Results obtained show that the drying parameters had a noticeable influence on the rates of heat transfer and moisture diffusion in the maize samples. The average drying rates varied between 0.83 and 1.4 g/min, whereas drying duration ranged from 305 to 515 min. The thermal efficiency of the drying process ranged from 4.23% to 8.07%. Its values had a direct relationship with the drying air temperature and an inverse relationship with the drying air velocity. The specific energy consumption, which varied between 129.95 and 227.63 kWh/kg increased with increasing air temperature and velocity. Drying air temperature had an inverse effect on the values of the electric energy consumption of the dryer system at constant air velocity. The maximum and minimum thermal energy values were obtained as 97.12 and 55.4 kWhr, respectively. The activation energy and moisture diffusion coefficient values were in the range of 31.75 to 41.05 kJ/mol and 5.77 ×10 − 11 to 1.11 ×10 − 10 m 2 /s, respectively for the studied drying conditions. Prospects for commercial applications as well as recommendations for additional studies were stated.
The Chemical Oxygen Demand (COD) end value of effluent discharged from a bioreactor into the envi... more The Chemical Oxygen Demand (COD) end value of effluent discharged from a bioreactor into the environment is a critical indicator of its capacity to pollute the environment. A comparative parametric analysis of COD removal rate using three different biogas digesters is presented. The three bioreactors are Upflow Anaerobic Sludge Blanket (UASB), Upflow Bioreactor with Central Substrate Dispenser (UBCSD), and Continuous Stirred-Tank Reactor (CSTR). In order to select the most fitting bioreactor type among the three considered, experimentation was carried out using organic municipal waste (OMW) as substrate. A 10-day hydraulic retention time (HRT) was used, while cattle rumen microbes were used to improve digestion rate. UBCSD showed the highest level of percentage COD removal of 95.2%, followed by the CSTR with a value of 80.8%; while the UASB offered the lowest level of percentage COD removal of 79.0%. This outcome indicates that effluent from the UBCSD digested substrate is more su...
Volume 6A: Energy, 2013
ABSTRACT A performance study of anaerobic digestion of organic municipal waste in upflow bioreact... more ABSTRACT A performance study of anaerobic digestion of organic municipal waste in upflow bioreactor with central substrate dispenser is presented. The experimental rig is based on an integrated system of bioreactors consisting of Upflow Bioreactor (UB), Upflow Bioreactor with Central Subtrate Dispenser (UBCSD), and Continous Stirred Tank Reactor (CSTR) each having internal volume of 76 litres, 64.8 litres, and 76 litres respectively. The scheme is used for minimizing the mixing and fouling problems associated with some conventional bioreactors during digestion reaction. Organic municipal waste (OMW) was used to prepare the slurry for the reactors. Microbial reaction was enhanced during operation using a measured quantity (2kg) of substances from the rumen of a newly slaughtered cow. The experimentation from feeder tank to Bioreactors was carried out for a period of 10-days Hydraulic Retention Time (HRT) at 37°C. Effects of some basic parameters affecting anaerobic digestion in terms of biogas production and Chemical Oxygen Demand (COD) reduction were carried out. They include substrate temperature, minimal average temperature, changes in temperature, substrate content and properties, available nutrient, retention time, organic loading rate, pH level, nitrogen inhibition and C/N ratio, substrate agitation, and inhibitory factors. Results showed that UBSCD generated the highest level of Biogas yield of up to 52915 ml, while UB and CSTR yielded 23550ml and 28980ml respectively. Similarly for COD removal, 24343 mg/l, 5775.4 mg/l, and 23155 mg/l were achieved for UBCSD, UB and CSTR respectively from an initial value of 120,320 mg/l. These results show that the use of UBCSD better enhances biofuel production from organic municipal waste.
Nigeria as a developing country is witnessing population growth and rapid urbanization. Consequen... more Nigeria as a developing country is witnessing population growth and rapid urbanization. Consequently, the demand for electric power supply and other infrastructures to support the growth is on the increase. In response, many thermal power plants (TPP) that run on liquid and gaseous fossil fuels are widely used in the country. However, the effects of the emissions from these power plants on human health and the environment have become matters of serious concern. High concentrations of various air pollutants have been reported across the country, and evidences of air pollution related morbidities abound. This paper presents the major types of Air pollutants and Greenhouse gases emitted by these units and their adverse impacts on the environment and health of the citizenry. Abatement techniques for some of the major emissions are also highlighted. The monitoring of the level of emissions and their control systems at these thermal power plants is strongly suggested so as to ensure their strict compliance to appropriate Ambient Air Quality Standards. There is urgent need to put in place legislations to enforce air quality standards in Nigeria as well as reduce the indiscriminate use of diesel and petrol generators through adequate public power supply. These will guarantee the health of the citizenry and the safety of the environment.
The absence of slurry agitation mechanism in some conventional biodigesters has led to the malfun... more The absence of slurry agitation mechanism in some conventional biodigesters has led to the malfunctioning of a given number of biogas plants installed for biogas production. Inadequate or lack of mixing of slurry in biodigesters limits gas production and renders the biogas plant economically unfeasible. This paper presents a detailed and novel approach for the construction and operation of a simple biogas plant that can be used in farms, homes, schools, etc for the production of biogas and organic fertilizer. A version of Floating Drum Biogas Digester is considered and a small tool referred to as agitator stick was introduced to help for a periodic agitation of the slurry in the digester. For its operation, the creation of an anaerobic environment in the digester is advised. This will help for the enhancement of the activities of anaerobic bacteria acting on the organic waste. The expulsion of air from the biogas holder while the digester is being loaded at the initial phase is also recommended for safety reasons. .
Journal of Thermal Engineering
In this work, an experiment-based study of a double-effect, single-slope active solar still (SSAS... more In this work, an experiment-based study of a double-effect, single-slope active solar still (SSASS) is presented. The system comprises an upper and a lower basin incorporated with a paraffin wax acting as a phase change material (PCM). The use of phase change materials is very important due to their high storage density and the isothermal nature of the storage pro-cess. Paraffin wax was selected based on its attractive thermo-physical properties. The thermal behaviours of the system during the diurnal and nocturnal phases in both compartments were explored. Experimental results showed that the upper basin’s yield contributed more to the overall distillate production over a 24-hour cycle while that of the lower basin predominated the diurnal production. Though the PCM served as an energy source during the nocturnal phase, it did not translate to significant improvement in the yield of the lower basin. The heat retention ability of the lower glazing retarded the condensation of the hu...
Energy Nexus, 2022
The demand for freshwater has continued to soar amidst an increasing population, industrializatio... more The demand for freshwater has continued to soar amidst an increasing population, industrialization, and environmental pollution. The continuous shrinkage of this important resource has necessitated the need for a concerted effort on seawater desalination. Solar-powered desalination occupies a strategic position in the water-energy nexus and offers an alternative to taking off pressure from the already stressed freshwater sources. A numerical study with experimental validation of a single-slope double-effect solar still integrated with paraffin wax is thus presented. A transient mathematical model considering the humid air media in the upper and lower chambers was developed. Previous works in this area ignored the thermal analysis of the humid air medium, and as such, adopted the evaporation theory in the estimation of the freshwater yield. However, this study considers the thermal resistance offered by the humid air in the computation of the yield using the condensation theory. The energy-balance equations were discretized using the finite element method and solved with the aid of version 7.12 of the FlexPDE numerical solver. The model was validated with data from the experimental study. The correlation coefficients between the predicted and experimental data showed good agreement with values in the range of 0. 97 ≤ ≤ 0. 99 , and values of root mean square percent deviation of 3. 2% ≤ ≤ 16. 8%. The system achieved its best performance in November with a daily yield of 4.06 kg/m 2 and a mean efficiency of 33.7%. The upper basin contributed an average of 52% of the total yield with a greater percentage of its yield occurring during the nocturnal phase. The effects of the upper basin and the PCM on the diurnal performance of the system were evaluated.
Research in Agricultural Engineering
The fracture resistance of food grains is an essential piece of information required for the opti... more The fracture resistance of food grains is an essential piece of information required for the optimum design and development of agricultural post-harvest machinery. In this study, the strength properties of two varieties of Bambara kernels (TVSU-1395 and TVSU-1353) were examined in terms of the mean rupture force, absorbed energy, and deformation as affected by the moisture content and kernel size. To achieve this, a quasi-compressive force was applied on the two varieties of Bambara kernels of varying moisture contents (5.43%, 7.24%, 9.01%, 11.54%, and 13.62% wb) and kernel sizes (small, medium, and large) in between the loading compartments of a universal Testometric device at a 20 mm/min loading rate. The experiments take ten treatments with 20 replications subjected factorially to a completely randomised design (CRD) into consideration. The results revealed that the force needed to initiate the kernel fracture increased with an increase in the kernel size and moisture content fro...
International Journal of Advanced Science and Engineering
The activities of industries such as those of bleaching, mining, printing, electroplating and met... more The activities of industries such as those of bleaching, mining, printing, electroplating and metallurgical industries, textile and dye producing industries are among the major industries that have a problem of water contamination [1]. Unlike the biological or organic pollutants which are biodegradable , heavy metals like Nickel (Ni) and Chromium (Cr) are non-biodegradable [2]. This makes them a source of great concern. Heavy metals accumulate in living organism to a level that causes toxicological effect. Human health and the entire ecosystem are at great risk, unless the water and land systems are effectively managed. For example, the dye industry is one of the known largest industries that consume water. And the effluent coming out of the dye industries is known to contain various metallic compounds, chemical compounds and colouring compounds, which require adequate treatment before discharge into any available water body [3]. However, dye-laden effluents are very difficult to treat to a satisfactory extent because they are highly varying in composition, unlike other industrial wastewaters that can be treated easily because they are just contaminated in some ways, by either anthropogenic, industrial or commercial activities prior to their release into the environment, or its reuse [4]. Though most industries produce some form of wet wastes, the recent trends in developed technologies would be either to minimize such production, or recycle the waste within the production process. However, many of the ABSTRACT: Watermelon seed chaff was used to treat industrial wastewater from a paint industry. The packed bed filtration method was adopted, as the effect of the bed height, together with the adsorbent particle size were monitored. Adsorbent particle sizes of 1.18mm, 0.60mm and 0.125mm were used to pack the glass column at varying heights of 4cm, 6cm, 8cm and 10cm, while 100mls of the wastewater was filtered through the packed bed for each of the twelve cases. The time taken for the filtration, the volume of the treated water recovered, and the volumetric flow rates were all recorded. In the end, the analysis of the water quality test parameters show that the filtration through the smallest adsorbent particle size of 0.125mm packed to the highest height of 10cm had the greatest effect on the wastewater purification by bringing most of the test parameters closer to the permissible limits; giving pH value of 7.00 which is within the Federal Environmental Protection Agency (FEPA) permissible limit of 6.9; Temperature value of 25.3 0 C within the limit of 20-30 0 C; Turbidity result of 201NTU as against the FEPA limit of 250NTU; Conductivity value of 52µs/cm against the specified value of 200µs/cm; TDS and TSS values of 33.8mg/L and 200mg/L against the specified limits of 50mg/L and 250mg/L respectively; and Calcium, Iron and Zinc values of 0.40ppm, 0.07ppm and 23.07ppm which are all within the specified limits of 0.75ppm, 0.3ppm and 50ppm respectively. It is inferred that filtration of wastewater through a packed bed of watermelon seed chaff is a good method of wastewater purification and can be adopted on an industrial scale.
International Journal of Advanced Science and Engineering
The performance evaluation of a dual flat-plate solar thermal collector suitable for diurnal heat... more The performance evaluation of a dual flat-plate solar thermal collector suitable for diurnal heating and nocturnal cooling applications is presented. Two collectors, each with estimated area of 0.784 m2 were designed, developed and experimentally investigated. The plates were made with mild steel and coated with matte black and polyethylene terephthalate (PET) powder. The results obtained showed that in the diurnal heating mode, the hybrid plate attained a maximum temperature of 68.8oC while the ambient temperature ranged from 25.3oC-30.4oC, at a peak insulation of 937.3W/m2during the test period. In the nocturnal cooling phase, the hybrid plate attained a minimum temperature of 21.3oC, while the ambient temperature ranged from 23.4oC-24.3oC. During the nocturnal phase at clear sky, the maximum water temperature drop recorded was about 10.3oC. Also,8oC difference in temperature occurred between the top water zone and the bottom zone in the tank, signifying a clear thermal stratification in the tank. The overall performance of the system revealed that the device is a promising technology in locations that have similar climatic conditions as Owerri; thus, showing a dual-purpose seasonal adaptability and energy saving capabilities. Therefore, an installation of the device into a building can ensure a supply of domestic hot water for domestic and other activities all year round. The system can also deliver heat for comfort heating in cold seasons or for comfort cooling during periods of elevated ambient temperatures, hence offsetting the seasonal energy bills in a building.
SSRN Electronic Journal, 2022
Biofuels, 2016
This paper represents the Performance operating characteristics of single cylinder diesel engine ... more This paper represents the Performance operating characteristics of single cylinder diesel engine using blend of chicken fat based Biodiesel at various loading conditions at constant speed. We compare the performance characteristics and smoke intensity of petroleum diesel with various blends of chicken fat based biodiesel with petroleum diesel.
Scientific Research Journal
Evaluation of the energy consumption during the thin-layer drying of yam slices in an exhaust gas... more Evaluation of the energy consumption during the thin-layer drying of yam slices in an exhaust gas waste heat recovery dryer is presented. The study took cognizance of some energy parameters such as the electric power consumption, thermal energy consumption and specific energy consumption during the drying process. Blanched white yam samples of different thicknesses were subjected to varying conditions of drying air temperatures and velocities of 55, 65, and 75°C; and 1.0, 1.5, and 2.0 m/s. The minimum value of electric power consumption (44.63 W-hr) was achieved at the drying air temperature and velocity of 75 ℃ and 1.0 m/s, and slice thickness of 1.0 cm; whereas a maximum value of 157.70 W-hr was obtained at the drying air temperature and velocity of 55 ℃, 2.0 m/s, and 1.0 cm slice thickness, respectively. The specific energy consumption values were in the range of 40.25 to 97.80, 52.33 to 108.79 and 58.77 to 124.16 kW-hr/kg, respectively for 1.0, 1.5 and 2.0 cm slice thicknesses. The results obtained revealed that the drying air temperature and velocity had an appreciable influence on the values of the energy consumption parameters of the dryer for the yam slice drying. It was observed that for all the experimental treatments, the higher the slice thickness of the yam samples, the higher the obtained energy consumption values.
This paper presents the energy parameters of corn drying in a convective crop dryer powered by ex... more This paper presents the energy parameters of corn drying in a convective crop dryer powered by exhaust gas waste heat. The empirical study was applied for drying 1,500 g batch size of an indigenous variety of maize grains (corn kernels). The study considered the impact of the drying air temperature and velocity on the energy indices (total and specific energy consumption, electric and thermal energy demand), drying rate, of the crop dryer, and the moisture diffusion coefficient of the studied samples. Tests were run at varying drying air temperatures (50, 55, and 60 °C) and air velocities (1.0, 1.5, and 2.0 m/s). Results obtained show that the drying parameters had a noticeable influence on the rates of heat transfer and moisture diffusion in the maize samples. The average drying rates varied between 0.83 and 1.4 g/min, whereas drying duration ranged from 305 to 515 min. The thermal efficiency of the drying process ranged from 4.23% to 8.07%. Its values had a direct relationship with the drying air temperature and an inverse relationship with the drying air velocity. The specific energy consumption, which varied between 129.95 and 227.63 kWh/kg increased with increasing air temperature and velocity. Drying air temperature had an inverse effect on the values of the electric energy consumption of the dryer system at constant air velocity. The maximum and minimum thermal energy values were obtained as 97.12 and 55.4 kWhr, respectively. The activation energy and moisture diffusion coefficient values were in the range of 31.75 to 41.05 kJ/mol and 5.77 ×10 − 11 to 1.11 ×10 − 10 m 2 /s, respectively for the studied drying conditions. Prospects for commercial applications as well as recommendations for additional studies were stated.
The Chemical Oxygen Demand (COD) end value of effluent discharged from a bioreactor into the envi... more The Chemical Oxygen Demand (COD) end value of effluent discharged from a bioreactor into the environment is a critical indicator of its capacity to pollute the environment. A comparative parametric analysis of COD removal rate using three different biogas digesters is presented. The three bioreactors are Upflow Anaerobic Sludge Blanket (UASB), Upflow Bioreactor with Central Substrate Dispenser (UBCSD), and Continuous Stirred-Tank Reactor (CSTR). In order to select the most fitting bioreactor type among the three considered, experimentation was carried out using organic municipal waste (OMW) as substrate. A 10-day hydraulic retention time (HRT) was used, while cattle rumen microbes were used to improve digestion rate. UBCSD showed the highest level of percentage COD removal of 95.2%, followed by the CSTR with a value of 80.8%; while the UASB offered the lowest level of percentage COD removal of 79.0%. This outcome indicates that effluent from the UBCSD digested substrate is more su...
Volume 6A: Energy, 2013
ABSTRACT A performance study of anaerobic digestion of organic municipal waste in upflow bioreact... more ABSTRACT A performance study of anaerobic digestion of organic municipal waste in upflow bioreactor with central substrate dispenser is presented. The experimental rig is based on an integrated system of bioreactors consisting of Upflow Bioreactor (UB), Upflow Bioreactor with Central Subtrate Dispenser (UBCSD), and Continous Stirred Tank Reactor (CSTR) each having internal volume of 76 litres, 64.8 litres, and 76 litres respectively. The scheme is used for minimizing the mixing and fouling problems associated with some conventional bioreactors during digestion reaction. Organic municipal waste (OMW) was used to prepare the slurry for the reactors. Microbial reaction was enhanced during operation using a measured quantity (2kg) of substances from the rumen of a newly slaughtered cow. The experimentation from feeder tank to Bioreactors was carried out for a period of 10-days Hydraulic Retention Time (HRT) at 37°C. Effects of some basic parameters affecting anaerobic digestion in terms of biogas production and Chemical Oxygen Demand (COD) reduction were carried out. They include substrate temperature, minimal average temperature, changes in temperature, substrate content and properties, available nutrient, retention time, organic loading rate, pH level, nitrogen inhibition and C/N ratio, substrate agitation, and inhibitory factors. Results showed that UBSCD generated the highest level of Biogas yield of up to 52915 ml, while UB and CSTR yielded 23550ml and 28980ml respectively. Similarly for COD removal, 24343 mg/l, 5775.4 mg/l, and 23155 mg/l were achieved for UBCSD, UB and CSTR respectively from an initial value of 120,320 mg/l. These results show that the use of UBCSD better enhances biofuel production from organic municipal waste.
Nigeria as a developing country is witnessing population growth and rapid urbanization. Consequen... more Nigeria as a developing country is witnessing population growth and rapid urbanization. Consequently, the demand for electric power supply and other infrastructures to support the growth is on the increase. In response, many thermal power plants (TPP) that run on liquid and gaseous fossil fuels are widely used in the country. However, the effects of the emissions from these power plants on human health and the environment have become matters of serious concern. High concentrations of various air pollutants have been reported across the country, and evidences of air pollution related morbidities abound. This paper presents the major types of Air pollutants and Greenhouse gases emitted by these units and their adverse impacts on the environment and health of the citizenry. Abatement techniques for some of the major emissions are also highlighted. The monitoring of the level of emissions and their control systems at these thermal power plants is strongly suggested so as to ensure their strict compliance to appropriate Ambient Air Quality Standards. There is urgent need to put in place legislations to enforce air quality standards in Nigeria as well as reduce the indiscriminate use of diesel and petrol generators through adequate public power supply. These will guarantee the health of the citizenry and the safety of the environment.
The absence of slurry agitation mechanism in some conventional biodigesters has led to the malfun... more The absence of slurry agitation mechanism in some conventional biodigesters has led to the malfunctioning of a given number of biogas plants installed for biogas production. Inadequate or lack of mixing of slurry in biodigesters limits gas production and renders the biogas plant economically unfeasible. This paper presents a detailed and novel approach for the construction and operation of a simple biogas plant that can be used in farms, homes, schools, etc for the production of biogas and organic fertilizer. A version of Floating Drum Biogas Digester is considered and a small tool referred to as agitator stick was introduced to help for a periodic agitation of the slurry in the digester. For its operation, the creation of an anaerobic environment in the digester is advised. This will help for the enhancement of the activities of anaerobic bacteria acting on the organic waste. The expulsion of air from the biogas holder while the digester is being loaded at the initial phase is also recommended for safety reasons. .