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Predictive mathematical modeling and computer simulation of direct ethanol fuel cell

  • Authors: Abdulkareem, A. S. , Jimoh, A. , Afolabi, A. S. , Muzenda, E. , Okeke, A. C.
  • Date: 2016
  • Subjects: Fuel cell , Direct ethanol fuel cell , Predictive mathematical modeling
  • Language: English
  • Type: Article
  • Identifier: http://hdl.handle.net/10210/213692 , uj:21184 , Citation: Abdulkareem, A.S. et al. 2016. Predictive mathematical modeling and computer simulation of direct ethanol fuel cell.
  • Description: Abstract: The challenges of finding a better substitute of energy as well as the short comings identify with direct ethanol fuel cell, this includes; high anode over potential and crossover necessitate the need to investigate the influence operating parameters on the performance of fuel through computer simulation. This study focus on the development of a predictive mathematical modeling for direct ethanol fuel cell for the purpose of investigating the influence pressure, temperature cathode and reactants concentration on the performance, efficiency and heat generated by the cell. Results obtained indicate that increase in operating temperature resulted led to decrement in output voltage and cell efficiency, while same condition of increasing the temperature positively favour the heat generated from the cell. Simulated results also show that cell performance is improved with increase in concentration of the fuel (ethanol) and oxidant (oxygen). It can be inferred from this study that the cell performance of DEFC can be theoretically predicted with the developed model.
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Diffusion in saturated clayey barrier medium

  • Authors: Agbenyeku, E. E. , Muzenda, E. , Msibi, M. I.
  • Date: 2017
  • Subjects: Leachate , Percolation , Earthen barrier
  • Language: English
  • Type: Conference proceedings
  • Identifier: http://hdl.handle.net/10210/223036 , uj:22415 , Citation: Agbenyeku, E.E., Muzenda, E. & Msibi, M.I. 2017. Diffusion in saturated clayey barrier medium. International Conference on Sustainable Materials Processing and Manufacturing, SMPM 2017, 23-25 January 2017, Kruger National Park.
  • Description: Abstract: The design of clay/clayey barriers for the containment of buried wastes conventionally has been based on the assumption that the hydraulic conductivity controls the rate of leachate percolation. However, recent studies show that diffusion is a controlling mechanism of solute transport in many fine-grained soils. Although the measurement of the hydraulic conductivity of finegrained soils is comparatively a common practice in soil engineering, the measurement of diffusion coefficients is not. As such, it is becoming increasingly essential to assess the movement of chemicals through soil barriers due to diffusion. Studies indicate that diffusion may be an important, if not dominant mechanism of contaminant transport through waste containment barriers. This paper is therefore in line with the efforts made in the measurement of diffusion coefficients of inorganic chemicals passing through saturated soils. Herein, both steady-state and transient equations relating to the diffusive transport of inorganic chemicals are presented. A number of factors affecting diffusion coefficients are identified and a simple method for measuring diffusion coefficients for a compacted barrier is defined. The definition for the diffusion coefficient of soil called the effective diffusion coefficient, D* is seen to vary widely. Generally, the variations are due to the different factors affecting diffusion of solutes in soil and the various ways of including the volumetric water content in the governing equations. Hence, errors in interpretation and comparison of D* values can occur if the appropriate definition is not used. In a nutshell, the concept of diffusion may be unfamiliar to many soil specialists, worsened by the myriad terminologies linked to the study of diffusion in soils. Thus the study attempts to acquaint soil engineers with vital information for the measurement of diffusion coefficients for barrier designs.
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Provisional equations for determining leachate leakage rate through composite barriers from compromised geomembrane

  • Authors: Agbenyeku, E. E. , Muzenda, E. , Msibi, M. I.
  • Date: 2017
  • Subjects: Leachate leakage , Geomembranes
  • Language: English
  • Type: Conference proceedings
  • Identifier: http://hdl.handle.net/10210/223280 , uj:22449 , Citation: Agbenyeku, E.E., Muzenda, E. & Msibi, M.I. 2017. Provisional equations for determining leachate leakage rate through composite barriers from compromised geomembrane. International Conference on Sustainable Materials Processing and Manufacturing, SMPM 2017, 23-25 January 2017, Kruger National Park.
  • Description: Abstract: From years ago to present date the equations available for determining the rate of leachate leakage through composite barriers from geomembrane (GM) failures necessitated the use of graphs to attain the value of one of the terms of the equations for the case where the leachate head is larger than the thickness of the low-permeability soil medium of the composite barrier. This work reveals that the terms requiring graphs can be expressed analytically, which shows a new set of equations that leads to an entirely analytical approach of determining the rate of leachate leakage through composite barriers. The provisional set of equations is principally beneficial when the leachate level is large as against the thickness of the low-permeability soil medium of the composite barrier. This is usually the case when the low-permeability soil medium allied with the GM to form a composite barrier is a geosynthetic clay liner (GCL). Whether the failure in the GM is small or large or where the leachate level on top of the barrier is large as against the thickness of the low-permeability soil layer of the composite system, a provisional equation can be used to determine the leakage rate through the system. Although in such a scenario, graphs are essential in attaining the value of one of the terms of the equations. Therefore, this paper shows that the graphs can be replaced by equations, which proceeds to the generation and utilization of an entirely analytical method of determining the rate of leachate leakage through a failed composite waste containment barrier, irrespective of the leachate level overlying the system.
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Preliminary design of a biogas-solar PV hybrid mini-grid system for off- grid agricultural communities

  • Authors: Bambokela, J.E. , Belaid, M. , Muzenda, E.
  • Date: 2020
  • Subjects: Agricultural , Biogas , Hybrid
  • Language: English
  • Type: Conference proceedings
  • Identifier: http://hdl.handle.net/10210/475292 , uj:42870 , Citation: Bambokela, J.E., Belaid, M. & Muzenda, E. 2020. Preliminary design of a biogas-solar PV hybrid mini-grid system for off- grid agricultural communities.
  • Description: Abstract: Mini-grid technologies are rapidly growing and occupying predominant place in Sub-Saharan Africa (SSA). Rural electrification rate is drastically rising because of the wide adoption of mini-grid systems in off-grid communities. However, there is still a lot of efforts needed from a regulatory, technological, and financial point of view. The mini-grid concept is currently being reviewed by African energy stakeholders to be integrated in their national and regional energy plan. To achieve an effective integration, the design of mini-grid set-ups must be understood. To understand its design, various factors such as the system components, the sizing and optimization tools and major implementation phases must be considered carefully. For this reason, this paper seeks to define the concept of mini-grid and propose a biogas-solar Photovoltaic (PV) hybrid mini-grid (BSPVHM) as a power solution for underserved agricultural communities.
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Fostering biomass-solar PV hybrid mini-grids in offgrid agricultural communities of sub-Saharan Africa : case of the Democratic Republic of Congo, a mini review

  • Authors: Bambokela, J.E. , Belaid, M. , Muzenda, E.
  • Date: 2020
  • Subjects: Biomass , Hybrid , Mini-grid
  • Language: English
  • Type: Conference proceedings
  • Identifier: http://hdl.handle.net/10210/475284 , uj:42869 , Citation: Bambokela, J.E., Belaid, M. & Muzenda, E. 2020. Fostering biomass-solar PV hybrid mini-grids in offgrid agricultural communities of sub-Saharan Africa : case of the Democratic Republic of Congo, a mini review.
  • Description: Abstract: In Africa, large energy infrastructures projects are often very complex. Their complexity lies in various aspects such as administration, regulation, technicality, and finances. Most Sub-Saharan African (SSA) countries, in the likes of the Democratic Republic of Congo (DRC), have very low electrification rate that is usually below 10%. As such, there are multiple communities that are still undeserved. These offgrid communities generally use diesel generators to obtain electricity despite the cost of fuel that is not affordable for everyone. For this reason, this paper sought to concisely present the biomass-solar photovoltaic (PV) hybrid mini-grid (BSPVHM) as a cost-effective solution to electrify disconnected communities that have untapped large farming potential. While referring to the DRC that has an average of 492,692 off-grid agricultural households, this paper demonstrated that multiple BSPVHM of capacities ranging from 5 to 15 MW could be implemented in localities of the 26 provinces of DRC that has an average energy deficit of 246 MW. The purpose of this research is to encourage the wide adoption of the BSPVHM to electrify undeserved SSA communities.
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Predicting organic waste performance in soil treatment from x-ray fluorescence analysis

  • Authors: Bambokela, Jonathan Empompo , Agbenyeku, E. E. , Muzenda, E.
  • Date: 2016
  • Subjects: Fertilizer , Horse manure , Potassium
  • Language: English
  • Type: Conference proceedings
  • Identifier: http://hdl.handle.net/10210/215518 , uj:21427 , Citation: Bambokela, E.J., Agbenyeku, E.E & Muzenda, E. 2016. Predicting organic waste performance in soil treatment from x-ray fluorescence analysis.
  • Description: Abstract: Soil analysis was carried out on samples collected from a farm located on the out scares of Thokoza Township in Johannesburg, South Africa. The Farm operational site currently used for farming was once a waste dumping site. The moisture content of different samples was determined with an initial weight of 100g; each sample was placed in an oven and heated at 107 °C for 2 hours. The X-Ray fluorescence (XRF) analysis was used in the determination of samples composition. Magnesium (Mg), Calcium (Ca), Potassium (K) and Phosphorus (P) were mainly discussed in this study. Horse dung and crushed bones were reported more suitable as fertilizers due to large amount of K and P considered as potential plant growth catalysts. Wood saw dust revealed particularities in its effect on sand especially in agriculture. The purpose of this study was to analyse, compare and predict the impact of horse dung, crushed bones, and wood sawdust in the land remediation and fertility improvement.
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Impact of substrate composition in biomethane production under thermophilic conditions

  • Authors: Bambokela, Jonathan Empompo , Matheri, A. N. , Belaid, M. , Agbenyeku, E. E. , Muzenda, E.
  • Date: 2016
  • Subjects: Anaerobic digestion , Co-digestion , Substrate
  • Language: English
  • Type: Conference proceedings
  • Identifier: http://hdl.handle.net/10210/215517 , uj:21426 , Citation: Bambokela, E.J. et al. 2016. Impact of substrate composition in biomethane production under thermophilic conditions.
  • Description: Abstract: In this investigation, the anaerobic digestion (AD) results from different substrates were evaluated. By means of two co-digestion processes with cow dung, it was observed a good performance in the first process and a poor production trend in the second one. NaOH was used as chemical absorbent in two different bottles in the CO2 fixing unit to compare the volume of biomethane produced. A batch anaerobic codigestion was carried out in 500 mL digesters which were placed into a water bath at 45°C and maintained at the initial pH of 7. Important AD factors such as pH, Carbon and Nitrogen ratio (C/N), concentration, substrate composition were observed. Through an ultimate analysis, amount of Carbon (C), Hydrogen (H), Nitrogen (N), and Sulphur (S) were also discussed. The toxicity of other elements found in substrates appeared higher in the second process than in the first. It was concluded that inhibitory elements identification and control before furthering any biogas production process were primordial.
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Technology selection and siting of a biogas plant for OFMSW via multi-criteria decision analysis

Energy potential of food waste generated by a middle class neigbourhood in Nigeria through anaerobic digestion

Comparative evaluation of the performance of a bi-fuel vehicle on biogas and natural gas

Biogas use as fuel in spark ignition engines

Chemical absorption of carbon dioxide in biogas purification

Factors influencing chemical absorption of CO2 and H2S in biogas : a review

  • Authors: Maile, O.I. , Tesfagiorgis, H. , Muzenda, E.
  • Date: 2015
  • Subjects: Absorption rate , Efficiency , Solvent
  • Language: English
  • Type: Conference proceedings
  • Identifier: http://hdl.handle.net/10210/72927 , uj:18345 , Citation: Maile, O.I., Tesfagiorgis, H. & Muzenda, E. 2015. Factors influencing chemical absorption of CO2 and H2S in biogas : a review.
  • Description: Abstract: Absorption is a process in which a substance (solute) is brought into contact with a solvent normally for a purpose of separation, which can be either physical or chemical. pH and concentration of the solvent, temperature of both the gas and the solvent, and absorbing surface area influence the absorption process. pH affect the absorption rate and if an acid or base is added into the system the absorption rate is lowered. Concentration of carbon dioxide in the gas stream and the loading rate influence the rate of absorption. MEA has an optimum absorption rate at liquid temperature of 35 °C. Ammonia has high removal efficiency at ambient temperature and there exists a direct relationship between absorption rate and temperature. Absorption of CO2 with sodium hydroxide is normally done at a temperature range of - 1-16 °C (30-60 °F). Calcium oxide requires high temperature for absorption ranging from 300-390 °C, while 22-80 °C is used for H2S absorption with K2CO3. A linear increase results from heating the CO2 gas stream prior to absorption. The rate of absorption is influenced by the contact area between the absorbing fluid and the gas.
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The potency of monoethanolamine in biogas purification and upgrading

Effect of blending coal with torrefied biomass for possible application in energy production

  • Authors: Mamvura, T. , Muzenda, E.
  • Date: 2016
  • Subjects: Coal , Biomass , Blending , Torrefaction
  • Language: English
  • Type: Article
  • Identifier: http://hdl.handle.net/10210/93696 , uj:20382 , Citation: Mamvura, T. & Muzenda, E. 2016. Effect of blending coal with torrefied biomass for possible application in energy production.
  • Description: Abstract: Emissions of greenhouse gases mostly from fossil fuels are responsible for global warming and climatic changes. This has led to research in bioenergy to reduce greenhouse emissions because bioenergy is part of the carbon cycle, and can only emit greenhouse gases that are part of the carbon cycle. The drawback is its low calorific value when it is in its raw form. Torrefaction improves its energy content to values that are comparable to coal. In this study, marula seeds and blue gum wood, two of South Africa most abundant biomass, were blended with coal both raw and torrefied to see the impact of the torrefaction process on energy density. Blending was done at different ratios to see the optimum results. Results showed that highest calorific value was obtained at 100% marula seeds and 0 % coal, and it was recommended for further studies. Blue gum wood due to its high moisture had slightly higher heating value than the reference coal but from an economical point of view it was not attractive for further studies. This showed the significance of the torrefaction process in increasing heating value of selected biomass in the hope of reducing effects of greenhouse gas emissions.
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Value addition of coal fines and sawdust to briquettes using molasses as a binder

Biological treatment of distillery wastewater by application of the vermifiltration technology

Resource recovery from municipal waste and bio solids (digestate) through vermicomposting: a waste management initiative

Anaerobic treatment of opaque beer wastewater with enhanced biogas recovery through Acti-zyme bio augmentation

Bio ethanol from sewage sludge: A bio fuel alternative

  • Authors: Manyuchi, M. M. , Chiutsi, P. , Mbohwa, Charles , Muzenda, E. , Mutusva, T.
  • Date: 2018
  • Subjects: Bio ethanol , Biomass , Hydrolysis
  • Language: English
  • Type: Article
  • Identifier: http://hdl.handle.net/10210/267396 , uj:28365 , Citation: Manyuchi, M.M. 2018. Bio ethanol from sewage sludge: A bio fuel alternative. South African Journal of Chemical Engineering, 25:123-127. https://doi.org/10.1016/j.sajce.2018.04.003. , ISSN: 1026-9185
  • Description: Abstract: In this study, the potential to fully exploit sewage sludge as a raw material for bio ethanol a source of bio fuel is investigated. Sewage sludge hydrolysate was first made by introducing Bacillus flexus in order for saccharification to take place before fermenting to bio ethanol using yeast. The hydrolysate was then prepared for fermentation by introducing 10 g/L of peptone, 2 g/L of KH2PO4 and 1 g/L of MgSO4. Af- terwards, fermentation was allowed to take place at varying pH (4.0e7.0), temperature (15e45 o C), in- cubation time (10e70 h) and yeast concentrations (2e10% (v/v). Bio ethanol concentrations were characterized through spectrophotometry and its physicochemical properties analyzed by standard methods. Pearson Correlations Coefficients in MATLAB 13.0 were used to determine the coefficients of interaction between the various parameters in bio ethanol production at 95% confidence interval. Highest bio ethanol yields of greater than 40 mL/L were achieved at an incubation period of 10 days, with an operating temperature of 30 o C and pH of 6.5 with yeast concentration of 6% wt. The interactions between incubation temperature and pH had the best interaction coefficient of 0.9759 being achieved for optimal bio ethanol yield. The bio ethanol produced had a flash point of 19.2 o C, pour point of 4.9 o C, cloud point of 20 o C and viscosity of 1.30 cP.
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