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Prediction of the heating value of municipal solid waste : a case study of the city of Johannesburg

  • Authors: Adeleke, Oluwatobi , Akinlabi, Stephen , Jen, Tien-Chien , Dunmade, Israel
  • Date: 2020
  • Subjects: Physical Composition , Lower heating value , Municipal Solid Waste
  • Language: English
  • Type: Article
  • Identifier: http://hdl.handle.net/10210/461229 , uj:41073 , Citation: Adeleke, O. et al. 2020. Prediction of the heating value of municipal solid waste : a case study of the city of Johannesburg.
  • Description: Abstract: In this study, a municipality-based model was developed for predicting the Lower heating value (LHV) of waste which is capable of overcoming the demerit of generalized model in capturing the peculiarity and characteristics of waste generated locally. The city of Johannesburg was used as a case study. Artificial Neural Network (ANN) and Adaptive Neuro Fuzzy-Inference System (ANFIS) models were developed using the percentage composition of waste streams such as paper, plastics, organic, textile and glass as input variables and LHV as the output variable. The ANFIS model used three clustering techniques, namely Grid Partitioning (ANFIS-GP), Fuzzy C-means (ANFIS-FCM) and Subtractive Clustering (ANFIS-SC). ANN architectures with a range of 1-30 neurons in a single hidden layer were tested with three training algorithms and activation functions. The GP-clustered ANFIS model (ANFIS-GP) outperformed all other models with root mean square error (RMSE), mean absolute deviation (MAD), and mean absolute percentage error (MAPE) values of 0.1944, 0.1389 and 4.2982 respectively. Based on the result of this study, a GP-clustered ANFIS model is viable and recommended for predicting LHV of waste in a municipality.
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Towards sustainability in municipal solid waste management in South Africa : a survey of challenges and prospects

  • Authors: Adeleke, Oluwatobi , Akinlabi, Stephen , Jen, Tien-Chien , Dunmade, Israel
  • Date: 2020
  • Subjects: Intelligent modeling , Circular economy , Sustainability
  • Language: English
  • Type: Article
  • Identifier: http://hdl.handle.net/10210/461231 , uj:41072 , Citation: Adeleke, O. et al. 2020. Towards sustainability in municipal solid waste management in South Africa : a survey of challenges and prospects.
  • Description: Abstract: In most developing countries, the huge amount of unmanaged municipal solid wastes and the inefficiency of the current waste management system has resulted in an unprecedented effect on human health and the quality of the environment. The drive towards sustainability in solid waste management in South Africa has led to the promulgation of several legislations and policies directed towards increased efficiency of solid waste management strategies. However, despite the progress in South Africa’s waste management systems over the years, it is still being constantly faced with some challenges and shortcomings. To achieve sustainable development through the transition from a linear economic model to a circular economy, there is a need to revamp the waste management sector. This study presents a survey of the key physical elements of integrated waste management in South Africa. The study further discusses the challenges with major emphasis on the future directions of integrated waste management. Waste management decisions are data-driven decisions. This study identifies the lack of accurate and reliable waste-related data as one of the major factors that impede the fast-track growth towards sustainable waste management in South Africa. A data-mining approach that emphasizes intelligent modeling of waste management systems is recommended to support the national waste database which will aid waste management decisions and optimizes waste management facilities and investments. Sustainability in waste management in South Africa requires a multi-sector intervention and involvement to stimulate sustainable development in waste management.
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Prediction of municipal solid waste generation : an investigation of the effect of clustering techniques and parameters on ANFIS model performance

  • Authors: Adeleke, Oluwatobi , Akinlabi, Stephen A. , Jen, Tien-Chien , Dunmade, Israel
  • Date: 2020
  • Subjects: Waste generation , Adaptive Neuro-Fuzzy Inference System , Clustering-techniques
  • Language: English
  • Type: Article
  • Identifier: http://hdl.handle.net/10210/461246 , uj:41074 , Citation: Adeleke, O. et al. 2020. Prediction of municipal solid waste generation : an investigation of the effect of clustering techniques and parameters on ANFIS model performance.
  • Description: Abstract: The present waste management system and facilities in most developing countries are insufficient to combat the challenge of increasing rate of solid waste generation. To achieve success in sustainable solid waste management, planning plays a crucial role. Accurate prediction of waste quantities generated will immensely help to overcome the challenge of deficient-planning of sustainable waste management. This challenge has necessitated the need for modelling approach. In modelling the complexity within a system, a paradigm-shift from classical-model to artificial intelligent model has been necessitated. Previous researches which used Adaptive Neuro-Fuzzy Inference System (ANFIS) for waste generation forecast did not investigate the effect of clustering-techniques and parameters on the performance of the model despite its significance in achieving accurate prediction. This study therefore investigates the impact of the parameters of three clustering-technique namely: Fuzzy c-means (FCM), Grid-Partitioning (GP) and Subtractive-Clustering (SC) on the performance of the ANFIS model in predicting waste generation using South Africa as a case study. Socio-economic and demographic provincial-data for the period 2008-2016 were used as input-variables and provincial waste quantities as output-variable. ANFIS model clustered with GP using triangular input membership-function (tri-MF) and a linear type output membership-function (ANFIS-GP1) is the optimal model with Mean Absolute Percentage Error (MAPE), Mean Absolute Deviation (MAD), Root Mean Square Error (RMSE) and Correlation Co-efficient (R2) values of 12.6727, 0.6940, 1.2372 and 0.9392 respectively. Based on the result in this study, ANFIS-GP with a triangular membership-function is recommended for modelling waste generation. The tool presented in this study can be utilized for the national repository of waste generation data by the South Africa Waste Information Centre (SAWIC) in South Africa and it is also applicable to waste-planners in developing countries for reliable and accurate prediction of annual waste generation.
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Predicting the effect of seasonal variation on the physical composition of municipal solid waste : a case study of the City of Johannes-burg

  • Authors: Adeleke, Oluwatobi , Akinlabi, Stephen , Hazzan, S. , Jen, Tien-Chien
  • Date: 2020
  • Subjects: Adaptive Neuro-Fuzzy Inference System , Season , Municipal Solid Waste
  • Language: English
  • Type: Article
  • Identifier: http://hdl.handle.net/10210/461222 , uj:41071 , Citation: Adeleke, O. et al. 2020. Predicting the effect of seasonal variation on the physical composition of municipal solid waste : a case study of the City of Johannes-burg.
  • Description: Abstract: Several factors influence the physical, chemical, and thermal properties of waste at different sources. One of the major indexes to variation in the morpho-logical composition of municipal solid waste is the season. A significant discrep-ancy in the composition of municipal solid waste at different seasons has been re-ported in the literature. However, this study explores the Adaptive Neuro-Fuzzy Inference System (ANFIS) with a fuzzy c-means (FCM) clustering technique to predict the physical content of waste in South Africa based on the varying weather parameters at different seasons. Four different models (I-IV) were developed to forecast the percentage fraction of Organics, Plastics, Paper, and Textile, respec-tively. The choice of these streams was because a closer look at the historical data reveals a significant variation in the percentage of these waste fractions at different seasons with little or no difference in other waste streams. The percentage compo-sition of samples of waste collected and characterized at Marie Louise Landfill, Jo-hannesburg in summer 2015 and winter 2016 was used as the output variable. Weather parameters for the same period were extracted from South Africa Weather Service data and used as the input variables. M-file script was written and computed on a workstation with configurations of 64 bits, 4GB ram Intel(R) core(TM) i3. The performance of the ANFIS models I-IV was evaluated using Mean Absolute Devi-ation (MAD), Root Mean Square Error (RMSE), and Mean Absolute Percentage Error (MAPE).
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Organic acid-catalyzed hydrolysis of Magnesium hydride for generation of hydrogen in a batch system hydrogen reactor

One-pot synthesized visible light-driven BiOCl/AgCl/BiVO4 n-p heterojunction for photocatalytic degradation of pharmaceutical pollutants

Titanate based photocatalysts for climate-efficient water treatment

  • Authors: Akbarzadeh, Rokhsareh , Jen, Tien-Chien , Asadi, Anvar
  • Date: 2019
  • Subjects: Titanium peroxide gel , Amourphus , Thin film
  • Language: English
  • Type: Conference proceedings
  • Identifier: http://hdl.handle.net/10210/402794 , uj:33724 , Citation: Akbarzadeh, R., Jen, T.C. & Asadi, A. 2019. Titanate based photocatalysts for climate-efficient water treatment.
  • Description: Abstract: The sol-gel dip-coating method is a simple method to synthesize TiO2 thin film, using titanium butoxide and hydrogen peroxide as precursors. In this study in addition to TiO2 thin film, the photocatalytic activity of its intermediate products, titanium peroxide gel and ambient dried titanium peroxide film, was evaluated. The titanium peroxide gel was used directly after gelation, ambient dried titanium peroxide film coated on glass rings was used without thermal treatment and anatase TiO2 thin film was used after thermal treatment at 500oC. These photocatalysts were characterized by different characterization techniques and their adsorption and photocatalytic activity were evaluated by using methylene blue as a model pollutant. All three photocatalysts adsorbed the selected dye model and degraded it in the presence of sunlight but with different removal rate. It was found that the gel had the highest removal rate followed by ambient dried titanium peroxide film and TiO2 thin film. However, this sequence was found to be vice versa in the case of life span when the photocatalysts were reused. The photocatalytic study showed that all three photocatalysts are very effective for 100% degradation of methylene blue between 5-60 minutes of contacts times under sunlight irradiation. This can be a breakthrough of using titanate based photocatalyst for cost-effective adsorption and photocatalytic degradation of pollutants based on climate and availability of sunlight.
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Photocatalysis and energy cost analysis of Vanadia Titania thin films synthesis

Evaluation of aerated lagoons performance and suggestion to develop more sustainable energy consumption in a STP plant; a case study

Titanate based photocatalysts for climate-efficient water treatment

Effect of synthesis method on NS-TiO2 photocatalytic performance

Effect of synthesis method on NS-TiO² photocatalytic performance

  • Authors: Asadi, Anvar , Akbarzadeh, Rokhsareh , Eslami, Akbar , Jen, Tien-Chien , Oviroh, Peter Ozaveshe
  • Date: 2019
  • Subjects: NS co-doped TiO² , Photocatalyst , Ibuprofen
  • Language: English
  • Type: Conference proceedings
  • Identifier: http://hdl.handle.net/10210/406933 , uj:34233 , Citation: Asadi, A. et al. 2019 : Effect of synthesis method on NS-TiO² photocatalytic performance.
  • Description: Abstract : In this study, highly visible-light photoactive nitrogen and sulfur co-doped TiO2 nanoparticles and nanosheets were synthesized via sol-gel and hydrothermal methods, respectively. The photocatalytic activity of N,S-TiO2 photocatalysts were evaluated and compared by degradation of non-steroidal anti-inflammatory drugs, ibuprofen(IBP) and naproxen (NPX), under simulated solar light. The sol-gel method developed a mesoporous structure N,S-TiO2 nanoparticle which contains both anatase and rutile phases with large BET surface area (132 m2/g). N,S-TiO2 nanosheets with pure anatase phase, with larger mesoporous structure and a smaller BET surface area (64 m2/g) was formed via hydrothermal method. NS-TiO2 nanoparticles were coated on UVC-treated polycarbonate (PC) (NS-TiO2@PC) by simple deposition method. The results showed that under identical condition, N,S-TiO2 nanoparticles can degrade 85% and 99.3% of ibuprofen and naproxen while 71.6% of IBP and 99.1% of NPX were degraded by N,S-TiO2 nanosheets. Optimization results showed that maximum degradation efficiency was achieved at the optimum conditions: irradiation intensity 8.36 mW/cm2 (for ibuprofen) and 10 mW/cm2 (for naproxen), initial drugs concentration 10 mg/L and reaction time 121 min. Under this condition, the maximum degradation efficiency of 83% and 100% were achieved for ibuprofen and naproxen, respectively. The results of this study elucidate co-doped NS-TiO2 nanoparticles prepared by sol-gel methods are photocatalytically more effective and practically easier to reproduce for the practical application, both in terms of energy saving and cost reduction. The energy cost analysis indicated that sol-gel method for synthesis of N,S-TiO2 is more cost effective.
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Yield response from the catalytic conversion of Parsley seed oil into biodiesel using a Heterogeneous and Homogeneous catalyst

Thermo-chemical characteristics of R134a flow boiling in helically coiled tubes at low mass flux and low pressure

  • Authors: Chen, Chang-Nian , Han, Ji-Tian , Jen, Tien-Chien , Shao, Li
  • Date: 2011
  • Subjects: Helically coiled tubes , Heat transfer , Low mass flux , Low pressure
  • Type: Article
  • Identifier: uj:5282 , http://hdl.handle.net/10210/14951
  • Description: The characteristics of R134a heat transfer coefficients and wall temperature distribution were investigated under low mass flux and low pressure conditions in a helically coiled tube with heated length of 7070mm, outer diameter of 10mm, inner diameter of 7.6mm, coil diameter of 300mm and helical pitch of 40mm. System pressures, mass fluxes and inlet qualities range from 0.20 to 0.75 MPa, 50 to 260 kg/m2 s and −0.18 to 0.40, respectively. It was found that the wall temperatures in descending segments of coiled tube were higher than those of climbing ones, while the heat transfer coefficients varied inversely. Around the section circumference, the outside temperature was lower than the inside one; this is more apparent at very low mass flux and pressure conditions. The heat transfer coefficient increases with increasing mass flux, vapor quality and heat flux. However, the pressure has an indeterminate effect. New heat transfer coefficient correlations for current conditions were developed comparing with existing correlations.
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Fluid-to-fluid modelling of two-phase flow critical heat flux in horizontal helically coiled tubes

  • Authors: Chen, Chang-Nian , Han, Ji-Tian , Jen, Tien-Chien , Shao, Li , Chen, Wen-wen
  • Date: 2011
  • Subjects: Critical heat flux , Fluid flow , Helically coiled tubes
  • Type: Article
  • Identifier: uj:5287 , http://hdl.handle.net/10210/14956
  • Description: The new similarity laws for fluid-to-fluid modeling of two-phase flow critical heat flux (CHF) in horizontal helically coiled tubes were derived based on the dimensional analysis and similarity theory considering the effect of the geometrical parameters on CHF. A generalized factor Dn was introduced to the new similarity laws, and all the new dimensionless numbers were derived from the classical theorem of Buckingham for dimensional analysis. The obtained dimensionless parameter sets were a reasonable extension to Ahmad’s compensated distortion model, which may be considered as a special case of the new dimensionless parameter sets when the variable n is equal to unity. Based on the experimental data, the specific similarity numbers were determined for CHF phenomena in horizontal helically coiled tubes. A new equivalent characteristic parameter De-helix was developed, which could reflect the influence of complex flow channels on the occurrence of CHF. The equivalent characteristic parameter consists of the essential geometrical parameters of tubes and the fluid thermophysical properties. The new fluid-tofluid modeling methods were proposed for CHF of R134a-water in horizontal helically coiled tubes, which could be used readily to derive the CHF data of water through the CHF data of R134a at the corresponding experimental conditions.
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Experimental study on critical heat flux characteristics of R134a flow boiling in horizontal helically-coiled tubes

  • Authors: Chen, Chang-Nian , Han, Ji-Tian , Jen, Tien-Chien , Shao, Li , Chen, Wen-wen
  • Date: 2011
  • Subjects: Critical heat flux , Helically coiled tubes , Heat transfer
  • Type: Article
  • Identifier: uj:5284 , http://hdl.handle.net/10210/14953
  • Description: Critical heat flux (CHF) experiments were performed to study the R134a CHF characteristics in horizontal helically-coiled tubes. The stainless steel test sections were heated uniformly, with tube inner diameters of 3.8e11 mm, coil diameters of 135e370 mm, helical pitches of 40e105 mm and heated lengths of 0.85e7.54 m. The experimental conditions are pressures of 0.30e1.10 MPa, mass fluxes of 60e480 kg m 2 s 1, inlet qualities of 0.32e0.36 and heat fluxes of 6.0 103e9.0 104Wm 2. It was found that the wall temperatures jumped abruptly once the CHF occurred. The CHF values decrease with increasing heated lengths, coil diameters and inner diameters, but the DNB (departure from nucleate boiling) CHF seems independent when length-to-diameter L/di> 200. The coil-to-diameter ratios are more important than length-to-diameter ratios for CHF in helically-coiled tubes, while the helical pitches have little effect on CHF. The CHF value increases greatly with increasing mass flux and decreases smoothly with increasing pressure. It decreases nearly linearly with increasing inlet and critical qualities, but it varies more acutely at xcr< 0.5 than higher critical qualities. New correlations for R134a flow boiling CHF in horizontal helically-coiled tubes were developed for applications.
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A passive control method of HAWT blade cyclical aerodynamic load induced by wind shear

  • Authors: Chen, Hong-Sheng , Jen, Tien-Chien
  • Date: 2017
  • Subjects: Wind energy , Wind shear , Passive control
  • Language: English
  • Type: Conference proceedings
  • Identifier: http://hdl.handle.net/10210/231934 , uj:23641 , Citation: Chen, H. & Jen, T. 2017. A passive control method of HAWT blade cyclical aerodynamic load induced by wind shear.
  • Description: Abstract: Modern wind turbines are mainly horizontal axis and operate in bottom atmospheric boundary layer driven by wind shear flow, therefore as the blades rotating the aerodynamic load vary cyclically, with horizontal axis wind turbine (HAWT) large-scaling the cyclical characteristic becomes more obvious, shortening blade life and increasing cost of wind turbine. As the development of wind turbine largescaling is the essential trend, load fluctuation control is more and more critical in HAWT design and manufacture. In common, individual pitch control is introduced to solve the problem, but cost much energy from electric net. In this paper, a concept of telescopic blade root is introduced to reduce fluctuate load induced by wind shear passively, and considering the blades as rigid assessment is operated, meanwhile aerodynamic model based on blade element method in order to analysis the aerodynamic load on NREL Phase VI reference based blade. The result shows that after introducing the equipment the blade fatigue load can be released, lengthening blade life.
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Development and fabrication of a wood gasifier to power an internal combustion engine

  • Authors: Chinguwa, Simon , Nyemba, Wilson R. , Jen, Tien-Chien , Boora, Kudzai
  • Date: 2018
  • Subjects: Carbon , Combustion , Fossil Fuels
  • Language: English
  • Type: Conference proceedings
  • Identifier: http://hdl.handle.net/10210/285610 , uj:30890 , Citation: Chinguwa, S. et al. 2018. Development and fabrication of a wood gasifier to power an internal combustion engine.
  • Description: Abstract: Fossil fuels have been the main source of energy for many years hence the depletion of resource. There is therefore a need for alternative cleaner energy sources of fuel to be explored. The use of these conventional fuels led to land degradation global warming and air pollution. A wood gasifier machine which produces combustible gas from solid fuels like charcoal, wood and agriculture residue was designed. The combustible gas can be used for heating purposes or to produce mechanical or electrical energy. There was a great literature search for the technology currently being used for gasification processes which led to the design and manufacture of the gasifier prototype which was tested and came out successfully. An internal combustion engine was run on the combustible gas. Gasification bi-products that came out were tar and ash which could be used for water proofing and fertilizer respectively. Biofuels are renewable energy sources and are carbon neutral as they do not increase the total amount carbon dioxide in the atmosphere. The test also revealed some shortcomings in the design. The air which was used to allow for combustion to take place was inadequate, hence there is a need for further research.
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Conceptualization of the optimal design of a hydroxyl booster dry cell for enhancing efficiency of internal combustion engines

  • Authors: Chinguwa, Simon , Jen, Tien-Chien , Akinlabi, Esther T.
  • Date: 2020
  • Subjects: Dry cell , Hydroxyl , Internal combusion
  • Language: English
  • Type: Conference proceedings
  • Identifier: http://hdl.handle.net/10210/437148 , uj:37948 , Citation: Chinguwa, S., Jen, T.C. & Akinlabi, E.T. 2020. Conceptualization of the optimal design of a hydroxyl booster dry cell for enhancing efficiency of internal combustion engines.
  • Description: Abstract: Current internal combustion engines (ICEs) are powered by fossil fuels which create the challenges of low combustion efficiency and the emission of greenhouse gases. This has negatively affected the environment, leading to global warming and climate change. Interim technologies can be implemented to reduce these effects whilst alternative technologies are being explored. This research aimed at selecting the most appropriate geometrical design of a hydroxyl booster dry cell, a device which operates on the principles of electrolysis to produce hydroxyl gas commonly referred to as Brown gas or HHO. When a voltage is applied to a body of water, it splits it into its base components, i.e. hydrogen and oxygen cold plasma, a mixture sometimes referred to as hydroxyl gas. The addition of hydroxyl gas into the combustion chamber of an ICE initiates a more complete combustion due to the explosive and diffusive nature of hydrogen accompanied by the cooling effect of water thus reducing potential for NOx formation. This leads to fuel savings, cost savings and reduced emissions. A rectangular hydroxyl booster dry cell was selected and designed, fabricated and tested for effectiveness. The HHO generator is later connected to the ICE system to check mainly on the positive contributions of this Brown’s gas as HHO is popularly known.
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The fluid flow effect on the inlet injection of the thin film deposition in a square type atomic layer deposition reactor

  • Authors: Coetzee, Rigardt Alfred Maarten , Lu, Hongliang , Jen, Tien-Chien
  • Date: 2019
  • Subjects: Nanotechnology , Atomic layer deposition , Computational fluid dynamics
  • Language: English
  • Type: Article
  • Identifier: http://hdl.handle.net/10210/400082 , uj:33374 , Citation: Coetzee, R.A.M., Lu, H., & Jen, T.C. 2019. The fluid flow effect on the inlet injection of the thin film deposition in a square type atomic layer deposition reactor.
  • Description: Abstract: In recent years, industry is ever striving to deposit optimal thin films on Nano devices. This strive led to interest in utilising advance Nano-manufacturing techniques that can fabricate ever-decreasing scale products along with films that provide highly uniform, conformal, and pin-hole free quality thin films. Atomic layer deposition provides a technique that fulfil these requirements. However, the understanding of the deposition process within the fabrication of these thin films are still greatly not well-known. The fluid flow patterns and distributions within the atomic layer deposition reactors are rarely investigated and lacks the fluid flow effect incorporated along with the deposition process near the substrate. Per se, these effects due to the geometrical effect of the inlet injection location from the deposited substrate of a square type Gemstar Reactor is investigated. The findings reveal the inlet flow effect, near substrate flow behaviour, and optimal selection for the deposition of aluminium oxide (Al2O3) thin film. The study simulates the fluid flow properties along with the chemical kinetics by utilizing computational fluid dynamics incorporated within ANSYS Fluent Software. The flow and surface reaction of Trimethylaluminium and Ozone as precursors, along with Argon as the purging substance, are incorporated within the atomic layer deposition sequence. The findings reveal close similarities to that of previous literature.
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