Theses and dissertations (Engineering and Built Environment)

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Acousto-ultrasonics for defect assessment of composite materials
(2002) Dugmore, Kevin M.; Jonson, Jon David; Walker, Mark
The experiments and their results contained herein will form the basis for the development of a portable non-destructive testing device for composite structures. This device is to be capable of detecting any of a variety of defects and assessing their severity within a short time
An adaptive quotation system for web-based manufacturing
(2005) Li, Qingxue; Walker, Mark
Increased global competition is challenging manufacturing industries to bring competitively priced, well-designed and well-manufactured products into the marketplace as quickly as possible. Manufacturing companies are responding to these challenges in their industry by extending current internet trends to create virtual marketplaces where factories, suppliers, and customers are part of the solution. Pressing demands to reduce lead-time by providing a suitable manufacturing price for a product has become an important step in the current competition age. This thesis presents an approach for providing a quotation for a product via the web, automatically and autonomously.
Adoption of intelligent transport systems for sustainable transportation in secondary cities of South Africa : a case of Port Shepstone
(2019-08) Madihlaba, Goodness Lerato; Musvoto, Godfrey Gombana
Transportation is one of the major phenomenon which often directs population increase, investments and land use patterns in cities. Most cities, particularly secondary cities often do not entirely plan for future transportation when planning for massive investment developments thus leaving such cities with transportation challenges which include aging transport infrastructure, increased traffic patterns, insufficient parking spaces, high-accidents rates, to name a few. The most ignored transportation solution in secondary cities is the use of technology to manage transportation challenges in which such solutions may include the establishment of Intelligent Transport Systems (ITS). This research study seeks to examine what are the possibilities of using ITS to address the transportation challenges of the secondary city of Port Shepstone, what are the recommendations that can be put forward for establishment of ITS in Port Shepstone. In an attempt to discover these questions, the study conducts a literature review analysis which outlines what others have done in this research area and progressively attempts to provide recommendations on the possible establishment of ITS solutions in Port Shepstone. The literature review focuses on five (5) functional areas (i.e. Advanced Traveller Information Systems (ATIS); Advanced Transportation Management Systems (ATMS); Advanced Public Transport Systems (APTS); Enabled Transportation Pricing System (ETPS) and Data Acquisition Management Systems (DAMS)) which their possibility of being established in the secondary city of Port Shepstone is investigated The literature review analysis is supplemented by semi-structured interviews with various stakeholders within the transportation sector; and their views are constructively analysed to draw converging findings. The empirical findings from both literature review analysis and conducted interviews provide meaningful answers to the research questions and enabled the researcher to draw fundamental recommendations and possible ITS solutions to address the transportation challenges of Port Shepstone.
Advanced reliability analysis of road-slope stability in soft rock geological terrain
(2023-05) Sengani, Fhatuwani
Most of the national, regional, and local roads in Limpopo Province have been developed through a rugged topography and artificial slopes have been created with loose rocks scattered across the slopes as a results road slope instability is the common challenge. The objective of this research study is to conduct an advanced reliability analysis of road-slope stability in soft rock geological terrain using the national road (N1) and its tributary (R71) as case studies. Limit analysis, limit equilibrium, finite element methods, finite difference methods, machine learning and GIS-based tools have been used for this purpose. Meanwhile, the accuracy classification chart of limit equilibrium methods in homogenous slope and a new method for predicting the stability of slope in multiple faulted slopes were developed. The reproduction of failure evolution of slope instability was also performed, followed by reliability analysis of the slope based on probabilistic analysis. Lastly, an integrated approach to slope stability assessment based on machine learning, geographic information systembased tools and geotechnical methods was presented. To achieve the above, field observations and measurements, structural mapping, limit equilibrium, limit analysis, Monte Carlo simulation, fuzzy inference analysis, and GIS digitization and analysis were performed. Software packages such as SLIDE, FLACslope, Optimum 2G, DIPS, RocLab, and ArcGIS, were used. The accuracy classification chart for Limit Equilibrium Methods LEM), a new method for performing stability analysis in multiple faulted slopes, reproduction of failure evolution of slope was developed. Monte Carlo simulation was established as the most reliable and effective technique to analyze slope stability. The steepness of the slope, rock and soil properties, extreme rainfall and geological features were demonstrated to influence slope instability based on an integrated approach as stated above. From the above-mentioned major findings, it was concluded that the developed accuracy error classification chart of LEMs and the new method of slope stability in multi-faulted slopes are useful. Though the reproduction of failure evolution of slope was successfully achieved, for material to flow for a longer distance, high kinetic energy and more shearing of material are expected to take place during this process. It is recommended that other sophisticated methods be utilized to expand the results.
Aerobic sequencing batch reactor for the treatment of industrial wastewater from the brewery
(2017) Shabangu, Khaya Pearlman; Chetty, Maggie; Bakare, Babatunde F.
One of the major effects of socio-economic change due to industrialisation is the generation of industrial wastewater, which requires treatment before being released into the environment. Laboratory-scale aerobic sequencing batch reactors under suspended-growth heterotrophic activated sludge were operated in different aeration configurations to study their effect on the treatment of wastewater generated by a local brewery. The main purpose of this study was to evaluate the performance of the two laboratory-scale aerobic sequencing batch reactors treating brewery wastewater under continuous low-oxygen dosing concentration and cyclic aeration schemes on SBR operation. The characterisation of brewery wastewater was undertaken to assess the physicochemical composition of the wastewater produced from one of the breweries in South Africa (SAB). The data showed distinctive characteristics of brewery wastewater, which coincided with studies previously carried out on characterisation of brewery wastewater. The COD average concentration of the brewery influent was 7100 mg/L, with average pH values of 7. The BOD and the total solids content of the brewery wastewater influent from the facility were both high, implying that the influent was very rich in organic content and its discharge into water-receiving bodies or the municipal treatment plant could have adverse effects. From these results, a need for a competitive treatment technology was clearly highlighted so as to carry out a feasible treatment of the influent for the brewery industry. The aerobic sequencing batch reactors were designed, fabricated and set up for laboratory-scale treatment of wastewater from the brewery for 15 weeks. The performance of the two SBR configurations was determined with reference to COD, BOD, TS, VS and TSS. The experimental results demonstrated that wastewater generated from the breweries can be treated successfully using both aeration configurations. The results obtained indicated that treatment efficiencies in terms of COD and BOD were 94 % and 85 % respectively, for the reactor operated under continuous aeration configuration, while 81 % and 65 % was achieved for the reactor operated in the cyclic aeration scheme. The findings from this study demonstrate that the performance of the reactor operated under the continuous aeration scheme was successful, and showed statistically significant differences from the performance of the reactor operated under cyclic aeration schemes. These findings imply that there is a potential for the equipment, including financial benefit as a result of operating aerobic sequencing batch reactors for treating brewery wastewater under continuous low-oxygen concentration dosing schemes. In this study, it was also established that the maximum COD removal could be reached at an optimum hydraulic retention times of 5 days for both reactors. This was based upon viewing the experimental data; it appeared that the most significant difference in percentage COD removal was for HRTs 3 days and 4 days. Although, due to less percentage COD removal observed from HRTs 5 days till 7 days, it was hence established that the optimum removal of high strength organics in the brewery wastewater could be achieved within 5 days of treatment time. The pH adapted at an average of 7 for all batch experimentations of the study. The temperature maintained an average of 23 oC ambient, throughout the experimental period. These physical parameters ensured that the microbial population was kept healthy, without inhibiting its biological degradation activity. Although, sludge build up was observed in both aerobic SBRs on completion of each batch operation due to solids retention and organic pollutants biodegradation from the brewery wastewater. It was perceived that frequently reseeding both aerobic SBRs, as an alternative to 28 days sludge retention time would enhance the recovery of biomass, thus improving the overall removal of TSS consequently minimising sludge bulking in both reactors.
Alcohols conversion over transition metal based catalyts
(2018) Ndebele, Mthobisi Sbonelo; Isa, Yusuf Makarﬁ
Ethanol and butanol obtainable through fermentation of lignocellulose biomass have become promising alternative feedstock for production of fuels as they are biodegradable and sustainably regenerated via the photosynthesis cycle. The properties of hydrocarbons produced through alcohol conversion closely resemble those of gasoline. Catalytic systems are reported to play a vital role during alcohol conversion to hydrocarbons. In this study ethanol and butanol were used as a feedstock for production of hydrocarbons over Fe, Zn and Ni catalyst systems supported on zeolite ZSM-5 (Zeolite Socony Mobil-5) and activated carbon (AC). X- Ray Diffraction (XRD), Scanning Electron Microscope (SEM) coupled with Energy- dispersive X-ray spectroscopy (EDS) and Brunauer, Emmet, and Teller (BET) analyses were employed for catalyst characterization. XRD patterns confirmed the success of metal doping on ZSM-5 and activated carbon supports. Major peaks at 7.96° and 23.97° corresponding to ZSM-5 crystals were observed in ZSM-5, and AC was found to be amorphous. Impregnation with metals reduced the crystallinity of ZSM-5 supported catalysts. Whereas SEM analysis showed that catalysts supported on ZSM-5 exhibited irregular shapes and catalyst supported on activated carbon exhibited disordered structures. The BET analyses confirmed that the surface areas of promoted catalysts decreased after metal doping. Evaluation of the catalysts were carried out in a ½ inch stainless steel reactor at 400 °C and atmospheric pressure with a weight hourly space velocity (WHSV) of 2.5 h-1 (g feed)/ (g catalyst). The ZSM-5 support performed better than activated carbon support. More than 90% conversion was achieved over catalysts supported on ZSM-5. Production of hydrocarbons over catalysts supported on activated carbon were as a result of the active component. Conversion of feedstock was observed to produce more benzene, toluene and xylene (BTX) compounds with an increase in butanol content. 100% conversion was achieved with pure butanol and not more than 99.86% conversion was achieved with pure ethanol. Catalyst systems supported on HZSM-5 and activated carbon were successfully synthesised. Ethanol, butanol and ethanol-butanol mixtures were successfully converted to liquid hydrocarbons and the conversion was greater than 90%. On the promoted catalysts, production of BTX were suppressed and various metals were observed to perform differently.
Anaerobic co-digestion of agricultural biomass with industrial wastewater for biogas production
(2021-03-26) Armah, Edward Kwaku; Chetty, Maggie; Deenadayalu, Nirmala
With the increasing demand for clean and affordable energy which is environmentally friendly, the use of renewable energy sources is a way for future energy generation. South Africa, like most countries in the world are over-dependent on the use of fossil fuels, prompting most current researchers to seek an affordable and reliable source of energy which is also,a focal point of the United Nations Sustainable Development Goal 7. In past decades, the process of anaerobic digestion (AD) also referred to as monodigestion, has proven to be efficient with positive environmental benefits for biogas production for the purpose of generating electricity, combined heat and power. However, due to regional shortages, process instability and lower biogas yield, the concept of anaerobic co-digestion (AcoD) emerged to account for these drawbacks. Given the considerable impact that industrial wastewater (WW) could provide nutrients in anaerobic biodigesters, the results of this study could apprise decisionmakers and the government to further implement biogas installations as an alternative energy source. The study aims at optimising the biogas production through AcoD of the agricultural biomasses: sugarcane bagasse (SCB) and corn silage (CS) with industrial WW sourced from Durban, KwaZulu-Natal, South Africa. The study commenced with the characterisation of the biomasses under this study with proximate and ultimate analysis using the Fourier transform infrared spectroscopy (FTIR), the thermo gravimetric analysis (TGA), the scanning electron microscopy (SEM) and the differential scanning calorimetry (DSC). The untreated biomass was subjected to biochemical methane potential (BMP) tests to optimise and predict the biogas potential for the selected biomass. A preliminary run was carried out with the agricultural biomass to determine which of the WW streams would yield the most biogas. Among the four WW streams sourced at this stage, two WW streams; sugar WW (SWW) and dairy WW (DWW) produced the highest volume of biogas in the increasing order; SWW ˃ DWW ˃ brewery WW > municipal WW. Therefore, both SWW and DWW were selected for further process optimisation with each biomass. Using the response surface methodology (RSM), the factors considered were temperature (25-55 °C) and organic loading rate (0.5-1.5 gVS/100mL); and the response was the biogas yield (m3 /kgVS). Maximum biogas yield and methane (CH4) content were found to be 5.0 m3 /kgVS and 79%, respectively, for the AcoD of CS with SWW. This established the association that existed among the set temperatures of the digestion process and the corresponding organic loading rate (OLR) of the AcoD process operating in batch mode. Both CS and SCB have been classified as lignocellulosic and thus, ionic liquid (IL) pretreatment was adapted in this study to ascertain their potential on the biogas yield. Results showed that the maximum biogas yield and CH4 content were found to be 3.9 m3 /kgVS and 87%, respectively, after IL pretreatment using 1-ethyl-3-methylimidazolium acetate ([Emim][OAc]) for CS with DWW at 55°C and 1.0 gVS/100mL. The IL pretreatment yielded lower biogas but of higher purity of CH4 than the untreated biomass. Data obtained from the BMP tests for the untreated and pretreated biomasses were tested with the existing kinetic models; first order, dual pooled first order, Chen and Hashimoto and the modified Gompertz. The results showed that for both untreated and pretreated biomass, the modified Gompertz had the best fit amongst the four models tested with coefficient of correlation, R 2 values of 0.997 and 0.979, respectively. Comparatively, the modified Gompertz model could be the preferred model for the study of industrial WW when used as co-substrate during AcoD for biogas production. The study showed that higher biogas production and CH4 contents were observed when CS was employed as a reliable feedstock with maximum volume of the untreated and pretreated feedstock reported at 31 L and 20 L respectively.
Anaerobic co-digestion with industrial wastewater for biomethane production
(2020-10-20) Adedeji, Jeremiah; Chetty, Maggie
The increasing demand for energy has led to the utilization of fossil fuels more abundantly as a quick alternative for generation of energy. The use of these sources of energy however as led to the generation of greenhouse gases which tend to cause climate change, thus affecting the ecosystem at large. Thus, there have been the search for alternative sources which cannot be depleted but do generate minimal greenhouse gases. One of such alternate sources is industrial wastewater which have shown to have high concentration of nutrients in the form of organic contents which can be converted by micro-organisms into energy, usually known as biogas, comprising majorly of CH4, CO2 and H2. Another important factor is that industrial wastewaters are a renewable energy source which are continuously generated due to increasing urbanisation and population growth. In this study, the characteristics of three agro-industrial based wastewaters used shows their potential for application in anaerobic co-digestion”. Anaerobic co-digestion method was utilized to harness the synergetic effect of both sewage sludge and agro-industrial wastewater as co-substrate for the generation of biomethane. The result of the effect of varying mix-ratio of the substrates on biomethane production of sugar wastewater and dairy wastewater indicated that mix-ratio of 1:1 for sewage sludge to sugar wastewater operated at 35oC was suitable for optimum generation of biomethane of 1400.99 mL CH4/g COD added and COD reduction of 54%. The model generated using design expert was found to navigate the design space and could perfectly predict the yield of biomethane effectively for the sugar wastewater mix. The biomethane potential tests (BMP) experiment using varying inoculum-substrate ratio (ISR) showed that operating at mesophilic temperature of 25oC with ISR of 1:2 and 2:1 for sugar wastewater and dairy wastewater respectively does increase the methane production within the first three (3) weeks. The kinetic models that best fit the anaerobic co-digestion for sugar wastewater was the first order model while the simplified Gompertz model favoured the dairy wastewater perfectly. The biomethane potential tests indicate significant increase the biomethane production and as well reduction in the volatile solid and chemical oxygen demand (COD) content. In conclusion, both sugar and dairy wastewater can be recommended as co-substrates for anaerobic digestion of sewage sludge for increased and improved biomethane production while simultaneously reducing their COD content at the same time.
Analysing South Africa’s automotive energy consumption : application of index decomposition analysis
(2021-01) Machivha, Rofhiwa Tevin; Olanrewaju, Oludolapo Akanni
This research focuses on applying the Index Decomposition Analysis (IDA) to South Africa’s automotive industry to decompose energy consumption and further make use of regression analysis to understand how it relates to the economy. South Africa has been going through an energy crisis, which has resulted in ongoing load shedding as a way to manage this crisis. Looking at South Africa’s energy generation, it can be noted that the entire country depends on Eskom as the main supplier and of electricity, but it is unable to keep pace with the demand. The results of the research show that there exists a nexus across all segments between energy consumption and GDP; furthermore, the decomposition results show that energy consumption in some years experienced a reduction. However, it can be seen that an increase in energy consumption year on year is predominant; this then suggests that the reductions experienced were the result of a special event; hence, it can be deduced that overall energy consumption has increased slightly. The increase is as a result of the activity effect which contributed the most towards this whilst the structural effect yielded a negligible contribution. Lastly, the intensity effect contributed to the reduction in energy consumption as a result of sectoral shifts; this reduction contributed towards keeping the overall increase in energy consumption low. This study aimed to outline the differences in energy consumed during the production of different vehicle classes, citing various factors responsible for the changes in energy consumption during vehicle production, raising awareness with manufacturers on the impact industrial energy consumption has on the national energy grid and on advising medium to large manufacturers to become suppliers.
Analysis of student success in Mechanical Engineering at the Durban University of Technology
(2016) Graham, Bruce Robert; Walker, Mark
The department of Mechanical Engineering at the Durban University of Technology currently offers a National Diploma (ND) and a Bachelor’s Degree in Technology (BTech), as well as a MEng. and a DEng. This thesis details four areas of study that were undertaken in an attempt to identify potential impediments to student success in the department, using readily available data. The universities’ management information system (ITS) was the primary source of data, but limited data was also obtained from courses that the author taught, as outlined in section (4) below. A grounded action research framework was selected as the methodological framework for these studies as it allowed the freedom to refine an investigation as it progressed as well as to implement potential solutions and determine their efficacy. The four areas covered were: (1) Analysis of trends in student success rates. A number of changes were made to the National Diploma over a five year period including the introduction of supplementary examinations, the removal of elective offerings, the change in the sequence of subjects offered and a reduction in contact time. This same period also coincided with the first cohort of students entering with the new NSC matric qualification. This study examined the success rates within subjects, across four semesters of study, from 2007 until 2010 and attempts to show the effects, either positive or negative, that these changes have had. The success rates of subjects within the BTech programme were also interrogated for this same period. These results were also categorised according to whether students obtained their diploma at DUT or at another institution allowing a comparison between the two cohorts. (2) Workplace Learning (WPL). Anecdotal evidence suggested that the manner in which the WPL components were offered had a negative effect on student throughput as well as not providing substantial opportunity for the integration of experience gained in industry with the academic programme. This study, utilising WPL registrations from 2007 to 2010, examined the average time taken to complete the WPL components, the percentage of the academic component completed before and during the WPL period as well as the dropout rate. (3) Relationship between NSC results and success in Mechanical Engineering. The purpose of this study was to determine if relationships could be found between student’s NSC results and success within the programme. This would inform if the departmental entrance requirements were of an appropriate level to ensure prospective students a reasonable chance of success. Results of selected NSC subjects were correlated with those of selected diploma subjects. The distributions of success in these subjects were tabulated against the NSC results allowing a better understanding of the relationship between them. (4) Investigation into causes of poor performance in Hydraulic Machines III. This study was undertaken to better understand the competencies and learning practices of the students in the author’s class. This involved the interrogation of the performance of students over a number of assessments, the tracking of usage of online resources and the tracking of lecture attendance, and subsequent correlation with performance. These studies have led to a better understanding of the programmes offered and have put the department in a position to make informed decisions regarding interventions aimed at increasing student success. The work covered in this thesis was presented in two full papers (Graham and Walker, 2011, Graham and Walker, 2015) and two extended abstracts (Graham and Walker, 2013, Walker and Graham, 2013).
An analysis of the factors influencing the relationship between soil properties and optimum moisture content and the formulation of an abbreviated test method of determinig maximum dry density
(1997) Allinsin, Anthony James; Coetzee, J.
The strength and durability of any soil structure is dependent on the quality of the compaction of the soil. This quality is measured by employing a standard compaction test, which provides a standard with which density may be compared, called the maximum dry density, and the moisture content of the soil at which this is achieved, called the optimum moisture content. As a matter of routine during quality control, the particle size distribution, plasticity index and liquid limit of the soil are determined at the same time as its maximum dry density and optimum moisture content.
Analysis of the viability of additive manufacturing for rapid tooling: A case study for the plastic industry
(2022-05-13) Pancha, Uttam Bhana; Olanrewaju, Oludolapo Akanni
The current environment of changing market trends that include mass customization, sustainability, environmental impact and localized production drives the manufacturing industry to strive for additive manufacturing because of the versatility of the technology. Injection Moulding Company (IMC) is using traditional manufacturing approaches which compromise its competitiveness resulting in decreased production rate and high operational costs due to lengthy changeover times. The aim of the study was to investigate the viability of additive manufacturing technology for the manufacture of moulds to reduce operational costs. ABC mould demand classification analysis conducted for the top 16 moulds revealed that the moulds for the switch cover ranked highest in terms of the demand of moulds that were fabricated by IMC. The value stream map revealed that there was room for improvement in terms of push to pull and frequent lot transfer, standardising work, reducing cutting time and process scrap, as well as introducing poka yokes and cellular manufacturing, and it was proposed to reduce material movements and setup times. Through the deployment of group technology and rank clustering algorithm, three mould families and three machine cells were derived. As a result, the mould fabrication process was improved by reducing material movements and reducing setup times. Analytic hierarchical process was deployed as criteria for comparison and selection of the best 3D printing technology from among the recent additive manufacturing (AM) technologies that would meet surface finish, dimensional accuracy, cost, and manufacturing lead time requirements. Four AM options included Multilevel Concurrent Printing, MELD technology, Metal Jet 3D printer, and VELO3D. The final results indicated that the VELO3D is better than other additive manufacturing technologies for rapid tooling for the manufacture of moulds. The switch cover mould was then assessed for viability of fabrication through AM. The research proposed a process for evaluation of investment in VELO3D machine. A final decision was made through the comparison of AM technology, VELO3D versus traditional manufacturing capabilities in tool production. The traditional manufacturing was found to be characterised by a huge mould cost which was absent when additive manufacturing technology is adopted. The results demonstrated that VELO3D outperformed the traditional approach from a cost perspective leading to an 80% overall cost savings from the adoption of AM.
The analytical and experimental study on the establishment of a tidal power plant in South Africa
(2021-02) Mtukushe, Namhla Faith; Ojo, Evans Eshiemogie
The majority of South Africa’s electricity is generated from fossil-fuel plants that use mainly coal. In these power plants, the combustion of these fossil fuels liberates greenhouse gasses into the atmosphere that contribute to climate change. This problem coupled with the rapid depletion of fossil fuels has necessitated the need to explore the alternative form of energy such as renewable energy. Tidal energy is a form of ocean energy that can be considered as an alternative energy resource or renewable energy source. This form of energy has not been explored in South Africa, the only country in the world that is bounded by two oceans; the Indian and the Atlantic. Tidal energy can be harnessed from the movements of tides to generate electrical power. This study considered the possibility of harnessing tidal energy as the alternative energy source for power generation which can be used to mitigate the challenges associated with the energy crisis currently being experienced in the country. For this study, an extensive literature review was carried out to understand the tidal phenomenon, the concept of energy conversion from tides, the different techniques or technologies that can be used to generated power from tides. There are two main technologies used for converting tidal energy to electrical energy and these are the tidal barrage and the tidal streams. Based on the inferences drawn from the literature reviews concerning the tides experienced around the South Africa coastal region, it was identified that the tidal stream technique is applicable. Harmonic analysis of the tidal resource for four identified sites was conducted, from these analyses, Esikhawini was selected as an optimum site. Tidal streams extract the kinetic energy of tides and the mode of operation of tidal stream plants is determined by the type of tidal turbine employed. Several turbine designs were reviewed, a helical cross-flow turbine was selected due to its self-starting capability and its ability to operate in reverse stream flows. For this helical turbine, an analytical model using the blade element momentum theory (BEMT) was developed and was implemented on MATLAB environment. For the experimentation, a prototype was developed and tested in a laboratory concrete flume in the department of Civil Engineering at the University of KwaZulu-Natal. Based on the experimental results, an analysis of the unit turbine was done which was used to propose a conceptualized tidal power plant. Hence, the proposed tidal power plant was used to justify the reason for embarking on this study which is to ascertain the possibility of establishing a tidal power plant in South Africa.
Application of DMAIC to improve energy consumption in a commercial building
(2021-03) Kanyinda, Kabuya; Lazarus, Ian Joseph
Improving energy use in a commercial building has become the subject of great importance in organizations worldwide. Improving energy usage refers to the efforts to reduce energy consumption. Reducing energy consumption in commercial buildings can be accomplished through continuous supervision using appropriate managerial techniques. Commercial companies are required to use energy more efficiently and participate in energy improvement. This study seeks to improve electrical energy consumption in commercial buildings by Analysing the electrical data consumption and identifying the factors that contribute to high consumption using Six Sigma DMAIC (Define-Measure- Analyse-Improve-Control) problem solving methodology. A case study was used to validate the DMAIC framework. Two years of electrical consumption data of a case study done from January 2018 to December 2019 was collected and analysed. The study revealed an average increment in energy consumption of 3.9 %. The outcomes using statistical Pareto chart showed that the boiler is the highest significant energy user in the building with 38.3% due; followed by the kitchen with 24.2 %, followed by DB A and lifts with 20,1 % and the rest with 17.37 %. After the campaign of DMAIC, there was a reduction of 6 % in boiler consumption which was 2.3 % reduction of total consumption of the month for the building. Therefore, the study successfully demonstrates how Six Sigma DMAIC methodology can be applied to improve electrical consumption in a commercial building and reduce its related costs.
Application of kaolin-based synthesized zeolite membrane systems in water desalination
(2021-12-01) Aliyu, Usman Mohammed; Isa, Yusuf Makarfi; Rathilal, Sudesh
Accessibility to potable water worldwide is threatene, despite 71% of the earth’s surface being covered with water. However, 97% of the 71% is too saline for consumption. A usual way of treating salinity is by membrane desalination using reverse osmosis. The disadvantage of this approach is its high cost and short life span of the polymeric membrane used. Creating a new robust high-quality water treatment system using a ceramic membrane will address these challenges due to its robust mechanical properties. In this work, we synthesized different zeolites from South African kaolin under varying conditions such as crystallization time, ageing time and temperature and their effects on the properties of zeolites synthesized was investigated. Sample characterization confirmed the successful synthesis of ZSM-5 and zeolite A. In the synthesis procedure, metakaolin served as the alternative source of silica and alumina and was use to synthesize different types of zeolites under varying synthesis conditions. Synthesized samples were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectroscopy and Brunauer–Emmett–Teller BET surface area. The properties of the synthesized ZSM-5 were influence by the synthesis parameters, typically, crystallization temperature, ageing time and crystallization time. Crystalline ZSM-5 zeolite produced at an ageing time of 24 hours, crystallization time of 48 hours and crystallization temperature of 180°C with Si/Al ratio of 43 and BET surface area of 282 m2 /g. After a 12-hour ageing period, Zeolite A produced at crystallization time of 20 hours, the crystallization temperature of 100°C, Si/Al ratio of 1.3 and BET surface area of 143.88 m2 /g. The findings indicate that aging influences the synthesis of zeolite A, as a relatively crystalline material formed at an ageing time of 12 hours, which continued to decrease as the ageing time was increased. We do not exclude the possibility of Ostwald ripening playing a role in this relationship. Subsequently, the efficiency of zeolite A and ZSM-5 zeolite in removing salt ions, Ca2+, K+ , Mg2+ , and Na+ from synthetic seawater was investigated at room temperature using a batch adsorption system. The effect of adsorbent dosage, agitation speed and contact time were consider. Dosages varied from 2.5 to 6.0 g/100 ml while the contact time varied from 30 to 180 minutes. The results obtained showed that a zeolite dosage of 6.0g/100 ml and agitation speed of 140 revolutions per minute (rpm) yielded a maximum removal efficiency of 89.7 % for Ca2+ and minimum removal efficiency of 1.8 % for Mg2+ at agitation rates of 30 and 120 minutes, respectively. Ion exchange of Na+ by Ca2+, K+ and Mg2+ in the zeolite framework was established. The preference of the overall ion-exchange selectivity of both zeolites A and ZSM-5 are in the order of Ca2+ > K+ > Na+ > Mg2+. Zeolite A showed higher removal efficiency compared to ZSM-5 zeolite. The results point out that the synthesized zeolite was able to desalinate the salt ions in synthetic seawater to a limit below the World Health Organization (WHO) recommended values. Consequently, zeolite synthesized from kaolin offers a cost-effective technology for the desalination of seawater. The desalination and material characterization results used in selecting a potential zeolite for use in reverse osmosis (RO). The material successfully deposited on etched alpha-alumina support to produce zeolite membrane by a hydrothermal technique using a modified in-situ method. Zeolite A and ZSM-5 membranes produced and applied in the RO unit for desalination. The RO membrane experimental results show potential in desalination of synthetic seawater. A machine-learning tool was use to predict the properties of the synthesized ZSM-5 as a function of the hydrothermal parameters. Finally, a techno-economic analysis of synthesizing zeolite using locally available kaolin at a capacity of 5 x 105 kg/yr. has shown that the plant is economically viable with rapid break-even and the payback period is less than 4 years.
The application of lean principles to mitigate greenhouse gas emissions in an automotive industry
(2020-09) Ramsunder, Keshav; Olanrewaju, Oludolapo Akanni
A common factor for industrial production is energy, and the level of energy consumed is typically used to measure the growth and economic development of countries. However, as the industrial sector expands and makes efforts to gain competitive advantage, there is a growing concern regarding energy consumption and the ecological burden related to energy use. Thus far, industry has relied on the Lean manufacturing paradigm to gain the contemporary benefits of profitability, flexibility, and increased efficiency. More recently, the association of Lean manufacturing and environmental impacts has grown in both the industrial and academic fields. The main aim of this research is to investigate the correlation between lean tools and their effect on Green House Gas emissions, ultimately measuring environmental performance. The research is quantitatively based and entails the study of a weld process production line at Toyota South Africa Motors. The environmental impacts of the production process were observed and measured before and after the implementation of three lean tools: Value Stream Mapping (VSM), Total Productive Maintenance (TPM) and Standardized Work. Comparing the outcomes, the study found significant differences in the pre-test and post-test of each lean technique applied. VSM allows one to visualize and magnify the environmental performance of the process, which allows for simple quantifying of environmental metrics. TPM brings to light that equipment that is regularly maintained to operate at optimum condition reduces non-value adding energy usage. However, in contrast, Standardized Work has shown minimal benefits within the context of this research. The findings of this research are beneficial as they contribute to gaining a better understanding of the way lean tools affect environmental performance. While the study contributes to the current body of knowledge, it can also enlighten Small to Medium Enterprises, practitioners and larger organizations to rethink current strategy and allow for simultaneous implementation of Lean Green operations.
An application of lean six sigma techniques to accelerate the implementation of Kaizen in the film packaging industry
(2021-01) Moso, Matshidiso; Olanrewaju, Oludolapo Akanni; Dewa, Mendon
The integration of lean six sigma techniques in manufacturing results in substantial improvement and hence a more profitable organization. The case study company is based in South Africa and specialises in manufacturing plastic film, which uses thin micron plastic for food packaging. The main goal of this research was to accelerate the rate of kaizen implementation by utilizing lean six sigma techniques in order to construct a semi-automated model. Lean six sigma is comprised of various problem-solving techniques. In this case study, 5Whys was combined with Ishikawa to construct a semi- automated model for an effective defect trouble shooting closure system. Defect trouble shooting system is also called a “non-conformance closure system”. It was evaluated that the procedure of non-conformance closure at the company was inadequate; this was identified as a major finding during an external ISO audit. An opportunity to utilize lean techniques was identified and implemented in order to satisfy the objectives of this research. The first objective was to define the requirements of ISO standards in order to find a suitable system that could be used. Defining the requirements was key for the researcher to get an idea of how the model should be constructed to suit ISO standard requirements. The second objective was to evaluate the current method and find the root cause of the problem; this objective highlighted all the possible causes that had resulted in an inadequate procedure for non-conformance closure. The third objective was to construct a model by integrating lean techniques that matched ISO standards. This objective was implemented in order to satisfy the research goals; a semi-automated model resulted in a catalyst for continual improvement. The fourth objective was to implement the semi-automated model on each non-conformance that was raised and the fifth objective was to reflect by monitoring and recording the results from the semi-automated model. This method resulted in a smooth flow system of non- conformance closure; the major finding closure was accepted after the auditors monitored the new semi-automated method. Automated non-conformance software, which integrates any system that needs corrective action, was recommended, and seven types of waste were recommended for further analysis. This semi-automated model can be used as a future programme parameter for completing an automated system to resolve non-conformances.
Application of optimal control for power systems considering renewable energy technologies
(2021-03) Chetty, Dhanpal; Sharma, Gulshan; Davidson, Innocent Ewaen
Over the last decade, power generation from renewable energy sources such as wind, hydro and solar energies have substantially increased globally and in South Africa. Of all the renewable energy sources, wind energy appears to be the most promising, considering design and costs. However, due to the intermittent nature of wind, the increased integration of wind energy into existing power systems raises several control challenges related to load frequency control (LFC) and tie-line power system stability. The stability of modern power systems, incorporating wind energy generations, will be significantly enhanced with the development of LFC strategies based on modern control theory, which is the focus of this research. This thesis presents the design, modelling and analysis, of two LFC control strategies for interconnected power systems, having wind power integrations. The first design is an optimal control strategy, based on error minimization through full state vector feedback, for a two-area interconnected power system consisting of hydro-thermal generations. The second design is a model predictive control (MPC) strategy, based output vector feedback of system state parameters, for a two-area interconnected power system consisting of thermal generations in each area. Both designs include the active power support from doubly fed induction generator based wind turbines (DFIG) in conjunction with the combined effort of a thyristor control phase shifter (TCPS) and super conducting magnetic energy storage unit (SMES). Both control strategies were simulated in MATLAB Simulink and positive results were obtained. The results show that the optimal control strategy is enhanced with power integrations using DFIG based wind turbines combined with the TCPS-SMES units and the MPC strategy is very robust and provides better dynamic performances even with parameter variations and generation rate restrictions.
Application of synthesized magnetic nanoparticles for biogas production using anaerobic digestion
(2023) Amo-Duodu, Gloria; Rathilal, Sudesh; Chollom, Martha Noro
South Africa is encountering severe challenges in the areas of energy, water, and wastewater management in recent times. This study addresses both water and energy aspects. It aims at using synthesised magnetic nanoparticles (MNPs) on anaerobic digestion (AD) for biogas production from various wastewater sources in South Africa. The study experimented the feasibility of five different synthesized magnetic nanoparticles, magnetite (Fe3O4), copper ferrite (CuFe2O4), nickel ferrite (NiFe2O4), magnesium ferrite (MgFe2O4) and aluminium ferrite (AlFe2O4) on two different wastewater samples (industrial and municipal wastewater) from three sampling sources, Umbilo water works, Umgeni water and a sugar refinery industry. Five research objectives were accessed. The first objective was the synthesis and characterisation of MNPs using scanning electron microscopy/energy dispersive x-ray (SEM/EDX), Brunauer-Emmett-Teller (BET), Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD) analysis. The results showed a surface morphology of facecentred and monoclinic crystal structures with a size less than 20 nm. The nanostructures of ferrimagnetite and magnetite were obtained, and it had an O-H stretching and Fe-O vibration functional groups. The surface area obtained was found to be high for magnetite (Fe3O4) which was 27.597 m2 /g. The second objective was to evaluate the AD performance in terms of water quality and biogas production. This was carried out in two stages. The first was to evaluate the five MNPs with sugar refining wastewater. The second stage was to evaluate the performance of three best performing MNPs on two wastewater samples from Umbilo wastewater. The results for the first stage showed good degradation of organic matter for the bioreactors with MNPs which resulted in a higher yield of biogas and methane as compared to the control as well as good removal of contaminant (chemical oxygen demand (COD), colour and turbidity). Among the five MNPs used, Fe3O4, NiFe2O4 and CuFe2O4 had a contaminant removal efficiency of 60- 70% and a cumulative biogas yield of more than 140 ml/day with more than 85% methane composition, hence these three MNPs were found to be the best performed MNPs. The results obtained from the second stage for the three best performed MNPs indicated a high pollutant removal efficiency of more than 70% for Fe3O4, as well as a biogas yield of more than 1100 ml/day and a methane composition of approximately 98%. The third objective was the evaluation and optimisation of the anaerobic magnetised system for biogas production while the fourth objective involved a comparative study between the performances of magnetised biochemical methane potential (BMP) to non-magnetised biochemical methane potential. From the optimisation study, the predicted results obtained from the BBD-RSM showed an average contaminant removal of 70% and a biogas yield of 522 ml/day at an optimum MNP load of 0.5 g, retention time of 45 days, inoculum load of 500 ml, and a temperature of 35℃ with a desirability of 96% as the optimum conditions. With less than 2% deviation, the confirmatory test demonstrated equal performance at the optimum conditions. Findings from the fourth objective indicated that the BMP system with MF exposure exhibited a contaminant removal rate of over 80% and a biogas generation of 1715 ml/day with a 99.94% methane composition. Overall, the system that included both MF and MNP performed better than the other in terms of biogas yield and colour removal. The final objective was the kinetic study of the anaerobic magnetised system using modified Gompertz and first-order kinetic models. The results obtained from the kinetics showed that the modified Gompertz model described the kinetics and dynamics of the anaerobic magnetised system better than the firstorder kinetic model with a correlation co-efficient (R2 ) over 0.9999 and an error less than 0.0002. Therefore, the possibility of using MNPs, particularly magnetite (Fe3O4), in an AD system for biogas production from wastewater was found to be extremely feasible and without negative environmental consequences. Incorporating both MF and MNP in AD was also beneficial for wastewater treatment because it eliminated the need for post-treatment.
Appraisal and optimization of energy-efficient green buildings in South Africa
(2024-05) Agbajor, Favour David; Mewomo, Modupe Cecilia
Generally, over 35% of global energy use and 40% of carbon emissions are attributed to the built environment while future forecasts indicate that these values may rise much further. In South Africa (SA), building stocks account for 40% of the country’s final energy demand which strains the country's coal-dependent energy grid and oftentimes results in power outages. Optimizing energy efficiency and thermal comfort while attaining the lofty goal of carbon neutrality is essential for all concerned stakeholders in the building sector globally. Meanwhile, green building (GB), being a recognized revolutionary theory and practice in the building industry, is suggested as a solution to SA’s environmental challenges. On this wise, this research aimed to develop energy-efficient models for optimizing green buildings into the design and operation of buildings to allay their environmental impacts. The goal was to enhance energy efficiency, decrease energy consumption, and mitigate carbon emissions across diverse climates, thus benefiting South Africa's built environment. To achieve the study's goals, three primary research objectives were identified and pursued namely: (i) To provide an overview on status-quo of green building development in South Africa with a view to explore the status quo and provide roadmap for improvement; (ii)To examine the energy-saving potential of incorporating building-integrated greenery systems towards climate-resilience in the subtropical climate zone of South Africa; and (iii) To investigate the energy-performance of green building renewable energy utilization systems within South Africa’s hot and arid climate zones. Initially, the study's first objective entailed a comprehensive literature overview integrating climate, sustainability, and building energy modeling within the South African context. This was carried out through a scoping review approach via the PRISMA guideline of reporting Subsequent objectives involved selecting reference buildings and creating hypothesized models as case studies based on six climate zones from the South African National Standard. For the second objective, a thorough and integrative approach that linked building energy modelling and varying climatic change was devised. The numerical parametric simulation and analysis, being a quantitative research approach was adopted as a data collection method. Similarly, the third objective employed numerical parametric simulation as a data gathering method in this research, which is based on a quantitative analysis to explore various design options iteratively. In the second and third objectives, Global climate databases, Meteonorm, Climate Consultant, and energy simulation software such as DesignBuilder, EnergyPlus, and Polysun were used for weather data analysis, climate modeling, and building energy simulation. The findings highlighted that while South Africa boasts notable green construction projects, scientific research progress has not matched international levels. The focus was on promoting green building adoption through standards, certifications, and incentives. However, gaps were observed in optimized energy performance and post-occupancy evaluation of existing buildings. Despite high awareness, the utilization of green building technologies among South African professionals did not meet anticipated levels. For the second objective, the study's findings indicated an increase in extreme heat waves with higher peak temperatures in the future. Building energy use in the study area is projected to rise by 8-24% from 2030 to 2080. Notably, heat gains primarily result from envelope thermal transfer rather than solar radiation. Greenery systems were found to effectively support green building goals and urban sustainability across anticipated seasons. Nature-based solutions proved successful in adapting to climate change compared to non-retrofitted conventional buildings. For the last objective, the study revealed regions with substantial solar irradiance, indicating potential for renewable energy adoption. It emphasized the need for durable BIPV systems in hightemperature conditions. BIPV modules generated more energy in Upington than Nelspruit due to varying solar radiation. Opportunities were identified for BIPV systems to achieve optimal power generation. The study provides a foundation for informed decision-making, policy formulation, and targeted research in sustainable building practices. The study presents practical principles to guide urban planners and policymakers in integrating eco-friendly technology into both new and existing building designs. This promotes sustainable urban development and reduces cities' carbon emissions. Going forward, to showcase the effectiveness of these energy-efficient and climate-responsive systems to the public and industry stakeholders, it is recommended to establish and enhance largescale demonstration projects in South Africa's subtropical, hot and arid regions.