Faculty of Engineering and Built Environment
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Item Energy assessment and scheduling for energy optimisation of a hot dip galvanising process(2021-12-01) Dewa, Mendon; Nleya, Bakhe; Dzwairo, BloodlessThe dearth of energy sustainability is posing major challenges both locally and glob- ally. Galvanising furnaces are categorised as dominant consumers of electricity in the overall galvanising industry. Relatively little research has been carried out concerning energy optimisation through sequencing or scheduling algorithms by way of enhancing the performance of galvanising lines. In this regard, the research centres on evaluating overall energy performance in this industry. The research sought to introduce an opti- mal energy optimisation-scheduling algorithm for a hot dip galvanising process. A DMAIC based methodology was presented for the provisioning of a structured prob- lem-solving process for improving energy efficiency in a galvanising process. Its framework embraces an energy sustainability assessment of four batch hot-dip galva- nising plants. Four energy minimisation opportunities were identified and quantifiable energy and cost savings, as well as avoided carbon dioxide emissions were derived from the analysis of one of the plants. Production or zinc used was identified as the main driver for electricity consumption for Plant 1, while the number of dips per month, amount of zinc used, and ambient temperature conditions were identified as the rele- vant variables for developing a regression model for Plant 2. The amount of zinc used and ambient temperature conditions were found to be the relevant variables for Plant 3. The derived regression model for Plant 4 was based on the amount of zinc used and ambient temperature conditions. The energy performance indicators for a galvanising plant were established through a comparison of actual and expected consumption, energy intensity index, cumulative sum, and specific energy consumption. A bi-objective GECOS algorithm was further introduced to reduce the total energy consumption as well as makespan. The simula- tion results revealed that the GECOS algorithm outperforms McNaughton’s algorithm, Shortest Processing Time Algorithm, and Integer Linear Programming algorithms on minimising makespan on parallel processing machines. The key contributions to the body of knowledge from the study include a unique eval- uation of electrical energy consumption by a hot-dip galvanising plant, development of an energy consumption baseline and performance indices, and the developed novel bi-objective GECOS algorithm that considers reducing total energy consumption by the process tanks as well as makespan. Future research work may focus on hybrid genetic algorithm-artificial immune system scheduling tools that would derive synergy from the advantages of both algorithms to improve energy performance.Item Analysing South Africa’s automotive energy consumption : application of index decomposition analysis(2021-01) Machivha, Rofhiwa Tevin; Olanrewaju, Oludolapo AkanniThis 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.Item A design methodology for the supply of subterranean water through the use of wind energy(2005) Marais, Brett RichardThe Reconstruction and Development Programme adopted by the Government of National Unity is more than a list of the services required to improve the quality of life of the majority of South Africans. It is not just a call for South Africans to unite to build a country free of poverty and misery; it is a programme designed to achieve this objective in an integrated and principled manner. Based on the strategic objectives, as highlighted in the White Paper on Water Supply and Sanitation Policy, with regard to alleviating the chronic potable water shortages in South Africa, this thesis investigates a design methodology to supply potable water through the use of wind energy. The design focuses on small rural off-grid developments where grid electricity either has not or will not reach, and where renewable energy is the only viable option. This thesis provides an overview of wind energy and presents the fundamentals of wind power calculations. It also formulates an overview of the historic and present situation with regards to potable water supply, and reflects on the need for urgent intervention. The feasibility of using wind energy to supply potable water to rural communities in South Africa is explored in a case study. The various problem areas are identified and examined and a wide range of possible solutions are recommended. A final flow chart for the system design is proposed, thus ensuring comprehensive design methodology from which future design of similar systems can be based.