Theses and dissertations (Engineering and Built Environment)

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Fabrication and analysis of nanoparticle-infused natural fibre honeycomb core in sandwich structures
(2024-05) Govender, Sumeshan; Kanny, Krishnan
his study investigates the feasibility of employing natural fibre materials to fabricate honeycomb core structures, addressing concerns over the environmental impact associated with conventional cores composed of aluminium, Nomex, and petroleum-based materials. The research process involves the fabrication of honeycomb cores utilizing a 3D printed moulding technique, followed by the adhesion of these cores to flax and glass fibre facings, thereby augmenting structural durability. Through the incorporation of cellulose and nanoclay as additives to the adhesive, the investigation reveals a substantial enhancement in flexural strength and impact resistance, surpassing the performance of structures bonded solely with epoxy. However, a notable reduction in compressive strength is observed upon the introduction of these additives to the adhesive. Quantitatively, the study demonstrates that the addition of 3wt% cellulose to the epoxy adhesive results in a remarkable 7.43% increment in flexural strength, a 4.09% increase in yield stress, a 0.17% rise in flexural modulus, a 6.45% enhancement in core shear ultimate strength, a 7.17% increase in facing bending stress, and a 7.94% elevation in absorbed energy. Similarly, the addition of 3wt% nanoclay to the epoxy leads to a significant enhancement, with a 10.48% rise in flexural strength, a 4.09% increase in yield stress, a substantial 20.92% augmentation in flexural modulus, a 10.75% improvement in core shear ultimate strength, a 10.5% increase in facing bending stress, and an elevated absorbed energy by 14.37%. Furthermore, in out-ofplane oriented structures, ultimate compressive strength experiences an increase of 7.32% and 20.1% for cellulose and nanoclay additives, respectively, while compression modulus rises by 6.6% and 29.65%. Nevertheless, it is noteworthy that the structures bonded with nanoclayfilled epoxy exhibit the most favourable overall performance, boasting an ultimate compressive strength of 7.72 MPa and a compression modulus of 7.77 MPa, outperforming their in-plane counterparts due to the larger compressive area of the out-of-plane samples. In terms of tensile properties, the study establishes that hybrid face sheets display an impressive 33.65% higher ultimate tensile strength compared to plain flax fibre samples. Additionally, the hybrid face sheets manifest a 69.45% increase in tensile strength and a substantial 58.73% enhancement in yield stress and Young's modulus, respectively, in contrast to exclusively flax fibre facings. Moreover, the research indicates that hybrid face sheets lead to significantly reduced moisture absorption, with structures employing solely flax fibre face sheets experiencing a mass increase of 11.88% after 168 hours of exposure, while structures utilizing hybrid face sheets encounter a substantially lower mass increase of 6.31%. This corroborates the effectiveness of hybrid face sheets in enhancing the water resistance properties of the composite. In summation, the study underscores the potential of natural fibre honeycomb composite structures to perform comparably to traditional honeycomb materials such as Nomex and aluminium, while being constructed from environmentally sustainable materials. The integration of an efficient additive manufacturing process further bolsters the prospects of these structures, enabling customization and scalability for diverse applications across industries, including aerospace, automotive, and marine sectors.
Development of integrated model and framework for sustainable energy resources and systems planning
(2024-05) Akpan, Joseph Samuel; Oludolapo, Olanrewaju Akanni
Sustainable energy development (SED) is a crucial component of the Sustainable Development Goals (SDG), aiming to maintain economic and social progress while protecting the environment and mitigating climate change's effects. SED serves as a transition paradigm for sustainable development, providing a blueprint for energy peace and prosperity for people and all uses. The first objective of this dissertation is to identify 10 interlinked themes of SED and explore 2 of them, which are the least studied in existing SED reviews. These two themes include energy financing and commitment to climate change and the need for 100% renewable energy (RE), a part of the decarbonization strategy towards the 1.5 - 2.0 °C Scenario. The study suggests that the current G20 countries' contributions, if done continuously per annum, in addition to 80% more funding from private investment of the same amount in the 1.5°C scenario financial requirement for clean energy, is sufficient to limit global warming. In addition to the present drive for 100% RE for all purposes, an emphasis is placed on addressing other issues, such as energy storage options, developing countries' development agenda, and regional security stability to prevent energy wars. Emerging SED decarbonization strategies are presented across power, transport, building, and industrial sectors. This part concludes with a summary of SED progress and directions for future research, mainly the need for re-defining Nationally Determined Contribution (NDC) through a centralized global or regional stock-taking strategy for greenhouse gas emissions reduction. Consequently, the next study attempts to address the limitations of the current NDC by formulating a policy hypothesis and applying it to an integrated assessment tool (here, termed the environmental model) for strategic stock-taking in reducing GHG emissions. In developing this indexing model, being the first objective of this thesis, we analysed the potential impact of Nationally Determined Contributions (NDCs) under the Paris Agreement on global temperature rise used as the key model input parameters with countries' historical data and other parameters such as GDP, population growth. With the use of an integrated assessment tool based on the concept of system dynamics, the analysis constructs a framework to project global temperature changes under five policy scenarios, namely baseline, current (announced energy policies 1 and 2), and optimum (2.0 0 C Scenario), and most optimum (1.5 0 C) case scenarios. The hypothesis is formulated based on the analysis of current, announced, and best-case global and or applicable national policy scenarios. The model aims to address critical questions regarding the effectiveness of the on-going NDCs commitments in limiting global temperature rise to well below 2 0 C, in alignment with the Paris Agreement's goals. The simulation results offer a roadmap for optimizing the current NDCs in global and national energy policies and treaties, fostering international collaboration, and reinforcing the global commitment to combating climate change. Leveraging on the preceding simulation result of the environmental model, a novel emissions budgeting (EB) model tool (here, termed the economic model) was introduced as a simplified approach for the determination of the economic attractiveness of the policy scenarios of the environmental model. Hence, the second objective, which was to determine the economic benefit of policy scenarios, was achieved. Some advanced countries’ rapid population, economic growth, and energy consumption from mostly 100% electricity that is majorly fossil-based contributes significantly to global CO 2 emissions. In contrast, the case in most developing countries is different. For instance, electricity access in Africa is less than 60%. Hence, this presents challenges and opportunities for achieving the United Nations’ Sustainable Development Goals (SDGs) 7 and 13 of generating all energy from cleaner or low-carbon sources to reduce CO 2 emissions in all countries and combating climate change consequences. Therefore, considering the peculiar situation of other developmental goals, such as increasing population access to electricity while being obliged with the need to transit to complete renewable energy, as our third objective, we explored the idea and transition paradigm of reaching a 100% renewable energy that is void of unjust energy transitioning, climate injustice, and unbiased drive for increasing renewables energy penetration in the global energy mix. The increasing need for renewable energies has been widely acknowledged to greatly advance the climate change agenda as increasing clean energy usage depletes the accumulation of GHG in the atmosphere. Alongside reducing the accumulation of GHG, increasing RE share in the national mix has constantly become the core of many countries' energy policies and the agenda of many of the NDCs reported by countries. Presently, about 30 countries already with over 70% of their national electricity mix from RE. A part of this has birthed a new paradigm and an emerging field of 100% RE for all purposes, recently receiving much attention from academia and in public discourse. Upon establishing the need for analysing the transition towards 100% RE, the thesis demonstrated this conceptual idea through a model (here, termed the energy model) to analyse the possibilities for a 100% renewable energy system at the global level. Because several studies have already done such analysis, however, this has hardly been directly linked to the climate scenarios. Therefore, this thesis bridged this gap in the literature by synthesising the energy transition at different percentage shares in the global primary energy mix over time with the effect on global temperature levels. The rationale behind this was to present a discussion on the pathway possibilities and challenges of achieving 100% RE and whether it is possible to meet the total global energy demand through RE, with what effect on the climate scenarios. To do this analysis, we further define our hypothesis using baseline, optimum, more optimum, and extreme optimum path scenarios to ascertain such possibilities. Finally, we used an integrated assessment model based on the principles of system dynamics to analyse these hypotheses and to find the implications of each action or scenario on other factors such as global temperature, GHG emissions, energy storage breakthrough while keeping the population growth at maximum possible value of 12.4 billion persons by 2100 with GDP growth rate not less than 1.5%. The findings are valuable in helping us discuss if 100% RE can be a reality and what the implications are. Our results show that in the baseline current scenarios, the global average temperature will most likely be kept at 3.3 0 C. Hence, the world would need very urgent and unprecedented efforts beyond the current baseline of business as usual. Interestingly, our findings also indicate that to stay within the 1.5 and 2.0 0 C Scenarios, the world may need just between (58.6 - 77.3) % and (62.7 - 82.8) %, respectively, in the global energy mix. For the most optimistic scenario, (75.5 - 99.8) % RE may be required, and this is able to keep the temperature rise even well below 1.5 0 C but at 1.1 0 C. The 1.1 0 C possibility is quite highly ambitious, in my opinion, because it requires the intensity of global mix energy generation of about 6627 extra joules from renewables only. The major challenge with the idea of 100% RE for all purposes is that achieving such a feat requires a more diverse approach and scarcely are there 100% RE studies that incorporate holistically the interrelation of several pertinent strategies. Therefore, there exists a need to meet both the technical and non-technical requirements. In order to address this shortcoming, our third objective introduces six methodological or evaluation mechanisms (herein, identified as 100% RE evaluation metrics) suitable for existing and future 100% renewable energy analysis. It then reviews energy modelling tools to identify their applicability to 100% RE analysis. The perspectives presented in this thesis are valuable in developing a common integrated methodology and modelling tool for analysing full renewable energy adoption in countries or regions with best trade-offs, using performance indices that have not been previously used. The proposed metrics could also help with proper national and regional energy resources and system planning for new energy projects and installations, contributing to sustainable development. The framework and narrative, presented in the form of a model within this dissertation, make a noteworthy contribution to the ongoing discourse surrounding the energy transition as, to the best of my knowledge, this concept has not been presented this way. The results from this dissertation can be further investigated through a streamlined application of the approach at individual country or regional level to facilitate inclusive and climate-responsive planning and execution strategies for sustainable energy and electricity generation, distribution, and utilization at both national and urban levels. The implications of the findings have the potential to inform the United Nations Framework on Climate Change Convention (UNFCCC) and Conference of Parties (COP) policies in better ways of promoting equitable support for countries, regions, energy consumers, utilities, and prosumers.
Shifting territories : towards a methodology for a creative emancipatory approach to place-making, the role of Spaza shops in Cornubia, Blackburn, KZN
(2024-05) Jahangeer, Mohammud Anwar Noorani; Erwin, Kira
This research argues that the idea of a ‘breaking new ground’ initiative in urban planning demands the effort of unearthing existing alternative practices and attitudes in the pursuit of spatial justice (Soja 2010). The study is located in Cornubia, a large human settlement development on the north coast of KwaZulu-Natal, Durban, South Africa. Contextualised within the national landscape of state-housing provision, and the theoretical lens of place-making and spatial justice, it aims to offer both theoretical and practical insights into the gap between theory and practice in current participatory practices in planning and housing. It explores how creative methodologies may be useful mechanisms for participatory planning, especially in facilitating and translating how residents in housing developments make meaning out of the places they live in. It engages how these may differ, or not, from meaning-making done by state planners and officials. To demonstrate the argument, the thesis uses the example of spaza shops both as a metaphor and a popular initiative. Following on, it suggests that spaza (as creative impulses) owners could take the form of interlocutors who can facilitate dialogue between official top-down planning and quotidian bottom-up operations within the context of the Cornubia development. In doing so, the potential for dialogue in a creative form that already exists ‘informally’ as the popular innovations/manifestations exemplified in the spaza shop, can be revealed. It is in the interstitial space of misunderstanding, where communication often breaks down between the state and the street, that this research has positioned art/creative practice as a way of opening up dialogue within and between individuals, communities, and the state. In addition, arts-based/informed methods, including the use of drawing, Lego blocks, image theatre (drama), and Scrabble are employed as data-generating tools. Furthermore, workshops, focus groups, and face-to-face interviews are conducted to reflect, articulate and reveal the experience of the participants living in a human settlement and their understanding of space and urban planning. The thesis also draws on a series of interviews with the built environment specialists involved both directly and administratively in the project. The objective is to explore the potential for the conceptualisation of powerful catalysts for transformative forms of politics and for providing new sets of resources for urban and spatial thinking Theoretically, the dissertation argues that spazas should be read as popular culture since popular culture is both evasive and resistant (Fiske 1989) and is created “out of the resources, both discursive and material that are provided by the social system that disempowers [the people]” (Fiske 1989:2). Spazas are creative impulses in their own right, developed organically, as critical responses to an environment which has limited access and spaces for the working-class and poor to exercise their various freedoms whether they be economic, spatial, social or cultural.
Design and application of passive filters for improved power quality in standalone PV system
(2024-05) Dlamini, Sandile; Adebiyi, Abayomi Aduragba; Kabeya, Musasa
Harmonic components have developed in power systems due to the non-linear properties of the circuit components utilized in power electronics-based products and their rapid application. Power systems rely on fundamental quantities like sinusoidally varying voltage and current, which oscillate at a frequency of 50 Hz. The standard restrictions of IEEE-519-1992 were utilized as a benchmark in this study. To generate the best output, the total harmonic distortion (THD) should be decreased below the limit, even for certain individual harmonic numbers, and reflect the power factor output. Using the results of the simulation and projections for each mitigation strategy, the THDI can be reduced below the IEEE-519 standard whilst also providing cost and electrical advantages. Analysed and modelled is the PV system, which comprises solar panels, a DC-DC converter, a DC-AC inverter, and a non-linear load. Passive filters are an effective solution for improving power quality in standalone photovoltaic (PV) systems. This dissertation provides an overview of the design and application of passive filters for this purpose. Firstly, an introduction to PV systems and the power quality issues associated with them was preferred. Next, different types of passive filters, namely LC filters, LCL filters and LLCL filters, are discussed along with their advantages and disadvantages, and the design considerations for these filters, including the selection of filter components and the calculation of filter parameters. The application of passive filters in standalone PV systems was then discussed, including their implementation in DC-DC converters and Z-Source inverters and, the design of PWM controllers such as the constant boost control method and simple boost control method. The analysis of the outcome of the engineered systems was conducted according to the IEEE standard and SANS 10142 Standard to protect the connected equipment within the off-grid network. The outcomes pertain to the single-phase stand-alone/off-grid photovoltaic system and the single-phase Z-Source inverter. The Z-Source inverter is equipped with two distinct methods for PWM control, namely the constant boost control method and the simple boost control method. All three designs incorporate three passive filters, namely the LC filter, the LCL filter and the LLCL filter. The results were obtained from the network consisting of three distinct designs. LLCL demonstrates superior performance as a passive filter, substantiating its position as the optimal choice. The optimal outcomes of a single-phase off-photovoltaic (PV) network can be achieved using LC, LCL and LLCL filters, with corresponding percentages of 2.99%, 2.45% and 1.71% respectively. Unfiltered was 89.05%, which is not good for the equipment connected to the network. The Z-Source showcases the capability of voltage amplification to an infinite level, rendering it highly effective in minimizing total harmonic distortion. This research investigation further demonstrated the efficacy of the Z-Source Inverter with Constant Control Boost Method and Simple Boost Control Method, achieving unfiltered total harmonic distortion levels of 38.85% and 44.96% respectively. The Z-Source inverter, when combined with the Constant Boost Control method and Simple Boost Control method, exhibits various filter configurations such as LC, LCL, and LLCL filters. In the context of the constant boost control and simple boost control methods, it is imperative to assess the total harmonic distortion percentage of voltage and current for LC, LCL, and LLCL configurations. The constant boost control voltage (LC, LCL, LLCL) and current total harmonic distortion (LC, LCL, LLCL) are measured at 4.177%, 2.655%, 1.951%, and 2.958%, 2.09%,1.465% correspondingly. The voltage-based boost control methods, namely LC, LCL and LLCL, exhibit total harmonic distortion levels of 2.345%, 1.920% and 0.211%, respectively. Similarly, the current-based boost control methods, LC, LCL and LLCL, demonstrate total harmonic distortion levels of 2.346%, 1.921%, 0.211%, and 2.346%, 1.921%, 0.211%, respectively. Finally, the dissertation wrapped up by exploring the potential of passive filters for enhancing power quality in standalone PV systems. The thesis offers a comprehensive investigation of the design and implementation of passive filters in standalone PV systems, providing valuable insights for engineers and researchers in the field. It enhances understanding and utilization of these imperative devices.
Optimization of water distribution networks : a digital approach
(2024-05) Mongwe, Regionald; Telukdarie, Arnesh; Rathilal, Sudesh
Water stands as the fundamental cornerstone of life, and with the human population growing exponentially, the critical importance of sustainable water management becomes increasingly evident. Water not only serves as the essential working fluid for major chemical processes, including thermal energy generation, but it is also integral to manufacturing and domestic use. Despite its significance, water is a scarce commodity, and the planet continues to lose this precious resource due to theft, pipe bursts, and leakages in water distribution networks (WDNs). The consequences of water loss extend beyond the impact on physical resources, as it is intricately linked to financial challenges. Thus, water loss has the potential to result in substantial financial setbacks for companies, organizations, and government entities, underscoring the interdependence of water management and fiscal sustainability. In response to these challenges, digital technologies have been harnessed to optimize WDNs. A major constraint lies in deciphering the applicable digital technologies due to the multidisciplinary nature of the research area encompassing WDNs and digital technologies; therefore, this study adopts a systematic literature review (SLR) combined with digital tools, to comprehensively extract all aspects of a WDN, ranging from sensors to enterprise resource planning (ERP), including equipment and systems. This literature forms the foundational basis for constructing a framework aimed at creating a content repository for digital WDN sustainability. To further develop the framework, this study reviews international best practices in digital WDN. This is adopted in developing a digital WDN framework based on the literature and classifying a database structure from sensor to ERP for a generic WDN. Furthermore, the study explores tools and systems for optimization as well as updating the theoretical structure with Johannesburg WDN data and provides a comprehensive evaluation for enabling digital WDN in South Africa. The digital WDN framework comprises three distinct components: security, a central management database (CMDB), and best practice architecture. The architecture involves five layers, including the physical layer, communication layer, data storage and analysis layer, benefit layer, and application layer. Utilizing systematic literature review and bibliometric keyword analysis, the study determines the equipment, systems, and their uses, leading to the development of a generic WDN. Validation of the framework using the generic WDN emphasizes the equipment and systems used in each of the five layers. Furthermore, the framework is validated using Johannesburg Water's WDN, leading to the development of a CMDB. The CMDB underscores the possibility of storing physical layer and communication layer configuration items (CIs) and highlights asset management, CI relations, change management, and historian capabilities. Maintaining an accurate and updated CMDB necessitates employing asset discovery solutions, while CMDB relationship mapping plays a crucial role in assessing the ripple effects of CI changes within a complex system. Finally, the measurement of the digital maturity of Johannesburg Water's WDN using the Administração e Gestão de Sistemas de Salubridade (AGS) maturity index reveals a maturity index of 62%. The index emphasizes strong capabilities in GIS integration and data collection through the SCADA system. Despite advancements in planning systems, such as domestic flow metering, there remains an opportunity to enhance asset management capabilities for continuous improvement in WDN operations.
Sustainable construction through the implementation of post-occupancy evaluation practices : a case study of RDP buildings in Mpumalanga
(2024-05) Simelane, Nkuthalo John-Junior; Mewomo, Modupe Cecilia; Okorafor, C
Abstract Reconstruction and Development Programme (RDP) buildings in South Africa were promulgated to alleviate poverty and provide better social services for previously disadvantaged South Africans by allocating tax money for development projects. However, there is a growing concern about the quality of housing developed under the RDP programmes. Post-occupancy evaluation is one of the measures that has been proposed to ensure the quality of these buildings is well understood and improved upon. The study sought to investigate the current status of post-occupancy evaluation (POE), understand the barriers to effective implementation of POE, and investigate the critical success factors and the benefits of POE in Mpumalanga Province, South Africa. To achieve this objective, the study adopted a quantitative approach utilising a questionnaire survey to expedite the collection of data, which was then analysed descriptively and inferentially. The study population was purposively selected due to the specific nature of the data collected. Professionals employed by the Department of Human Settlement in Mpumalanga and involved in the construction of the RDP building in Mpumalanga province provided the data. The findings indicate that the critical success factors for effective implementation of post-occupancy evaluation are: participation and commitment; leadership; education and skills; benchmarks and indicators; top management support; availability of resources; POE information management; and effective feedback. With respect to barriers that affect the effective implementation of the POE, the study identified the following: lack of adequate resources; lack of knowledge of POE procedures; lack of awareness of POE; lack of top management support; lack of coordination by departments; lack of owner’s knowledge of POE and benefits; and POE is not integrated into the scope of work of the facility department. The study posited that POE could provide the basis for necessary changes, help increase design know-how, determine building defects, increase building performance, reduce maintenance costs, and increase occupants’ satisfaction.
Evaluating the removal of emerging contaminants from the eThekwini Municipality REMIX Water Treatment Plant
(2024-05) Manyepa, Prince; Bux, Faizal; Seyam, Mahommed; Banoo, Ismail
The eThekwini Municipalities Department of Water and Sanitation (EWS) has initiated feasibility studies to determine whether it is financially and environmentally viable to implement direct potable water reuse (DPR) projects, and one of them is the REMIX Water Treatment Plant (RWTP) which is located within the Port of Durban and abstracts wastewater and sea water for treatment and potential future re-use. However, a review of the extant literature has highlighted that wastewater and seawater are primary sources and "sinks" for various contaminants of emerging concern (CEC). Emerging contaminants (ECs) can be endocrine-disrupting chemicals or cancercausing agents in humans and animals if they are constantly present in drinking water. This study evaluated the efficiency of the RWTP for the removal of different classes of pharmaceutical compounds by measuring the feed water and effluent of each treatment unit along the RWTP. The Quantitative structure-activity relationship (QSAR) model and OPBT criteria were used to screen these compounds for persistence, bioaccumulation, and toxicity (PBT) behaviour in the water matrix. This was done to produce a priority list that allowed effective monitoring of each treatment unit for observed PBT compounds that should not be present in reclaimed water intended for human consumption. The QSAR is a suitable alternative to the costly and labourintensive in vivo screening experiments in the water matrix. It works in tandem with the new animal rights regulations, is safer than laboratory experiments, and also saves time. The study found that 4 out of 20 compounds were identified as potential PBT compounds by consensus agreement in both methodologies. The goal of this study was to assess the removal of ECs prioritised using the QSARINS model and OPBT criteria by carrying out a human risk analysis for reclaimed water proposed for drinking purposes within the City of Durban. This informed decision-makers, plant managers, and operators on what to constantly monitor or add to the treatment plant for the safe production of drinking water. Excellent removal rates of ECs were observed in the membrane biological reactor (MBR) and the reverse osmosis systems (ROs). The removal rates in MBR and ROs ranged from 38% to 100% and 96%, respectively. Excellent removal rates for heavy metals and nutrients across the treatment technology were also achieved in the final product water. The calculated risk/hazard quotients (RQ) for all ECs and heavy metals were also conducted in the reclaimed REMIX water. An RQ/HQ > 1 meant a high risk of ECs or heavy metals, and <1 meant the risk was negligible. Except for some anomalies caused by ion suppression or matrix effects during the analysis, the majority of the ECs in the reclaimed water RQ were found to be less than 1. Identification of chemical, biological, and physical hazards using HACCP system principles led to the identification of critical control points for the technology. Five critical control points were examined, and techniques for successful RWTP monitoring were proposed based on the study findings.
An investigation of a scalable flight control system for a variable pitch, fuel powered, quad-rotor craft
(2024-05) Nielsen, Byron Vaughn Roy; Gilpin, Mark; Ghayhoor, Fahzad
Quadrotor platforms continue to face scalability issues that can be linked to factors such as energy density of polymer battery power sources and the limited efficiency of their fixed pitch propulsion systems. This study employs a dual-method analysis, integrating both experimental and theoretical approaches, to explore the trade-offs between endurance and payload capacity in a quadrotor equipped with a scalable variable pitch rotor system. By applying this development framework, the key objective of this work is to broaden the scope of feasible mission profiles by clarifying the inherent constraints and compromises between endurance and payload capacity and illuminating factors contributing to efficiency. In this pursuit, the first main aspect focused on empirically validating various rotor geometries using test bench system. Data collected is analysed using the computational tool MATLAB, whereas XFOIL simulates airfoil lift and drag characteristics. Rotor performance is then characterised through comparative analysis between experimental data and theoretical predictions made by the Blade Element Momentum Theory (BEMT) rotor model. From comparisons it was found that the BEMT model performance and behaviour remained consistent at varying rotor geometry scales and correlated well with empirical thrust results. It was also found that approximations for power output levels were marginally overestimated at high blade pitch angles – the possible causes of which are further explored in an article published in parallel to this work. [1] The 6-DOF (degrees of freedom) nature of quadrotors in a dynamic environment is then explored using Simulink wherein a flight control system (FCS) architecture is formulated by integrating control laws with a BEMT rotor model. Comparative performance evaluations focusing on dynamic behaviour, thrust generation, and power efficiency are then realised by subjecting a standardised quadrotor airframe with varying rotor geometry and payload capacities to an idealized climb-to-hover (C2H) trajectory. From comparisons of simulation tests, it was significant to find that varying rotor geometry and payloads yielded highly contrasting dynamic behaviours and efficiency performance in terms of thrust generation and power demands. Simulation data also indicated that the B04 rotor configuration was the most energy efficient and enabled superior climb rates and accelerations. By employing figures for simulated hovering power demands, abstracted endurance times are shown to be greatly affected by the energy density and payload constraints between chemical battery systems and carbon fuels. Comparative analysis of rotor performance also revealed that the choice of hardware configuration may necessitate prioritising durability and responsiveness over efficiency. Moreover, mission profiles optimised for high dynamic responsiveness must ensure that FCS sensitivity does not exceed the strength constraints of mechanical subsystems or airframe structure. Collectively, this work successfully established a robust framework for future research and early-stage development of scalable quadrotor platforms can be achieved by integrating variable pitch rotor systems with modularized quadrotor control system architectures. This framework provided key insights into improving quadrotor performance and efficiency, particularly through scalable rotor geometry and payload capacity.
Development of a multi-criteria decision-support tool for improving water quality to assist with engineering infrastructure and catchment management
(2024-05) Ngubane, Zesizwe; Sokolova, Ekaterina; Stenström, Thor-Axel; Dzwairo, Bloodless
Research combining water quality modelling, quantitative chemical/microbial risk assessment, and stakeholder engagement to prioritise catchment areas facing water pollution problems to devise effective pollution mitigation strategies are limited. This research therefore aimed to address this gap by providing a practical and comprehensive framework that supports wellinformed decision-making processes in water pollution alleviation. By integrating multiple criteria and catchment aspects, this framework can assist infrastructure, operational, and ecological managers within a catchment in prioritising best management practices (BMPs) to reduce pollution and mitigate against potential resultant impacts. Given this context, uMsunduzi catchment, in KwaZulu-Natal, South Africa was chosen as a study site. UMsunduzi River is a major tributary of uMngeni River that is used for water supply to the cities of Pietermaritzburg and Durban. The study begins with the data synthesis from diverse sources of scientific data to identify chemical and microbial hazards, utilising a water quality modelling tool to map point and nonpoint source pollution in the catchment. The assessment encompasses the presence of pathogens such as Cryptosporidium and Escherichia coli (E. coli) in the catchment, with rural areas showing a greater contribution from animal sources, while urban areas are affected by impaired wastewater infrastructure. Quantitative microbial risk assessment (QMRA) was conducted, assuming no water treatment within the catchment. The investigation considered multiple exposure routes, including domestic drinking and recreational activities for both adults and children. The results indicate that the probability of infection from Cryptosporidium and E. coli exceeds acceptable levels set by South African water quality guidelines and the World Health Organization. The assessment further included a chemical risk assessment on various chemical groups, including organochlorinated pesticides (OCPs), pharmaceuticals and personal care products (PPCPs), heavy metals, nitrates, and phosphates. Elevated carcinogenic risks were observed for most OCPs, while noncarcinogenic pesticide effects pose long-term risks. Heavy metals and PPCPs are within sub-risk levels, but phosphates have notable ecological and health impacts, particularly in Inanda Dam, a key source of potable water for Durban. In this study, a unique contribution is made by incorporating both chemical and microbial risk assessment. Furthermore, the risk assessment methodology not only encompasses various chemical pollutants and exposure pathways but addresses the nuanced issue of water consumption variability between children and adults. To address these identified risks, a multi-criteria decision analysis methodology is employed to engage stakeholders in the risk management process. Affected, involved, and interested stakeholders, along with economic, environmental, and social criteria, contribute to the selection of Best Management Practices (BMPs). The Simple Multi-Attribute Rating Technique for Enhanced Stakeholder Take-up (SMARTEST) is utilised to identify suitable interventions. The study culminates in the recommendation of BMPs that aim to change behaviour, including public education on livestock grazing management, safe medication disposal, and responsible fertilizer and pesticide use. Pollution management measures, such as solid waste control and river cleanup, are suggested, along with infrastructure management improvements, like sewer system maintenance. This research strived to bridge the gap in water pollution alleviation by presenting a practical and comprehensive framework designed to support well-informed decision-making processes. This framework, with its integration of multiple criteria and considerations, stands poised to aid infrastructure, operational, and ecological managers within a catchment in prioritising BMPs aimed at reducing pollution and mitigating resultant health impacts.
Inhibiting carbon dioxide hydrate formation using deep eutectic solvents
(2024-05) Ngcobo, Themba Luyanda; Ramsuroop, Suresh; Tumba, Kaniki; Lasich, Madison M.
The formation of gas hydrates in pipelines during gas and petroleum extraction processes can result in multiphase systems including gas hydrates. These will form as solids in the presence of water and gas under thermodynamically favourable temperature and pressure conditions. Gas hydrates raise safety concerns, hinder process performance, and impact on financial resources as they block pipelines. The formation of gas hydrates can be efficiently prevented by using certain substances referred to as inhibitors. However, most inhibitors are expensive, potentially dangerous, and damaging to the environment. Hence, there is need to investigate environmentally friendly alternatives to mitigate gas hydrates. The objective of this study was to examine the efficiency of green additives referred to as deep eutectic solvents (DES) in inhibiting carbon dioxide gas hydrate formation. Deep eutectic solvents consisting of Tetrapropylammonium bromide + glycerol (DES-1), Tetramethylammonium chloride + glycerol (DES-2), and Tetramethylammonium chloride + ethylene glycol (DES-3) on carbon dioxide hydrates is investigated. These solvents are worth studying because their synthesis, purification, and environmental friendliness offer economic advantages. Molecular Dynamics (MD) simulations were used to theoretically determine the conditions that promote or inhibit the formation and stability of cardon dioxide hydrates in the presence of the selected inhibitors. The conditions investigated include temperature, pressure, and inhibitor concentration. The use of rigorous computational methods for preliminary screening significantly reduces the cost and the duration of experiments. MD simulation results were further validated using experimental gas hydrate equilibrium data. Results obtained in the present study indicated that the various DES solutions have both inhibiting and promoting effects. It was also found that low concentrations promoted hydrate dissociation, whereas high concentration greater than 0,20 stabilised hydrate formation. Pressure and temperature also impacted on the concentration of the DES solutions that inhibited or promoted hydrate formation. The concentration of the DES solutions shifted the hydrate curve to inhibit or promote hydrate formation.
Optimising post-harvest farm yield through utilization of a machine learning based-fruit disease classification model
(2024-05) Ngongoma, Mbulelo Siyabonga Perfect; Kabeya, Musasa; Moloi, Katleho
This research study proposed 4 key improvements to the classical fruit disease detection models which have been proven to increase their classification and accuracy levels. The globe and, more particularly, the economically developed regions of the world are currently in the era of the Fourth Industrial Revolution (4IR). Conversely, the economically developing regions in the world (and more particularly, the African continent) have not yet even fully passed through the Third Industrial Revolution (3IR) wave. Moreover, Africa’s economy is still heavily dependent on the agricultural field. On the other hand, the state of global food insecurity is worsening on an annual basis due to exponential growth in the global human population, which continuously heightens food demand in both quantity and quality. This justifies the significance of the focus on digitizing agricultural practices to improve farm yield to meet the global steep food demand and stabilize the economies of the African continent and countries such as India that are largely dependent on the agricultural sector for revenues. Technological advances in precision agriculture are already improving farm yields, especially in the more economically developed regions of the globe, although several opportunities for further improvement still exist. Hence, this study evaluated a particular area of precision agriculture, the plant disease detection models which fall under decision support systems. The aim was to gauge the status of the research in this field, identify opportunities for further research, and propose technical amendments to the traditional plant disease detection models to improve their functional efficiency and accuracy. Hence, through reviewing the available literature, this study has realized the dearth of literature focused on the real-time monitoring of the onset signs of diseases before they spread throughout the whole plant. There is also substantially less focus on real-time mitigation measures such as actuation operations, spraying pesticides, spraying fertilizers, etc., once a disease is identified. Very little research has focused on the combination of monitoring and phenotyping functions into one model capable of multiple tasks. Most of the proposed plant disease classification models are based on a 2-Dimensional ‘view’ of the sample, which might pose challenges in the case of spherical or cylindrical plant samples such as fruits. Therefore, four key proposals were made in this research study. Proposal 1 was an improved image pre-processing technique for Machine Learning-based plant disease classification models. This technique dissolves a Red-Green-Blue (RGB) image into individual red, green and blue planes and performs the thresholding process on one or more planes and superimposes the resulting binary images. This has proven to yield better feature segmentation depending on the application. Proposals 2 and 3 aimed to grant a classification model a ‘3-Dimensional view’ of the sample to eliminate any ‘blind spot’ which might be hiding important features that would directly impact the classification decision had they not been hidden. Proposal 2 achieved this by using multiple input image cameras, while Proposal 3 employed a revolving sample stand that allows a single input camera to take multiple input images (at different angles) from the sample. Proposals 2 and 3 were tested in classifying healthy from black rot-affected oranges, and they outperformed the traditional plant disease detection model by classifying correctly even the oranges with small and uneven distribution of black rot. Proposal 4 combined crucial processes that are traditionally stand-alone in farming operation into a single hybrid model, hence the Hybrid Fruit Disease-Quality Monitoring and Sorting Model. This model offers post-harvest benefits and has also been conceptualized based on fruit plant samples. This model could detect diseases; perform quality checks (punchers, skin pills, etc.); perform grading based on these quality checks; and sort the fruits into designated bins according to their assigned class. It aims to lower the price of digital farming technology and avail it to low-budget farms. This model was tested on oranges (healthy, black rot-affected, and generally damaged) and apples (healthy, botch-affected, and generally damaged). The model managed to classify each of these diseases; perform the quality check based on the general fruit damages; and sort/grade (conceptually) these fruits according to these different classes. Its classification accuracy was 100% since all the test samples were classified correctly. Although proposals 3 and 4 of this study were electromechanical systems, their modelling and testing have been limited to the electrical aspect. A full electromechanical design still needs to be implemented for a full capability study to be done in practical settings. Another limitation of this study was collecting the fruit samples with the desired disease symptoms distribution. The test samples were collected from the local vendors and the variety was greatly limited.
Feasibility of blue energy production using reverse electrodialysis In KwaZulu-Natal coastal region : modelling study using Comsol multiphysics
(2024-05) Ngcobo, Lungisani; Ngema, Peterson Thokozani; Tumba, Kaniki
Renewable energies have gained an increasing focus in recent years, due to the climate crisis contributed or associated with the current energy generation sources in South Africa. Thus, in this thesis, a renewable energy source called salinity gradient energy or blue energy will be presented and studied. The main objectives outlined in this dissertation were to evaluate the theoretical potential of electric energy production from the KwaZulu Natal rivers which are uThukela, uMvoti, uMkhomazi, Amanzimtoti, Umgeni, and uMfolozi. Finally, to optimize and simulate RED membrane and design reverse electrodialysis membranes and feeding pumps. In terms of the theoretical potential for producing electricity in the studied estuaries, it was concluded that the uThukela estuary has a considerably higher potential than the others. So, by this information, the possibility of designing the pilot plant in this estuary was studied, noting that the location of the pilot plant where the energy produced is greater and the capital cost are lower is at the mouth of the uThukela river. As for the pilot plant of RED, it was concluded that it is economically viable since the profit/loss found was R0 which is a break-even point, the plant is not generating a profit, but it’s also not generating a loss and since the focus for now is to try generating power. It’s economically viable in the sense that it covers its costs, but it is not profitable in terms of generating surplus revenue. It was concluded that using cheap and very thin membranes with high fluxes can increase the performance of the reverse electrodialysis. Also, the performance can be increased by using more than two reverse electrodialysis stacks instead of one.
Durban Container Terminal role in achieving national development plan goals on sustainable development
(2024-05) Ntuli, Muziwokuthula Nkanyiso; Allopi, Dhiren
Durban Container Terminal (DCT) operations contribute significantly to emission release. DCT operations directly threaten sustainable development and South Africa’s Sustainable National Development Plan (NDP) goals. Sustainable port development aims to create scenarios for “Ports of the Future” that are green, sustainable and have minimal or no impact on the environment. The problem statement is defined as DCT's role in failure to achieve sustainable development targets set by the NDP and the United Nations (UN). The current DCT operation setup promotes an increase in cargo handling coupled with numerous socioeconomic activities, which is a constant source of increasing pressure on the limited natural resources and a continuous threat to sustainable development in the Durban areas. The aim and objectives are to investigate and explore the reasons why DCT fails to achieve sustainable development goals set up by the NDP and the UN. The quantitative research method helped to answer questions on relationships within measurable variables to explain, predict, and control a phenomenon concerning sustainable development goals for the container terminal. The findings presented challenges and a threat to DCT if the current position concerning service requirements, costs and demands for sustainability is not addressed. The literature, studies and engineering reports illustrate the available technologies that respond to sustainable development requirements. The theory supports the critical role played by the dry port, terminal layout, and operating system in mitigating emissions release during operations. The engineering and DCT electricity consumption annual reports confirm the high consumption of energy during operations. The results from the port equipment, infrastructure, road and rail integration, and dry port explain why DCT fails to achieve the sustainable development goals set by the NDP and the UN. DCT depends on the main grid energy supply originating from fossil energy sources. This has led to 58 967tCO2e for DCT operation from equipment and electrical infrastructure. The poor rail conditions have increased temporary speed restrictions (TSRs). The lack of investment in the rail infrastructure, rail maintenance, and TSR takes away the opportunity to have a dry port and reduces the number of containers travelling by road. The DCT integrated logistics system is missing the possibility of reducing CO2 emission release by 30 085.4tCO2e. The simulating model confirmed the dominance of trucks and was followed by port equipment concerning CO2 release. The results illustrate the impact of the ineffective role of rail freight. It indicates that if the number of wagons is increased, the number of trucks on the road will decrease, resulting in a CO2 release reduction. The DCT integrated operating model assessment results explain why DCT is not realizing the national development plan’s objectives for sustainable development goals. DCT consumes high amounts of energy and contributes to CO2 emissions, primarily through road and rail freight. Ineffective operational planning and poor rail conditions significantly impact CO2 release. The DCT terminal operation itself contributes only 10% of the integrated operation's CO2 emissions, with road and rail freight releasing 90%. The simulated model highlights the dominance of trucks in CO2 emissions, followed by port equipment, and poor rail conditions preventing DCT from achieving sustainable development goals. The introduction of a dry port as an intermodal hub could promote economic growth and reduce road congestion and carbon emissions. However, the poor rail conditions make the proposed Cato Ridge/Camperdown dry port unviable. DCT's main challenges in achieving sustainable development goals are categorized into three focus areas: Affordable and Clean Energy, Decent Work and Economic Growth, and Climate Action. This analysis will help provide the best operating and sustainable development scenario for DCT, which could include the introduction of hybrid equipment, energy-saving technology, and improved rail infrastructure. Adopting a reconfigured DCT-integrated operating model is recommended since it has no significate operational changes within the DCT terminal. The reconfigured DCT integrated operations introduce a dry port and a rail infrastructure upgrade to accommodate 150 wagon trains. The reconfigured DCT integrated operating model promotes the reduction of container trucks calling for a DCT terminal, unlocking decent work and economic growth, sustainable cities, and communities within the Midlands region.
Designing a stormwaterharvest system in new smart cities in KwaZulu-Natal, South Africa
(2024-05) Mukome, Bwija
The nexus between climate change and water management represents one of the contemporary challenges confronting economic development and sustainable livelihoods in many cities the world over. Thus, assessing the impacts of climate change for evolving smart-city water management, especially for a country like South Africa that is classified as a “water-stressed” country, constitutes an innovative way to water management. This study aimed at proposing an alternative water supply augmentation source that is sustainable for new smart cities under different climatic scenarios within the KwaZulu-Natal Province of South Africa. The specific objectives of the study were to assess the impacts of climate change and the imperativeness of a sustainable and efficient stormwaterharvesting (SWH) system in the new smart city; determine the social, economic and technical barriers to an efficient SWH system; evaluate the technical and financial feasibility of stormwaterharvesting system integration in smart cities; and design a prototype sustainable and efficient pilot-scale engineering SWH system. To address these objectives, the aggregated views of stakeholders within the Water/ Climate change sector were solicited through questionnaires and interviews collected data were analysed using a statistical package and thematic classification. The triangulation method was used to justify acceptable opinions where both the qualitative and quantitative responses were in opposing positions. The standardised rainfall anomaly index (SRAI), simple precipitation ratio (SR), coefficient of variation in rainfall distribution (CV), precipitation concentration index (PCI), and the seasonal precipitation index (SPI) were used to evaluate the impacts of climate change on rainfall variability; whilst different inferential statistics techniques like Mann Kendal, Sen slope, regression, correlations, multifactor analysis (MFA), and chi-square test values- interpreted using the p-values- were used to identify the abrupt changes, trend patterns and significant impacts of climate change on the hydrological water balance for the study area, which in turn influenced decision-making in designing a new smart city. Based on a monthly water balance evaluation, the technical and financial feasibility of stormwater harvest system integration in smart cities was thematically deduced from survey interviews conducted and validated with simple component costing for SWH design and operation. The design of a sustainable and efficient pilot-scale engineering SWH system was synthesised through an extensive literature review for future adaptation. The various analyses and results in ranking the socio-economic and technical barriers to SWH system integration into smart cities connotes ageing infrastructure; the lack of proactive maintenance; and a lack of finance as the biggest challenges to efficient stormwaterharvesting system implementation. The study concludes that SWH presents a viable alternate source for water that might improve urban water self-sufficiency sustainability under different climatic smart city assessments, whilst recommending capacity development where climate change experts transfer knowledge, skills and expertise to upcoming researchers.
Development of multi-objective optimization model for project portfolio selection using a hybrid method
(2024-05) Mogbojuri, Akinlo Olorunju; Olanrewaju, Oludolapo Akanni
Selecting inappropriate projects and project portfolios can result in irreversible wasted economic opportunities, reduced manpower value, and missed prospects and other resources for the organization. As a result, to achieve the best possible outcome, all criteria to enable the best possible choices to be made should be considered. Choosing projects wisely and managing the project portfolio can assist organizations in gaining a better understanding of their projects and their risks and advantages. When faced with budget and other constraints, the ability to select an optimal mix of projects is a significant advantage in the project selection process. The selection of projects by means of employing an effective method is uncommon because many methods are deemed ineffective due to limitations on the number of projects that can be chosen, along with the failure to select economical projects. Project selection is a complex, multicriteria decision-making procedure involving numerous and frequently competing goals. The complexities of project selection problems stem primarily from the large number of projects that are required to be selected for an appropriate collection of investment projects. The study identified some research gaps such as limited studies on social sustainability benefits, criteria for public project selection not being considered or mentioned, and the decision-making committee or expert generating weight to the deviational variables instead of using weighting techniques. The aim of this study is to employ an integrated approach to establish a multi-objective optimization approach for public project portfolio selection. The specific research objectives are to develop an integrated method of Analytic Hierarchy Process, Goal Programming and Genetic Algorithm (AHP-GP-GA), establish a relationship for the developed models to correct the bias of each model and apply the integrated method in a selected community with a set of projects. Data was collected by compiling a well-structured questionnaire for decision-makers analysed by applying the AHP and GP methods. The composition of the integrated approach includes decision support tool with exact and includes meta-heuristic modelling known as Analytic Hierarchy Process, Goal Programming and Genetic Algorithms (AHP-GP-GA) for solving public project portfolio selection problems. The Analytic Hierarchy Process model was used to develop project selection criteria, assign relative priority weights of decision makers, and determine the overall weight of project alternatives. The GP constructed the mathematical model to handle large numbers of objectives and constraints. The GA is the solution algorithm for the effective and flexible optimization model to produce optimal solutions. The AHP and GA employed Spice Logic and MATLAB software packages to analyse, validate and enhance the research. The AHP model highlighted some sub-criteria and project criteria attributes that are significant to project selection criteria. These criteria are economic development, job creation, community acceptance, structure aligned with company goals, employment record of project manager, locality of the project, finish period of the project selected, project threats and political impact. Meanwhile, empirical research on public agencies was undertaken with the AHP-GP-GA, AHP-GP and GP separately to address the problem. The GP and AHP-GP used the LINGO 18.0 software package, while the developed integrated method AHP-GP-GA was solved using MATLAB software package to exhibit the competence of the model and the research. The high point of the empirical research showed that the AHP-GP-GA model can solve large-scale, or complex problems with a large number of decision variables. It selected more projects compared to the AHP-GP and GP standalone model and provided more optimal solutions, which made the approach robust and flexible for solving decision-making problems. The theoretical and practical contributions of the study are the research, which will improve the knowledge and understanding of researchers or academia in PPSP and add to the literature to enhance the existing methods of integrated approaches. The stakeholders in project management practitioners like organization management, top executives, senior and junior supervisors, and personnel connected to the projects will also benefit from the research in selecting optimal projects from the various solution options, saving costs, and learning how to handle and select more complex projects in large-scale real-life situations. This study recommends further research on the integration of stochastic models, evolutionary algorithms, or computation with AHP and GP for the Public Project Portfolio Selection Problem.
Development of an Intelligent Standalone Solar Photovoltaic 48V DC microgrid system
(2024-05) Makhanya, Thandeka; Pillay, N; Sewsunker, R
With load shedding negatively affecting South Africans there are many concerns regarding stable power delivery to residential households. Amid all the power delivery concerns some rural communities are still not connected to the existing power infrastructure. Implementation of newer efficient clean energy sources is in demand. A standalone Photovoltaic (PV) Solar distributed renewable energy Direct Current (DC) microgrid can be the best possible approach to tackle the power grid shortcomings and to electrify communities that are not yet covered by the power grid or communities that want to transition to clean energy. The research focuses on the design of an optimal 48 VDC Multiple-PV Standalone microgrid in remote areas not covered by the main grid. The proposed microgrid can be typically used for lighting, charging phones, and other low-power applications. The microgrid will consist of 4 microgrid subgrids, each consisting of a dedicated Solar PV array, battery storage systems, loads, and other components that connect to the DC Bus and need to be monitored and controlled for efficient operation. Furthermore, the subgrids were designed based on the meteorological data of the selected location and the load demand for each subgrid. The microgrid design enables the subgrids to share power through a bidirectional DC-DC converter based on certain conditions. A power-sharing management system was implemented to manage power-sharing ensuring that the sharing subgrid does not drive its users to load shedding. Moreover, the microgrid design was simulated on Matlab/Simulink to observe the operation of the designed system and to determine if the proposed design would be able to achieve the desired goal. The results obtained from simulations indicate that the proposed microgrid design can provide an optimal service to its users by allowing the subgrid with surplus energy to share its power with the subgrid when needed.
An investigation into the effectiveness of industrialising Software Quality Assurance (SQA) in small software businesses
(2024-05) Patel, Meena; Olanrewaju, Oludolapo Akanni
Poor software quality has far-reaching consequences, including financial losses and potential risks to life. A significant proportion (92%) of software development is undertaken by very small to medium-sized software businesses. However, resource constraints often limit their ability to implement quality standards and methods that could enhance their product quality. Industrialization, a management concept for cost-effective production, offers potential solutions. While prior research has explored the industrialization of software development and quality assurance in large companies, a gap exists regarding its application in small software businesses. This study aims to investigate the effectiveness of industrializing the software quality assurance (SQA) process within small software businesses. Adopting a qualitative approach with an interpretivist philosophy, inductive methodology, and exploratory strategy, this study employed semi-structured interviews to collect data. Participants included software developers and quality assurance representatives from five small software development businesses located in KwaZulu Natal and Western Cape provinces, South Africa. The theoretical foundation of this study draws upon Total Quality Management (TQM) principles and dimensions of industrialization (modularization, standardization, specialization, automation, and continuous improvement), as developed by experts during the early and mid-20th century. The data collected was analysed using thematic analysis with support from Nvivo software. Results revealed that despite lacking established quality assurance strategies and process evaluation mechanisms, small software businesses effectively meet customer needs. Moreover, these businesses exhibit potential for successful industrialization, particularly focusing on the testing processes. Implications of these findings include the positive impact on the capacity of small businesses to sustain themselves within local economies.
An investigation into harvesting solar energy using thermoelectric generator coupled IBR sheeting
(2024-05) Malik, Momina; Gilpin, Mark; Graham, Bruce Robert
There is a current global impending need for clean and renewable energy sources. Fossil fuels are non-renewable finite resources, which are dwindling because of high cost, and environmentally damaging retrieval techniques. South Africa’s coal resources may soon reach their end, which further stresses the need for green energy. An efficient and more feasible alternative is solar energy. Thermoelectric generators (TEGs) may use the energy from the sun to generate power and are an innovative means to harvest electricity. The proposed study intends to validate whether TEGs are a potential method to harvesting solar power. The study herein is a preliminary experimental investigation into a development in a TEG modular prototype. Relevant tests are run, and the performance characteristics obtained from experiments are discussed. The TEG system developed and tested in this study consists of 2 equally sized pieces of Inverted Box Rib (IBR) sheeting with one side exposed to a light source, while the other side remains shaded. An Arduino, connected and coded to read and display resulting temperatures, Peltier tiles, magnets, simple heatsinks and Multimeters are connected to measure open circuit voltage and closed-circuit current generated from the temperature difference between the two sides of the IBR sheeting. The system aims to harvest energy whilst keeping the assembly and construction simple, practical, and minimalistic. Outdoor experiments were conducted to determine the temperatures and the resultant temperature gradients the configuration may experience in operation. The data collected established parameters for the laboratory experimental setup. The laboratory experiments characterized the power output of the units. For comparative purposes, some variables were removed, such that the testing variable was isolated. Some environmental variables were removed by testing in a laboratory. The TEG was tested in the vertical position to allow for maximum natural convection, and hence may not reflect results that would be obtained in all applications. The TEG system is exposed to the light source at different distances, perpendicular to the sheets. The study intends to investigate the effect that the 2 variables have on the amount of solar power generated i.e., the colour of metal IBR sheeting, and the ideal electrical arrangement for scalability of Peltier tiles for maximum power output (𝑃𝑚𝑎𝑥). The IV curve generation method (later explained in chapter 2.4.1) is used to read the parameters required to calculate 𝑃𝑚𝑎𝑥. The results show a strong influence of the black coated sheets on the power output of the TEGs. It is deduced from solar experiments, that the aluminium rods used as the heatsink fulfilled its purpose of regulating a ∆T of 1-2°𝐶. Furthermore, the TEG in series configuration, generated the highest 𝑃𝑚𝑎𝑥 when located 300mm from the heat source, followed by 600mm and lastly, 900mm. The same pattern is found for the unit and parallel configurations. It may be concluded from the proposed TEG system that TEGs are a potential method of harvesting solar energy on IBR sheeting, specifically in a vertical position. However, applications of different orientations and geographical locations require further investigation. The results merit further investigation and refinement into the use of TEGs on IBR sheeting where the herein designed TEG system is set-up in a user friendly, simple, cost effective and practical manner for solar energy harvesting. While the power output per TEG tile is small in magnitude, the proposed configuration has potential in the coupling of multiple units to increase power output. The current work shows potential for the use of TEGs in this application. Through further investigation, refinement and cost analysis, the system may prove to be a practical method of solar energy harvesting.
Techno-economic analysis and life cycle assessment for production of biofuels from spent coffee grounds
(2024-05) Kisiga, Wilberforce; Chetty, Manimagalay; Rathilal, Sudesh
Spent Coffee Grounds (SCGs) are one of the most abundant agro-industrial residues generated from the coffee brewing industry and coffee espresso machines in restaurants, cafeterias, cafes and homes. It is believed that for every ton of coffee beans processed, 650 kg of SCG is left as solid residues. Coffee being the second traded commodity after petroleum, means that a lot of SCGs are generated annually and end up into landfills. Efforts are being made to turn this valuable waste into biofuels, however, most of these efforts end up at laboratory benches and few studies have focused on industrial scale production of biofuels from SCG. Six biomass-to-energy conversion technologies were compared from technical, economic and environmental perspectives: Fast pyrolysis, Hydrothermal Liquefaction (HTL), gasification, Anaerobic Digestion (AD), fermentation and biodiesel production. The processing technologies were selected because they are the most researched biomass-to-fuel conversion routes. Each of the processing routes was simulated in Aspen plus V11 using input data from literature. The mass and energy balances obtained from simulations were used to conduct Techno-Economic Analyses (TEAs) and Life Cycle Assessments (LCAs). TEA was conducted with help of Aspen Process Economic Analyzer (APEA) and Microsoft Excel spreadsheets whereas OpenLCA V1.11.0 software was employed for LCA. After the processing routes were successfully simulated, APEA was used to estimate the installed Cost of all Equipment (COE). The Capital Expenditure (CAPEX) required to build the biorefineries was then estimated basing on COE for each biorefinery. Then the Operating Expenses (OPEX) required for running the day-to-day operations of the plant were estimated as the sum of Variable Operating Expenses (VOC) and Fixed Operating Expenses (FOC). The revenues from the sales of finished products were estimated and used to calculate the gross profit. For the plant life of 25 years; using straight-line depreciation of 10% per year, discount rate of 12% and tax rate of 28%, the Discounted Cash Flow Analysis (DCFA) was used to calculate the economic indicators i.e. the Net Present Value (NPV), Profitability Index (PI), Internal Rate of Return (IRR) and Discounted Payback Period (DPBP). For LCA, the methodology outlined by the ISO 14040/44 framework was used. The method outlines four steps followed to conduct LCA i.e. goal and cope definition, Life Cycle Inventory (LCI), Life Cycle Impact Assessment (LCIA) and interpretation of results. The goal of this study was to identify the processing route with least environmental impacts and the cradle-to-gate system boundary was selected. LCI was conducted using the mass and energy balances obtained from Aspen plus simulation and the flows present in the Agribalyse Version 3 database, downloaded from OpenLCA nexus. LCIA was conducted using the ReCiPe 2016 Midpoint (H) and was also downloaded from OpenLCA nexus. Eight impact categories namely, global warming, fossil resource scarcity, particulate matter formation, terrestrial acidification, freshwater eutrophication, marine eutrophication, mineral resource scarcity and water consumption were selected. The results were analysed to identify the conversion route with less environmental effects. Results from the economic analysis showed that fast pyrolysis was the most economically profitable processing route with a NPV, PI, DPBP and IRR of 6.3 million USD, 1.85, 5.4 years and 37%, respectively. In the second position was biogas production with a NPV, PI, DPBP and IRR of 3.4 million USD, 1.65, 5.7 years and 34%, respectively. Gasification was in the third position with a NPV, PI, DPBP and IRR of 5.4 million USD, 1.48, 6.0 years and 32%, respectively. In the fourth position was biodiesel production with a NPV, PI, DPBP and IRR of 3.9 million USD, 0.86, 8.0 years and 24%, respectively. HTL was in the fifth position with a NPV, PI, DPBP and IRR of 0.68 million USD, 0.29, 13.0 years and 16%, respectively. Bioethanol production was not economically profitable as the revenues generated from sales of finished products were smaller than the operating expenses, thus no profit could be generated. Results from environmental impact assessment showed that fast pyrolysis was the most environmentally friendly processing route, followed by biogas production, biodiesel production, gasification, and bioethanol production, whereas HTL had the highest environmental impacts. Electricity consumption was the biggest contributor to the environmental impacts, making HTL, which was the highest electricity consuming processing route, to be the worst environmentally. However, biogas production was the least electricity consuming processing route but not the best environmentally due to large production of carbon dioxide and methane (biogas) from anaerobic digestion. The large production of carbon dioxide can be mitigated through using it to grow algae or in supercritical carbon dioxide extraction of lipids. However, the cost associated with additional unit processes can escalate the biogas production costs. These greenhouse gases were the biggest contributors of global warming, pushing biogas production to the second position after pyrolysis.Fast pyrolysis was proposed to be the best environmentally and economically feasible processing route for the production of biofuels from SCG.
Exploiting recycled plastic waste as an alternative binder for materials used in the construction industry
(2024-05) Gounden, Kimendren; Mwangi, Festus Maina; Mohan, Turup Pandurangan; Kanny, Krishnan
The population in the world is growing at an alarming rate and four local and global threats viz. plastic pollution, high unemployment, inadequate housing for all citizens and damage to the ozone layer causing climate change continue to emerge. The overwhelming demand for plastic goods in daily use resulting in plastic waste pollution has become an environmental challenge. Plastic waste is now becoming extremely dangerous due to their rapid accumulation in the environment and in landfills, and their improper disposal methods leads to many harmful effects on land, air, marine life and humans. Incineration of plastic waste is already posing several health risks. Concurrently, the cement, building and construction industry is amongst the biggest contributor to carbon dioxide (CO2) gas emissions, which poses an added environmental challenge. This creates a negative image on the use of cement-based masonry as construction materials, which renders it unsustainable. Hence, an alternative construction material is required. The manufacture and utilisation of burnt clay bricks have become an area of debate which led to a move towards greater sustainability. Therefore, there is need for a strategy to reduce plastic pollution, create job opportunities, provide alternate ways of constructing affordable ecofriendly houses, and reduce the depletion of the ozone layer for the benefit of all citizens. This strategy is explored in this research study that supports, enhances and promotes sustainability. The efficacy of producing eco-friendly plastic-sand bricks as a feasible solution and an attractive alternative to cement or burnt clay bricks have been investigated in this study. This investigation encompasses an effort to combat issues related to plastic waste, high unemployment, rising building costs and climate change. In the first stage the study analyses the use of High-Density Polyethylene (HDPE) and river sand using six different ratios of sand(s): plastic(p) viz. 60s: 40p; 65s: 35p; 70s: 30p; 75s: 25p; 80s: 20p and 85s: 15p. The second stage consisted of the addition of 1%, 5% and 10% of Kaolin Clay DSF which was experimentally added to each of the different ratios of sand: plastic respectively to improve the mechanical and environmental properties towards producing eco-friendly plastic-sand bricks. The mechanical tests showed significant improvement. Results revealed that the addition of 5% Kaolin Clay DSF, significantly increased the compressive strength from 21.4 MPa to 52.76 MPa in the 75s:25p ratio, the modulus of elasticity from 1109.35 gigapascal (GPa) to 2434.84 GPa and the short beam strength from 1.84 MPa to 2.27 MPa. The addition of 10% Kaolin Clay DSF, significantly increased the results for the impact test from 4.6 joules to 5 joules in the 75s:25p ratio. However, the addition of 5% Kaolin Clay DSF revealed an increase from 4.6 joules in the same ratio to 4.7 joules. The hardness test revealed that the impression of the nail did not affect the samples which implied that the plastic-sand bricks are durable and tough in all six ratios. The environmental tests also showed significant improvement. Results revealed that the addition of 5% Kaolin Clay DSF decreased the rate of water absorption from day 1, being 0.78% to 0.43% on the 21 st day. The plastic-sand brick as a composite material is an electrical insulator. The plastic-sand brick sample resisted the immediate absorption of water with respect to 0%, 1%, 5%, and 10% addition of Kaolin Clay DSF. No visible deposit of alkali was present when the efflorescence test was done. The fire test revealed that the addition of 10% Kaolin Clay DSF with an increase in sand content drastically reduced the linear burning rate significantly in the 75s:25p ratios from 10.52 mm/min to 2.10 mm/min respectively. This decrease in approximately 81% in the burning rate is significant. The main conclusion of this research study is that HDPE plastics can be used to produce plasticsand bricks that are durable, significantly high in strength and eco-friendly as compared to the conventional cement or burnt clay bricks. The addition of Kaolin Clay DSF improves both the mechanical and environmental properties of the plastic-sand brick. The manufacturing of plastic-sand bricks is an eco-friendly process. Thus, recycled plastic waste can be effectively used as an alternative binder material in the construction industry.

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