School of Water, Energy and Environment (SWEE)
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Browsing School of Water, Energy and Environment (SWEE) by Course name "MSc by Research in Energy and Power"
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Item Open Access Application of machine learning in assessment of combustion of liquified natural gas.(Cranfield University, 2021-05) Alexandropoulos, Christos Dimosthenis; Hanak, Dawid P.; Longhurst, PhilipThis work focuses on the implementation on carbon capture on ships which run on liquified natural gas (LNG). LNG ships present a real-world example of LNG as well as a study case for carbon capture on LNG combustion. There is also special interest for that as well, since the International Maritime Organization (IMO), imposed a limit of 0.5% wt. of sulphur content in ship fuel has been imposed from 2020 to reduce pollution emissions from global shipping activities. This initiative will lead to major changes since the previous limit was set at 3.5% wt., which broadened fuel options for ships. In addition, the IMO is developing a long-term plan to completely nullify shipping’s impact on CO₂ emissions by 2030. Consequently, stricter regulations will be imposed to marine activities worldwide. LNG fuel seems to be a promising solution. The sulphur emissions are lower, in compliance with the latest IMO regulations. Additionally, it has a greater energy density in comparison to traditional fuels, like heavy fuel oil (HFO). This paper aims to study the feasibility of a project, which equips an LNG fuelled ship with a carbon capture system. The study includes an examination of an on-board carbon capture system, by simulating the LNG engine as well as the carbon capture system in simulation software. The engine model chosen is the Wärtsilä 6L34DF. The results of these simulations are analysed to examine the correlation between the system’s variables and to evaluate the possibility of heat integration within the system. The economic feasibility of the project is then assessed, using economic data. The results show that heat integration is possible. For example, the heat provided from the flue gas is calculated at 1.323MW when the reboiler duty is 0.3353 MW. However, the project is not sustainable under current market conditions.Item Open Access Bioproduction of xylitol by oleaginous yeast yarrowia lipolytica.(Cranfield University, 2020-01) Thomas, Dominic James; Medina-Vayá, Ángel; Veerheecke-Vaessen, CarolXylitol is a commercially important chemical with multiple applications in the food and pharmaceutical industries. According to the US Department of Energy, xylitol is one of the top twelve platform chemicals that can be produced from biomass. The chemical method for xylitol synthesis is, however, expensive and energy- intensive. In contrast, the biological route using microbial cell factories offers a potentially cost-effective alternative process. The bioprocess occurs under ambient conditions and makes use of biocatalysts and biomass which can be sourced from renewable carbon originating from a variety of cheap waste feedstocks. In this study, the biotransformation of xylose to xylitol was investigated using Yarrowia lipolytica, an oleaginous yeast which, in this study was firstly grown on a glycerol/glucose medium for the screening of a co- substrate, followed by a media optimisation in shake flasks, scale-up studies in a bioreactor and then downstream studies where done on the processing of xylitol. A two-step medium optimization was employed using a central composite design and an artificial neural network coupled with a genetic algorithm. The yeast amassed a concentration of 53 g/L of xylitol whilst using pure glycerol (PG) and xylose media, with a bioconversion yield of 0.97 g/g. Similar results were obtained when PG was substituted with crude glycerol (CG) from the biodiesel industry (titre: 51 g/L; yield: 0.92 g/g). Even when xylose from sugarcane bagasse hydrolysate was used as opposed to pure xylose, a xylitol yield of 0.54 g/g was achieved. The xylitol was successfully crystallized from the PG/xylose and CG/xylose fermentation broths with a recovery yield of 40 and 35 %, respectively. To the best of the author’s knowledge, this study demonstrates for the first time, the potential of using Y. lipolytica as a microbial cell factory for xylitol synthesis from inexpensive feedstocks. The results obtained are competitive with other xylitol producing organisms.Item Open Access Co₂ separations and the role of surface functionality(Cranfield University, 2021) Wadi, Basil; Nabavi, Ali; Manovic, VasilijeTo curb irreversible environmental effects of climate change, urgent measures must be taken to limit anthropogenic emissions and achieve net-zero carbon goals by 2050. Carbon capture technology to meet these goals is wide ranging, with novel methods directed at biogas upgrading or direct air capture. Biogas is produced from the anaerobic digestion of biological waste and considered a valuable renewable energy source; to produce biomethane for use interchangeably with natural gas. However, widespread use of established separation processes is limited, primarily due to low CO₂ selectivity or high energy demands of cyclic operation. One method to tackle these issues is the development of novel sorbents for use in pressure swing adsorption, targeting maximum CO₂ capacity and selectivity, while minimising regeneration energy penalties. Adsorbents incorporated with amines can meet one of these criteria, selectively adsorbing CO₂, but require high regeneration energies. Herein, the adsorption performance of a diverse range of amines grafted on mesoporous silica at varying densities is studied, to understand developing adsorption mechanisms, and identify the ideal degree of functionalisation for gas separations. It was found that although high amine densities led to the highest enhancement in CO₂ capacity and selectivity, moderate levels have comparable selectivity and capacity in isothermal adsorption-desorption conditions, standing out are di- and secondary amines. Diamine loadings achieved an adsorption capacity of 1.12 mmol/g, a heat of adsorption of 35-50 kJ/mol, and an IAST selectivity of 374 at CO₂ partial pressures of 40 kPa. Secondary amines had a low capacity of 0.67 mmol/g, but a higher heat of adsorption comparatively. The optimal binder formulation for pellet preparation of amine grafted silicas was also studied, a necessary step in conducting laboratory scale fixed-bed adsorption studies. When applying amines for ambient air adsorption, very high amine loadings result in slow adsorption kinetics, rendering the advantage of their high capacity debatable. Moderate loadings of primary and triamine under humid conditions have higher adsorption rates >250 µg/g/min, making them more suited for fast cycle processes.Item Open Access Design and performance analysis of concentrated photovoltaic cooling.(Cranfield University, 2023-01) Ibrahim, Khalifa Aliyu; Luk, Patrick Chi-Kwong; Kahagala Gamage, UpulThe use of solar energy as a global energy source has increased over the past two decades. Photovoltaic cells, which utilise the sun to generate electricity, are a promising alternative to fossil fuels that contribute to climate change. However, the high intensity of concentrated solar radiation can cause overheating in photovoltaic cells, reducing their efficiency and power output. Researchers worldwide are improving cooling in concentrated photovoltaic cells (CPV) to enhance temperature uniformity and improve power output. Previous studies have demonstrated that pulsating flow can effectively enhance heat transfer in various fields, including electronics, mechanical engineering, and medicine. In this research, three flow patterns (continuous flow, uniform pulsating flow, and bio-inspired pulsating flow) were studied in both simulation and experimental designs. Two cooling designs were considered: the conventional design (C- Design) and the parallel design with baffles (W-B) and without baffles (Wout-B). With the implementation of 30 pulses per minute bio-inspired pulsating flow a reduction of 1.96% in solar cell temperature was observed when compared to continuous flow. This reduction in temperature was consistently observed across a range of flow rates from 0.5 to 2.5 L/m, employing the parallel Wout-B design. Notably, the bio-inspired pulsating flow shows better performance in comparison to uniform pulsating flow, as well as the conventional designs with continuous flow and uniform pulsating flow, resulting in notable improvements in cooling efficiency of 1.22%, 2.14%, and 4.00%, respectively. In terms of a direct comparison, the implementation of uniform pulsating flow in the parallel Wout-B design exhibited a maximum cooling improvement of 0.74% when contrasted with continuous flow. Furthermore, when assessing uniform pulsating flow against the C-design with uniform pulsating flow in the parallel Wout-B design, a noteworthy enhancement of 0.93% was observed. Remarkably, the C-design with uniform pulsating flow demonstrated a superior effectiveness of 1.90% when compared to the C-design with continuous flow.Item Open Access Improvements of electrochemical water splitting efficiency by using economically viable Co/CoPs/TiO₂/NiF electrocatalysts(Cranfield University, 2024-08) Kulathunga Mudiyansele, Soorya Dananjaya Bandara Kulathunga; Wijayantha, Upul; Jiang, YingThe drive for sustainable energy solutions has led to the search for efficient and cost-effective electrocatalysts for green hydrogen production via electrochemical water splitting (EWS). This study addresses the limitations of precious metal- based catalysts by investigating alternative, earth-abundant materials. This research introduces a novel Co/CoPs(240)/TiO₂/NiF electrocatalyst, synthesized using deep eutectic solvent (DES)-mediated electrodeposition of Co and cobalt phosphides (CoPs) on TiO₂-coated nickel foam (NiF) substrate. Electrophoretic deposition of TiO₂ nanoparticles was successfully applied to NiF, resulting in a smooth and even surface. On this TiO₂-coated substrate, subsequent Co/CoPs deposition produced unique hexagonal and cauliflower-like structures with a uniform distribution of Co and P. Energy dispersive X-ray spectroscopy (EDX), scanning electron microscopy (SEM), and X-ray diffraction (XRD) were used to confirm these features. Optimizing the Co/CoPs deposition times significantly reduced the hydrogen evolution reaction (HER) overpotential to 34.42 ± 4.2 mV at 10 mA cm⁻² in 1 M KOH. Remarkably, the Co/CoPs(240)/TiO2/NiF catalyst required only 27.43 mV with a Tafel slope of 48.35 mV dec⁻¹. Stability tests demonstrated minimal performance degradation after 5000 cycles and 40 hours of operation, demonstrating excellent durability. This optimized catalyst outperformed Co/CoPs(240)/NiF, commercial 10% Pt/C electrodes, and other reported catalysts. The oxygen evolution reaction (OER) performance also highlighted the catalyst's efficiency, with an overpotential of 331.70 mV at 10 mA cm⁻² in 1 M KOH and a Tafel slope of 73.96 mV dec⁻¹. Stability tests revealed minimal performance degradation after 1000 cycles. Furthermore, a full water electrolyser system using Co/CoP(240)/TiO2/NiF electrodes achieved a total voltage of 1.612 V at 10 mA cm⁻², indicating the practical viability of the optimized electrodes for water splitting applications. The remarkable performance of the Co/CoPs(240)/TiO₂/NiF electrode is primarily due to the presence of the TiO₂ layer, which enhances the surface area and acts as a catalyst promoter through synergistic effects and enhanced charge transfer kinetics. This research suggests that incorporating an intermediate TiO₂ layer can promote the catalytic activity of other catalysts as well. In conclusion, this study presents an effective and economical alternative to noble metal-based electrocatalysts for water splitting. By integrating TiO₂ with Co/CoPs on a NiF substrate, the research advances the development of high-performance, low-cost catalysts and contributes to the sustainable production of green hydrogen.Item Open Access An investigation into job role localisation in the oil and gas industry: a case study(2018-03) Pegram, Jack; Falcone, Gioia; Kolios, Athanasios; Craig, JonathanThis study investigates the viability of localising job roles in the oil and gas industry and whether job role localisation can reduce staffing costs. The principal barrier to job role localisation is high standards required by oil and gas companies and immature labour markets that do not meet these standards. A four stage mixed methods approach is taken. The first stage addresses the global level using a survey about local content issues. The second stage focuses on the national level using interviews to investigate how national factors can affect job role localisation. The third stage addresses the company level, using a decision tree methodology on a sample of ten job roles within one oil and gas company operating in Ghana to assess the viability of localising particular job roles. The fourth stage uses training and development investment timelines to model whether the costs of employing expatriates are greater than training, developing and employing Ghanaians to do the same job roles. The findings show that different stakeholders often share opinions about local content issues. At the national level there are many national context specific factors that affect job role localisation including legislations, culture, attitudes and experience within the labour market. The decision tree methodology developed in this study is an effective tool to assess the viability of localising different job roles over time. Training and development investment timelines show that it is more cost-effective to invest in the education, training and development of local people than it is to employ expatriates. This study finds that localisation is becoming increasingly prevalent worldwide. Oil and gas companies must adapt their localisation strategies to the national context where they are operating. Whilst not all job roles should be localised, decision trees can support companies to decide which job roles should be localised. Furthermore, companies can reduce costs if they train, develop and employ local people rather than employing expatriates.Item Open Access Numerical modelling of bipolar plate in pem fuel cells to analyse the pressure drop in various channels and development of a novel geometry of the bipolar plate.(Cranfield University, 2022-09) Jayabal, Jayvassanth; Verdin, Patrick G.; Nabavi, Sayed AliThis work centres on comprehending and elevating the performance of Proton Exchange Membrane (PEM) hydrogen fuel cells, with a specific emphasis on minimizing pressure drop in the bipolar plate. Fuel cell efficiency hinges upon core factors, including electrochemical reaction, temperature, and pressure management. Notably, pressure drop within the fuel cell plays a pivotal role in determining overall efficiency and power output. The study aims to tackle the pressing issue of pressure drop, primarily manifested in the bipolar plate, profoundly affecting the fuel cell's output power. Researchers have pursued ground-breaking designs to curtail pressure drop and augment power output. However, certain advanced designs pose challenges in fabrication, leading to a research gap impeding the development of efficient models. To bridge this gap, the study proposes a novel and straightforward bipolar plate design, demanding minimal external power and eliminating the need for intricate geometries. Furthermore, apart from pressure drop, fuel cell inefficiencies are compounded by obstacles like inadequate meshing and porosity integrity of the end plates. Consequently, costly platinum and gold-plated end plates are often deployed to achieve superior output performance. The research reveals that velocity variations influence pressure within existing models, furnishing valuable insights for attaining improved efficiencies in fuel cells. The work presents a comprehensive analysis of PEM fuel cells, with particular attention to the bipolar plate's design and its ramifications on pressure drop. The proposed novel geometry aims to enhance fuel cell performance while addressing challenges linked to complex designs. The research findings offer valuable recommendations for optimizing fuel cell efficiencies, thereby contributing to the advancement of clean energy technologies.Item Open Access Understanding and predicting flow behaviour of water and air in serpentine pipes using machine learning and CFD modelling(Cranfield University, 2023-09) Sekar, Rajesh; Verdin, Patrick; Lao, LiyunThe flow behaviour of two-phase fluid (water and air) in serpentine pipes is complex and poorly understood. This study aims to address this research problem by using machine learning concepts to gain a deeper understanding of the flow behaviour and optimize the geometry of serpentine pipes. Experimental data from the Cranfield process engineering laboratory was used in this work, for a fixed pipe diameter and varying water and gas velocities. Regression models were developed and trained. The study aimed to accurately predict the pressure drop, void fraction and liquid film thickness in serpentine pipes in a timely manner with high accuracy. In addition, Computational Fluid Dynamics (CFD) models were developed to predict the flow behaviour with two different geometries, and machine learning was applied to determine the best model for capturing the intermediate geometry flow behaviour. Results provide valuable insights into the behaviour of two-phase fluid in serpentine pipes. The use of machine learning in this research contributes to the field by offering a new approach for optimizing the geometry of serpentine pipes with improved accuracy and efficiency. The findings demonstrate the potential for machine learning to play a role in improving our understanding of two-phase fluid flow in serpentine pipes. This research is expected to have potential future applications in various sectors, including automotive, electronics cooling systems, and industrial and chemical processing systems.