20505 research outputs found
Sort by
Sensing charcoal making and understanding links to deforestation in Tanzania
No full textHarris, Neil R. P. - Associate Supervisor
Mead, Iq - Associate SupervisorCharcoal making produces atmospheric pollutants that have an impact on human
health. In Tanzania, charcoal making activity is widely spread and not properly
regulated. The spatial distribution of charcoal kilns is unknown, and this makes
management and control of such activity extremely difficult, especially in nature
reserves. The aim of this study was to advance current knowledge on
environmental impacts (i.e., deforestation and air quality) of charcoal making in
Tanzania. The specific objectives were, to develop a methodology to quantify
charcoal production emissions in ambient conditions; to identify areas of high-
density kilns and changes in charcoal production around the East Usambara
Mountains using GIS approaches; and to link charcoal production with catchment
impact and degradation. The data analysis involved the isolation of charcoal
emission plumes from other regionally important sources, the identification of
areas of high-density kilns and changes in charcoal production around east
Usambara mountains using GIS-based approaches and the link of charcoal
production with catchment environmental impacts. The statistical testing for
significant difference in the distribution of concentrations in the pre, during and
post periods was identified to comprehend the variation in the observed mean
across phases of the testing procedure. The results suggest that there were no
statistically significant differences between pre, during and post periods.
However, the sensor used in the study was effective in identifying pollutants in
tropical regions, despite calibration challenges. The study also identified the
sources of pollutants and their trajectories, with southern-eastern winds being a
significant factor. Human-induced activities and local emissions were found to
contribute to the pollution. The study analysed the emission ratios of pollutants,
but found insignificant links between CO and CO2, as well as PM1 and CO2.
Furthermore, this study establishes a connection between charcoal production
and negative effects on the East Usambara Mountain catchment area. The
research findings show that humid forest regions had a significant concentration
of proxy variables associated with charcoal production. The study also identifies
differences in charcoal-making activities among different forest regions. The
prevalence of dark patches indicates a high frequency of charcoal production in
the area. The study also reveals a decrease in the quantity of charcoal-making
activities between 2013 and 2015, followed by an increase from 2016 to 2019.
The study estimates that a significant amount of charcoal was produced, resulting
in the harvesting of many trees and the emission of CO and CO2. Overall, the
findings highlight the need for sustainable charcoal production practices to
mitigate the negative impacts on the surrounding environment. The findings
presented in this study demonstrate a mechanism that enables the
characterisation of and differentiation between charcoal burning and production
signatures. It is recommended that a citizen scale technique developed for
detection of emissions and consequence of charcoal making into the community.
To investigate strategies to move toward non-fossil fuel sources in Tanzania to
reduce pressure on the use of forest. To set up sound regulation around charcoal
making activities in Tanzania and development of approaches for sustainable
charcoal production in Tanzania.PhD in Environment and Agrifoo
Multi-fidelity investigation of low-reynolds number propeller for different design parameters
Get PDFThis paper presents a comparative multi-fidelity analysis of a small-scale UAV propeller (2-bladed, 0.3m diameter, NACA 4412 airfoil sections) operating at low Reynolds number. Three aerodynamic solvers, high-fidelity Lattice Boltzmann Method (LBM), mid-fidelity lifting-line free vortex wake (LLFVW) and mid-fidelity vortex lattice method (VLM), are evaluated across a broad range of advance ratios, number of blades, collective pitch settings, and skewed inflow angles. All methods predict consistent trends in thrust and torque as design and operational parameters are varied, with the mid-fidelity models closely replicating trends obtained using the high-fidelity LBM. LLFVW generally overestimates and VLM underestimates the magnitudes of thrust and torque relative to experiments (and LBM), but these biases remain approximately constant over the entire range of each parameter. By leveraging these mid-fidelity tools in place of expensive CFD, computational cost is reduced by over two orders of magnitude, with minimal loss of predictive capability. The results demonstrate that mid-fidelity simulations can reliably capture propeller performance trends at a fraction of the CPU cost, making them attractive for rapid design iterations and surrogate-based optimisation frameworks.This project has received funding from Innovate UK under Grant Agreement No 10003388.AIAA Aviation Forum and Ascend 202
Off-design performance control and simulation for gas turbine engines with sequential combustors
Get PDFA gas turbine engine with a sequential combustion system has the potential to offer high cycle efficiency at moderate turbine entry temperatures. Consequently, it has one more degree of power setting control, which offers more flexible but also more complex control of engine off-design operations. In this paper, a novel simulation method for off-design thermodynamic performance of sequential combustion gas turbines has been introduced and a novel performance control schedule for part-load operations at various ambient conditions have been proposed aiming to keep the relative workloads between the two turbine sections constant. The proposed control schedule is simple and can be adapted easily. By applying the off-design performance control schedule to a model industrial gas turbine engine with two sequential combustors, the performance of the model engine is simulated at different part-load and at different ambient conditions. The results show that by applying the proposed off-design performance control schedule, the model sequential combustion gas turbine engine could operate effectively at different part-load operating conditions and at different ambient conditions with both turbine sections keeping nearly constant workload distributions.Proceedings of the Institution of Mechanical Engineers, Part A: Journal of Power and Energ
Development of high-performance thermal shielding for space travel
Get PDFSkordos, Alexandros A. - Associate SupervisorAerogel is a fascinating material system with uniquely high porous structure,
consisting of 99.8% air, leading to properties with low density, high surface area
and low thermal conductivity. They have been used in numerous application such
as laser experiments, sensors (ultrasonic and gas), nuclear particle detection,
thermal insulation, waste management, high explosive research and X-ray
research. This thesis is focusing on the development of thermal insulation using
aerogel suitable for use in extreme environments, the evaluation of material is
obtained from the modelling dataset. Using the material properties from the
literature a 3D composite slab model is created using SOLIDWORKS and is been
analysed using ANSYS with environmental conditions. Numerous studies have
been accomplished with the coating preparation of aerogel and its application on
different materials. In this thesis, the material has been selected as a carbon-fibre
slab and the coating is done using aerogel supported with various binders.
Finally, from this thesis, a superlative binder is been found and discussed in the
results. The report demonstrates the novel technique to coat aerogel on top of a
composite without losing its properties and offering a way towards rapid
manufacture of these advanced structures.MSc by Research in Manufacturin
Critical factors influencing biohythane production from research to commercialization
Get PDFThe shift from fossil-derived energy to clean, renewable sources has accelerated due to the demand for sustainable and commercially viable energy solutions. Another possible clean fuel is biohythane, also known as HCNG, which is a blend of bio–CH4 and bio–H2 with a concentration of 10 and 30 % v/v, respectively. The chemical industries have eventually been utilizing bio–CH4 and bio–H2 extensively because of their high calorific values of 143 and 55 kJ g−1, respectively. The bio–H2 and bio–CH4 have been emerged as promising green energy carriers, offering a broad range of applications in chemical industries, owing to their high calorific value, renewability, and CO2 neutrality. In the pursuit of zero-emission technologies to mitigate the global warming, biohythane is gaining attraction as a potential future fuel. This study explores biohythane production through a sequential two–stage process that converts organic wastes into bio–H2 and subsequently into bio–CH4, offering an ideal pathway for sustainable biohythane generation. Further, this study provides an overview of key developments and applications in two–stage microbial synthesis of bio–CH4 and bio–H2, alongside insights into the demand, supply, and current global status of biohythane production. This study delves into the acidogenic phase, where bio–H2 is produced, and the methanogenic phase, which yields bio–CH4. While detailing the biochemistry, critical factors, challenges, and limitations of an integrated bio–hythane production system are discussed. Finally, the strategies for enhancing bio–H2 and biohythane production and an outlook on their commercialization potential are discussed.Energ
Design challenges and preliminary test results of a high temperature supercritical carbon dioxide dry gas seal test rig
Get PDFSupercritical carbon dioxide (sCO2) has shown a high potential in power generation cycles to increase thermal efficiency and decrease the physical footprint. Supercritical CO2 power cycles operate at relatively high temperatures compared to steam and air, necessitating the development of new sealing materials. In this paper, the design challenges, development and preliminary test results of a 500oC, 200 bar sCO2 dry gas seals test rig are presented. The main rig components are pressure control devices (liquid pump and expansion valves), heat exchangers (liquid condenser, gas heaters, and air cooler), and measuring instruments. Various design challenges are identified due to the thermo-physical properties as well as the operating conditions of the sCO2 test rig such as the ice formation during start-up, heat loss to the ambient air, and material compatibility with the various test rig components. A thermodynamic design model has been developed to size the test rig components and estimate the gas conditions across the rig. The model includes tube and valve sizing, heat exchanger design, and thermal insulation models. The initial phase of the test campaign was conducted at Cranfield University (CU) to verify the ability of the test rig to deliver sCO2 at the required conditions and to validate the developed numerical models. The results showed the validity of the proposed setup to supply sCO2 steadily at 500oC and 200 bar at a flow rate of 15 kg/h. The heat exchanger model applied to a finned tube bundle air cooler showed close estimations to the test results with a maximum deviation in the heat capacity of 2.3%. The thermal insulation model including the heating tape showed reasonable predictions for the temperature rise across the heating sections with a maximum deviation from the experimental measurements of 10oC when the temperature rise was around 240oC. The suitability of using rock wool insulation and stainless steel 316 tubes with dry CO2 at 500oC was verified.This research was funded by the Department for Energy Security and Net Zero (DESNZ) under its grant funding agreement for Carbon Capture, Usage, and Storage Innovation 2.0, Project Reference CCUS 2108: "Innovative High-Temperature Sealing Solution for Supercritical CO₂ Power Cycles."6th European Conference on Supercritical CO2 (sCO2) for Energy System
Thermoelectric materials with high surface area for the application of thermoelectric promotion of catalysis
Get PDFLeighton, Glenn - Associate SupervisorThermoelectric materials have been used for generating electricity from a
temperature difference and noiseless cooling from electricity for several
decades, but their application in the field of catalysis is still in its infancy. In fact,
only a few years ago my supervisor and his colleagues used thermoelectric
materials as a catalyst support and promoter for the first time in the world, and
discovered that a Seebeck voltage can increase the catalytic activity by several
tens to hundreds of times, and called this effect thermoelectric promotion of
catalysis (TEPOC), or thermoelectrocatalysis. This effect has since been
confirmed by other people in the world. This work aims to investigate other
fundamental aspects of the application of thermoelectric materials for catalysis
promotion, e.g., how to combine high surface area porous structure, how to
achieve highest possible temperature difference in a given reaction chamber,
and whether it is possible to use other thermoelectric materials which can work
at high temperatures, for the thermoelectric promotion of catalysis.
Numerical modelling has been used to simulate the transient thermal behaviors
of thermoelectric materials in a custom-made reaction chamber during a typical
chemical reaction run, and the modelling results were used to guide the sample
design. Firstly, thicker sample was found to generate higher Seebeck voltage.
Secondly, stacked samples were found to have the similar promotional effect
as if it is one single sample. The second point also enables the sample to be
consisted of a dense bulk and porous surface sample, so that both the high
Seebeck voltage and high surface area for the sample could be achieved for a
stacked sample.
Sol-gel technique and the addition of polymer particles to thermoelectric
powders have been used to obtained porous high surface area thermoelectric
materials. Their microstructural and thermal transport properties have been
characterized and their effect for the application of TEPOC on the reverse
water-gas shift (RWGS) reactions has been investigated. Generally speaking,
the porous sample has a much higher (>10 times) surface area than their non-
porous counterparts, but possesses much lower Seebeck coefficient. This
leads to a modest improvement of catalysis promotion as compared to the non-
porous ones. The previously observed TEPOC dynamic rate equation, i.e., the
linearity between the promotional ratio and the Seebeck voltage, was proved to
be effective for porous thermoelectric materials.
A new Figure of merit for thermoelectric materials for the application of TEPOC,
has been proposed as S/κ, here S is the Seebeck coefficient and κ the thermal
conductivity of the thermoelectric material. This Figure of merit is different from
the usual dimensionless Figure of merit ZT which is best for the indication of
energy conversion efficiency. A comprehensive literature survey has been
carried out and it was found out that among all the non-single crystal
thermoelectric materials, the previously used BiCuSeO have the highest S/κ,
and another oxide Ca₃Co₄O₉ systems which are stable at very high
temperatures also have a high S/κ. Following this, thermoelectric
Ca₂.₆Tb₀.₄Co₄O₉ samples were prepared and applied in CO₂ hydrogenation
reactions. The results reveal a strong enhancement in Seebeck coefficient by
doping Tb into Ca₃Co₄O₉, while Ca₂.₆Tb₀.₄Co4O₉ samples showed excellent
stability at the range of 373K-1073K. A highest CO₂ conversion of 64% was
obtained from Ca₂.₆Tb₀.₄Co₄O₉ samples at 700K and inlet gas ratio H₂:CO₂=3:1.
In summary, the high catalytic activity of porous BiCuSeO samples
demonstrates the great potential of combining high porosity with the
thermoelectric materials in the application of TEPOC. In the meantime, the use
of Ca₂.₆Tb₀.₄Co₄O₉ enables higher temperature range in the field of TEPOC
application.PhD in Manufacturin
Schistosomiasis and water resources development in Africa: a scoping review and multi-case evaluation of associated snail control
Get PDFBackground
Water resources development (WRD), specifically infrastructural man-made water bodies such as dams and irrigation schemes, are built to improve water supply, provide energy, and enhance food security. However, dams and irrigation schemes may lead to a dramatic increase in the prevalence of schistosomiasis.
Methodology/Principal findings
We conducted a scoping review of WRD impacts on schistosomiasis transmission risk in Africa using electronic databases including Scopus, Web of Science, and grey literature. From 1483 retrieved records, we assessed 186 full-text papers and identified 122 articles covering 54 dams and irrigation schemes in 32 African countries. We found that, although the relationship between WRD and schistosomiasis transmission risk is well-documented in the scientific literature, the vast majority of the approximately 1,600 medium- to large-sized dams currently operating in endemic regions of Africa lack before-and-after prevalence data necessary to evaluate their actual impact on schistosomiasis transmission. Our analysis revealed that rigorous epidemiological data to assess WRD’s effects exist for only 11 dams across 9 countries. Additionally, only a limited number of studies provided information on schistosomiasis control methods, surveillance, or monitoring for WRD. Few countries have implemented engineering and biological snail control measures, some of which have proven effective, enabling us to identify successful interventions employed at various stages of the WRD lifecycle. Lastly, to assess these measures in detail, we selected case studies from Africa that illustrate the success and challenges of schistosomiasis control with regard to WRD, thus gaining insights of the global relevance of lessons learnt for the future development of water resources.
Conclusions/Significance
Our analysis highlighted that an integrated and coordinated approach is vital for the successful control of schistosomiasis transmission risk associated with Water Resources Development. We provide key recommendations which could be adopted by the Continental Africa Water Investment Programme (AIP) with the ultimate goal of decreasing prevalence and moving towards elimination.This work was supported by the UK Engineering and Physical Sciences Research Council (EPSRC) Impact Acceleration Award block grant allocation to Cranfield University (grant # EP/X525534/1 to MNS).Belmont Collaborative Forum on Climate, Environment and Health; NSF grant # 2522282, NSF grant #DEB – 2011179)PLOS Neglected Tropical Disease
Techno-economic assessment of an integrated GTL facility for urea production
No full textDecarbonising industrial processes remains a critical challenge, particularly in gas-to-liquid (GTL) and chemical manufacturing sectors. This study conducts a comprehensive techno-economic assessment of an integrated GTL-urea facility that leverages hydrogen from Fischer-Tropsch (FT) tail gas and green hydrogen via proton exchange membrane (PEM) electrolysis. Using ASPEN Plus simulations, process synergies, emission reductions, and profitability are analysed across multiple configurations. Key findings indicate that utilising internally generated hydrogen is more cost-effective, achieving a 4 % reduction in equipment costs, lowering total equipment cost from 2.47 billion. This results in a total annualised cost saving of 412 million in the base case to $543 million.
The integration efficiently repurposes CO₂ emissions and nitrogen-rich waste streams to produce urea, demonstrating strong potential for promoting circularity . It enhances carbon efficiency to 84 % reducing overall emission from 180 tonnes CO2e/h in the business-as-usual case to 135 tonnes CO2e/h while PEM-based hydrogen reduces emissions by 14 tonnes CO2e/h compared to internally generated hydrogen. The high capital and operational costs due to electricity demands for PEM-based hydrogen process limit its viability. The study identifies the 9 tonnes/h internally generated hydrogen configuration as the optimal solution, offering significant emission reductions and financial benefits. These findings highlight the importance of process integration, renewable energy, and advanced hydrogen strategies for industrial decarbonisation, providing a sustainable pathway for GTL and urea production in line with global net-zero goals.Journal of CO2 Utilizatio
Applying artificial neural networks for multidimensional anomaly detection based on flight data monitoring during final approaches
Get PDFFlight Data Monitoring (FDM) programmes have become a key part of every major airline’s safety management system. They are primarily based on learning from unwanted deviations in flight parameters encountered during normal flight operations. Owing to its unique nature, anomaly detection of FDM presents distinct problem complexities from the majority of analytical and learning tasks. This methodology, while useful, concentrates only on a small part of the operation, leaving most of the data unprocessed, and does not allow for analysing events that had the potential to go wrong but were recovered in time by the crews. This research focused on analysing an FDM dataset of 1332 approaches between January 2018 and July 2022 at Tenerife South Airport (Spain), where there is a known phenomenon of increasing headwinds during the final approach. The flights were clustered using self-organising maps (SOM) by patterns of increasing headwinds, and the clusters were assessed in terms of clustering performance. The clusters were well differentiated. A further comparison between the results from the airline showed that 88 flights were affected by wind shifts, while 27 flights were picked up by the airline. The results demonstrate that SOMs are a meaningful tool for clustering flight data and can complement the current FDM analysis methodology. Combining both methodologies could shift FDM data analysis to look beyond exceedances into what went well, thus shifting the FDM paradigm towards a more safety-II-based method.The Aeronautical Journa