Browsing by Author "Alkhaledi, Abdullah N. F. N. R."

Now showing 1 - 9 of 9
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    Economic analysis of a zero-carbon liquefied hydrogen tanker ship
    (Elsevier, 2022-07-10) Alkhaledi, Abdullah N. F. N. R.; Sampath, Suresh; Pilidis, Pericles
    The green hydrogen economy is considered one of the sustainable solutions to mitigate climate change. This study provides an economic analysis of a novel liquified hydrogen (LH2) tanker fuelled by hydrogen with a total capacity of ∼280,000 m3 of liquified hydrogen named ‘JAMILA’. An established economic method was applied to investigate the economic feasibility of the JAMILA ship as a contribution to the future zero-emission target. The systematic economic evaluation determined the net present value of the LH2 tanker, internal rate of return, payback period, and economic value added to support and encourage shipyards and the industrial sector in general. The results indicate that the implementation of the LH2 tanker ship can cover the capital cost of the ship within no more than 2.5 years, which represents 8.3% of the assumed 30-year operational life cycle of the project in the best maritime shipping prices conditions and 6 years in the worst-case shipping marine economic conditions. Therefore, the assessment of the economic results shows that the LH2 tankers may be a worthwhile contribution to the green hydrogen economy.
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    Hierarchical zinc oxide nanobrushes ultraviolet photodetector
    (Wiley for Institution of Engineering and Technology (IET), 2022-07-12) Alenezi, Mohammad R.; Almeshal, Abdullah M.; Alkhaledi, Abdullah N. F. N. R.
    In order to synthesise hierarchical zinc oxide (ZnO) nanomaterials with a high surface-to-volume ratio, a well-controlled multistage hydrothermal method was developed. Hierarchical ZnO nanobrushes (ZNBs) built from initial mono-morphological nanomaterials, ZnO nanowires (ZNWs), and ZnO nanoplates (ZNPs) were developed using sequential nucleation and growth following a hydrothermal process. Hierarchical nanomaterials which are comprised of one-dimensional (1D) nanowire building blocks were obtained via a zinc ion source (zinc nitrate) during the second growth phase. In comparison to their first mono-morphological equivalents, the hierarchical nanomaterials which were grown showed improved ultraviolet (UV) detection, as well as improved sensitivity (∼104), an ultra-fast response time (235 ms), and a good recovery time (310 ms). Improvements to the response and recovery times were a result of distinct nanojunction barrier-dominated resistance. Moreover, the enhanced sensitivity of the ZNB photodetector (PD) was because of the reduced dimensionality and the ultrahigh surface-to-volume ratio. This work lays the groundwork for lower-cost, larger-scale, and lower-temperature production of high-performance nanostructured ZnO-based PDs on transparent and flexible substrates.
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    A hydrogen fuelled LH2 tanker ship design
    (Taylor and Francis, 2021-06-09) Alkhaledi, Abdullah N. F. N. R.; Sampath, Suresh; Pilidis, Pericles
    This study provides a detailed philosophical view and evaluation of a viable design for a large liquid hydrogen tanker fuelled by liquid hydrogen. Established methods for determining tank sizing, ship stability, and ship characteristics were used to evaluate the preliminary design and performance of the liquefied hydrogen tanker named ‘JAMILA’, designed specifically to transport liquid hydrogen. JAMILA is designed around four large liquid hydrogen tanks with a total capacity of ∼280,000 m3 and uses the boil-off gas for propulsion for the loaded leg of the journey. The ship is 370 m long, 75 m wide, and draws 10.012 m at full load. It has a fully loaded displacement tonnage of 232,000 tonnes to carry 20,000 tonnes of hydrogen. Its propulsion system contains a combined-cycle gas turbine of approximately 50 MW. The volume of the hydrogen cargo pressurised to 0.5 MPa primarily determines the size and displacement of the ship.
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    On-substrate fabrication of a self-activated nanostructured ZnO gas sensor
    (Royal Society of Chemistry, 2022-08-19) Alenezi, Mohammad R.; Almeshal, Abdullah M.; Alkhaledi, Abdullah N. F. N. R.
    Gaining rational control over bottom-up device fabrication processes is necessary to achieve high-performance devices and overcome technical obstacles. Among these is the need for activation of metal oxide gas sensors (GSs) by an external heating source, which limits their miniaturization and integration. A well-controlled, seedless, and position-selective hydrothermal method to fabricate high-performance self-activated zinc oxide (ZnO) nano-needle (ZNN) GSs directly on a substrate was developed. The morphology and position of the grown ZnO nanostructures were controlled by tuning the substrate coating and growth reaction parameters such as the growth solution concentration and the growth time, as well as introducing capping agents to the growth solution during the growth process. Furthermore, the efficiency of the fabricated device structure was improved and subsequently enhanced its performance substantially. Compared to other fabricated nanostructured ZnO GSs, the on-substrate fabricated bridging ZNN (BZNN) GS demonstrated superior sensitivity and self-activation, which were attributed to the reduction in the sensing material dimensions and ultrahigh surface-to-volume ratio, as well as the unique device structure with direct contact between ZnO and Au electrodes. This work paves the way for low cost, large scale, low temperature, seedless and position-selective fabrication of high-performance self-activated nanostructured ZnO GSs on flexible and transparent substrates.
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    Propulsion of a hydrogen-fuelled LH2 tanker ship
    (Elsevier, 2022-05-11) Alkhaledi, Abdullah N. F. N. R.; Sampath, Suresh; Pilidis, Pericles
    This study aims to present a philosophical and quantitative perspective of a propulsion system for a large-scale hydrogen-fuelled liquid-hydrogen (LH2) tanker ship. Established methods are used to evaluate the design and performance of an LH2-carrier propulsion system for JAMILA, a ship designed with four cylindrical LH2 tanks bearing a total capacity of ∼280,000 m3 along with cargo and using the boil-off as propulsion and power fuel. Additionally, the ship propulsion system is evaluated based on the ship resistance requirements, and a hydrogen-fuelled combined-cycle gas turbine is modelled to achieve the dual objectives of high efficiency and zero-carbon footprint. The required inputs primarily involve the off-design and degraded performance of the gas-turbine topping cycle, and the proposed power plant operates with a total output power of 50 M.W. The results reveal that the output power allows ship operation at a great speed even with a degraded engine and adverse ambient conditions.
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    Techno environmental assessment of Flettner rotor as assistance propulsion system for LH2 tanker ship fuelled by hydrogen
    (Elsevier, 2022-12-10) Alkhaledi, Abdullah N. F. N. R.; Sampath, Suresh; Pilidis, Pericles
    This study presents a novel design and development of a 280,000 m3 liquefied hydrogen tanker ship by implementing a set of 6 Flettner rotors as an assistance propulsion system in conjunction with a combined-cycle gas turbine fuelled by hydrogen as a prime mover. The study includes assessment of the technical and environmental aspects of the developed design. Furthermore, an established method was applied to simulate the LH2 tanker in different voyages and conditions to investigate the benefits of harnessing wind energy to assist combined-cycle gas turbine in terms of performance and emission reduction based on engine behaviour for different voyages under loaded and unloaded, normal as well as 6 % degraded engine, and varying ambient conditions. The results indicate that implementing a set of 6 Flettner rotors for the LH2 tanker ship has the potential to positively impact the performance and lead to environmental benefits. A maximum contribution power of around 1.8 MW was achieved in the winter season owing to high wind speed and favourable wind direction. This power could save approximately 3.6 % of the combined-cycle gas turbine total output power (50 MW) and cause a 3.5 % reduction in NOx emissions.
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    Techno-environmental assessment of a hydrogen-fuelled combined-cycle gas turbine for a liquid hydrogen tanker
    (Elsevier, 2022-08-27) Alkhaledi, Abdullah N. F. N. R.; Batra, Amit; Sampath, Suresh; Pilidis, Pericles
    The purpose of this study was a techno-environmental assessment analysis for a 280,000 m3 liquid hydrogen (LH2) tanker powered by a hydrogen-fuelled combined-cycle gas turbine (COGAS) as the prime mover. This study utilised established and reliable methods to simulate the LH2 tanker in different journeys and conditions for analysing the advantages of the hydrogen-fuelled COGAS in terms of performance and emission reduction. The assessment was based on engine behaviour on different journeys under cargo loaded and unloaded conditions, with a normal and a 6% degraded engine, and under various ambient conditions. According to the results, the single-pressure hydrogen-fuelled COGAS reached a maximum overall thermal efficiency of 55.5% in winter under unloaded and normal engine conditions at a ship speed of 18 knots during the journey from Marseille to Algeria. From an environmental perspective, the maximum NOx emission of the COGAS was 3.5 kg/h during the journey from Tangier to Southampton in summer with a 6% degraded engine under the loaded condition at a ship speed of 18 knots. The results of the techno-environmental assessment indicated that the LH2 tanker powered by the hydrogen-fuelled COGAS could successfully achieve high efficiency and low emission targets in off-design conditions. The outcome of this study will lead to a future investigation of the LH2 tankers operation economic aspects.
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    TERA of gas turbine propulsion systems for RORO ships
    (MDPI, 2023-08-08) Alzayedi, Abdulaziz M. T.; Alkhaledi, Abdullah N. F. N. R.; Sampath, Suresh; Pilidis, Pericles
    Recently, regulations on emissions produced by vessels from international maritime organizations, along with the instability of fuel prices, have encouraged researchers to explore fuels and technology that are cleaner than heavy fuel oil and diesel engines. In this study, we employed the TERA method to evaluate the feasibility of using gas turbine engines with cleaner fuels as a replacement for diesel engines as a propulsion system for RORO ships. A sensitivity evaluation and risk assessment were also conducted to investigate the impact of applied emission taxes on the economic results. The findings indicated that the diesel engine emitted higher nitrogen oxide emissions than the gas turbine fuelled by natural gas and hydrogen. The gas turbine with hydrogen had zero carbon dioxide emissions, making it a sustainable energy production option. The economic aspects were evaluated based on an international route, and they revealed that economic profitability significantly depended on fuel costs and consumption. The diesel engine fuelled by marine diesel oil and the gas turbine fuelled by natural gas were economically attractive, whereas the gas turbine fuelled by hydrogen was less viable due to its high operating cost. However, in a scenario where a carbon dioxide tax was introduced, the gas turbine fuelled by hydrogen showed high potential as a low-risk investment compared to the other technologies. In summary, this study demonstrated the usefulness of the TERA method in the maritime sector for selecting and comparing various propulsion systems.
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    ZnO nanoleaves with superior photodetection properties
    (Royal Society of Chemistry, 2022-07-19) Alenezi, Mohammad R.; Almeshal, Abdullah M.; Alkhaledi, Abdullah N. F. N. R.
    Controlled multiphase hydrothermal synthesis technique was developed to design and grow hierarchical zinc oxide (ZnO) nanostructures with high surface-to-volume ratio. ZnO nanoleaves (ZNLs) and nanoflakes (ZNFs) assembled from initial monomorphological nanostructures, ZnO nanowires (ZNWs), and ZnO nanodiscs (ZNDs), respectively. These hierarchical nanostructures with 2D nanosheets building blocks were obtained by sequential nucleation and growth following a hydrothermal process. Zinc sulphate was the source of zinc ions in the second growth phase. In comparison to their monomorphological counterparts, the hierarchically designed ZnO nanostructures demonstrated superior ultraviolet detection properties, an improved photosensitivity (∼105), and fast response-time (5 s) and fast recovery-time (1 s). The enhancement in photosensitivity of the ZNLs photodetector was ascribed to the reduced dimensions and increased surface-to-volume ratio. This work is part of the efforts leading the way toward low cost, large scale, and low temperature fabrication of high performance nanostructured ZnO PDs on flexible and transparent substrates.