Browsing by Author "Lao, Liyun"
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Item Open Access A three-step weather data approach in solar energy prediction using machine learning(Elsevier, 2024-09) Falope, Tolulope Olumuyiwa; Lao, Liyun; Hanak, DawidSolar energy plays a critical part in lowering CO2 emissions and other greenhouse gases when integrated into the grid. Higher solar energy penetration is hindered by its intermittency leading to reliability issues. To forecast solar energy production, this study suggests a three-step forecasting method that selects weather variables with a moderate to strong positive correlation to solar radiation using Pearson correlation coefficient analysis. Low-level data fusion is used to combine weather inputs from a reliable local weather station and an on-site weather station, significantly improving the forecasting model's accuracy regardless of the machine learning method used. Weather data was obtained from the Kisanhub Weather Station located in Cranfield University, UK and the meteorological station in Bedford, UK. In addition, PV power supply data was obtained from four solar plants. Using the Regression Learner app in MATLAB, the proposed architecture is tested on a utility scale solar plant (1 MW), showing a 6% and 13% prediction accuracy improvement when compared to solely using data from the on-site and local weather station respectively. It is further validated using data from three residential rooftop solar systems (8 kW, 10.5 kW and 15 kW), achieving root-mean square values of 0.0984, 0.0885, and 0.1425 respectively. The data was pre-processed using both rescaling and list-wise deletion methods. Training and testing data from the 1 MW solar plant was divided into 75% and 25% respectively, while 100% of the residential rooftop solar plants was used for validation.Item Embargo An improved energy management system framework for solar energy integration.(Cranfield University, 2024-05) Falope, Tolulope Olumuyiwa; Lao, Liyun; Huo, DaRenewable energy sources like wind and solar play a crucial role in decarbonizing energy supply, but their variable and intermittent nature lead to reliability and stability issues. One way of sustainably integrating these energy sources into the grid is through an energy management system. The study reported in this thesis gives a comprehensive definition of an integrated energy management system and creates a novel framework that identifies energy forecasting, demand-side management, and supply-side management, as crucial components for grid balancing. In addition, this research looks particularly at solar integration, and how the integrated energy management system offers a unique combination of solar energy forecasting, time-of-use tariffs, direct load control demand response, and generator control, in increasing penetration levels of solar energy. The significance of this research is that the proposed system presents a viable, sustainable, and cheaper way of increasing PV usage and thereby grid penetration by prioritising efficient use of available PV supply before calling up additional supply. To validate the proposed integrated energy management system, this research looks to understand the functions of each individual component and how their interconnectedness creates a novel management system. Firstly, this research develops a three-step solar forecasting approach that uses low-level data fusion to combine weather variables from both an on-site and a local weather station to improve solar energy forecasting. The forecasting model response is historic PV generation, and the predictors are weather variables with moderate to strong positive correlations to solar radiation. Data obtained is preprocessed using Low-level Data Fusion, Pearson Correlation Coefficient analysis, Rescaling method, and List-wise Deletion method. This approach is then tested on a 1MW utility scale solar plant, resulting in a 6% and 13% prediction accuracy improvement when compared to solely using data from an on-site, and local weather stations respectively. This approach is also validated for three residential rooftop solar systems (8 kW, 10.5 kW and 15 kW), achieving root mean square error values of 0.0984, 0.1425, and 0.0885 respectively. The resulting low root mean square error values, a measure of the predicted PV to actual PV generation, proves that the model can be adopted for different PV plant sizes and is suitable for any customer across the distributed generation spectrum. To further improve the accuracy of the model, other preprocessing techniques are investigated and applied. The study shows that the combination of Low-level Data Fusion, Linear Interpolation, filling outliers, data smoothing, Rescaling method, moderate to strong PV correlation of weather parameters using Pearson Correlation Coefficient, day/time/month decomposition, seasonal decomposition, Principal Component Analysis, and holdout validation, increases the accuracy of the model by 75%. The ability of direct load control to manage energy consumption is validated in a case study by using Connected Power’s unique smart sockets and Lumen radio’s Mira Mesh Radio Frequency wireless network. Small plug-in loads were connected to ten smart sockets located in a robotics laboratory and a café, resulting in reduced energy consumption by 44% and 72% respectively when compared to the baseline without direct load control. Finally, the integrated energy management system framework is validated by testing its capacity to increase PV usage for an off-grid residential house with a PV/diesel generator power source. A decision-based algorithm is created that adjusts PV supply forecast errors, initiates direct load control responses to reduce excess load during periods of low PV supply, and/or increase power supply by calling up a diesel generator. In addition, this is combined with the proposed three-step solar energy forecasting approach and a programmable load schedule based on time-of-use criteria. The effects of customer behaviour are also analysed by using a 14% override rate, with 80% preconditioning and 20% rebounding. The hybrid PV/diesel generator power source with the proposed integrated energy management system is compared against two configurations: a baseline configuration that uses a solely diesel generator source, and a hybrid PV/diesel generator power source. Results show that the integrated energy management system reduced the lifetime expenditure costs and CO2 emissions by 44% and 46% respectively when compared to the baseline configuration, and by 8% and 9% in the hybrid photovoltaic/diesel generator, while also increasing the PV usage from this configuration by over 113%. This research also addresses opportunities and limitations of the proposed system and lays the foundation for future research using other intermittent renewable energy sources such as wind.Item Open Access Behaviour of Water in Aviation Fuels at Low Temperature(2011-12-07T00:00:00Z) Carpenter, Mark D.; Hetherington, Janice I.; Lao, Liyun; Ramshaw, C.; Yeung, Hoi; Lam, Joseph K.-W.; Masters, Simon; Barley, Sarah; Morris, R. E.Item Open Access Canonical variate analysis for performance degradation under faulty conditions(Elsevier, 2016-06-01) Ruiz Cárcel, Cristóbal; Lao, Liyun; Cao, Yi; Mba, DavidCondition monitoring of industrial processes can minimize maintenance and operating costs while increasing the process safety and enhancing the quality of the product. In order to achieve these goals it is necessary not only to detect and diagnose process faults, but also to react to them by scheduling the maintenance and production according to the condition of the process. The objective of this investigation is to test the capabilities of canonical variate analysis (CVA) to estimate performance degradation and predict the behavior of a system affected by faults. Process data was acquired from a large-scale experimental multiphase flow facility operated under changing operational conditions where process faults were seeded. The results suggest that CVA can be used effectively to evaluate how faults affect the process variables in comparison to normal operation. The method also predicted future process behavior after the appearance of faults, modeling the system using data collected during the early stages of degradation.Item Open Access Character and interface shear strength of accreted ice on subcooled surfaces submerged in fuel(Cambridge University Press, 2016-01-27) Lam, Joseph K.-W.; Lao, Liyun; Hammond, David W.; Power, J. P.Sudden release of accreted ice in fuel systems could pose a serious challenge in aircraft operation. The resultant snowshower may reach the filter and fuel-oil heat exchanger, causing a restriction in fuel flow to the engine. It is fundamental to have an appreciation of the character and the interface shear strength of the accreted ice in aircraft fuel systems. This helps to recognise factors for the sudden release of the accreted ice and the intensity of the consequential snowshower. An experimental study was carried out to quantify the character and the interface shear strength of accreted ice on subcooled surfaces submerged in jet fuel. Ice was accreted on naked aluminium, painted aluminium and carbon fibre composite surfaces at various subcooled temperatures. The accreted ice was akin to fresh snow and exhibited soft and fluffy attributes. The character may be expressed quantitatively in terms of the porosity and was found to be c. 0·95. The ice weakly adhered to the substrate surfaces, and the interface shear strength was found to be c. 0·36Pa and c. 2·19Pa at the top surface and at the vertical surface of a specimen block, respectively. It was not possible to detect any variation in the porosity and the interface shear strength for different types of surface finishes and differences in water affnity in fuels due to the crude approach in the estimation of these parameters.Item Open Access Characterization of gas-liquid flows in annuli.(2019-07) Eyo, Edem Nsefik; Lao, Liyun; Falcone, GioiaGas–liquid two–phase flow in annulus is encountered during certain operations in the nuclear, chemical and petroleum industries. In the Oil and Gas industry, the knowledge of gas liquid two-phase flow in annuli is important during underbalanced drilling of wells and hole clean operations. This technique offers several advantages over the conventional drilling method including reducing formation damage, preventing fluid losses and enhancing the safety and efficiency of operation. Proper design of underbalanced drilling operations hinges on the accurate prediction and monitoring of gas-liquid two-phase flow parameters such as flow regimes, liquid holdup and pressure drop; however the complexities associated with two-phase flows coupled with complex geometry makes this difficult. Limited studies exist in literature for gas-liquid flow hydraulics in horizontal annuli and no studies have been undertaken on the effects of annulus eccentricity on two-phase flow parameters including flow regimes, liquid holdup and pressure drop. In order to provide an improved fundamental understanding of gas-liquid two-phase flow in horizontal annulus and give insight necessary for accurate model development, detailed systematic experimental studies are conducted at atmospheric conditions in horizontal concentric and fully eccentric annulus formed using a 3 inch outer and 2 inch inner pipes. Flow parameters including flow regimes, liquid holdup and pressure drop are investigated using high speed camera, conductance probes and pressure transducers, with air and water as testing fluids. Results show that annulus eccentricity affects the flow regimes, liquid holdup and pressure drop. Predictive models are compared with experimental data and new models are proposed for flow regime identification and liquid holdup prediction, while a new real-time objective flow regime identification tool is developed using Support Vector Machine (SVM). The data generated from this study can be used for developing models which would be incorporated into commercial software for study of flow through annulus.Item Open Access Characterization of two-phase flow in a typical metrological test flow loop.(Cranfield University, 2022-09) Egbue, Jude; Lao, Liyun; Bortone, ImmaThe understanding of the flow behaviour such as the flow regimes is important in multiphase flow metering for verification of the test meters especially during the reproducibility tests, as the meter could be transferred among different test flow loops or moved from one location to another within a flow loop. As the pipe geometry and configurations may vary for different testing laboratories and on the field, proper understanding of effect of geometrical variances on multiphase flow behaviour is deemed important for proper assessment of multiphase flow meter (MPFM) performance and as well developing testing protocols for commercial flow meters. To improve the performance assessment of MPFM, adequate understanding of the influence of pipe configurations on multiphase flow behaviour in a typical multiphase flow loop is important in order to design a flow loop for the purpose of calibration and validation of MPFM. To obtain this knowledge, a systematic study of flow characteristics transitioning from the horizontal to the vertical section in a typical MPFM testing installation with varying upstream and downstream configuration is needed to provide guidance on proper designing of MPFM calibration flow loop. To this aim, an experimental study was carried out in a typical MPFM flow loop which consists of 19.2 m long horizontal section followed by a 2.6 m long vertical section. All the sections are at industrial scale, being made of inner diameter (ID) of 0.077 m clear PVC pipe that allows for gas-liquid two-phase flow behaviour to be observed and determined. The alteration of upstream and downstream geometries of the flow loop are also carried out to investigate the effect of geometrical variances on the flow. Air and water are the fluids used for this study. The result of the study showed that the pipe configuration has significant effect on smooth stratified flow. The stratified flow regime observed in conventional straight pipe in horizontal section for low superficial velocities was observed to be absent in the present work. Instead, unstable wavy-slug (UWS) flow regime was observed. None of typical horizontal flow regime maps considered in this work were able to correctly predict UWS flow regime. The void fraction in the horizontal section was observed to be influenced by the pipe configuration due to liquid accumulation in the horizontal section. This could contribute to measurement uncertainties of phase fractions in the horizontal section. Analyses of the experimental results showed that no significant change in flow regimes was observed in the horizontal section with different development lengths of 100D and 200D (D is the pipe diameter) from the gas injection points. This suggests that a length of 100D may be sufficient development length for air-water two-phase flow in the horizontal section for such flow loop. Furthermore, more liquid accumulation is observed in 200D as compared with 100D case, which leads to lower void fraction in 200D development length. Downstream effect of the pipe configuration due to backward flow of the liquid phase was noticed to have significant effect on the flow structure in the horizontal section as observed in the probability density function (PDF) signature of the flows. The experimental investigation of effect of blind tee length on pressure fluctuation has shown that the 90-degree bend (equivalent to a blind length of 0D) has the highest-pressure fluctuation while the blind tee with 0.154 m clearance (2D length) has the lowest pressure fluctuation. The magnitude of pressure fluctuation is observed to be higher for intermittent flows than that of separated flows. The influence of blind tee length on pressure fluctuation tends to decrease with distance away from the blind tee in straight pipes. A set of guidelines for the MPFM test flow loop were proposed based on the outcome of the current studies.Item Open Access Comparative analysis of riser base and flowline gas injection on vertical gas-liquid two-phase flow(MDPI, 2022-10-10) Brini Ahmed, Salem K.; Aliyu, Aliyu M.; Baba, Yahaya D.; Abdulkadir, Mukhtar; Abdulhadi, Rahil Omar; Lao, Liyun; Yeung, HoiGas injection is a frequently used method for artificial lift and flow regime rectification in offshore production and transportation flowlines. The flow behaviour in such flowlines is complex and a better understanding of flow characteristics, such as flow patterns, void fraction/hold up distributions and pressure gradient is always required for efficient and optimal design of downstream handling facilities. Injection method and location have been shown to strongly affect downstream fluid behaviour that can have important implications for pumping and downstream facility design, especially if the development length between pipeline and downstream facility is less than L/D = 50 as reported by many investigators. In this article, we provide the results of an experimental investigation into the effects of the gas injection position on the characteristics of the downstream upwards vertical gas flow using a vertical riser with an internal diameter of 52 mm and a length of 10.5 m. A horizontal 40-m-long section connected at the bottom provides options for riser base or horizontal flow line injection of gas. The flowline gas injection is performed 40 m upstream of the riser base. A 16 by 16 capacitance wire mesh sensor and a gamma densitometer were used to measure the gas-liquid phase cross-sectional distribution at the riser top. A detailed analysis of the flow characteristics is carried out based on the measurements. These include flow regimes, cross-sectional liquid holdup distributions and peaking patterns as well as analysis of the time series data. Our findings show that flow behaviours differences due to different gas injection locations were persisting after a development length of 180D in the riser. More specifically, core-peaking liquid holdup occurred at the lower gas injection rates through the flowline, while wall-peaking holdup profiles were established at the same flow conditions for riser base injection. Wall peaking was associated with dispersed bubbly flows and hence non-pulsating as against core-peaking was associated with Taylor bubbles and slug flows. Furthermore, it was found that the riser base injection generally produced lower holdups. It was noted that the circumferential injector used at the riser base promoted high void fraction and hence low liquid holdups. Due to the bubbly flow structure, the slip velocity is smaller than for larger cap bubbles and hence the void fraction is higher. The measurements and observations presented in the paper provides valuable knowledge on riser base/flowline gas introduction that can directly feed into the design of downstream facilities such as storage tanks, slug catchers and separators.Item Open Access A comprehensive assessment of correlations for two-phase flow through Venturi tubes(Elsevier, 2020-04-17) Liu, Xiaolei; Lao, Liyun; Falcone, GioiaThe objective of this study is to comprehensively evaluate established correlations for two-phase (gas-liquid) flow through Venturi tubes. Two-phase flow metering plays a critical role in the oil and gas industry and several commercial metering solutions incorporate a Venturi. However, despite its significance, there is no widely accepted standard for two-phase flow metering applications. In this paper, sixteen differential pressure correlations are critically assessed from literature and international standards, focusing on the Venturi tube. The discussions are supported by an independent dataset obtained from a two-phase flow test rig with an installed Venturi tube (following ISO 5167-4 2005) to assess correlations' performance within their own respective application range. The wide literature review and the obtained comparison results trended to inform that the homogeneous model performs better in most scenarios.Item Open Access Data: Two-phase Gas-Liquid Flow Regimes Identification in an S-shape Pipeline-Riser Using Doppler Ultrasonic Sensor(Cranfield University, 2023-09-08 15:29) Godfrey Nnabuife, Somtochukwu; Whidborne, James; Lao, LiyunDifferent flow regime data was generated experimentally at Cranfield University using a 2-inch multi-phase flow S-shape pipeline-riser test loop. In order to obtain the desired flow regime condition, the air-water flow rate was automatically regulated using the DeltaV system. Allfiles.Mat contains all the Air (Sm3/hr) - Water (Kg/s) flow regime conditions investigated. The data was recorded using the LabVIEW program but converted to a MATLAB file for easy access. All the flow conditions that fall under category 1 are in slugging condition, all that fall into category 2 are in bubbly condition, the ones that fall under category 3 are in churn flow condition and the ones that fall under category 4 are in annular flow condition. Data_wave2.mat is also a MATLAB file that contains all the flow conditions investigated. It contains the same data as in Allfiles.mat. You can use either Data_wave2.mat or Allfiles.mat files.Item Open Access A dead reckoning localization method for in-pipe detector of water supply pipeline: an application to leak localization(Elsevier, 2020-12-09) Wang, Wenming; Yang, Dashan; Zhang, Jifeng; Lao, Liyun; Yin, Yuanfang; Zhu, XiaoxiaoUrban water supply pipeline system integrity is important for the urban life. The aim of the study reported in this paper is to locate the water pipeline leaks by using an in-pipe detector. In this study, a mathematical model is extracted from an actual inspection system. By using the homogeneous transformation theory, transformation matrix which is from carrier to a reference coordinate system is deduced, and then the global transformation matrix is obtained to describe the detector’s posture. Through measuring the distance increment of each sample time step in carrier coordinate system, the cumulative distance result is calculated. After combining the data of the inertial measurement unit (IMU) and odometer, the leak can be located. To improve the accuracy of leak localization, the magnetic markers are implemented about one in each 1 km distance, which provide reference points to be used to compensate accumulative error during the localization process. Furthermore, a dead reckoning localization method combining data of a micro electro-mechanical IMU, three odometers, and magnetic markers is proposed. To verify above localization algorithm, a simulation case study is conducted with the artificial error generated by the white noise. The simulation results show that the dead reckoning algorithm can effectively provide leak locations with a reasonable uncertainty. Based on this, an experimental platform was built in this study. The experimental results show that the relative error of leak locating achieves a reasonably good performanceItem Open Access Development of a real-time objective gas-liquid flow regime identifier using kernel methods(IEEE, 2019-04-22) Eyo, Edem; Pilario, Karl Ezra; Lao, Liyun; Falcone, GioiaCurrently, flow regime identification for closed channels have mainly been direct subjective methods. This presents a challenge when dealing with opaque test sections of the pipe or at gas-liquid flow rates where unclear regime transitions occur. In this paper, we develop a novel real-time objective flow regime identification tool using conductance data and kernel methods. Our experiments involve a flush mounted conductance probe that collects voltage signals across a closed channel. The channel geometry is a horizontal annulus, which is commonly found in many industries. Eight distinct flow regimes were observed at selected gas-liquid flow rate settings. An objective flow regime identifier was then trained by learning a mapping between the probability density function (PDF) of the voltage signals and the observed flow regimes via kernel principal components analysis (KPCA) and multi-class Support Vector Machine (SVM). The objective identifier was then applied in real-time by processing a moving time-window of voltage signals. Our approach has: (a) achieved more than 90% accuracy against visual observations by an expert for static test data; (b) successfully visualized conductance data in 2-dimensional space using virtual flow regime maps, which are useful for tracking flow regime transitions; and, (c) introduced an efficient real-time automatic flow regime identifier, with only conductance data as inputsItem Open Access Development of an integrated energy management system for off-grid solar applications with advanced solar forecasting, time-of-use tariffs, and direct load control(Elsevier, 2024-06-19) Falope, Tolulope Olumuyiwa; Lao, Liyun; Huo, Da; Kuang, BoyuEffectively managing and maximizing the integration of renewable energy sources is essential for a sustainable power grid due to the stochastic and intermittent nature of renewable energy generation. This study develops a comprehensive Integrated Energy Management System incorporating supply-demand side management in the form of time-of-use credit, direct load control, and generator control to enhance photovoltaic utilization in off-grid applications. A novel three-step solar energy forecasting approach is proposed in this paper, utilizing low-level data fusion and regression models to predict next-day photovoltaic generation with improved accuracy, and a rule-based decision algorithm is developed to correct forecast errors and manage loads dynamically. A techno-economic analysis covering a 20-year duration is carried out for scenarios with and without the integrated energy management system; three configurations are investigated for supplying an off-grid residential home, including diesel generator, diesel generator/photovoltaic system, and diesel generator/photovoltaic system/integrated energy management system. Results reveal that the hybrid configuration with integrated energy management system achieved 44 % and 46 % reductions in costs and carbon dioxide emissions compared to the diesel generator alone, and 8 % and 9 % compared to the diesel generator/photovoltaic setup respectively. The Integrated Energy Management System further enhanced photovoltaic utilisation rate by over 113 % when compared to the diesel generator/photovoltaic system. Further evaluations include customer behaviour impacts, demonstrating that a fully automated system with 100 % compliance significantly outperforms systems with manual customer control, highlighting the detrimental effect of overrides on the efficiency of direct load control. The flexibility of the Integrated Energy Management System framework allows potential adaptation for on-grid applications, showcasing its utility in diverse operational contexts.Item Open Access Devices and methods for wet gas flow metering: a comprehensive review(Elsevier, 2024-01-07) Salehi, Seyed Milad; Lao, Liyun; Xing, Lanchang; Simms, Nigel; Drahm, WolfgangWet gas is commonly encountered in various industries, including energy, chemical, and electric power sectors. For example, natural gas extracted from production often contains small amounts of liquid, such as water and hydrocarbon condensates, which classifies it as wet gas. The presence of liquid within the gas poses challenges for accurate flow measurement. To improve the performances of wet gas flow metering methods, significant research and development efforts have been invested into the wet gas flow metering technologies due to their vital importance in the production, transfer, and trade benefits. This paper presents a comprehensive overview of the recent development of wet gas flow metering. Firstly, a comprehensive discussion of the Lockhart-Martinelli parameter (Xlm) and its relation to the gas void fraction (Óg) is presented, which was mostly overlooked in previous wet gas research work. The occurrence of various flow patterns in wet gas conditions at different orientations (horizontal and vertical) was explored. Following an investigation of pressure impact on the wet gas flow patterns and development of the wet gas regions, a different test matrix for further research work was suggested. After a novel classification of wet gas measurement methods, the paper offers a detailed comparison of differential pressure (DP) meters including Venturi, Cone meter, and orifice meters, by considering both liquid and gas flow rate measurements. Secondly, the paper discusses and compares vortex flow meters, Coriolis and ultrasonic meters in comparison to DP meters. Notable phase fraction meters are also examined and compared to one another. Thirdly, the paper reviewed the concept of existing and potential hybrid wet gas meters, conducting a detailed discussion and comparison with commercial solutions by evaluating their ranges and accuracies. This assessment provides valuable insights into the capabilities of these hybrid meters, highlighting their potential to enhance the measurement of wet gas flow rates.Item Open Access Discharge coefficient of high viscosity liquids through nozzles(Elsevier, 2019-01-03) Essien, S.; Archibong-Eso, Archibong; Lao, LiyunExperimental investigation on discharge coefficient, Cd, for high viscosity fluid through nozzles was carried out. The viscosity of the fluid used for the test ranged from 350 to 1500 mPa s. The length-to-diameter ratio of the nozzle, l/d and the ratio of nozzle diameter to pipe diameter ratios β were used to investigate the influence of geometry on Cd. Results show a significant dependence of Cd on Re, l/d and β ratio. An empirical correlation on the discharge coefficient was developed based on the data from this study which was also compared with data from other published studies. This correlation, with an R-squared value of 0.9541, was valid for nozzle sizes 10–20 mm and for Re between 1 and 200. Cd values obtained from experimental data, and those from the empirical correlation were compared, and a mean standard deviation of 0.0231 was obtained.Item Open Access Dynamic effect analysis of the coiled tubing-in-riser system considering the operation and environmental parameters(Elsevier, 2020-06-01) Wang, Wenming; Hao, Yi; Wu, Zhenyu; Fan, Jinchao; Lao, Liyun; Chen, YingchunThe dynamic response of the coiled tubing (CT)-in-riser system is critical to the success of offshore CT operations. The purpose of this work is to investigate the mechanical behavior of the CT and the riser and analyze the influencing factors of the coupled system. This paper builds dynamic models of the micro elements of the CT and the riser, and then a coupled model of the CT-in-riser system is presented considering the excitation of ocean loads and the coupling interaction between the inner pipe and the outer pipe. The dynamic coupled model is solved by the finite element method. A finite element model of the CT-in-riser system is built using the Abaqus/AQUA module. The effect of the operating parameters including the top injection force, the top tension, the platform offset, the annular clearance, and the friction coefficient, and the environmental parameters including the ocean depth, current speed, wave period, and wave height are discussed. The results show that the top tension should be properly controlled; the platform offset and friction coefficients should be reduced; the annular clearance should be appropriately reduced; a low current speed and wave height should be selected for operation; and the wave period and wave height have a little effect on the CT axial force. This research can provide important theoretical support for the offshore CT application.Item Open Access Energy forecasting model for ground movement operation in green airport(MDPI, 2023-06-28) Ajayi, Adedayo; Luk, Patrick Chi-Kwong; Lao, Liyun; Khan, Mohammad FarhanThe aviation industry has driven economic growth and facilitated cultural exchange over the past century. However, concerns have arisen regarding its contribution to greenhouse gas emissions and potential impact on climate change. In response to this challenge, stakeholders have proposed the use of electric ground support vehicles, powered by renewable energy sources, at airports. This solution aims to not only reduce emissions, but to also lower energy costs. Nonetheless, the successful implementation of such a system relies on accurate energy demand forecasting, which is influenced by flight data and fluctuations in renewable energy availability. This paper presents a novel data-driven, machine-learning-based energy prediction model that compared the performance of the Facebook Prophet and vector autoregressive integrated moving average algorithms to develop time series models to forecast the ground movement operation net energy demand in the airport, using historical flight data and an onsite airport-based PV power system (ASPV). The results demonstrate the superiority of the Facebook Prophet model over the vector autoregressive integrated moving average (VARIMA), highlighting its utility for airport operators and planners in managing energy consumption and preparing for future electrified ground movement operations at the airport.Item Open Access Environmental impact on the corrosion behavior of marine grade steel in the Arabian Sea conditions - a comparative analysis of field and laboratory based corrosion tests(UCTEA Chamber Of Metallurgical and Materials Engineers, 2021-06-12) Abbas, Muntazir; Simms, Nigel; Lao, Liyun; Malik, Owais A.; Ashraf, LuqmanCorrosion-induced degradation of marine steel structures is highly dependent on the surrounding environmental conditions and so varies significantly around global seawaters. This research has investigated the dependence of corrosion of carbon steel alloy for marine service on seawater composition and climatic conditions typical of the Arabian Sea. Natural and polluted seawater sites in the Arabian Sea were selected for field exposures. In addition, environmental conditions spanning those anticipated for the shipping structures operating in the Arabian Sea have been simulated in laboratorybased experiments by using heated and aerated artificial seawater. Following their exposures, the performance of samples have been investigated using the weight-loss and dimensional metrology methods. High overall corrosion losses were observed in the polluted seawaters than in the natural seawater conditions of Arabian Sea.Item Open Access Estimating slug liquid holdup in high viscosity oil-gas two-phase flow(Elsevier, 2018-10-29) Archibong-Eso, Archibong; Okeke, Nonso Evaristus; Baba, Yahaya D.; Aliyu, Abdulkabir; Lao, Liyun; Yeung, H.Slug flow is one of the most critical and often encountered flow patterns in the oil and gas industry. It is characterised by intermittency which results in large fluctuations in liquid holdup and pressure gradient. A proper understanding of its parameters (such as slug holdup) is essential in the design of transport facilities (e.g. pipelines) and process equipment (slug catchers, separators etc.). In this paper, experimental investigation of slug liquid holdup (defined as the liquid volume fraction in the slug body of a slug unit) is performed. Mineral oil with viscosity, μ=−0.0043T3+0.0389T2−1.4174T+18.141 and air were used as test fluids. A 0.0254 m and 0.0762 m pipe internal diameters facilities with pipe lengths of 5.5 and 17 m respectively were used in the study. Electrical Capacitance Tomography was used for slug holdup measurements. Results obtained in the study shows that slug liquid holdup varied directly as the viscosity and inversely as the gas input fraction. Existing slug holdup correlations and models in literature did not sufficiently predict present experimental results. A new empirical predictive correlation for estimating slug liquid holdup was derived from present experimental databank and from data obtained in literature. The databank's liquid viscosity ranges from 0.189 – 8.0 Pa.s. Statistical analysis of the new correlation vis-à-vis existing ones showed that the present correlation gave the best performance with an average percent error, E1; absolute average percent error, E2 and standard deviation, E3 of 0.001, 0.05 and 0.07 respectively, when tested on the high viscosity liquid–gas databank.Item Open Access Examination of non-traditional wax management techniques for flow assurance in petroleum production(Society of Petroleum Engineers (SPE), 2022-12-01) Bassey, Bassey O.; Verdin, Patrick G.; Lao, LiyunWax deposition and build-up in reservoirs, wells and pipelines negatively impact asset productivity, integrity and economics. Several flow assurance techniques have been developed to mitigate or remediate waxing problems. Prominent among these are controlling operating conditions, chemical, thermal and mechanical methods. Their major drawbacks have remained exorbitant costs over life-of-field, no single method being sufficient, risk of costly mistakes due to overdesign or underdesign, etc. Some innovative, unconventional solutions were also developed over the past 2 decades, with promising results, though mostly yet to be commercialised. This paper highlights and reflects upon these hitherto standalone technologies given the largely sparse treatise they have received in the literature. The aim is to explore alternative wax management techniques as a means of improving the science of wax deposition and dissolution. Non-traditional methods were critically examined during a 12-month extensive literature survey. In-depth study of the rationale, principle of operation, results obtained, advantages and limitations of each method was performed. Independent studies using variants of the same method were juxtaposed to ascertain similarities and differences in applicability, with meeting points established to pave the way for future research collaboration. Reflections upon their merits, limitations, areas for improvement, and a case for scale-up are presented. Some non-traditional techniques have overcome certain perennial constraints of conventional techniques widely used in industry. The wax inhibition tool, for example, has low energy requirements, causes minimal environmental impacts and has relatively low costs. The precious metals and quartz used in making the tool are available locally, the alloys were mixed in the university's materials laboratory using in-house manpower and the flow loop was locally designed and fabricated. Having developed expertise on this project through repeat and improved experiments, preparing and implementing a cost-effective work program for its commercialization is doable by the research group with industry partnership. Adapting oscillatory motion based on Avrami theory to understand mechanism and kinetics of wax crystallization by experiments on North Sea crude had yielded two opposite effects that are interesting to note. Repeat experiments a decade later using synthetic oils from Southeast Asia yielded improved results and better understanding of wax deposition kinetics; an indication that this topic holds promise to unravel some mysteries in the subject, if its deliverables are embraced and implemented. The expose provided by this paper will hopefully contribute towards available knowledge on wax management. It is expected that conscious follow up on these technologies, some of which are related and could be hybridized, would inform future research directions for both the academia and industry in the field of flow assurance.