Browsing by Author "Okeke, Nonso Evaristus"
Now showing 1 - 4 of 4
Results Per Page
Sort Options
Item Open Access Characterization of water droplets size distribution in aviation turbine fuel: ultrasonic homogeniser vs high shear speed mixer(Elsevier, 2022-09-21) Ugbeh-Johnson, Judith; Carpenter, Mark; Okeke, Nonso Evaristus; Mai, NathaliePumps, pressure drops across fittings, and flight operations (such as turning manoeuvres, take-off, and landing) are some of the many sources of turbulence mixing and shearing in aircraft fuel systems, therefore, making it an inevitable condition. Literature established that shearing conditions would influence the droplets and droplets size distribution in an oil/water emulsion. So, low intensity shearing conditions could be beneficial as it promotes droplets coalescence, which could be a driving force for a weak emulsion. However, to date no experimental data has shown the influence homogenising intensity and total water content has on dispersed water droplets size distribution in aviation fuel. Therefore, to expand knowledge of quantification of measurements of dispersed water droplets in aviation fuel, this study characterizes dispersed water droplets in aviation turbine fuel, varying available laboratory homogenising devices and water content. Results presented show that droplets count increases with water concentration and shearing effect. To provide more statistical evidence, kurtosis and skew values were calculated from the extrapolated data and compared with data from a hexanol/water mixture given that hexanol is likely to form a stable emulsion. Experimental results show that the higher the homogenising intensity the more stable the emulsion is likely to be with a higher kurtosis and skew value close to that for the hexanol/water mixture. Therefore, observations show that mild shearing conditions (high shear mixing in this case) could help promote droplets coalescence, leading to a better separation ability.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 Investigation of water droplet size distribution in conventional and sustainable aviation turbine fuels(Society of Automotive Engineers, 2022-05-17) Ugbeh Johnson, Judith; Carpenter, Mark; Okeke, Nonso Evaristus; Nnabuife, Somtochukwu Godfrey; Mai, NathalieWater droplet size variation has been established in the literature as an important variable that influences the behavior and characteristics of water in fuel emulsion. However, with the growing demand for sustainable aviation fuels (SAF), no data is available that shows how these fuels will affect the size of dispersed water droplets and their frequency distribution. To address this lack of knowledge, this study explores and presents experimental results on the characterization of dispersed water droplets in alternative fuels and Jet A-1 fuel under dynamic conditions. The alternative fuels comprised of two fully synthetic fuels, two fuels synthesized from bio-derived materials, and one bio-derived fuel. The data and statistics presented reveal that water droplet frequency and size distribution are sensitive to changes in fuel composition. Observations showed an evident transition of the droplet percentile over time in the cumulative frequency distribution; this could be attributed to droplet coalescence to form larger droplets. Mean droplet diameters between 3 and 6 μm were observed for all the fuels tested. With further analysis based on recommendations proposed in this work, the data may assist in providing insight to filter manufacturers.Item Open Access Present and projected developments in hydrogen production: a technological review(Elsevier, 2022-04-05) Nnabuife, Somtochukwu Godfrey; Ugbeh-Johnson, Judith; Okeke, Nonso Evaristus; Ogbonnaya, ChukwumaEnergy supplies that are safe, environmentally friendly, dependable, and cost-effective are important for society's long-term growth and improved living standards, though political, social, and economic barriers may inhibit their availability. Constantly increasing energy demand is induced by substantial population growth and economic development, putting an increasing strain on fossil fuel management and sustainability, which account for a major portion of this rising energy demand and, moreover, creates difficulties because of greenhouse gas emissions growth and the depletion of resources. Such impediments necessitate a global shift away from traditional energy sources and toward renewables. Aside from its traditional role, is viewed as a promising energy vector and is gaining international attention as a promising fuel path, as it provides numerous benefits in use case scenarios and, unlike other synthesized carbon-based fuels, could be carbon-free or perhaps even negative on a life-cycle criterion. Hydrogen (H2) is one of the most significant chemical substances on earth and can be obtained as molecular dihydrogen through various techniques from both non-renewable and renewable sources. The drive of this paper is to deliver a technological overview of hydrogen production methods. The major challenges, development and research priorities, and potential prospects for H2 production was discussed.