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Ionospheric currents in the Equatorial and Low Latitudes of Africa

Journal of Atmospheric Science Research 2023年第1期6卷 68-74页

作者： g.c emenike T.N Obiekezie V.N Ojeh Department of Physics and Industrial Physics Nnamdi Azikiwe UniversityPMB 5025AwkaNigeria Department of geography Taraba State UniversityJalingo660213Nigeria

The magnetometer data obtained for 2008 from geomagnetic stations installed across Africa by magnetic data acquisition set (MAgDAS) have been used to study the ionospheric Sq current system in the equatorial and low-latitudes of Africa. The aim of this work is to separate the quiet-day field variations obtained in the equatorial and low latitude regions of Africa into their external and internal field contributions and then to use the paired external and internal coefficients of the SHA to determine the source current and induced currents. The method used involved a spherical harmonic analysis (SHA). This was applied in the separation of the internal and external field/current contribution to the Sq variations. The result shows that the variation in the currents is seen to be a dawn-to-dusk phenomenon with the variation in the external currents different from that of the internal currents both in amplitude and in phase. Furthermore, the seasonal variation in the external current maximizes during the March equinox and minimizes during the December solstice. The maximum current observed in AAB and ILR is due to the Equatorial Electrojet current present in the AAB and ILR stations. Seasonal variation was observed in the geomagnetic component variations as well as in the currents. This is attributed to the position of the sun with respect to the earth at different months of the year. The equinoctial maximum is observed in external current intensity which occurred mostly during the March Equinox.

关键词： Equatorial Low latitudes Africa Ionospheric Sq currents

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The Use of Models to Evaluate corrosion Effects on Mild Steel Heat Exchanger in Water and Mono Ethanol Amine (MEA)

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Advances in chemical Engineering and Science 2023年第4期13卷 336-350页

作者： Ojong Elias Ojong Jaja Zina Wosu chimene Omeke Ana Anakri Ekpenyong Dadet Wilson Anaba catherine Uloma emenike Aguma Sedi Patrick Forwah Jacques Ndeh Department of chemical Engineering Faculty of Engineering & Technology University of Calabar Calabar Nigeria Department of chemical/Petrochemical Engineering Faculty of Engineering Rivers State University Port Harcourt Nigeria Department of chemical Engineering Federal University Otuoke Otuoke Nigeria Department of Petroleum Engineering Faculty of Engineering & Technology University of Calabar Calabar Nigeria Department of chemical Engineering University of Benin Benin Nigeria Department of clinical Biochemistry and Immunology Faculty of Medical Laboratory Sciences University of Calabar Calabar Nigeria

Heat exchanger is an important equipment used in process industries for cooling and heating purposes. Its design configuration which involves the flow of cold and hot fluids within the exchanger subjects it to corrosion attack. The article utilized the principle of mass and energy conservation in the development of weight and temperature models to study the effect of corrosion on mild steel coupon inside the exchanger containing water and Mono ethanol amine (MEA). The models developed were resolved analytically using Laplace Transform and simulated using Excel as simulation tool and data obtained from experiment in the laboratory to obtain profiles of weight loss and temperature as a function of time. The weight loss and performance of mild steel under various corrosive conditions were examined which indicates the effect of corrosion on the mild steel heat exchanger in water and MEA media. The result shows that water is more corrosive than MEA at higher temperatures and at lower temperatures of 35°c and 1 atm, MEA has inhibitive properties than water as indicated by the weight loss result with time. The comparative analysis between the results obtained from the model simulation and experimental results shows that the result obtained from the model is more reliable and demonstrated better performance characteristics as it clearly shows mild steel heat exchanger experiences more corrosive effect in water medium than MEA at higher temperatures. And at lower temperatures, MEA becomes more inhibitive and less corrosive than water. The model simulation results correlate with various literatures and hence, it is valid for future referencing.

关键词： Model corrosion Effect Heat Exchanger Simulation Media Mild Steel coupon

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