Air pollution is a concern in the West Africa region where it is known that meteorological parameters such as ambient temperature and humidity can affect the particulate matter loading through atmospheric convection and dry deposition. In this study, we extend the investigation of these relationships to particulate matter less than 1 µm in diameter (PM₁), nitrogen dioxide (NO₂), nitrogen monoxide (NO) and ozone (O₃), for a complete period of rainy and dry seasons in Lagos. Regression analysis of the results indicate that there is a negligible to weak correlation (r < 0.39) between the temperature, humidity and air pollutants during the year, except for NO₂ and O₃ which respond moderately to humidity during the dry season, an observation previously unreported. The mean monthly values for all the air pollutants are lower during the rainy season compared to the dry season, indicating a potential higher contribution of the transport of pollutants from the north-eastern desert regions and the reduction of the wet removal of particles during the dry season. The World Health Organization air quality guidelines are mostly exceeded for fine particles with diameters less than 2.5 µm (PM_2.5), supporting previous studies, as well as for the NO₂ concentration levels. As PM_2.5 contributes to at least 70% of the particulate matter pollution throughout the year, policy guidelines could be enacted for people with chronic respiratory issues during the January/February months of intense high air pollution, high temperature but low humidity values.

Exposure of humans to high concentrations of PM_2.5 has adverse effects on their health. Researchers estimate that exposure to particulate matter from fossil fuel emissions accounted for 18% of deaths in 2018—a challenge policymakers argue is being exacerbated by the increase in the number of extreme weather events and rapid urbanization as they tinker with strategies for reducing air pollutants. Drawing on a number of ensemble machine learning methods that have emerged as a result of advancements in data science, this study examines the effectiveness of using ensemble models for forecasting the concentrations of air pollutants, using PM_2.5 as a representative case. A comprehensive evaluation of the ensemble methods was carried out by comparing their predictive performance with that of other standalone algorithms. The findings suggest that hybrid models provide useful tools for PM_2.5 concentration forecasting. The developed models show that machine learning models are efficient in predicting air particulate concentrations, and can be used for air pollution forecasting. This study also provides insights into how climatic factors influence the concentrations of pollutants found in the air.

This paper describes a two-step method to prepare novel copper-methanol nanofluids capped with a short chain molecule, (3-Aminopropyl)trimethoxysilane (APTMS). Two commercial nanopowders were dispersed at various powers using a 20 kHz ultrasonic probe into solutions of methanol and the capping agent. Ultrasonic energy input was measured by calorimetry with z-average diameters, intensity and number size distributions recorded by a dynamic light scattering technique. The stability of the dispersion was monitored visually, and quantified by recording the zeta potential. Dispersions of the bare powder were used as a control. Absorption spectroscopy was used to confirm the presence of the capping agent. The thermal conductivities of 0 to 10% wt./vol. (1.1% vol.) dispersions of the capped copper-methanol nanofluid were determined using a C-Therm analyzer. Optimum ultrasonic de-agglomeration conditions gave dispersions with a z-average particle size of <200 nm and a PdI of <0.2. The capped particles showed good stability; up to six months in some instances, and an average zeta potential of +38 mV was recorded. The thermal conductivity of the nanofluid increased with concentration, and an enhancement of 9% over the base fluid was found at 10% wt./vol. (1.1% vol.). This innovative work has demonstrated the ultrasonic preparation and stability of copper nanoparticles protected with APTMS; a short chain molecule which binds to copper and prevents oxidation. The protected particles can enhance the thermal conductivity of methanol with no interference from the capping ligand.

Our environment is increasingly being endangered by the introduction of greenhouse gases which are\ud continuously produced from gas flaring processes. Currently, total volume of gas flared globally amounts\ud to 100 billion cubic meters (BCM) annually. Nigeria flares about 18.27 BCM and loses approximately $2\ud billion yearly. This statistics indicates the urgent need to conduct research aimed at addressing both the\ud environmental impact of gas flaring and the economic implications. This research studies the economic\ud viability of using gas to wire (GTW) technology as an integral component of gas flare management. The\ud investigation critically evaluates the cost implications and impact of the GTW technology. The research\ud method involves the interview of key experts and practitioners in the field. The interviews are structured\ud to obtain information on the total volume of gas produced, utilised and flared in two major gas and electricity\ud producing firms in Nigeria. The data obtained show that the gas producing company flares about\ud 8.33% of its total production which is in excess of the 6.6 million cubic meters (MCM) utilised daily. This\ud study demonstrates that in the Nigerian oil and gas sector, one unit of gas turbine having 0.93 MCM gas\ud consumption capacity generates 150 MW of electricity daily. It is found in result evaluation that 50 turbines\ud are sufficient to consume an average of 46.5 MCM of gas daily to generate 7500 MW of electricity.\ud Economic analysis shows that there is an annual net profit of £2.68 billion gained from flare prevention\ud and overall environmental protection

We address highly swirling, confined-bluff-body-flow evolving through a burner; particularly, contributions of the swirling motion to a central-recirculation-zone (CRZ) downstream the injector. Previous studies suggest that flame stability reduces in combustors lacking this zone; careful consideration of the CRZ is thus desirable. We use Reynolds-Averaged-Navier–Stokes (RANS) and Large-Eddy-Simulation (LES) to simulate the flow, and the influence of the swirl device was included in defining the inflow conditions for LES simulations. We use mean velocity profiles and turbulence statistics to test results. There is qualitative agreement between computed and reported experimental data, and we document quantitative differences obtained with the RANS models. LES velocity field results are mostly within 3% of the experimental data, better than the latest reported LES data, reinforcing the suitability of our approach. We took advantage of the quality of the LES mesh, which solves 95.6% of the resolved-turbulence-energy, to present the vorticity structures showing the precessing vortex motion on the CRZ boundaries. Anisotropic states of the Reynolds-stress were characterized with the aid of an anisotropy invariant map, a novelty for this type of burner; the turbulence states considerably vary inside the burner, behaving isotropically in the center of the CRZ, whereas axisymmetric turbulence is predominant in the other areas of the CRZ. The results reinforce the importance of applying appropriate turbulence models and inflow conditions for simulations involving confined-bluff-body-flows in order to capture the main flow fields and structures in the CRZ.

Globally, over 100 billion cubic metres (BCM) of gas is flared annually and, this is linked to an annual emission of 400 million tons of carbon dioxide. In Nigeria the annual gas production is valued at 33.21 BCM, out of which more than 50% is wasted through flaring, thereby emitting about 35 million tons of carbon dioxide. About 14.94 BCM of gas produced in Nigeria is used for a variety of activities including electricity generation. Despite this scenario, Nigeria is still unable to generate and distribute enough electricity for the citizenry. This paper therefore evaluates the use of gas to wire technology as the option to minimise gas flaring in Nigeria while minimising the associated environmental impacts. The research methodology was based on interviewing top level managers in an electricity generation company, and gas Production Company, as well as the researchers’ site observations within the two case companies. Results from this study showed that electricity generation could be improved from its current daily production rate of 4358 MW to about 12000 MW from the use of part of 18.27 BCM of gas flared annually in Nigeria. This serves as fuel for 50 units of gas turbine with power output of 150 MW each, with a potential increase in daily electricity generation of 7500 MW.