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Ethanol is an attractive alternative fuel because it is a renewable bio-based resource and it is oxygenated, thereby providing the potential to reduce particulate emissions in compression-ignition engines. In this review the properties and specifications of ethanol blended with diesel fuel are discussed. Special emphasis is placed on the factors critical to the potential commercial use of these blends. These factors include blend properties such as stability, viscosity and lubricity, safety and materials compatibility. The effect of the fuel on engine performance, durability and emissions is also considered. The formulation of additives to correct certain key properties and maintain blend stability is suggested as a critical factor in ensuring fuel compatibility with engines. However, maintaining vehicle safety with these blends may entail fuel tank modifications. Further work is required in specifying acceptable fuel characteristics, confirming the long-term effects on engine durability, and ensuring safety in handling and storing ethanol-diesel blends.

Ethanol is an attractive alternative fuel because it is a renewable bio-based resource and it is oxygenated, thereby providing the potential to reduce particulate emissions in compression-ignition engines. In this review the properties and specifications of ethanol blended with diesel fuel are discussed. Special emphasis is placed on the factors critical to the potential commercial use of these blends. These factors include blend properties such as stability, viscosity and lubricity, safety and materials compatibility. The effect of the fuel on engine performance, durability and emissions is also considered. The formulation of additives to correct certain key properties and maintain blend stability is suggested as a critical factor in ensuring fuel compatibility with engines. However, maintaining vehicle safety with these blends may entail fuel tank modifications. Further work is required in specifying acceptable fuel characteristics, confirming the long-term effects on engine durability, and ensuring safety in handling and storing ethanol-diesel blends.

AbstractInvestigations are reported on high‐ and low‐temperature vulcanized silicone rubber composite insulators that were exposed to service for three, nine and eleven years under industrial or marine pollution conditions. Wetting angles and thermally stimulated depolarization (TSD) current spectra were measured. Microscopic observations of selected insulator surfaces were carried out as well. The prolonged services cause gradual and inhomogeneous losses of hydrophobicity on surfaces and inside of insulator housing materials. It is shown that there exists a correlation between the measured TSD current spectra and the wettability changes. In addition, the spectra also allow to predict an ability to support a process of hydrophobicity recovery at a housing surface. It seems that TSD measurements may be applied as a complementary test method during performance assessment of silicone rubber composite insulators.

AbstractInvestigations are reported on high‐ and low‐temperature vulcanized silicone rubber composite insulators that were exposed to service for three, nine and eleven years under industrial or marine pollution conditions. Wetting angles and thermally stimulated depolarization (TSD) current spectra were measured. Microscopic observations of selected insulator surfaces were carried out as well. The prolonged services cause gradual and inhomogeneous losses of hydrophobicity on surfaces and inside of insulator housing materials. It is shown that there exists a correlation between the measured TSD current spectra and the wettability changes. In addition, the spectra also allow to predict an ability to support a process of hydrophobicity recovery at a housing surface. It seems that TSD measurements may be applied as a complementary test method during performance assessment of silicone rubber composite insulators.

This study investigated the relationship between per capita income and environmental degradation in Africa, using longitudinal data on suspended particulate matter and organic water pollutants. The specific objective was to estimate environmental Kuznets curves for two indicators of environmental quality and to establish whether the estimated relationships conform to the inverted U-shape hypothesis. The results of the empirical investigation generally suggest the existence of an environmental Kuznets curve for suspended particulate matter. In the case of organic water pollutants, the evidence weighs more in favor of rising pollution as per capita income increases. The turning point levels of income established for the two indicators of environmental quality were however generally low, when compared to evidence from existing studies. On the face value, this suggests that African countries may be turning the corner of the environmental Kuznets curve, much faster, and at lower levels of income, much in line with the emerging idea of a “revised environmental Kuznets curve”. The results also suggest that economic growth and rising incomes may matter in African countries in order to curb pollution from these pollutants, but more stringent policy measures, particularly at the industrial level would be required to curb environmental degradation from organic water pollutants.

This study investigated the relationship between per capita income and environmental degradation in Africa, using longitudinal data on suspended particulate matter and organic water pollutants. The specific objective was to estimate environmental Kuznets curves for two indicators of environmental quality and to establish whether the estimated relationships conform to the inverted U-shape hypothesis. The results of the empirical investigation generally suggest the existence of an environmental Kuznets curve for suspended particulate matter. In the case of organic water pollutants, the evidence weighs more in favor of rising pollution as per capita income increases. The turning point levels of income established for the two indicators of environmental quality were however generally low, when compared to evidence from existing studies. On the face value, this suggests that African countries may be turning the corner of the environmental Kuznets curve, much faster, and at lower levels of income, much in line with the emerging idea of a “revised environmental Kuznets curve”. The results also suggest that economic growth and rising incomes may matter in African countries in order to curb pollution from these pollutants, but more stringent policy measures, particularly at the industrial level would be required to curb environmental degradation from organic water pollutants.

Abstract In this paper, the effects of magnetic field, nonlinear thermal radiation and homogeneous-heterogeneous quartic autocatalysis chemical reaction on an electrically conducting (36 nm) alumina-water nanofluid containing gyrotactic-microorganism over an upper horizontal surface of a paraboloid of revolution is presented. The case of unequal diffusion coefficients of reactant A (bulk-fluid) and reactant B (catalyst at the surface) in the presence of bioconvection is presented. In this article, a new buoyancy induced model for nanofluid flow along an upper horizontal surface of a paraboloid of revolution is introduced. The viscosity and thermal conductivity are assumed to vary with volume fraction and suitable models for the case 0% ≤ ϕ ≤ 0.8% are adopted. The transformed governing equations are solved numerically using Runge-Kutta fourth order along with shooting technique (RK4SM). Good agreement is obtained between the solutions of RK4SM and MATLAB bvp5c for a limiting case. The influence of pertinent parameters are illustrated graphically and discussed. It is found that at any values of magnetic field parameter, the local skin friction coefficient is larger at high values of thickness parameter while local heat transfer rate is smaller at high values of temperature parameter.

Abstract In this paper, the effects of magnetic field, nonlinear thermal radiation and homogeneous-heterogeneous quartic autocatalysis chemical reaction on an electrically conducting (36 nm) alumina-water nanofluid containing gyrotactic-microorganism over an upper horizontal surface of a paraboloid of revolution is presented. The case of unequal diffusion coefficients of reactant A (bulk-fluid) and reactant B (catalyst at the surface) in the presence of bioconvection is presented. In this article, a new buoyancy induced model for nanofluid flow along an upper horizontal surface of a paraboloid of revolution is introduced. The viscosity and thermal conductivity are assumed to vary with volume fraction and suitable models for the case 0% ≤ ϕ ≤ 0.8% are adopted. The transformed governing equations are solved numerically using Runge-Kutta fourth order along with shooting technique (RK4SM). Good agreement is obtained between the solutions of RK4SM and MATLAB bvp5c for a limiting case. The influence of pertinent parameters are illustrated graphically and discussed. It is found that at any values of magnetic field parameter, the local skin friction coefficient is larger at high values of thickness parameter while local heat transfer rate is smaller at high values of temperature parameter.

Abstract The intrinsic reactivities, that is the reaction rates per unit area of pore surface in the absence of any mass transfer restrictions, for combustion of a wide range of carbons have been calculated from published data. The intrinsic reactivities, corrected to a common oxygen pressure of 101 kPa, were ascertained over the temperature range 580 to 2200 K. The reactivities of ‘non-porous’ carbons (diamond, soot, vitreous carbon and pyrolytic graphite) between 770 and 4000 K were also considered. Porous carbons of various origins show intrinsic reactivities that differ by up to 4 orders of magnitude at a given temperature. However, after high-temperature heat treatment, certain carbons of different origin (e.g. sugar and wood charcoals, nuclear and spectroscopic graphites) show closely similar reactivities when reacted with purified oxygen. The reactivities of the ‘non-porous’ carbons show a temperature dependence similar to the average temperature dependence of the porous carbons, but their reactivity expressed per unit external surface area is generally higher than the median intrinsic value of the porous materials.