A low-dispersion 3-D second-order in time fourth-order in space FDTD scheme (M3d/sub 24/)

A second-order in time fourth-order in space modified finite-difference time-domain (FDTD) scheme for three dimensional electromagnetic problems "M3d/sub 24/" is presented. The algorithm enables the numerical phase error to be minimized, so that it leads to high accuracy with low resolution grids. The advantage of this method is demonstrated by considering the long distance propagation of the wave radiated from a time harmonic elementary dipole using a low resolution grid, and comparing the results with other FDTD schemes.     

Investigation of silicates as a catalyst in biodiesel production: A review

Hiking of crude oil prices and diesel fuel shortage is incentive for the researchers to develop bioenergy sources. Biodiesel has environmental beneficial attributes, and its production processes are worthy of continued studies. Many biodiesel production processes are available but, most of them are not on a commercial scale. Biodiesel production using solid catalysts involved fewer unit operations compared with homogeneous catalyzed processes. Many heterogeneous catalysts have been extensively investigated in the recent years and well established. Researchers' focus is how to obtain active and more stable silicates catalyst that can be recycled for several times in the process. Silicates catalyst activity and stability are critically discussed in this work to assess their industrial application, as excessive purification steps could be avoided. This review provides a brief overview on semi‐novel heterogeneous catalyst types ‘silicates’ used in the transesterification of vegetable oils for biodiesel production. Process conditions and leaching out of catalyst active sites are also highlighted. Product quality analysis is presented, in addition to concluded remarks regarding silicates as a selected catalyst. A preliminary economic assessment of biodiesel production catalyzed by the suggested catalyst ‘silicates’ compared with potassium hydroxide (KOH) and lime (CaO) is performed. Copyright © 2016 John Wiley & Sons, Ltd.     

Performance and emissions characteristics of C.I. engine fueled with palm oil/palm oil methyl ester blended with diesel fuel

The rapid increasing worldwide demand for energy, continuous increasing of fuel consumption and the progressive depletion of fossil fuels led to an intensive search for biodiesel as alternative fuel for diesel engine. Performance and emissions characteristics of C.I. engine fueled with palm oil/palm oil methyl ester blended with diesel fuel is investigated experimentally. Biodiesel was prepared from palm oil by transesterification process. Diesel, biodiesel and palm oil blends were prepared in volume percentages of 20 and 100% as B20, B100 and PO20. Physical and chemical properties of biodiesel blends were near to diesel fuel. The experimental study is conducted on a diesel engine at different engine loading from zero to full loads using palm oil and palm biodiesel and its blends with diesel fuel. Thermal efficiency of biodiesel and oil blends with diesel fuel was lower than diesel fuel. Specific fuel consumptions for biodiesel and oil blends were found to be higher than diesel oil. Unburned hydrocarbons and carbon monoxide emissions have been decreased for biodiesel blends but it increased for oil blends compared to diesel fuel. Nitrogen oxide emissions have slightly been increased for biodiesel and oil blends compared to diesel fuel. Blends of diesel – biodiesel up to 20% biodiesel percentage by volume are recommended because of the improvement in performance and emissions as compared to diesel fuel.     

Study on the characteristics of palm oil–biodiesel–diesel fuel blend

Palm oil/palm oil methyl esters are blends with diesel fuel, the blends were characterized as an alternative fuels for diesel engines. Density, kinematic viscosity, and flash point were estimated according to ASTM as key fuel properties. Palm oil and palm oil biodiesel were blended with diesel. The properties of both blends were estimated. The results showed that the fuel properties of the blends were very close to that of diesel till 30% unless other characteristics are within the limits. The experimental data were correlated as a function of the volume fraction of oil/biodiesel in the blend. Different correlations were developed to predict the properties of the oil/bio-oil-diesel blends based on our experimental results. The developed correlations were validated by comparing the correlation prediction with experimental data in literature. A good agreement was found between modeled equations prediction and experimental data in literature. The developed equations can be used as a guide for determining the best blending mixture to be used for diesel engines.