This paper presents an investigation on the effect of multi-variant biofuel towards engine performance parameter and emission characteristic, using mix of diesel dual fuel (DDF) engine of different blend biodiesel (B5-DDF and B10-DDF) of palm oil and coconut oil in comparison to pure diesel, diesel-biodiesel (B5 and B10). This experiment was conducted with variable speed between 1400-2700 rpm at an interval of 400rpm. The collected data for engine performance showed that B5- DDF coconut oil produced the highest torque, but the brake specific fuel consumption was reduced as compared to diesel with 36% and 28.02%, respectively. In case of engine emission, lower emission of CO2 was recorded by B5-DDF coconut oil. B10 palm oil e mitted low emission of CO2 compared to other fuels. Significant reduction of NOx concentration was recorded for B5-DDF palm oil compared to other fuel. It can be concluded that, diesel engine with some modifications can be used as engine DDF, which has beneficial effects both in terms of emission reduction and performance as alternative fuel.

The turbulent fluid flow through sudden expansion duct studies raise the knowledge of scientific and contribute many practical applications. The sudden change in the surface geometry of the duct cause the severe pressure gradient, the boundary layer separates at the step edge and forms a recirculation zone. The knowledge about the recirculation zone is useful in study turbulent flow properties. This paper presents a numerical study of 2D turbulence flow was modeled by the standard k-e, realizable k-e , and shear stress transport (SST) k- ? models. The stimulation was conducted by a sudden expansion duct with Reynolds number of 20000 at the inlet of the solution and expansion ratio of 1:2. In this research, flow characteristics at the recirculation zone in the sudden expansion pipe are analyzed. The recirculation size, velocity profile and turbulent intensity are compared between three models of turbulence flow. The results show that SST k- ? model has the best prediction of separation flow compared to two others models. Furthermore, the trends of mean velocity of these three models are same as the experimental results.

During well operation transient flows develop as soon as production begins and further withdrawal continues to cause disturbances which resulted into flow propagation throughout the period with time. The whole scenario experienced significance changes in energy exchange mechanism of the wellbore and formation which lead to unsteady production. Previous predictions are mostly based on steady state condition but the actual situation of gas well is unsteady due to the operation and geometry of the well. This paper presented a model based on unsteady state flow of gas in the producing well taking into consideration the general physical situation of the well(the formation, the wellbore and surface materials).Systems of partial differential equations which account for the unsteady flow with their necessary boundary conditions are presented and solved by finite scheme method