Analysis of diesel engine injector nozzle spray characteristics fueled with residual fuel oil

Abstract

Experimental analysis on the spray characteristics of a diesel engine injector nozzle fueled with Residual Fuel Oil (RFO) was carried out in this study. To achieve this, the fuel was characterized to determine its physicochemical properties, and an experimental set up was designed to visualize and capture the spray pattern of the fuel. The images obtained were processed and analysed using Image J software to determine the spray length, spray cone angle, spray area, spray volume, and spray velocity values of the fuel. Experimental results obtained agree with validation models and reveal that spray parameter values of RFO are higher than those of diesel fuel. The values of spray parameters of RFO such as 456mm spray length, 2.85mm Sauter Mean Diameter (SMD) and the low spray cone angle of 12.69°, led to a higher spray volume causing the engine to run on a rich mixture after initial start-up conditions. This would create such challenges as reduction in power and clogging of injector nozzle tip due to an increase in carbon deposits. Regression models generated reveal that these challenges could be eliminated when the spray parameters run on optimal values of 256mm, 6.41cm2, 16.18cm3, 0.96 mm/s and 13.59° for the spray length, spray area, spray volume, spray velocity and the spray angle respectively. These optimal values were obtained when the engine fuel injection time was set to 500μs while running on fuel of viscosity 4.305 mPa.s and temperature of 48 °C.