Optimization of diesel injection timing, producer gas flow rate, and engine load for a diesel engine operated on dual fuel mode at a high engine speed

Jatropha seed cake is a byproduct of biodiesel production, and the seed cake can be used as a feedstock for a gasifier. The gasified seed cake can partially reduce fossil diesel consumption to run a diesel engine. However, an increase in gas flow rate is associated with a higher diesel substitution rate, but a higher specific CO2 emission is observed. This study attempts to optimize diesel injection timing (DIT), gaseous fuel flow rate, and engine load to offset the specific diesel consumption and the specific CO2 emissions at a high engine speed of 3,000 rpm. Response Surface Methodology (RSM) was applied to statistically develop mathematical models of the response variables as functions of the design variables. A desirability function was then applied to maximize overall desirability. It highlighted that an overall desirability of 0.829 was obtained at 11° before top dead center (BTDC) of the DIT, a 10 kg/h gas flow rate, and 70% of the full engine load. At the optimum operating settings, the specific diesel consumption (SDC) and the specific CO2 emission were 0.0967 kg/kWh and 0.6123 kg/kWh, respectively. A value of electrical-thermal efficiency was found to be 14.10%. It is evident from these findings that a dual producer gas-diesel fuel engine should not be operated at the maximum diesel replacement rate. © 2019, Paulus Editora. All rights reserved