STUDY OF COMBUSTION PROCESS OF DIESEL FUEL INJECTED IN PREMIXED CHARGE

Abstract

Combustion control in dual-fuel engines wherein diesel is injected in a premixed fuel-air mixture has been of interest for many years. The combustion process in diesel engine and in dual-fuel engine differs due to physical and chemical effects of the supplementary fuel. Pre-ignition physical and chemical processes during the ignition delay period govern the subsequent combustion process and engine performance. An exhaustive literature review was done to study the factors affecting the ignition delay. Published information on initial combustion period when diesel is injected in_pre-mixed fuel-air charge was reviewed and it was observed that the delay was influenced by the physical and, chemical characteristics and flow rate of supplementary fuel, and the engine operating conditions. For computer simulation of combustion process in dual-fuel engines, prediction of ignition• delay is one of the important steps. The present study was aimed at studying the effect of alcohol as supplementary fuel on ignition delay in a diesel engine and to develop mathematical correlations for prediction of ignition delay. iv A single cylinder, 4-stroke, Ricardo Hydra research' diesel engine was converted to run on methanol-diesel and ethanol-diesel fuel combinations in dual-fuel mode. The engine was run at different loads and speeds with various manifold injected alcohol flow rates. Effect of various engine and fuel parameters and intake charge temperature on ignition delay was experimentally studied. Effect of intake charge temperature on ignition delay in dual-fuel engines showed some interesting trend. Based on experimental data, mathematical correlations for predicting the ignition delay in dual-fuel engines with methanol-diesel and ethanol-diesel fuel combinations have been proposed