Diesel engine startability and white smoke formation under cold temperature conditions

The control of white smoke requires a basic understanding of the combustion process under the cranking conditions. This investigation was conducted on a single cylinder, air cooled, four stroke cycle diesel engine. The engine was instrumented to measure the cylinder pressure, instantaneous angular velocity, instantaneous air flow, instantaneous blowby in addition to the other engine operating parameters. Tests were conducted at different ambient temperature ranging between 25{dollar}spcirc{dollar}C to 30{dollar}spcirc{dollar}C, with five different fuels at three different injection timings.; A computer program was developed to calculate the rate of energy release taking into consideration the effect of blowby losses and heat transfer losses. The mass of fuel burned was determined and compared with the mass of fuel injected.; The analysis of the data indicated that the engine operates on different modes, depending on the fuel, ambient temperature and injection timing. As the ambient temperature was lowered the engine skipped or misfired one cycle every two cycles. At lower temperatures, the engine skipped or misfired two cycles every three cycles. The details of such operation were examined and analyzed. Lowering the ambient temperature was found to have a great effect on the cranking speed, cylinder gas pressure, cylinder gas temperature, blowby rate, volumetric efficiency, evaporation rate, ignition delay and amount of fuel burned.; The mass of unburned fuel is considered to be an indication of the mass of unburned hydrocarbons or white smoke emitted. The effects of the different operating conditions on white smoke were investigated.; The fraction of the fuel emitted as white smoke increased as the ambient temperature increased due to lower cyclic fuel injection under cold temperature conditions. The cyclic fuel injection was inhibited by the increase of the fuel viscosity, the decrease of the volumetric efficiency in the filling of the plunger cavity, and the increased friction of the needle. Early fuel injection timing is crucial to successfully start a cold diesel engine and reduce white smoke emission to the atmosphere.