The Autoignition and Combustion of Coal-Water Slurry Under Simulated Diesel Engine Conditions

The combustion characteristics of a coal-water slurry spray were examined under diesel engine conditions. A two-stage combustion process was used to simulate the diesel engine conditions in a constant-volume combustion bomb. The combustion characteristics investigated were ignition delay, ignition site, combustion development, combustion duration, and combustion completeness. The results show that the ignition delay of the coal-water slurry fuel is temperature and pressure dependent. Also, the coal slurry ignition delay is approximately a factor of five longer and the energy release rate is significantly slower in comparison to the ignition delay and energy release rate for conventional No. 2 diesel fuel. The combustion of the slurry spray was incomplete for all test conditions due to the impingement and the adherence of the coal slurry on the wall. This fundamental testing provides insight into engine design parameters which must be considered if coal-water slurry is to be used in practice.