Development of a cycle simulation for a coal-fueled, direct-injected, internal combustion engine

Abstract

An engine cycle simulation for a coal-fueled internal combustion, reciprocating engine was developed. The primary objective of this work was to develop the simulation for evaluating the viability of coal fuels for engines. The cycle simulation was used to investigate details of the combustion process to identify controlling phenomena and to establish directions for future evaluations. Models for coal particle combustion and devolatilization, liquid droplet vaporization, fuel vapor combustion, cylinder heat transfer, piston work, and mass flow rates were combined with a thermodynamic analysis of the engine to yield instantaneous cylinder conditions and overall indicated engine performance. For selected engine and operating conditions, sensitivity of engine performance on fuel characteristics such as coal reactivity, devolatilization, liquid carriers, atomization, and pilot fuels for ignition were investigated. Several commercially manufactured engines were also simulated with the model. The major conclusions of this work include: (1) devolatilization can have a significant effect on the ignition and combustion processes, (2) liquid carriers can have a significant effect on the ignition and combustion processes, (3) the cylinder gas temperature and pressure at fuel injection are important engine operating parameters for coal fuels, (4) the characteristics of the coal fuel (such as particle size and reactivity) can have a significant impact on the ignition and combustion processes, and (5) the combustion process of coal slurry fuels is largely diffusion (air mixing) controlled.