Atomization of composite liquid fuels in experimental setup with variated gas temperature and pressure

The efficiency of slurry fuel combustion can be improved by developing a predictive mechanism to estimate fuel atomization characteristics. However, no data are available on slurry fuel atomization behavior under near-real conditions. This paper presents the experimental research findings on the combined and separate effect of gas temperature and pressure on slurry fuel atomization characteristics. The experiments involved composite liquid fuels based on water and filter cake (typical coal processing waste) in variable concentrations. These conditions are the same as in advanced fuel slurry preparation units involving pre-combustors, swirlers, and other elements. In this research we have recorded such spray characteristics as droplet sizes and velocities, volume fraction of droplets with given sizes, jet angle, as well as the angle its deviation from the original trajectory. As has been observed, an increase in the ambient gas temperature leads to a 30% increase in the jet velocity and a 40-60% increase in the volume fraction of small droplets, whereas a pressure increase, on the contrary, reduces these parameters by 11-32% and 100%, respectively). Combined effects of chamber gas pressure and temperature on atomization characteristics have been identified: the variation of atomization characteristics did not exceed 18%. Mathematical expressions have been obtained to predict the atomization characteristics of composite liquid fuels in power-generating units with the known gas temperature and pressure. Maps have been plotted using a set of dimensionless parameters that can help control droplet size, velocity, jet angles, and angles of its deviation from its original path.