Determination of heat of vaporization and vapor pressure by micro-liter fuel droplet vaporization

摘要

Fuel physical properties including vapor pressure and heat of vaporization are of great importance for spray atomization, mixing and evaporation processes in IC engines affecting their combustion and emission characteristics. This work utilizes small volumes and heated fuel droplets in the order of microliters to study the evaporation process. Measurements are obtained at atmospheric pressure over a range of temperatures relevant to in-cylinder fuel injection processes. Single droplets generated by a piezoelectric device at elevated temperatures are stroboscopically imaged to record the droplet size change during evaporation. By tracking the droplet evaporation process and modeling it using the Abramzon-Sirignano model, vapor pressure and heat of vaporization can be estimated. Measurements of these two physical properties of n-heptane and isooctane are compared with literature data at different temperatures. This novel property measurements and prediction procedure provides a pathway to identify potential fuel candidates for further development as drop-in replacements or blending components for use in advanced, high performance, low-emission engines.