Publication: Numerical analysis of the autoignition of isolated wet ethanol droplets immersed in a hot and humid air atmosphere
Loading...
Identifiers
Publication date
2021-04
Defense date
Advisors
Tutors
Journal Title
Journal ISSN
Volume Title
Publisher
Elsevier
Impact
Export
Abstract
Results of time-dependent, spherically symmetrical computations of the vaporization and combustion of
ethanol and ethanol/water droplets are reported. Mixture-average transport was employed, along with a
systematically reduced chemical-kinetic mechanism involving 15 overall steps among 17 chemical species,
to speed the computations by a factor of about 100 over what would be required if full detailed chemistry had been used. Absorption of water from the gas surrounding the droplet and its diffusive transport
within the liquid phase were taken into account, providing excellent agreement with previous experimental and computational results for the combustion of ethanol droplets in air. On the other hand, the
assumption of rapid liquid-phase mixing produced very poor agreement when water condensation on the
droplet surface or hydrous ethanol are considered. To characterize autoignition, we define the critical autoignition temperature Tc
∞ as the critical ambient temperature below which autoignition is not observed.
Computations for autoignition of cold ethanol/water droplets in air showed that Tc
∞ decreases with increasing initial droplet diameters. In the range of parameters under consideration, ignition was found to
take place always before complete vaporization of the droplet, and the ignition time was found to become
longer with the increasing initial water content of the liquid ethanol droplet. On the contrary, addition
of water vapor to the initial air atmosphere was found to shorten the ignition time, increasing ethanol
vaporization rate as a consequence of the extra heat release associated with water absorption into the
liquid.
Description
Keywords
Auto-ignition, Ethanol droplet combustion, Humidity, Reduced chemistry
Bibliographic citation
Millán-Merino, A., Fernández-Tarrazo, E. & Sánchez-Sanz, M. (2021). Numerical analysis of the autoignition of isolated wet ethanol droplets immersed in a hot and humid air atmosphere. Combustion and Flame, 226, 42–52.