skip to main content

DOE PAGESDOE PAGES

Title: Distillation-based Droplet Modeling of Non-Ideal Oxygenated Gasoline Blends: Investigating the Role of Droplet Evaporation on PM Emissions

In some studies, a relationship has been observed between increasing ethanol content in gasoline and increased particulate matter (PM) emissions from vehicles equipped with spark ignition engines. The fundamental cause of the PM increase seen for moderate ethanol concentrations is not well understood. Ethanol features a greater heat of vaporization (HOV) than gasoline and also influences vaporization by altering the liquid and vapor composition throughout the distillation process. A droplet vaporization model was developed to explore ethanol's effect on the evaporation of aromatic compounds known to be PM precursors. The evolving droplet composition is modeled as a distillation process, with non-ideal interactions between oxygenates and hydrocarbons accounted for using UNIFAC group contribution theory. Predicted composition and distillation curves were validated by experiments. Detailed hydrocarbon analysis was applied to fuel samples and to distillate fractions, and used as input for the initial droplet composition. With composition calculated throughout the distillation, the changing HOV and other physical properties can be found using reference data. The droplet can thus be modeled in terms of energy transfer, which in turn provides the transient mass transfer, droplet temperature, and droplet diameter. Model predictions suggest that non-ideal vapor-liquid equilibrium along with an increase in HOV canmore » alter the droplet composition evolution. Results predict that the presence of ethanol causes enrichment of the higher boiling fractions (T90+) in the aromatic components as well as lengthens the droplet lifetime. A simulation of the evaporation process in a transient environment as experienced within an engine cylinder predicts a decrease in mixing time of the heaviest fractions of the fuel prior to spark initiation, possibly explaining observations linking ethanol to PM.« less
Authors:
 [1] ;  [2] ;  [2] ;  [3] ;  [1]
  1. Colorado State Univ., Fort Collins, CO (United States)
  2. National Renewable Energy Lab. (NREL), Golden, CO (United States)
  3. Univ. of Colorado, Colorado Springs, CO (United States)
Publication Date:
Report Number(s):
NREL/JA-5400-67616
Journal ID: ISSN 1946-3960
Grant/Contract Number:
AC36-08GO28308; AC36-99GO10337
Type:
Accepted Manuscript
Journal Name:
SAE International Journal of Fuels and Lubricants (Online)
Additional Journal Information:
Journal Name: SAE International Journal of Fuels and Lubricants (Online); Journal Volume: 10; Journal Issue: 1; Journal ID: ISSN 1946-3960
Publisher:
SAE International
Research Org:
National Renewable Energy Lab. (NREL), Golden, CO (United States)
Sponsoring Org:
USDOE Office of Energy Efficiency and Renewable Energy (EERE), Vehicle Technologies Office (EE-3V); USDOE Office of Energy Efficiency and Renewable Energy (EERE), Bioenergy Technologies Office (EE-3B)
Country of Publication:
United States
Language:
English
Subject:
30 DIRECT ENERGY CONVERSION; 02 PETROLEUM; ethanol; spark-ignition engine; particle emissions; distillation; heat of vaporization
OSTI Identifier:
1351160