Thermal properties of combustion chamber deposits and their effect on engine heat transfer and octane requirement increase
Hayes, Timothy Keith
This item is only available for download by members of the University of Illinois community. Students, faculty, and staff at the U of I may log in with your NetID and password to view the item. If you are trying to access an Illinois-restricted dissertation or thesis, you can request a copy through your library's Inter-Library Loan office or purchase a copy directly from ProQuest.
Permalink
https://hdl.handle.net/2142/20934
Description
Title
Thermal properties of combustion chamber deposits and their effect on engine heat transfer and octane requirement increase
Author(s)
Hayes, Timothy Keith
Issue Date
1991
Doctoral Committee Chair(s)
White, Robert A.
Department of Study
Mechanical Science and Engineering
Discipline
Mechanical Engineering
Degree Granting Institution
University of Illinois at Urbana-Champaign
Degree Name
Ph.D.
Degree Level
Dissertation
Keyword(s)
Engineering, Automotive
Language
eng
Abstract
An investigation of the thermal properties of combustion chamber deposits and their effect on engine heat transfer and Octane Requirement Increase (ORI) has been completed. Deposits were grown in a Chrysler 4-cylinder 2.2 liter engine with total test times of 50- and 250-hours. Two fuels were used, both having the same unleaded premium fuel base, but one was doped with reformer bottoms which promoted deposit growth and octane requirement increase. Thicknesses were measured using a machinist's microscope and the thermal diffusivity and conductivity were measured with high speed thermocouples and steady and flash laser techniques.
The results indicate that the fuel with reformer bottoms produces deposits which are 15-25 percent thicker in the end gas region. The 250-hour test indicated that the deposits grow quickest in the end gas region, but stabilize there sooner, with the central region growing slower. The thermal diffusivity of the deposits grown with reformer bottoms was 1/2 to 1/3 that of the clean fuel. For the clean fuel, the thermal diffusivity ranged from 3.5 to 3.9 e-7 m$\sp2$/s, and for the fuel doped with reformer bottoms, the diffusivity ranged from 1 to 1.9 e-7 m$\sp2$/s. These deposit diffusivity values fall within the reported range in the literature of 0.39 to 27.2 e-7 m$\sp2$/s. For the doped fuel, the conductivity values ranged from 0.15 to 0.6 W/mK, while the clean fuel ranged from 0.3 to 1 W/mK. Reported values of thermal conductivity for unleaded fuel deposits in the literature ranged from 0.04 to 0.7 W/mK. Engine simulation calculations indicated that the clean fuel produces lower Octane Requirement Increase (ORI) and unburned temperatures. The simulation results also indicated that larger values of deposit conductivity and deposit diffusivity should be the aim of fuel additives in order to reduce ORI.
Use this login method if you
don't
have an
@illinois.edu
email address.
(Oops, I do have one)
IDEALS migrated to a new platform on June 23, 2022. If you created
your account prior to this date, you will have to reset your password
using the forgot-password link below.