Advanced

Lean Burn Natural Gas Operation vs. Stoichiometric Operation with EGR and a Three Way Catalyst

Einewall, Patrik LU ; Tunestål, Per LU and Johansson, Bengt LU (2005) SAE World Congress In SAE Special Publications 2005(SP-1972). p.343-362
Abstract
Exhaust emissions from lean burn natural gas engines may not always be as low as the potential permits, especially engines with open-loop lambda control. These engines can produce much higher emissions than a comparable diesel engine without exhaust gas aftertreatment. Even if the engine has closed-loop lambda control, emissions are often unacceptably high for future emission regulations. A three-way catalyst is, today, the best way to reduce hazardous emissions. The drawback is that the engine has to operate with a stoichiometric mixture and this leads to; higher heat losses, higher pumping work at low to medium loads, higher thermal stress on the engine and higher knock tendency (requiring lower compression ratio, and thus lower brake... (More)
Exhaust emissions from lean burn natural gas engines may not always be as low as the potential permits, especially engines with open-loop lambda control. These engines can produce much higher emissions than a comparable diesel engine without exhaust gas aftertreatment. Even if the engine has closed-loop lambda control, emissions are often unacceptably high for future emission regulations. A three-way catalyst is, today, the best way to reduce hazardous emissions. The drawback is that the engine has to operate with a stoichiometric mixture and this leads to; higher heat losses, higher pumping work at low to medium loads, higher thermal stress on the engine and higher knock tendency (requiring lower compression ratio, and thus lower brake efficiency). One way to reduce these drawbacks is to dilute the stoichiometric mixture with EGR. This paper compares lean burn operation with operation at stoichiometric conditions diluted with EGR, and using a three-way catalyst. The results show that nitric oxides (NOdx) and hydrocarbon (HC) emissions are several orders of magnitude lower than at lean operation. Higher loads can be achieved, and brake efficiency is higher than lean operation optimized for low NOdx production. A fast burning (high turbulence) combustion chamber is used to allow high amounts of dilution. (Less)
Please use this url to cite or link to this publication:
author
organization
publishing date
type
Chapter in Book/Report/Conference proceeding
publication status
published
subject
keywords
lean, stoichiometric, Engine, Natural Gas, CNG
in
SAE Special Publications
volume
2005
issue
SP-1972
pages
21 pages
publisher
Society of Automotive Engineers
conference name
SAE World Congress
external identifiers
  • scopus:84877216880
ISSN
0148-7191
DOI
10.4271/2005-01-0250
language
English
LU publication?
yes
id
f4ca99df-8a3c-45c2-88b9-06af54eb979b (old id 538197)
date added to LUP
2007-09-17 09:10:28
date last changed
2018-07-08 04:02:54
@inproceedings{f4ca99df-8a3c-45c2-88b9-06af54eb979b,
  abstract     = {Exhaust emissions from lean burn natural gas engines may not always be as low as the potential permits, especially engines with open-loop lambda control. These engines can produce much higher emissions than a comparable diesel engine without exhaust gas aftertreatment. Even if the engine has closed-loop lambda control, emissions are often unacceptably high for future emission regulations. A three-way catalyst is, today, the best way to reduce hazardous emissions. The drawback is that the engine has to operate with a stoichiometric mixture and this leads to; higher heat losses, higher pumping work at low to medium loads, higher thermal stress on the engine and higher knock tendency (requiring lower compression ratio, and thus lower brake efficiency). One way to reduce these drawbacks is to dilute the stoichiometric mixture with EGR. This paper compares lean burn operation with operation at stoichiometric conditions diluted with EGR, and using a three-way catalyst. The results show that nitric oxides (NOdx) and hydrocarbon (HC) emissions are several orders of magnitude lower than at lean operation. Higher loads can be achieved, and brake efficiency is higher than lean operation optimized for low NOdx production. A fast burning (high turbulence) combustion chamber is used to allow high amounts of dilution.},
  author       = {Einewall, Patrik and Tunestål, Per and Johansson, Bengt},
  booktitle    = {SAE Special Publications},
  issn         = {0148-7191},
  keyword      = {lean,stoichiometric,Engine,Natural Gas,CNG},
  language     = {eng},
  number       = {SP-1972},
  pages        = {343--362},
  publisher    = {Society of Automotive Engineers},
  title        = {Lean Burn Natural Gas Operation vs. Stoichiometric Operation with EGR and a Three Way Catalyst},
  url          = {http://dx.doi.org/10.4271/2005-01-0250},
  volume       = {2005},
  year         = {2005},
}