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Comparison of Negative Valve Overlap (NVO) and Rebreathing Valve Strategies on a Gasoline PPC Engine at Low Load and Idle Operating Conditions

Borgqvist, Patrick LU ; Tunestål, Per LU and Johansson, Bengt LU (2013) SAE World Congress & Exhibition, 2013
Abstract
Gasoline partially premixed combustion (PPC) has the potential of high efficiency and simultaneous low soot and NOx emissions. Running the engine in PPC mode with high octane number fuels has the advantage of a longer premix period of fuel and air which reduces soot emissions. The problem is the ignitability at low load and idle operating conditions.



In a previous study it was shown that it is possible to use NVO to improve combustion stability and combustion efficiency at operating conditions where available boosted air is assumed to be limited. NVO has the disadvantage of low net indicated efficiency due to heat losses from recompressions of the hot residual gases. An alternative to NVO is the rebreathing valve... (More)
Gasoline partially premixed combustion (PPC) has the potential of high efficiency and simultaneous low soot and NOx emissions. Running the engine in PPC mode with high octane number fuels has the advantage of a longer premix period of fuel and air which reduces soot emissions. The problem is the ignitability at low load and idle operating conditions.



In a previous study it was shown that it is possible to use NVO to improve combustion stability and combustion efficiency at operating conditions where available boosted air is assumed to be limited. NVO has the disadvantage of low net indicated efficiency due to heat losses from recompressions of the hot residual gases. An alternative to NVO is the rebreathing valve strategy where the exhaust valves are reopened during the intake stroke. The net indicated efficiency is expected to be higher with the rebreathing strategy but the question is if similar improvements in combustion stability can be achieved with rebreathing as with NVO.



The results show that the rebreathing valve strategy has similar improvements on combustion stability as NVO when the same fuel injection strategy is used. This work also includes results with the NVO valve strategy where a fuel injection is added during the NVO. When a fuel injection is added during the NVO, an additional improvement on combustion stability can be seen which is unmatched by the rebreathing valve strategy. (Less)
Please use this url to cite or link to this publication:
author
; and
organization
publishing date
type
Chapter in Book/Report/Conference proceeding
publication status
published
subject
keywords
Internal Combustion Engines, Partially Premixed Combustion, Valve Strategies
host publication
SAE Technical Paper Series
publisher
Society of Automotive Engineers
conference name
SAE World Congress & Exhibition, 2013
conference location
Detroit, Michigan, United States
conference dates
2013-04-16 - 2013-04-18
external identifiers
  • other:2013-01-0902
  • scopus:84878785266
ISSN
0148-7191
DOI
10.4271/2013-01-0902
project
Competence Centre for Combustion Processes
language
English
LU publication?
yes
id
27a96984-93cc-4231-be81-ed240f68c04c (old id 4318401)
alternative location
http://papers.sae.org/2013-01-0902/
date added to LUP
2016-04-01 14:35:03
date last changed
2022-04-22 04:07:46
@inproceedings{27a96984-93cc-4231-be81-ed240f68c04c,
  abstract     = {{Gasoline partially premixed combustion (PPC) has the potential of high efficiency and simultaneous low soot and NOx emissions. Running the engine in PPC mode with high octane number fuels has the advantage of a longer premix period of fuel and air which reduces soot emissions. The problem is the ignitability at low load and idle operating conditions.<br/><br>
<br/><br>
In a previous study it was shown that it is possible to use NVO to improve combustion stability and combustion efficiency at operating conditions where available boosted air is assumed to be limited. NVO has the disadvantage of low net indicated efficiency due to heat losses from recompressions of the hot residual gases. An alternative to NVO is the rebreathing valve strategy where the exhaust valves are reopened during the intake stroke. The net indicated efficiency is expected to be higher with the rebreathing strategy but the question is if similar improvements in combustion stability can be achieved with rebreathing as with NVO.<br/><br>
<br/><br>
The results show that the rebreathing valve strategy has similar improvements on combustion stability as NVO when the same fuel injection strategy is used. This work also includes results with the NVO valve strategy where a fuel injection is added during the NVO. When a fuel injection is added during the NVO, an additional improvement on combustion stability can be seen which is unmatched by the rebreathing valve strategy.}},
  author       = {{Borgqvist, Patrick and Tunestål, Per and Johansson, Bengt}},
  booktitle    = {{SAE Technical Paper Series}},
  issn         = {{0148-7191}},
  keywords     = {{Internal Combustion Engines; Partially Premixed Combustion; Valve Strategies}},
  language     = {{eng}},
  publisher    = {{Society of Automotive Engineers}},
  title        = {{Comparison of Negative Valve Overlap (NVO) and Rebreathing Valve Strategies on a Gasoline PPC Engine at Low Load and Idle Operating Conditions}},
  url          = {{http://dx.doi.org/10.4271/2013-01-0902}},
  doi          = {{10.4271/2013-01-0902}},
  year         = {{2013}},
}