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Valve timing optimisation of a spark ignition engine with skip cycle strategy

Valve timing optimisation of a spark ignition engine with skip cycle strategy
Valve timing optimisation of a spark ignition engine with skip cycle strategy
Skip cycle strategy (SCS) is a stroke volume modulation method leading to reduction in pumping loss through deactivation of engine valves under part-load conditions. Although SCS achieves a significant fuel economy, it increases regulated pollutant emissions such as nitrogen oxide and unburned hydrocarbon in comparison to normal 4-cycle engine operation. This paper investigated normal cycle strategy, skip cycle strategy as well as combination of skip cycle strategy and variable valve timing strategy for a spark-ignition engine using one-dimensional numerical model. The skip cycle engine was modelled at several steady-state operation points and then optimised at best ignition timing providing maximum brake torque at each simulation case. The numerical results obtained for both normal cycle and skip cycle have been validated against the experimental data. After completing the validation of numerical results with engine test bench data for both normal and skip cycle operations, optimisation of intake and exhaust valve timing profiles have been carried out regarding advancing or retarding camshaft relatively to the crankshaft position. In case of SCS and variable valve timing application together, NOx concentration was reduced by 35.1%, 39.4%, 26.8% and HC emission was reduced by 54.9%, 49.3% and 47.4% on average for brake mean effective pressure load levels of 1, 2 and 3 bar respectively at all among engine speed ranges between 1200 and 1800 rpm compared to stand alone SCS strategy. Furthermore, no remarkable additional brake specific fuel consumption was observed for SCS plus variable valve timing strategy compared to stand alone SCS.
0196-8904
95-112
Dogru, Baris
4ba10dd1-64cb-4966-9e31-70b543471a2b
Lot, Roberto
ceb0ca9c-6211-4051-a7b8-90fd6f0a6d78
Ranga Dinesh, K.K.J
6454b22c-f505-40f9-8ad4-a1168e8f87cd
Dogru, Baris
4ba10dd1-64cb-4966-9e31-70b543471a2b
Lot, Roberto
ceb0ca9c-6211-4051-a7b8-90fd6f0a6d78
Ranga Dinesh, K.K.J
6454b22c-f505-40f9-8ad4-a1168e8f87cd

Dogru, Baris, Lot, Roberto and Ranga Dinesh, K.K.J (2018) Valve timing optimisation of a spark ignition engine with skip cycle strategy. Energy Conversion and Management, 173, 95-112. (doi:10.1016/j.enconman.2018.07.064).

Record type: Article

Abstract

Skip cycle strategy (SCS) is a stroke volume modulation method leading to reduction in pumping loss through deactivation of engine valves under part-load conditions. Although SCS achieves a significant fuel economy, it increases regulated pollutant emissions such as nitrogen oxide and unburned hydrocarbon in comparison to normal 4-cycle engine operation. This paper investigated normal cycle strategy, skip cycle strategy as well as combination of skip cycle strategy and variable valve timing strategy for a spark-ignition engine using one-dimensional numerical model. The skip cycle engine was modelled at several steady-state operation points and then optimised at best ignition timing providing maximum brake torque at each simulation case. The numerical results obtained for both normal cycle and skip cycle have been validated against the experimental data. After completing the validation of numerical results with engine test bench data for both normal and skip cycle operations, optimisation of intake and exhaust valve timing profiles have been carried out regarding advancing or retarding camshaft relatively to the crankshaft position. In case of SCS and variable valve timing application together, NOx concentration was reduced by 35.1%, 39.4%, 26.8% and HC emission was reduced by 54.9%, 49.3% and 47.4% on average for brake mean effective pressure load levels of 1, 2 and 3 bar respectively at all among engine speed ranges between 1200 and 1800 rpm compared to stand alone SCS strategy. Furthermore, no remarkable additional brake specific fuel consumption was observed for SCS plus variable valve timing strategy compared to stand alone SCS.

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ECM-D-18-03419R1-accepted - Accepted Manuscript
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More information

Accepted/In Press date: 21 July 2018
e-pub ahead of print date: 26 July 2018
Published date: 1 October 2018

Identifiers

Local EPrints ID: 422765
URI: http://eprints.soton.ac.uk/id/eprint/422765
ISSN: 0196-8904
PURE UUID: e8d7f8bf-3e46-4e07-a3eb-457c79f767b8
ORCID for Roberto Lot: ORCID iD orcid.org/0000-0001-5022-5724
ORCID for K.K.J Ranga Dinesh: ORCID iD orcid.org/0000-0001-9176-6834

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Date deposited: 03 Aug 2018 16:30
Last modified: 17 Dec 2019 05:18

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Contributors

Author: Baris Dogru
Author: Roberto Lot ORCID iD

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