University of Oulu

Aghahasani, M., Gharehghani, A., Mahmoudzadeh Andwari, A., Mikulski, M., & Könnö, J. (2022). Effect of natural gas direct injection (Ngdi) on the performance and knock behavior of an SI engine. Energy Conversion and Management, 269, 116145.

Effect of natural gas direct injection (NGDI) on the performance and knock behavior of an SI engine

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Author: Aghahasani, Mahdi1; Gharehghani, Ayat1; Mahmoudzadeh Andwari, Amin2;
Organizations: 1School of Mechanical Engineering, Iran University of Science and Technology, Narmak, Tehran, Iran
2Machine and Vehicle Design (MVD), Materials and Mechanical Engineering, University of Oulu, P.O. Box 4200, FI-90014 Oulu, Finland
3School of Technology and Innovation, Energy Technology, University of Vaasa, Wolffintie 34, FI-65200 Vaasa, Finland
Format: article
Version: published version
Access: open
Online Access: PDF Full Text (PDF, 8 MB)
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Language: English
Published: Elsevier, 2022
Publish Date: 2022-10-26


The unique properties of natural gas (NG), including high availability and lower cost compared with other fossil fuels, make it attractive in internal combustion engine (ICE) application. NG is composed mainly of methane and has greater knock resistance than gasoline, enabling higher compression ratios (CR). In contrast with the distinctive advantages, the NG fueled engines suffer from lower power and torque outputs. To address the subject, this study proposes an approach employing NG direct injection (NGDI) strategy (with higher volumetric efficiency unlike port injection), enabling a higher CR irrespective of knock limit. This work applies reactive computational fluid dynamics (CFD) to investigate spark ignited co-combustion of direct-injected NG with port-admitted gasoline. The results are validated against experimental data. In all simulated cases, the equivalence ratio (i.e., ∅ = 1) and the total input energy are kept constant. Engine performance is evaluated for three CRs (10.5, 11.5, and 12.5:1), five proportion of CNG (RCNG) and at part- and full-load conditions at an engine speed of 1500 rpm. Results indicated that while running RCNG = 100 % with a CR of 10.5:1, carbon monoxide (CO) and carbon dioxide (CO₂) emissions were decreased by 29.3 % and 23.5 % respectively, compared to RCNG = 0 %. The corresponding emission reduction at CR = 11.5:1 was 27.1 % and 24 %; at CR = 12.5:1 they were 29.6 % and 23.5 % respectively. At each CR, the knock intensity at full load fell significantly as the percentage of NG increased. At a CR of 12.5:1, ringing intensity (RI) at full load decreased by 88.6 % when using RCNG = 100 %, instead of RCNG = 0 %. Under the same conditions, RCNG = 25 % cut RI by 56 %.

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Series: Energy conversion and management
ISSN: 0196-8904
ISSN-E: 1879-2227
ISSN-L: 0196-8904
Volume: 269
Article number: 116145
DOI: 10.1016/j.enconman.2022.116145
Type of Publication: A1 Journal article – refereed
Field of Science: 214 Mechanical engineering
Copyright information: © 2022 The Author(s). Published by Elsevier Ltd. This is an open access article under the CC BY license (