Cycle-by-cycle variations in a direct injection hydrogen enriched compressed natural gas engine employing EGR at relative air-fuel ratios.
Since the pressure development in a combustion chamber is uniquely related to the combustion process, substantial variations in the combustion process on a cycle-by-cycle basis are occurring. To this end, an experimental study of cycle-by-cycle variation in a direct injection spark ignition engine f...
| Main Authors: | Olalekan, W.S., Rashid, A.A., Baharom, M. |
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| Format: | Conference or Workshop Item |
| Institution: | Universiti Teknologi Petronas |
| Record Id / ISBN-0: | utp-eprints.32254 / |
| Published: |
EDP Sciences
2014
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| Online Access: |
https://www.scopus.com/inward/record.uri?eid=2-s2.0-84904995783&doi=10.1051%2fmatecconf%2f20141302009&partnerID=40&md5=2f014e6e1e0ff0051020d8f2376a7717 http://eprints.utp.edu.my/32254/ |
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| Summary: |
Since the pressure development in a combustion chamber is uniquely related to the combustion process, substantial variations in the combustion process on a cycle-by-cycle basis are occurring. To this end, an experimental study of cycle-by-cycle variation in a direct injection spark ignition engine fueled with natural gas-hydrogen blends combined with exhaust gas recirculation at relative air-fuel ratios was conducted. The impacts of relative air-fuel ratios (i.e. λ = 1.0, 1.2, 1.3 and 1.4 which represent stoichiometric, moderately lean, lean and very lean mixtures respectively), hydrogen fractions and EGR rates were studied. The results showed that increasing the relative air-fuel ratio increases the COVIMEP. The behavior is more pronounced at the larger relative air-fuel ratios. More so, for a specified EGR rate; increasing the hydrogen fractions decreases the maximum COVIMEP value just as increasing in EGR rates increases the maximum COVIMEP value. (i.e. When percentage EGR rates is increased from 0 to 17 and 20 respectively. The maximum COVIMEP value increases from 6.25 to 6.56 and 8.30 respectively). Since the introduction of hydrogen gas reduces the cycle-by-cycle combustion variation in engine cylinder; thus it can be concluded that addition of hydrogen into direct injection compressed natural gas engine employing EGR at various relative air-fuel ratios is a viable approach to obtain an improved combustion quality which correspond to lower coefficient of variation in imep, (COVIMEP) in a direct injection compressed natural gas engine employing EGR at relative air-fuel ratios. © 2014 Owned by the authors, published by EDP Sciences. |
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