Various effects of reformer gas enrichment on natural-gas, iso-octane and normal-heptane HCCI combustion using artificial inert species method

Reyhanian, M ; Sharif University of Technology | 2018

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  1. Type of Document: Article
  2. DOI: 10.1016/j.enconman.2017.12.074
  3. Publisher: Elsevier Ltd , 2018
  4. Abstract:
  5. Reformer gas (syngas) addition to main fuel is a practical solution for combustion timing control in HCCI engines. This study emphasizes the understanding of various effects of reformer gas (RG) addition, with composition of 75%vol H2 and 25%vol CO, in HCCI combustion by developing an artificial inert species method and using a detailed chemical kinetics multi-zone model. Three fuels (iso-octane, n-heptane, and natural gas) with different autoignition characteristics were used in this study. The developed multi-zone model was validated for mentioned fuels at various percentages of RG using six experimental cases of a single-cylinder CFR engine. The results showed that increasing reformer gas fraction in the fuel mixture advanced methane fuel combustion timing, retarded the combustion of n-heptane and had insignificant effect on iso-octane combustion. Thermal effect of RG in all fuels resulted in earlier start of combustion (SOC) because of the mixture specific heat ratio enhancement. The SOC for methane and iso-octane fuels was advanced by RG addition due to the chemical effect of RG. However, the chemical effect of RG for methane fuel is more significant. By adding 30% RG to methane fuel, H2 advanced the SOC by −5.6 °CA and CO retarded it by 1.4 °CA due to chemical effect and also the interaction effect of CO and H2 advanced the SOC by −1.8 °CA. For iso-octane fuel, adding 30% RG, both CO and H2 advanced the SOC by 0.4 CA due to their chemical effect. On the other hand, in n-heptane fuel, H2 is almost responsible for all of the chemical effects of RG for retardation of SOC. © 2017 Elsevier Ltd
  6. Keywords:
  7. Homogeneous charge compression ignition (HCCI) ; Hydrogen additive ; Reformer gas ; Syngas ; Engine cylinders ; Ignition ; Methane ; Mixtures ; Natural gas ; Polyols ; Specific heat ; Synthesis gas ; Thermal effects ; Chemical kinetics model ; Detailed chemical kinetic ; Homogeneous charge compression ignition ; Hydrogen additives ; Practical solutions ; Single cylinder CFR engine ; Start of combustion ; Syn-gas ; Heptane
  8. Source: Energy Conversion and Management ; Volume 159 , March , 2018 , Pages 7-19 ; 01968904 (ISSN)
  9. URL: https://www.sciencedirect.com/science/article/pii/S0196890417312335