Numerical study of hydrogen addition impact on combustion characteristics of a natural gas fueled Engine

This work investigates the effects of hydrogen addition to compressed natural gas (CNG) on combustion characteristics and emission reduction using a closed cycle simulation with exact geometry of piston and cylinder head. The effect of equivalence ratio on combustion characteristic were investigated using a spark ignition (SI) engine fueled with CNG and addition of ۱۰% vol, ۱۵% vol and ۲۰%vol hydrogen. Two different speed of ۱۵۰۰ and ۳۰۰۰ rpm have considered at full load condition. The modeling includes ECFM combustion model combined with K-ζ-f turbulent modeland has been done by AVL Fire software. Different volume fraction of Hydrogen with different excess air modeled and validated with experimental data. The validation procedure included in-cylinder pressure profile, maximum pressure, angle of maximum pressure, indicated mean effective pressure, and carbon monoxide (CO) emission showing a good agreement with the experimental results. The value of the peak pressure increases by hydrogen addition and it takes place sooner as the hydrogen volume fraction increases. However, the mean effective pressure drops ۳.۵%, ۷% and ۱۵% for HCNG ۱۰, HCNG۱۵ and HCNG۲۰, respectively. CO emission decreases by increasing the hydrogen volume fraction. The results also indicate that hydrogen addition in lean combustion causes more CO reduction compared to the fuel-rich mixtures.

کلیدواژه ها:

Spark Ignition (SI) Engine ، Hydrogen ، Compressed Natural Gas (CNG) ، Carbon Monoxide ، Emission.