The effects of fuel-injection timing at medium injection pressure on the engine characteristics and emissions of a CNG-DI engine fueled by a small amount of hydrogen in CNG

Mixture formation analysis in a direct-injection NG SI engine under different injection timings

“…According to [4,6,11], the injection timing is a key parameter to be set in order to obtain a high-quality mixing and combustion processes. In the project, the effect of the EOI timing on the mixture formation process was experimentally analyzed on the transparent engine, for the operation point at 2000 rpm and imep of 3 bar.…”

“…In such cases, the piston is in fact too far from the jet to exert a proper reflection, and the mixture motion is generated by the air entering the cylinder during intake. In the last decade, many researchers have concentrated their efforts in pursuing research projects focused on direct injection NG engines, both from an experimental and numerical point of view [4][5][6][7][8][9][10][11][12][13][14][15][16].…”

“…Zeng et al [6] performed an experimental investigation into the combustion characteristics and engine performance for different EOIs, at fixed engine speed, injected-fuel amount and spark timing, and found an optimum EOI timing which gave rise to the fastest combustion process, as well as to the lowest HC and CO emissions. Mohammed et al [11] investigated the EOI effect on a single-cylinder engine at different engine speeds, and found that the optimum injection timing had to be advanced as the engine speed was increased. In addition to the EOI effect on the mixture homogeneity, in [4] the high impact of the EOI timing on the volumetric efficiency was pointed out.…”

Effects of compression ratio on performance and emissions of a modified diesel engine fueled by HCNG

“…So, it can be said that CNG losses the advantages at high excess air ratios. This can attributed to the low flame speed of CNG [6,21], as seen in Table 3. Moreover, when the CR values are 9.6 and 12.5, torque values increase with addition of hydrogen (about 5e10%) to CNG.…”

Natural Gas Engine Technologies: Challenges and Energy Sustainability Issue

“…This is mainly done for fossil-fuel substitution and oxygenation. In gaseous fuels, with CNG in particular, the lower laminar-flame-speed characteristics attracted researchers to add higher laminar-flame-speed fuels, such as hydrogen and syngas [218,[231][232][233][234][235]. Figure 20 shows the effect of hydrogen blending in natural gas over a range of equivalence ratios.…”