Volume 9 Issue 1 ( March 2022 )

Disparities in the constituents among biogases pose various control challenges during combustion, thus complicating its operability. Improving biogas by eliminating carbon dioxide (CO₂) remains difficult, and high CO₂ concentration is known to affect combustion. Still, the effect on Biogas/Diesel dual-fuel reactivity-controlled compression ignition (RCCI) combustion is not well explored. The influence of high diluent (CO₂) proportions (25 – 45%) and Biogas fraction (40 – 70%) on Biogas/Diesel dual-fuel RCCI combustion was evaluated experimentally, at full load and 1600 rpm. The results show distinct temperature trends across the combustion regimes for all the CO₂ ratios and Biogas fractions. The radiation absorption effect of high CO₂ reduces the cylinder temperature and delays the expansion to a 10 – 20^o crank angle after the top dead centre (CA ATDC). The temperature and pressure decrease with the increase in CO₂ ratios and Biogas fractions, unlike heat released rate. Burning Diesel and 45% CO₂ indicate the fastest combustion, with combustion phasing (CA50) at 6.353 ms ATDC while 25 and 35% CO₂ were slowed by 0.258 and 0.578 ms, respectively. Inferentially, 35% CO₂ at a fraction of 50% could form the best reactivity.

Keywords: RCCI combustion; high CO₂ content; biogas