Study on the effect of using reformed biogas as a low reactivity fuel in a dual-fuel engine (RCCI)

The scarceness of non-renewable energies, rising fossil fuels prices, as well as strict environmental regulations have forced many researchers to focus on utilizing environmentally friendly renewable energies such as biogas in internal combustion engines. Variety in raw materials and process of biogas production results in different components and percentages of various elements, including methane. These differences make it hard to control the combustion, effectively, in internal combustion engines. In this research, by means of 3D-CFD model, the effect of reformed biogas (R.BG) was investigated on the combustion characteristics, emissions and performance of a RCCI engine. Validation of the model was done on a single-cylinder compression ignition engine in conventional diesel and dual-fuel operations. The combustion model of the RCCI engine was simulated by replacing diesel with 20%, 40% and 60% of R.BG as low reactivity fuel. The results showed that by increasing the R.BG energy share with a constant equivalence ratio of 0.43, the average combustion temperature decreases to 1300 K and the maximum in-cylinder pressure increases up to 22.63%. Instead, it results in 2.3%, 7.9%, and 14.5% engine output losses, respectively. Also, the emission of NOx, against CO, is reduced by 50%. Soot and UHC emissions were found to be slightly decreased while using R.BG more than 40%.