Hangga Wicaksono, Sugeng Hadi Susilo, Bayu Pranoto
The conventional biodigester has a high probability of CO2 contamination. As an inert gas in the combustion process, further investigation needed to clarify the effect of CO2 in CH4 premixed combustion. This study aims to determine the effect of CO2 dilution by using numerical approach to identify the changes in the chemical reaction chain especially in CO gas formation. To get the most suitable mixture, the range of equivalence ratio was varied from 0.11-3.14 and 0.5-1.68 in CH4/CO2/O2 and CH4/CO2/Air respectively. The amount of CO2 diluted in each reactant mixture was varied from 0-40% mass based on conventional biogas composition. The flow rate was maintained in ±6 L/min. The distance of the two counterflow nozzles was 20mm so that the stagnation point gained at 10mm in z coordinate. Results from this study showed a decreasing temperature caused by CO2 addition that more significant on the fuel-rich side. CO2 does not only decrease the temperature by absorbing heat but also has the potential to make changes in chemical reactions path. On both reactants, the CO mass fraction showed an increasing value as the CO2 was added to the mixture. This is due to the decreasing heat release rate of some reactions that convert CO into CO2. Those reactions such as CO + O (+M) ↔ CO2 (+M), CO + O2 ↔ CO2 + O and CO + OH ↔ CO2 + H reactions. © School of Engineering, Taylor's University
Mechanical Engineering Department, State Polytechnic of Malang, Jl. Soekarno Hatta No. 9, East Java, Malang, Indonesia