Entropy Generation and Exergy Assessment of Methane-Nitrous Oxide Diffusion Flames in a Triple-Port Burner

A triple-port burner was used in this study, and a numerical simulation was employed to investigate the entropy generation rate of CH4-N2O diffusion flames at the Rratio=1. Here, R ratio refers to the ratio of the oxidizer flow velocity to the fuel flow velocity. In order to scrutinize the decomposition effect of N2O on entropy generation, an oxygen-enriched gas with the same nitrogen to oxygen ratio as N2O (N-to-O=2) was used in CH4-N-2-O-2 diffusion flames. Besides, because the N2O could decompose into the oxygen-enriched gas, the oxygen-enriched effect was also studied by the CH4-air diffusion flames that were conducted in this research. The entropy generation rate comprises of three items in this study, including heat conduction, mass diffusion, and chemical reaction. As a result, the different reaction pathways would take part in the major reaction pathway in CH4-N2O diffusion flames, causing more entropy generation rate being produced through the more intense reactions in CH4-N2O diffusion flames. The irreversibility in CH4-air diffusion flames are dominated through heat conduction and chemical reaction, which is an identical result in CH4-N-2-O-2 diffusion flames. However, in CH4-N2O diffusion flames, chemical reactions dominated the irreversibility because of the more intense reaction caused by the thermal effect of N2O decomposition. As a result, the decomposition effect of N2O influences the availability of CH4-N2O diffusion flames.