Effects of Soret diffusion on the exergy losses in hydrogen laminar premixed flames

Abstract

The analysis of the exergy loss is an effective tool for evaluating second-law irreversibility in laminar flames. However, despite numerous studies underlining the importance of taking into account thermal diffusion in laminar flame studies, especially in hydrogen/air flames, this phenomenon is usually neglected in the exergy analysis of these flames. Therefore, this work investigates the effect of Soret diffusion on the exergy loss in laminar premixed flames for hydrogen/air mixtures using a detailed reaction mechanism and the multicomponent transport model. The study starts from conditions in which the importance of the Soret effect is well established in the scientific literature. It is found that, while the exergy losses directly due to the Soret effect are negligible, the Soret effect can appreciably affect the other exergy loss contributions and hence the total exergy loss. Hence, the Soret effect, unlike what has usually been assumed, is not negligible in flame calculations at least when this effect is known to affect laminar flame speed.