2023 ASEE Annual Conference & Exposition

The traditional presentation of the second law of thermodynamics uses imaginary heat engines undergoing specific imaginary processes to derive the Clausius Inequality, which, in turn is used to derive entropy and exergy relations. The specific and abstract nature of this derivation is an impediment to conceptual clarity and generalization. An alternative method of deriving the Clausius Inequality and other second-law results was recently proposed by the author. It does not rely on imaginary reversible processes occurring inside heat engines; all results can be derived for any arbitrary control volume with heat and/or work interactions. The efficacy of the alternate derivation has been assessed in this work, by comparing students from two class sections of an undergraduate introductory Thermodynamics course. Both sections received identical instruction for the traditional presentation, but only one section was taught the new derivation during one class lecture period; the derivation was then referred to multiple times during subsequent conceptual discussions. Conceptual understanding of both sections was then compared using a second-law concept inventory, and a few supplemental questions. The experiment was repeated for two years during the fall semesters of 2017 and 2018. The results show that the participating section performed better than the non-participating section in general. It is hoped that these results will convince other instructors to try to use the new derivation to improve student outcomes.