Probing Student Understanding of Basic Concepts and Principles in Introductory Engineering Thermodynamics

We report on an ongoing research study on student understanding of thermodynamic concepts and principles in the context of an introductory engineering thermodynamics course at Hamburg University of Technology (TUHH). Through analysis of student responses to mostly qualitative questions, we have identified prevalent and persistent difficulties. In this paper, we describe the research methods, present some preliminary results, and discuss the implications of our work for instruction and the development of curricular materials. We also illustrate the use of interactive lecture questions as an instructional tool. In recent decades, research on student understanding in science and engineering has revealed that traditional quantitative problems often are not a suitable tool for the assessment of conceptual understanding. On the basis of results from prior investigations in the context of thermal physics we have therefore begun to administer “conceptual” questions to students of engineering thermodynamics. These questions are delivered through ungraded quizzes, course examinations, and as interactive lecture questions (ILQs or “clicker questions”) via a classroom communication system. While only the two written formats require students to explain the reasoning supporting their answers, we have found that there is good agreement between the results obtained through different methods. Our work so far has concentrated on probing student understanding of (1) work and the application of the first law to closed systems and flow processes, (2) the distinction between state and process quantities, in particular student understanding of entropy as a state function, and (3) the application of the second law, especially to refrigeration cycles. Conceptual difficulties that we have observed include, for example, the students’ tendency to associate an increase in entropy of the system with any irreversible process even if the state function property of the entropy leads to a different result. Similar difficulties have been documented in the context of introductory and upper-level physics courses. While ILQs serve as a research instrument, we also recognize their potential as an effective instructional tool. Data from post-tests suggest that the use of such questions can enhance student learning in traditional lectures. In addition, we discuss how results from this study contributed to the writing of a textbook on engineering thermodynamics.