(19d) Encouraging Students to Critically Think about the Origins and Assumptions Behind Heat and Mass Transfer Convection Coefficient Correlations Through a Simple Demonstration

A significant portion (~25-35%) of most undergraduate heat and mass transfer texts and courses are dedicated to instructing students in the use of convection coefficient correlations.  While most students become proficient at using the correlations, they have often commented that they do not really understand how the correlations were derived or why so much error (~25%) is associated.  To overcome this limitation in student education, a simple classroom demonstration and follow up assignment are presented.  The demonstration encourages students to not just think about what correlation to use, but to critically think about 1) how were the correlations in the text experimentally determined, 2) why is there so much error associated with each correlation, 3) where can I go to find the original experiments that led to the development of a given correlation, and 4) after I have finished this course and I need a convection coefficient correlation what resources will be available.  Specifically, a simple apparatus was constructed to collect heat transfer data while varying independent variables of convection coefficient correlations such as the Reynolds number.  Using the raw data students, generated their own convection correlation and calculated the error associated with their correlation as part of their homework assignment.  Students were also assigned to find and describe the use of a heat or mass transfer convection coefficient correlation from a common resource that they may have access to later in their career such as Perry’s Chemical Engineer’s Handbook.  Finally, students were given the opportunity to search archival journals for correlations and explain their use.  Following IRB approval, the effectiveness of this approach was assessed by a student survey at the end of the course.