EngrI 1120 introduces design and analysis. The theme is chemical engineers create processes based on chemical change. The chief product of chemical engineering is an idea or solution to a problem, as opposed to tangible items. Although most chemical processes are sophisticated, they have simple beginnings. My lectures on design begin at a key processing unit, for example a chemical reactor, and culminate in a complex process of several interconnected units. The first key concept is that designs evolve by adding to and modifying simple ideas.
Students practice design during weekly two-hour calculation sessions. During these sessions the students assemble into ad-hoc teams to develop chemical process designs. They are advised to carefully define the design objective (Is the goal to separate air into oxygen and nitrogen, or is the true goal to produce nitrogen, which allows one to convert the oxygen into a more-easily separated chemical?) and explore many options (How does one explain a creative idea to a team and encourage creative thinking from team members?) The teaching assistants (seniors in chemical engineering) and I circulate to assist some groups in completing their design (guidance through careful questioning) and challenge other groups to improve their designs. During the calculation sessions various teams present their solutions for comments by the class. Students readily devise a complex flowsheets similar to designs in commercial use (albeit designs that lack the details of an actual process) and thus gain confidence in their ability to design chemical engineering processes.
The second key concept of the freshman course is that an optimal design evolves from devising many designs and choosing the best. Students explore alternative designs to maximize product, minimize by-products and energy consumption, and optimize costs; processes are improved by creating several alternatives and selecting the best. Because chemical engineering processes tend to be large (100 million kg/year) and one-of a kind, it is impractical to build alternatives for a process, operate each alternative, and then choose. Rather, one must analyze the design. Students are introduced to three analytical methods: mathematical modeling, empirical modeling, and dynamic scaling by dimensional analysis. I also use these different methods to reinforce concepts in learning styles, for example, mathematical modeling versus the graphical empirical modeling illustrates verbal versus visual styles.