2019 ASEE Annual Conference & Exposition

The Chemical Engineering unit operations laboratory provides a unique hands-on experience in engineering experimentation on pilot-scale equipment. During a semester of unit operations laboratory, student experiments cover the following topics: fluid flow, heat transfer, and separation processes. In addition, the students perform an operability study (e.g., reverse osmosis, spray drying, injection molding) to obtain practical experience of atypical chemical engineering unit operations. After completing three full experiments and one short operability study, students are required to work on a final study whereby they are required to define their experimental objective(s) and parameters of study. This final experiment is structured as an open-ended experience, however, the students have limitations in what materials can be used (due to cost and safety considerations) and the experimental variables that can be manipulated (due to equipment limitations). Final experiments are based upon existing equipment within the laboratory, and each group selects their preferred equipment. Students must extend these experiments past the typical format of defining an objective, obtaining data and providing data analysis found in the earlier experiments. Examples of final experiment extensions involve equipment redesign, operating on novel materials, or using/developing advanced models and correlations during data analysis and interpretation. Also, since laboratory groups consist of three to four students, it has been a challenge to assign topics of interest to everyone in a single group. Here, we seek to enhance the final experiment experience in the unit operations laboratory by providing students with experiments in the context of environmental stewardship, alternative energy, and sustainable farming with available technology. The intention is to have students select their project based on their interests in one of the above topics and reorganize groups around these themes with the goal of having more group members interested in their final experiment. A new final experiment assigned this year involves developing biodiesel using a continuous-stirred tank reactor (CSTR).
Due to safety considerations, there are not many different undergraduate CSTR experiments typically implemented in a unit operation laboratory course. One of the most common experiments is the saponification reaction of ethyl acetate and a base. Finding an alternative reaction that is both safe and suitable for a teaching laboratory is a challenge. Here, we propose using the transesterification reaction between oil and alcohol with a catalyst. For this project, the students are challenged: (1) to run the reaction with ethanol—a solvent commonly used in undergraduate laboratory experiments—instead of methanol to promote a safe laboratory environment, and (2) to find the yield of the reaction to add this topic to the initial round of experiments. The groups worked collaboratively on defining experimental conditions, such as the type of oil to use, the mixing conditions, volumetric flow rates, temperature conditions, catalyst type and amount, and the oil to alcohol ratio. Available characterization equipment for the biodiesel production included a refractometer, a UV-Vis probe, and a gas chromatograph. Ultimately, the students reported their technical findings for this new CSTR experiment by delivering a team presentation and a final report.