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Chemical Engineering Laboratory Exercises with Design Problems for First Year Engineering Students

Polly R. Piergiovanni and Kaushal Silwal. Chemical Engineering, Lafayette College, Easton, PA 18042

Many students enter engineering programs with little idea of what engineering is or how a practicing engineer functions. At Lafayette College, we have developed an Introduction to Engineering course (ES 101) to help students understand some of the aspects of each field. Through this course, we try to help students understand the profession, the available options and opportunities upon graduation, and what to expect in their education.

The overriding course objective is to teach students the fundamental nature of engineering in the form of the engineering method and design/problem solving approach. In the chemical engineering block, this is accomplished mainly during two three-hour laboratory periods, where the students do an experiment and use information obtained from the experiment in a design problem using the Ten Step Design Process1.

In the first laboratory, the students use uncomplicated bioreactors to grow yeast. The students measure yeast cell concentration, glucose consumption and ethanol production using simple techniques. While the cells are growing, the students work on the design problem. In this instance, they are provided with equations for cell growth, glucose and sucrose consumption rates and the ethanol production associated with these rates. Costs for glucose and sucrose are also provided. They are to use this data to determine which sugar provides more economical ethanol production. Next, they are given costs for various sizes of airlift bioreactors, the associated operator and energy costs, and they are to determine what combination of reactors would be most economical for large scale ethanol production.

In the second laboratory, the students polymerize vinyl acetate to produce polyvinylacetate. They measure the temperature as a function of time to follow the polymerization. When the polymerization is nearly finished, each group receives their polymer to test its waterproofing ability against two standards. For the design portion, the students must create (on paper) a temporary shelter for a displaced family. [For the last two years, this has been the overall theme of ES 101]. The students draw the tent and calculate its surface area. They are provided with costs for the polymer they produced, fabrics and laborers. They are encouraged to use their data to develop the least expensive tent. An alternative design problem is to have the students scale up the process, taking into account the cooling costs for the reaction and the heating costs for the evaporation process which makes the polyvinylacetate a better waterproofing agent.

The chemical engineering block was offered in this form for the fall semesters of 2004 and 2005 (and will be offered again in the fall of 2006). Student comments about the laboratory and design portion of the block have been generally positive with 29% of those who commented calling the labs “interesting and good” and 25% of the commenters writing that they were “fun and enjoyable”. Details of the laboratory procedures and design problems will be presented, along with student results and comments.

References: 1. Oakes, William C., Leone, Les L., and Gunn, Craig J., Engineering Your Future: An Introduction to Engineering, Great Lakes Press, Inc., Okemos, MI, 2004