Katie Bagwell works on her Stirling engine project with Lian-Ping Wang (center) and Roger Stahl.

Discovery learning

Hands-on activities broaden engineering students' view of thermodynamics

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2:12 p.m., Dec. 18, 2012--Carbon dioxide, candle wax, a hobby rocket and water would not seem to have much in common but they all were among the topics presented by 14 students in the Honors sections of the course MEEG341 Thermodynamics on Wednesday, Dec. 5, as a means to cement classroom learning.

“I want students to leave the course knowing there are many uses for what they learn in this class, learning that they can apply later on as real-world engineers,” said Lian-Ping Wang, a mechanical engineering professor who holds a joint appointment as professor of physical ocean science and engineering.

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Thermodynamics is a field at the interface of science and engineering that examines the relationship between heat and other forms of energy. The projects allowed students to gain hands-on experience by choosing a topic, formulating a problem, then building a device to demonstrate a specific thermodynamics topic.

As a requirement, each experiment had to cost under $100 in parts and materials, be homemade and include the student’s quantitative measurements along with a comparison to the theoretical calculations. The University’s Honors Program and the Department of Mechanical Engineering provided Honors Course Enrichment Funds for the project.

Discovery learning was a big part of these projects, according to Wang, and the students agree that doing hands-on experiments help account for what is happening as opposed to simply learning the concepts.

Katie Bagwell, a junior studying mechanical engineering, assembled a working Stirling engine model driven by a single candle. The engine functions purely on the compression and expansion of air from heating and cooling cycles, generating sufficient energy to drive a flywheel. 

Her experiment tested whether the engine’s output depended on the temperature difference between the heat source and heat sink by using a candle as the heat source and interchanging the heat sink with room temperature air, tap water and ice cubes. Bagwell discovered a positive correlation between the flywheel rotation speed and the temperature difference.

With the help of Wang and Roger Stahl, mechanical engineering laboratory manager who assisted with instrumentation for many of the projects, Bagwell was able to overcome several obstacles. “Friction from the connecting rods not being perfectly parallel was a challenge as well as air leaks from the pinhole in the diaphragm. We glued around the opening of the mount to reduce the leaks and made many adjustments to reduce rubbing from the rods,” Bagwell explained.

Because of the emphasis on discovery learning, “Not all of the students succeeded in achieving a quantitative explanation for their demonstrations, but they all learned a lot from building and testing their demonstrations,” said Wang, adding, “It is quite challenging to perform quantitative analysis on small-scale demonstrations as many assumptions we usually make in the classroom are simply not valid.”

Heather Doty, an assistant professor of engineering who teaches another section of MEEG341, also worked with Wang to incorporate a more interactive and communicative learning environment. “We encouraged students to ask questions during weekly discussion sections, as well as before lectures,” Doty explained.

This method allowed the instructors to customize the learning experience and direct the course toward concepts the students needed more assistance in understanding. Wang said, “Students learn best when they can ask questions.”

Article by Sarah E. Meadows.

Photo by Evan Krape

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