Measurement of Work and Power in a Coffee-Mug Stirling Engine as a First-Year Physics Laboratory

This paper describes an experimental setup using a coffee mug, a low delta-temperature model Stirling engine, and a gas pressure sensor. The experiment is targeted toward first-year calculus-based physics labs and was designed to be implemented at low cost (approximately $120 for engine and pressure sensor) and minimal modification to off-the-shelf components for an instructor. The gas pressure sensor we used plugs directly into a USB port, and no data acquisition hub was required. Software to operate the sensor is available from the manufacturer at no additional cost. A sample student procedure handout is provided in Appendix B. Modifications for use in high school physics, algebra-based college physics, and upper-division thermodynamics courses are presented in Appendix A. Two simple modifications to the Stirling engine are required: (1) drilling a hole in the top plate of the Stirling engine and gluing a Luer lock fitting over the hole; and (2) 3D printing a spool that is then hot glued to the driveshaft of the Stirling engine. A more advanced experiment can be performed by 3D printing two gears and using a rotary motion sensor to track the phase of the system. A video demonstration of these modifications is provided. Student calculations of work done by the engine show good correlation with predicted theoretical calculations. Students also rated the experimental procedure highly for both interest and understanding.