Technology Center makes Stirling product
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Skeptical? Well, it?s true. Of course, the engine is only about the size of a toaster. It?s called a Stirling engine, and it runs on heat differential.
This unique creation is the brainchild of Technology Center instructor Kenny Dunn. His machine shop class has produced a dozen of the engines, which were originally designed to pump water out of mines instead of using steam engines.
A man named Robert Stirling designed the engines in 1827, getting a patent on the system, which got its power from the change in pressure of air in a closed system as it was alternately heated and cooled. According to information provided by Dunn, the engine had a number of advantages over the steam engine of that day.
It operated on low pressure differentials, so there was no possibility of an explosion. It was much quieter in operation since all the working fluids were enclosed. Water was not used, so a boiler attendant was not needed. And because it was simpler in design and operation, it did not require an experienced operator.
Dunn and his class have presented two of these amazing machines to Tennessee legislators, one to Gov. Bredesen, and one to state Rep. Charles Curtiss. Dunn says Bredesen has put his engine, which runs off the heat from a small electric bulb, in a conference room on Capitol Hill.
?A commissioner told me in an e-mail that the governor either closed or opened every meeting with some comment about it,? Dunn said. ?How it worked and all that. He really loves it.?
The small engines are quite beautiful, jewel-like in construction. All but a very few of the parts, such as screws and ball bearings, are machined in the shop and the units are hand assembled. One of the main elements is a flywheel which spins as the piston moves in and out, giving the engines an almost perpetual motion feel, since they run almost silently.
The students design their own engines and each is unique, with different appearances, including one with Tennessee Volunteer colors.
?The students choose their own painting schemes,? Dunn said.
Students also utilize computer aided design to produce the parts for the engines, so the projects are as much a learning experience as a creative one.
Dunn says the engines have a special place in his teaching methods, and he has his reasons for using them in his class.
?I like for the students to do things that are meaningful and enjoyable to do,? Dunn said. ?I try to put some fun in the class. With these I can teach and have them make a project they can be proud of when they get through. I try to combine teamwork with putting things together to understand the principles of machining, making sure they understand fit, making sure they understand tolerances. And teamwork is essential because each student makes one certain part.?
Dunn says he enjoys teaching his classes and feels taking on machining and tool and die work is a challenging and rewarding career, both financially and creatively. He explained why he chose the career.
?It?s something where you use your mind and your hands,? Dunn said. ?That?s what I like about it. There aren?t many careers that do that.?
The students who participated in this project were Alan Betts, Jesse Esparsa, Brandon Gallagher, Ricky Henderson, Stanley Oakes, Phillip Reed, Chris Rowland, Kyle Yates and Dunn himself.
Those interested in learning more about the Stirling engine can visit Dunn?s class at TTC.