Initial Design #1 

This was the first prototype we built. It used a balloon & steel wool to create a displacer and piston in the same chamber. We also used a wire hanger, bent into an offset configuration to hold the wire that moves the piston and the ballon. This design did not work, due to the high amount of friction produced by the turning of the rod. Also because of the thin soda can, we predict heat escaped while it traveled, so it did not all pass through the displacer. The seals and the height of the bends would need to be fixed for this design to work.

Prototype Design #2 

The second prototype was meant to correct the flaws that occurred in the initial engine that was built by the team. Issues regarding sealing the engine with the proper dimensions was meant to be resolved. With a similar structure, we used a thicker tin can in order to conduct the heat more effectively. In this tin can, we placed the compacted steel wool with a copper wiring, to act like a piston. We then sealed this over with a larger balloon than before, to run as a displacer. By using popsicle sticks we attached the rod to the displacer, by doing so we hoped this would help pump the engine and allow the rods to spin with ease. However, to our demise, the sticks were ultimately preventing the engine from running efficiently due to the high amounts of friction that was acting on the sticks and rod. It was also later found that there was an uneven weight distribution on both of the sides of the bent turning rod. This caused the engine to fail and needed to be balanced.

Prototype Design #3

In this iteration of the project a spray pan can was implemented as the cylinder to attempt to fix the problem that as previously encounter during in the first prototype. A similar design was followed, and a bigger balloon was use as the diaphragm to allow for a greater expansion in the cool region of the engine. For the displacer a roll of steel wool was compacted and tied to a fishing line which connected it to crankshaft made from wire. In the crankshaft two wooden sticks were used to drive the diaphragm, and a flywheel was fabricated from carboard. Despite the effort to pack the steel wool into a cylinder of the can’s diameter, there was an excessive amount of friction, that did not allow the piston to travel as the crackshaft rotated. Temperature measurements were taken after having the can in contact with a candle for 10 minutes and a temperature difference between the top most surface and the base of the can of 14 ˚F was observed.