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demonstrations:4_thermodynamics:4f_entropy_and_the_second_law:nitinol_windmill:start
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demonstrations:4_thermodynamics:4f_entropy_and_the_second_law:nitinol_windmill:start [2019/02/14 23:33] 127.0.0.1 external edit |
demonstrations:4_thermodynamics:4f_entropy_and_the_second_law:nitinol_windmill:start [2019/04/17 19:30] (current) demoroom |
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| ====== Nitinol Windmill ====== | ====== Nitinol Windmill ====== | ||
| - | {{tag> needs_review untagged unlocated}} | + | {{tag> heat_engine thermodynamics shape_memory_effect nitinol unlocated}} |
| <WRAP box right> | <WRAP box right> | ||
| Line 11: | Line 11: | ||
| ===== Description ===== | ===== Description ===== | ||
| - | Perpetual Motion Machine? Classes Used: PHYS 153 | + | A chassis connects two wheels of equal size. Around them is a loop of nitinol- a shape memory alloy- that has been 'trained' to straighten when heated up. The top wheel has a propeller attached. |
| - | + | ||
| - | + | ||
| - | + | ||
| - | This works off a temperature gradient across the Nitinol wire, and boiling water (or close to, about ~90) is usually good enough for a room temperature environment. Submerge the bottom wheel into said boiling water (just enough to cover the wire) and give the blades a small flick to start. | + | |
| ===== Purpose ===== | ===== Purpose ===== | ||
| + | Illustrate another example of the huge variety of heat engines. Demonstrate the action of a much simpler heat engine, and show what unites all heat engines: a heat differential. | ||
| ===== Apparatus ===== | ===== Apparatus ===== | ||
| + | * Nitinol windmill | ||
| + | * Cup of nearly boiling water | ||
| ===== Setup ===== | ===== Setup ===== | ||
| + | This works off a temperature gradient across the Nitinol wire, and boiling water (or close to, ~90ºC) is usually good enough for a room temperature environment. Submerge the bottom wheel into the boiling water (just enough to cover the wire) and give the blades a small flick to start it. | ||
| + | ===== Notes ===== | ||
| - | ===== Notes ===== | + | The one with tape on its supporting beam doesn't work as well. There is also a cup near the windmills that has tearing to indicate the maximum filling line. |
| - | The one with tape on its supporting beam doesn't work as well. There is also a cup near the windmills that has tearing to indicate the maximum filling line. Updated on 05/30/13 | + | This simple engine works using a more complicated principle: the [[wp>Shape-memory_alloy|shape memory effect]]. When the wire is bent around a wheel and heated, it will exert a force attempting to straighten itself out. Once the wheel is given a spin, a temperature asymmetry will cause more force to be exerted on one side of the thermobile, so it continues to spin. |
| <WRAP group> | <WRAP group> | ||
demonstrations/4_thermodynamics/4f_entropy_and_the_second_law/nitinol_windmill/start.1550187203.txt.gz · Last modified: 2019/02/14 23:33 by 127.0.0.1
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