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--- demonstrations:4_thermodynamics:4f_entropy_and_the_second_law:stirling_engine:start [2019/02/14 23:33] – external edit 127.0.0.1
+++ demonstrations:4_thermodynamics:4f_entropy_and_the_second_law:stirling_engine:start [2020/03/13 21:01] (current) – demoroom
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 ====== Stirling Engine ======
-{{tag>heat nitrogen stirling lamp oil needs_review untagged unlocated}}
+{{tag>heat thermodynamics liquid_nitrogen stirling heat_engine located}}
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 ===== Description =====
-Demonstrate the Stirling engine.    Classes Used: PHYS 157, PHYS 203
+Large gamma-type Stirling heat engine with fan attached.
-Entropy, Energy Conversion, Stirling cycle
-Useful Links:
-How Stuff Works provides an excellent description of Stirling Engines and some physical concepts behind them: [[ http://auto.howstuffworks.com/stirling-engine.htm | http://auto.howstuffworks.com/stirling-engine.htm ]]
-American Stirling Company is the place to go if one was interested in purchasing a Stirling Engine that can run using the heat of your monitor! [[ http://www.stirlingengine.com/ |  http://www.stirlingengine.com/ ]]
-For those interested in creating their own Stirling Engine, perhaps Koichi Hirata can help out. [[ http://www.bekkoame.ne.jp/~khirata/ |  http://www.bekkoame.ne.jp/~khirata/ ]]
 ===== Purpose =====
+Demonstrate the functionality of a stirling engine and the principles of heat engines. Shows that heat engines can be run in reverse by changing the direction of the thermal gradient.
-Demonstrate the Stirling engine.
 ===== Apparatus =====
-- Stirling Engine
+  * Stirling Engine
-- Alcohol lamp
+  * Alcohol burner
-- Lighter or matches
+  * Plexiglass shield
-- Liquid nitrogen
+  * Lighter or matches
-- Styrofoam cup
+  * Liquid nitrogen and styrofoam container (Optional)
+===== Setup =====
+  - Place the burner under the engine and light it. You'll probably have to refill this with ethanol before you start.
+  - Let the burner warm up the cylinder for 5-10 minutes.
+  - The engine then needs to be started by hand. Spin the blades counterclockwise (from the front) and if it's hot enough it'll continue spinning under it's own power. You can also try starting it before it's ready- as the engine heats up, the amount of resistance to rotation diminishes until it finally goes on it's own. There's an arrow on the front that gives it's direction of rotation. If you find it difficult to get it started a drop of all-purpose lubricant oil in the pistons may help.
-===== Setup =====
+Alternatively, the engine may be run in reverse by applying the opposite temperature differential.
+  - Fill the styrofoam container with liquid nitrogen and place it under the engine so that a substantial part of the cylinder is in the LN2. This container may have to be refilled.
+  - Give it a while to chill.
+  - The engine must then be started by hand. Note that since we're running the engine in reverse by giving it the opposite heat differential the fan will also run in reverse. To start it, spin the blades clockwise (when looking from the front).
-. Remove the lid from the alcohol lamp, place it beneath the engine and ignite.
+===== Notes =====
-. Let the lamp warm up the cylinder for 5-10 minutes then spin the blades counterclockwise (when facing from front).
-//Cold Alternative//  1. To run the engine off a cold source, pour liquid nitrogen into the Styrofoam cup and immerse the bottom end of the engine in it. This might take a couple refills. (Or use a 2L pop bottle with the top cut off, takes one refill)
-. The engine will run in the reverse direction, therefore a clockwise spin will be required to start it.
+If the lamp is empty, refill it with ethanol. Do not use lamp oil.
+A plexiglass shield was recently made for the bottom of the engine, as in some lecture halls there may be a strong enough breeze to put out the burner.
-===== Notes =====
+Placing the burner on a wooden block to bring the flame closer to the cylinder will help the engine heat up faster.
-If the lamp is empty, there's ethanol in the fumehood near the sink. Do not use the lamp oil.
+Useful Links:
+How Stuff Works provides an excellent description of Stirling Engines and some physical concepts behind them: [[ http://auto.howstuffworks.com/stirling-engine.htm | http://auto.howstuffworks.com/stirling-engine.htm ]]
+American Stirling Company is the place to go if one was interested in purchasing a Stirling Engine that can run using the heat of your monitor! [[ http://www.stirlingengine.com/ |  http://www.stirlingengine.com/ ]]
+For those interested in creating their own Stirling Engine, perhaps Koichi Hirata can help out. [[ http://www.bekkoame.ne.jp/~khirata/ |  http://www.bekkoame.ne.jp/~khirata/ ]]
-Updated on: 01/19/16
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-| **Location** | ---- |
+| **Location** | C2 |
 | **Maker** | Unknown |
 | **Current State** | Working |