The Magic of Steam… Unit 4

Sound the steam whistle… Time for work

einstein cartoon left looking

steam loco

Steam locomotives are still actively pulling trains in India and Russia with their very long rail lines the steam locomotive is efficient and fuel is readily available. Not good for the environment… But the sound of the whistle is so nice to hear… The white cloud coming from the chimney is a mixture of steam and smoke, the steam is used to increase the draft of the short chimney. Very modern steam locomotives use light oil in the fire chamber and then they are clean and not bad for the environment.

steam-locomotive-whistle

When we blow the whistle, POTENTIAL ENERGY in the steam does WORK make the whistle sound. The louder the whistle to more work is done to make SOUND ENERGY.

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steam press cooker on stove

We use electric energy to heat the water in the boiler to make steam that has potential energy to make sound energy, or to cook vegetables, make soup and more…

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Remember: While energy can change from one form into another the amount of energy remains the same BUT, its quality goes from high to low. In this experiment it is high quality electric energy that heats water and makes steam that is used to make the whistle sound, after this the energy is still around but lost in our surroundings and we can not get it back to use again.

Think about this: We CAN NOT  blow into the whistle to make steam to make hot water to make electricity.

Energy becomes useless after we have used it to do work.

But we can use it smartly before it is lost.

Example

In a generating station heat energy is used to boil water to make high pressure steam that is sent to a turbine which will drive an electric generator, that sends the electricity down the net to our houses and industries where it does work. The waste heat can be used to heat houses or hospitals or university buildings, or greenhouses. This is called CO-GENERATION.

energy, co gen 1

energy cogen-pic

Two examples of co-generation, in both systems electricity is made and in the first system the waste heat from the engine heats apartment buildings. In the second example the waste heat warms a large municipal swimming pool. 

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Show time…

energy cylinder pop gun a

We have a tube, used as a CYLINDER, at one end closed with a cork, at the other end a leather disk on the end of a stick is our PISTON and the stick is the PISTON ROD..

Push the piston rod and piston into the cylinder and you have a MACHINE that can POP the cork and  make a loud noise… But you have to do WORK to compress the air in the cylinder to pop the cork!

Hmm… Maybe the steam can do the work?

Put the one end with the piston rod, the red handle, on a steam outlet and let the steam do the work, great sound and great spectacle…

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Now finally, let’s look at a steam engine… The animation shows a sliding valve that admits the steam to one side and then to the other side of the piston, try to figure it out.

steam-anim

steam engine schema 1

And here is the inside, it is difficult to figure out but give it a try, follow the arrows for the steam into the cylinder and on the other side of the piston follow the arrow for the steam to flow out off the cylinder. The valve slides back and forward and lets steam into the cylinder on one side of the piston or the other, this is called double acting. It is as if you have two poppers one work in one direction and the other in the opposite direction. Clever engineering … Also note that the valve keeps the inlet steam and outlet steam apart!

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And a real engineering sketch of a steam engine. A is the cylinder, B is the piston, C is the piston rod, L is where the steam goes out, and M is where it comes in. Note that the incoming steam is at the inside of the valve system it is the hottest steam and we like to keep it hot until in enters the cylinder and expands to make mechanical energy. O is the valve drive rod.

Sorry it is so complicated, but just look at the parts and try to make sense of it all, at least you have seen a real cylinder and piston…

steam engine schema 3

 

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steam6_jpg.mht henk demo

Steam is scary but blowing the steam whistle at the Boys and Girls Club at Kingston, Ontario gets the attention of the children!

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