Dave steam 6 (newcomen)(44)

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Steam engine history - Part 6 - The first steam engines in the world.

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Dave steam 6 (newcomen)(44)

  1. 1. Steam Engines<br />A series of lessons <br />by David C<br />Dec 2010<br />
  2. 2. Part 6<br />The piston<br />
  3. 3. What I like about history is that there are so few straight lines in it. <br />A fellow can be trying to solve a particular problem in one part of the world, and he comes up with a solution that is picked up by another inventor in another part of the world, working on a problem that has absolutely nothing to do with what the first fellow was working on. …<br />
  4. 4. What I like about history is that there are so few straight lines in it. <br />A fellow can be trying to solve a particular problem in one part of the world, and he comes up with a solution that is picked up by another inventor in another part of the world, working on a problem that has absolutely nothing to do with what the first fellow was working on. …<br />– EXCEPT that they have exactly the same answer. <br />
  5. 5. Now something like this happened to a Frenchman named Denis Papin, who invented this thing in the 1690s. This is a pressure cooker.<br />
  6. 6. Now something like this happened to a Frenchman named Denis Papin, who invented this thing in the 1690s. This is a pressure cooker.<br />You put food into the container and then fill it to the brim with water. Then you seal it very tightly and light a fire underneath it. <br />
  7. 7. The water heats up and wants to boil, but it can’t because there’s no room for the steam to expand into. <br />
  8. 8. The water heats up and wants to boil, but it can’t because there’s no room for the steam to expand into. <br />…so the water stays liquid even though the temperature has risen higher than the temperature at which water normally boils.<br />
  9. 9. The water heats up and wants to boil, but it can’t because there’s no room for the steam to expand into. <br />…so the water stays liquid even though the temperature has risen higher than the temperature at which water normally boils.<br />The result is food that has been cooked at very high temperature; very tender and cooked quickly.<br />
  10. 10. Papin’s invention made him quite famous for a time. <br />
  11. 11. Papin’s invention made him quite famous for a time. <br />But what’s important here is that this is a container loaded with boiling water under pressure. <br />A thing like this could blow apart and injure someone. <br />
  12. 12. Papin’s invention made him quite famous for a time. <br />But what’s important here is that this is a container loaded with boiling water under pressure. <br />A thing like this could blow apart and injure someone. <br />Papin had to keep the lid screwed down very tight to resist the tremendous pressure that built up inside it. <br />
  13. 13. I can imagine the thing leaking from time to time, and steam shooting out the top, and Papin trying very carefully to push the lid back down again without scalding himself. <br />
  14. 14. I can imagine the thing leaking from time to time, and steam shooting out the top, and Papin trying very carefully to push the lid back down again without scalding himself. <br />It was probably this experience that got Papin to thinking that maybe this tremendous pressure could be used for something else. <br />
  15. 15. Papin set up an experiment that looked kind of like this:<br />You put some water into a brass cylinder and drop this odd-shaped thing inside. <br />It’s a disk with a kind of a handle on it. <br />
  16. 16. Papin set up an experiment that looked kind of like this.<br />You put some water into a brass cylinder and drop this odd-shaped thing inside. <br />It’s a disk with a kind of a handle on it. <br />The disk is ever-so-slightly smaller than the diameter of the cylinder, which means that a tiny bit of water will squish up the side of the disk and allow it to slide up and down without letting any air in or out. <br />
  17. 17. Now if you heat the cylinder, the water will boil and expand and push the disk up. <br />
  18. 18. When the disk has gone up as far as it will go, you lock it in place so that it can’t come down again.<br />
  19. 19. Then you cool the cylinder down. You can do this efficiently by pouring water over it..<br />
  20. 20. The steam collapses back into water, which occupies only a fraction of the volume of the steam. <br />
  21. 21. That means there’s an awful lot of nothing above the water; a vacuum.<br />
  22. 22. The piston will want to get down to the water surface again, <br />
  23. 23. The piston will want to get down to the water surface again, <br />…really fast, because there’s 60km of atmosphere pressing down on it, which is really heavy. <br />
  24. 24. But before releasing it, Papin attached a rope to the top of the piston handle, and ran it over a couple of pulleys so that he could hang a heavy weight on the other end.<br />
  25. 25. So when he released the piston, it slammed down immediately to the water surface and lifted the heavy weight off the floor.<br />
  26. 26. That weight was 27 kg. <br />That’s the weight of a not-so-small child! <br />
  27. 27. In effect, Papin had shown how to lift a heavy weight off the ground by boiling a kettle! <br />
  28. 28. Papin knew he was on to something significant, <br />but wasn’t really sure where to go next. <br />
  29. 29. He wrote some scientific papers on the subject, and suggested a few ideas, but none of them inspired a rich-financier to sponsor any further work.<br />
  30. 30. However, there was one Englishman, a fellow named Thomas Newcomen who knew exactly how to get rich using Papin’s invention.<br />
  31. 31. You see, the important part of Papin’s invention was this part here; the brass cylinder with a sort of disk-shaped thing inside it. <br />Today we call it a piston.<br />
  32. 32. You see, the important part of Papin’s invention was this part here; the brass cylinder with a sort of disk-shaped thing inside it. <br />Today we call it a piston.<br />You can make the handle go up by letting steam in through one of the vents.<br />
  33. 33. You see, the important part of Papin’s invention was this part here; the brass cylinder with a sort of disk-shaped thing inside it. <br />Today we call it a piston.<br />You can make the handle go up by letting steam in through one of the vents.<br />And you can make the handle come down again by letting steam out of the other vent.<br />
  34. 34. You see, the important part of Papin’s invention was this part here; the brass cylinder with a sort of disk-shaped thing inside it. <br />Today we call it a piston.<br />You can make the handle go up by letting steam in through one of the vents.<br />And you can make the handle come down again by letting steam out of the other vent.<br />… and if you really want the handle to come down fast, pour water over it to condense the steam first.<br />
  35. 35. MrNewcomen installed Papin’s invention in the middle of this monstrous structure. Can you see it?<br />
  36. 36. Steam goes into the piston chamber and makes the handle go up<br />
  37. 37. Steam goes into the piston chamber and makes the handle go up<br />… which causes the balance beam at the top to tilt so that the cable on the left goes down.<br />
  38. 38. You can make the balance beam tilt the other way by pouring water over the piston and condensing the steam into water.<br />
  39. 39. You can make the balance beam tilt the other way by pouring water over the piston and condensing the steam into water.<br />You have to open and close the two valves at just the right times to make it work. <br />
  40. 40. Now, if you have a bucket on the end of the cable on the left, you can use it to scoop water out of a mine.<br />
  41. 41. Now, if you have a bucket on the end of the cable on the left, you can use it to scoop water out of a mine.<br />Better yet, put a long tube on it and you can siphon the water out of the mine.<br />
  42. 42. But the great thing is that you can put anything on the end of that cable, and use it for things that’ve got nothing to do with mining.<br />?<br />
  43. 43. But the great thing is that you can put anything on the end of that cable, and use it for things that’ve got nothing to do with mining.<br />That’s what triggered the Industrial Revolution.<br />?<br />
  44. 44. End<br />dtcoulson@gmail.com<br />

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