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Running an engine in boiling water.

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  • Paul M
    Yes, you heard that right! Why you might ask, the anwer is simple: while testing (I keep testing, if I got paid for every test I d be rich!) I noticed the
    Message 1 of 5 , May 27, 2012
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      Yes, you heard that right! Why you might ask, the anwer is simple: while testing (I keep testing, if I got paid for every test I'd be rich!) I noticed the temperature of the water in my thrusty test bed, a plate, quickly rose without affecting the performance of the engine.
      Odd, efficiency and thus performance should be less! (carnot cycle, thermodynamics, bla bla) So out of curiosity I boiled some water and ran the engine in it. Guess what happened...

      No, you guessed wrong! The engine didn't stall nor did the performance became poor. On the contrary! The engine performed much better, it had power squirts every few seconds and in no time the engine had blown almost all water out of the plate!

      Why did this happen? With a small temperature difference, condensation of steam should take longer and affect the performance of an engine in a bad way.

      I always assumed that for a good runner you had to keep the pipes cool and for all engines I built before this was true. In this case the opposite is true, the water wasn't able to condense near the boiler so the condensation had to take place in the last few centimeters in the tubes, where they entered the water. In my experience an engine stalls when this happens.

      My best bet is that this engine isn't working at it's maximum capacity and more heat is needed. If this is true I'll need a gas burner, because I already used a huge flame. (I added a photo of the engine in "Paul's album" The aluminium can was filled with alcohol and surrounded the boiler with flames. The plate was filled to the edge at the start.)

      Any input on this, in my opinion, odd phenomenon would be appreciated.

      Cheers,
      Paul
    • zoomkat
      ... Not necessairly so. a couple of years back there was some discussion on how pop pop engines work and it appeared that there are differing opinions on the
      Message 2 of 5 , May 27, 2012
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        --- In pop-pop-steamboats@yahoogroups.com, "Paul M" <lordbthry@...> wrote:
        >
        > Odd, efficiency and thus performance should be less! (carnot cycle, thermodynamics, bla bla) So out of curiosity I boiled some water and ran the engine in it. Guess what happened...

        Not necessairly so. a couple of years back there was some discussion on how pop pop engines work and it appeared that there are differing opinions on the pop pop power cycle. The condensation mechanics of a pop pop engine haven't received much attention. To get work out of steam it must be allowed to expand to its maximum before being condensed into water. It has been postulated in the past that in small engines a condensation front is formed in the tubes when the steam from the engine ejects all the water form the tubes and comes in contact with the cool outside water. The tubes usually do not have any contact with the waternexcept at the very tip. This can be observed to an extent by connecting a short piece of clear aquarium tubing to the end of the exhaust tubing. In the larger engines, it appears that the exhaust rubing it self acts as the main condensation mechanism for the steam, which could be a point of efficiency loss. Keeping the exhaust pipes hotter might allow the steam to do more work ejecting the water in the tubes before the condensation process is started. In steam plants the piping carrying the steam is always insulated. I would think that in some engines the ideal exhaust tubing setup the tubing would have very low specific heat and well insulated. just some thoughts
      • Paul M
        I just tested the theory. I wound toilet paper around the tubes and covered it with aluminium foil to not let it catch fire. The performance seemed to be a
        Message 3 of 5 , May 27, 2012
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          I just tested the theory. I wound toilet paper around the tubes and covered it with aluminium foil to not let it catch fire. The performance seemed to be a little better.
          After a while the toilet paper sucked up water, although the engine kept running the performance was really bad. Steam escaping from under the aluminium foil proved that the temperature of the tubes was still at least 100 deg. Celcius. The boiler itself was, of course, much hotter, a droplet of water instantly flashed to steam.

          That leaves only one conclusion: keep those tubes as hot as possible. Well, at least for this engine that is...

          --- In pop-pop-steamboats@yahoogroups.com, "zoomkat" <Zoomkat@...> wrote:

          > Not necessairly so. a couple of years back there was some discussion on how pop pop engines work and it appeared that there are differing opinions on the pop pop power cycle. The condensation mechanics of a pop pop engine haven't received much attention. To get work out of steam it must be allowed to expand to its maximum before being condensed into water. It has been postulated in the past that in small engines a condensation front is formed in the tubes when the steam from the engine ejects all the water form the tubes and comes in contact with the cool outside water. The tubes usually do not have any contact with the waternexcept at the very tip. This can be observed to an extent by connecting a short piece of clear aquarium tubing to the end of the exhaust tubing. In the larger engines, it appears that the exhaust rubing it self acts as the main condensation mechanism for the steam, which could be a point of efficiency loss. Keeping the exhaust pipes hotter might allow the steam to do more work ejecting the water in the tubes before the condensation process is started. In steam plants the piping carrying the steam is always insulated. I would think that in some engines the ideal exhaust tubing setup the tubing would have very low specific heat and well insulated. just some thoughts
          >
        • zoomkat
          I just made my first large coil engine (below) using 1/4 copper tubing filled with aquarium sand and wraped around a 1 piece of plastic water pipe. Also
          Message 4 of 5 , May 27, 2012
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            I just made my first large coil engine (below) using 1/4" copper tubing filled with aquarium sand and wraped around a 1" piece of plastic water pipe. Also tested a simple 91% isopropal alcohol burner made from a wick, sponge, and an Altoid mint tin (isopropal is half the price of denatured alcohol at WalMart). One supprising thing I noticed was that when applying a lot of heat to the coils, the tubes also got hot enough to sizzle spit a ways down the tubes. At this point I suspect the actual flashing was occurring in the tubes and not the coils. The next one I wind will only have 3 or two coils instead of four.


            http://web.comporium.net/~shb/pix/coil1.jpg
            http://web.comporium.net/~shb/pix/coil2.jpg
            http://web.comporium.net/~shb/pix/coil3.jpg

            --- In pop-pop-steamboats@yahoogroups.com, "Paul M" <lordbthry@...> wrote:
            >
            >
            >
            > I just tested the theory. I wound toilet paper around the tubes and covered it with aluminium foil to not let it catch fire. The performance seemed to be a little better.
            > After a while the toilet paper sucked up water, although the engine kept running the performance was really bad. Steam escaping from under the aluminium foil proved that the temperature of the tubes was still at least 100 deg. Celcius. The boiler itself was, of course, much hotter, a droplet of water instantly flashed to steam.
            >
            > That leaves only one conclusion: keep those tubes as hot as possible. Well, at least for this engine that is...
            >
          • Paul M
            Copper is an excelent heat conductor, that s why the tubes also get real hot. I wonder if the two coil engine will perform equally to the three coil engine,
            Message 5 of 5 , May 28, 2012
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              Copper is an excelent heat conductor, that's why the tubes also get real hot.
              I wonder if the two coil engine will perform equally to the three coil engine, since the flashing seems to occur in the tubes you might think that boiler size is less important.

              --- In pop-pop-steamboats@yahoogroups.com, "zoomkat" <Zoomkat@...> wrote:
              >
              > I just made my first large coil engine (below) using 1/4" copper tubing filled with aquarium sand and wraped around a 1" piece of plastic water pipe. Also tested a simple 91% isopropal alcohol burner made from a wick, sponge, and an Altoid mint tin (isopropal is half the price of denatured alcohol at WalMart). One supprising thing I noticed was that when applying a lot of heat to the coils, the tubes also got hot enough to sizzle spit a ways down the tubes. At this point I suspect the actual flashing was occurring in the tubes and not the coils. The next one I wind will only have 3 or two coils instead of four.
              >
              >
              > http://web.comporium.net/~shb/pix/coil1.jpg
              > http://web.comporium.net/~shb/pix/coil2.jpg
              > http://web.comporium.net/~shb/pix/coil3.jpg
              >
              > --- In pop-pop-steamboats@yahoogroups.com, "Paul M" <lordbthry@> wrote:
              > >
              > >
              > >
              > > I just tested the theory. I wound toilet paper around the tubes and covered it with aluminium foil to not let it catch fire. The performance seemed to be a little better.
              > > After a while the toilet paper sucked up water, although the engine kept running the performance was really bad. Steam escaping from under the aluminium foil proved that the temperature of the tubes was still at least 100 deg. Celcius. The boiler itself was, of course, much hotter, a droplet of water instantly flashed to steam.
              > >
              > > That leaves only one conclusion: keep those tubes as hot as possible. Well, at least for this engine that is...
              > >
              >
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