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Thread: glycerin engines

  1. #1
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    glycerin engines

    I had posted earlier that I think glycerin would be a very useful fuel. I has anybody given this thought. I could be wrong about these advantages, but very hard to start on fire. Very low Volatile organic compounds. Low toxicity, non polluting in water. Is there a process where large volumes could be made from trees, grass, or other vegatation. Would it work well in small engines as a diesel type engine and in boats?
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    Googled glycerin fuel. A bunch of articles, mostly dating from the mid-2000s.
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  3. #3
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    You get a lot more hits if you use glycerol, which is the more common name for glycerin.

    Essentially, it is a good fuel in some ways: as you mentioned, it is environmentally friendly and non-toxic, so a spill would be easy to deal with. And it is safe, as it is difficult to make it explode. The biggest issues are that it is heavy, sticky, and has low energy content (about half that of gasoline), and it has a low cetane value (the inverse of an octane value), so it is difficult to ignite (this of course is the side-effect of being safe). And it is easy to make from plant oil. So it would be quite good as a fuel (given modifications to fuel injectors to deal with the stickiness) to power generators for producing electricity. But you definitely would not want to use it in an application (say an aircraft engine) where weight is an issue.
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    Quote Originally Posted by Jens View Post
    You get a lot more hits if you use glycerol, which is the more common name for glycerin.

    Essentially, it is a good fuel in some ways: as you mentioned, it is environmentally friendly and non-toxic, so a spill would be easy to deal with. And it is safe, as it is difficult to make it explode. The biggest issues are that it is heavy, sticky, and has low energy content (about half that of gasoline), and it has a low cetane value (the inverse of an octane value), so it is difficult to ignite (this of course is the side-effect of being safe). And it is easy to make from plant oil. So it would be quite good as a fuel (given modifications to fuel injectors to deal with the stickiness) to power generators for producing electricity. But you definitely would not want to use it in an application (say an aircraft engine) where weight is an issue.
    I would think that the efficiency of burning glycerol, could be higher than diesel.
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    Quote Originally Posted by Copernicus View Post
    I would think that the efficiency of burning glycerol, could be higher than diesel.
    According to this site, the calorific values of both gasoline and diesel are about 36, while glycerol is only like 19.
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    Though actually, I'm not sure exactly what you mean by efficiency, so perhaps it's true for some measure. There is certainly less calorific content in glycerol (both per volume and per weight) than either gasoline or diesel, and the cetane number (so easiness of burning) is lower than that of either of the other two.
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    Quote Originally Posted by Copernicus View Post
    I would think that the efficiency of burning glycerol, could be higher than diesel.
    The flame temperature of glycerol in air (2020 K) is a little lower than the same for diesel ~(2280 K). So else being equal in a heat engine we would expect glycerol have lower maximum thermal efficiency. In transport or earth-bound power generation applications, I believe thermal NOx production would be the limiting factor on either.

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    Quote Originally Posted by VQkr View Post
    The flame temperature of glycerol in air (2020 K) is a little lower than the same for diesel ~(2280 K). So else being equal in a heat engine we would expect glycerol have lower maximum thermal efficiency. In transport or earth-bound power generation applications, I believe thermal NOx production would be the limiting factor on either.
    What I was thinking was that less nox was produced with glycerol, so it could be operated at a higher temperature, making up for some of the lower fuel value. I really don't know how much less nox is produced, but here is one article. https://www.researchgate.net/publica..._fuels_by_SNCR
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    The Caloric Content of Gasoline and Diesel

    Quote Originally Posted by Copernicus View Post
    What I was thinking was that less nox was produced with glycerol, so it could be operated at a higher temperature, making up for some of the lower fuel value. I really don't know how much less nox is produced, but here is one article. https://www.researchgate.net/publica..._fuels_by_SNCR
    Has not changed in the forty years since I researched alternative fuel. Gas and diesel were the best choices then and they still are. Keep in mind that the engineers who design the machines are not stupid; they do not miss much.

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    Quote Originally Posted by John Mendenhall View Post
    Has not changed in the forty years since I researched alternative fuel. Gas and diesel were the best choices then and they still are. Keep in mind that the engineers who design the machines are not stupid; they do not miss much.
    I thought this was a way to stop producing carbon dioxide since the glycerine would be made from renewable sources. Sorry if it looked like I was suggesting the engineers didn't know what they are doing.
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  11. #11
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    You might have trouble with soot formation. Add a few drops glycerin to a small mound of potassium permanganate. The glycerin will start to burn in 8-10 seconds.
    A fair amount of nasty char is left over at the end of reaction.
    If your engine does not provide enough oxygen, it will suffer the problem.
    The high viscosity of glycerin will make accurate metering more difficult than it is with plain hydrocarbons.

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    Quote Originally Posted by John Mendenhall View Post
    Has not changed in the forty years since I researched alternative fuel. Gas and diesel were the best choices then and they still are. Keep in mind that the engineers who design the machines are not stupid; they do not miss much.
    Best by which metric?
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    Quote Originally Posted by Noclevername View Post
    Best by which metric?
    I think by a couple: high energy density, safety.

    Sustainability is the downside I think.
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    Quote Originally Posted by Jens View Post
    I think by a couple: high energy density, safety.

    Sustainability is the downside I think.
    We'll have to settle for the best of what's long term available, then. I know biodiesel can be made from veggie oil in a mason jar on a kitchen counter, so it's not necessarily from fossil, but it's still polluting and bio has production issues relating to water use, land and agriculture.
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  15. #15
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    I donít know how it works out ecologically, but itís worth noting that glycerol like other biofuels is made from some kind of plant oil, so if we want to make it from scratch we need some kind of oil, like palm oil or soy oil, to do it. The thing is, currently it is a by product of the production of biodiesel, so we essentially have a free supply. And for both biodiesel and glycerol, starting from waste kitchen oil would be ideal but there isnít that much waste oil available so it would still require farming to produce.


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    Looks like someone found an app for glycerine.https://scx2.b-cdn.net/gfx/news/2019/niobiumuseda.jpg
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