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Thread: Heat transfer gel??

  1. #1 Heat transfer gel?? 
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    Hi all, first post so a bit out of my depth but from reading through old posts it looks quite friendly here.

    I am trying to find a product or solution to find out if something is possible.

    The qualities of this product should be able to, when heated from a constant hot surface retain its heat even if a constant cold surface is touching or running through this product. Simply to transfer heat from the hot surfce to the cold without affecting the temp of the hot surface.

    Thanking you in advance


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  3. #2  
    Forum Ph.D.
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    WTF????


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  4. #3  
    Moderator Moderator AlexP's Avatar
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    What you're describing sounds a bit like a frying pan on a stove to me... it's hot, and it'll stay hot if you put something cold on it... Can you be more descriptive about what you're after?
    "There is a kind of lazy pleasure in useless and out-of-the-way erudition." -Jorge Luis Borges
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  5. #4  
    Forum Isotope Bunbury's Avatar
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    Not sure this is what youíre looking for, but a common method of transferring heat from a hot to a cold source when a heat exchanger canít be used is to fill the void between the two surfaces with a heat transfer mastic or cement. These are sticky substances with a reasonably high thermal conductivity.

    http://www.aefmfg.com/

    Your requirement for not affecting the temperature of the hot surface is of course impossible. If there is heat transfer occurring there will be a temperature gradient in all the components involved in the system and the hot surface will be cooled somewhat below its initial temperature. You equate the heat fluxes in each component to find their operating temperatures.
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  6. #5  
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    thanks for the link Bunbury. I will explore it more over the week.
    I understand the theory that if one side heats the other will cool.
    Combination boilers provide a steady flow of hot water (heated indirectly by gas flame) at a limited temp gradient. 10 l/min @ 35 degree Celsius

    I would like to make another heat exchanger to sit below the combination boiler and use the hot water leaving the boiler to slightly heat the cold water entering the boiler thus using less gas to get the same hot water temp.
    Using a metal heat exchanger would not work as the hot water would cool too much.
    Thus my question whether there is another product on the market that is affected more by the heat than by the cold transfer. Thanks for the comments so far. Probably one of those things that if possible would have been made already but with the advances in techs and all that.. just maybe.
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  7. #6  
    Forum Isotope Bunbury's Avatar
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    Quote Originally Posted by rusty
    thanks for the link Bunbury. I will explore it more over the week.
    I understand the theory that if one side heats the other will cool.
    Combination boilers provide a steady flow of hot water (heated indirectly by gas flame) at a limited temp gradient. 10 l/min @ 35 degree Celsius

    I would like to make another heat exchanger to sit below the combination boiler and use the hot water leaving the boiler to slightly heat the cold water entering the boiler thus using less gas to get the same hot water temp.
    Using a metal heat exchanger would not work as the hot water would cool too much.
    Thus my question whether there is another product on the market that is affected more by the heat than by the cold transfer. Thanks for the comments so far. Probably one of those things that if possible would have been made already but with the advances in techs and all that.. just maybe.
    I donít think that will work. The heat gain in the cold water will equal the heat loss in the hot water, regardless of whether you do the heat exchange in a metal heat exchanger or some other device. Q = mēCpēT applies to the hot and cold water just the same. If you have the same flow rate then the temperature rise in the cold stream equals the temperature drop in the hot stream and you will gain nothing. In fact you might lose a bit of efficiency because the water now enters the boiler at a higher temperature so the temperature difference between the hot gas and the cool water is reduced.

    It might be possible to put a heat exchanger in the flue gas, but you donít want to cool it below the dewpoint or youíll have corrosion issues, nor restrict the gas flow as this would be a very bad idea. If you have a modern high efficiency boiler you might find it quite hard to improve on its efficiency. If itís old there might be some opportunities.

    Edit:  This is supposed to be a delta.
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