Heat exchanger





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Thread: Heat exchanger

  1. #1
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    Default Heat exchanger

    Hi Guys

    Are there any heat exchanger people on here?

    Im getting a + - 60 Kw coal heater for the fish farm, and am looking at putting the water through a heat exchanger so the boiler doesnt get fouled up with suspended solids like my heat pump does.

    For 60 Kw I don't think a couple of rolls of pipe in the bottom of the sump will work, so I'm thinking of either a proper heat exchanger = Expensive, or maybe hanging a truck sized radiator in an area with some flow.

    the water will be pumped through an expansion tank so there is very little pressure in the system.

    Would a large radiator do the job? and if so how do I size it?
    Any other ideas?
    Thanks
    Ryan
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  2. #2
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    Default Re: Heat exchanger

    Talk to Gary Frank, he designs and build this type of thing for the dairy industry.

    But commercial brewers use a plate heat exchanger.

    Very similar to the oil cooler found on a lot of cars just MUCH bigger:

    https://www.macscool.co.za/online-le...at-exchangers/
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  4. #3
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    Default Re: Heat exchanger

    I have submerged oil coolers into hot water tanks and drawn heat off them.... works but very crude.

    PHE’s are the most efficient heat exchangers but very expensive (not many decent second hand units out there - they all end up at the scrappy)

    Places like GEA or Guth might have second hand units available.

    If you’re “hands on”, you could build a shell & tube heat exchanger......

    Give me a call on +27624206806 if you get stuck

  5. #4
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    Default Re: Heat exchanger

    i have been trying to find something to keep 50000l at a constant 27 degrees winter and summer , so very interested in this thread thanks,

    from what i have been told a heat pump. 27kw only uses 4kw of power, but nobody can say for sure if it works in the cold of winter.
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  6. #5
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    Default Re: Heat exchanger

    Thanks guys,
    Ive looked at plate heat exchangers, but my worry is if my heat pump clogs up in 10 days, the plate will too.Maybe the shell and tube will be the way to go....

    Peter,
    The heat pump give the best efficiency, I have it inside the tunnel to keep the air going in as warm as possible, and increase the output. problem is it draws a lot of cold air into the tunnel, so its a toss up between loosing the warm air, or heating the water. My min air temp in the tunnel this winter has been 15, when it was -3 outside. if the heat pump was outside it would have been at a 1 - 1 efficiency.

    Gary I'm definitely going to give you a call,

    Thanks all

    Ryan
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  7. #6
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    Default Re: Heat exchanger

    I'd go for a counter-flow copper jacket pipe heat exchanger.

    You have a 1" copper pipe feeding dam water inflow.

    Around this 1" pipe, you have a 2" copper jacket.

    Geyser water enters the 2" copper jacket at the cold dam input side and returns to the geyser at the warmer dam outflow side.

    Here is the science showing the Delta T effects. This is for cooling a hot liquid with a cold jacket, but it will work just as well to warm cold water with a hot jacket.

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  9. #7
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    Default Re: Heat exchanger

    Oh yes: you can make this system as long as you wish, or you can daisy chain the system and have the cold water move through a series of these counter flow systems until your outflow is at boiling point but that might be bad for the fish...........
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  10. #8
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    Default Re: Heat exchanger

    thanks guys, i just want a pump standing outside to heat tropical fish water, it has to be a constant 27 day and night.

    jelo that is way above my pay grade, but thanks i appreate the input.

    i will just follow this , i am now hijacking somebodys thing.
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  11. #9
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    Default Re: Heat exchanger

    Jelo this is brilliant, thank you

    Are the materials important - could it be made of PVC or something if the temps aren't too high? I'm sure I would loose some efficiency, but another couple of meters wouldn't make too much difference. Copper isnt great for fish....

    Peter If your water is clean you can just pump it straight through a heat pump, I use an ITS 26 with a 1,1 kw pump. The problem is at 4 am and its -3 outside you'll only get 4 kw of heat, but if you insulate well you'll be ok - the heat pump is a lot cheaper to run than a direct ultrazap type heater, and 50m3 doesn't change temperature quickly.
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  12. #10
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    Default Re: Heat exchanger

    PVC doesn't like boiling water.
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  13. #11
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    Default Re: Heat exchanger

    Will Pex-Al-Pex not work?

    It looses something like 900 times less heat than copper but once warm it should keep it's heat fairly consistent?
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  14. #12
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    Default Re: Heat exchanger

    jelo's proposal is basically a tube heat exchanger. In an industrial HEX there is inlet box, tube sheet, tubes, an other tube sheet and outlet box. Multiple tubes to have bigger heat transfer area. In all of these designs there is heat expansion issue. Tube can expand more or less than the shell. If the difference is too much something breaks. (I design expansion bellows for HEX to solve the differential expansion).

    Keep pressure under 50 kPa and the parts are not under pressure regulations.

    And yes. PVC doesn't like heat. Around 70 C most PVCs are useless.
    Jouko
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