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45356Re: Cross-flow adaptation

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  • Harry
    Jun 2, 2009

      --- In Distillers@yahoogroups.com, Rasputin Paracelsus <rasputin@...> wrote:

      > Hello
      > A while back I asked a question about setting up a VM on a 3" column
      > rather than 2". There was some variance in opinion with regards to the
      > constriction of the vapour for turbulence purposes. (I note this here
      > only for the record, it's not really the focus of my question this time
      > around.)
      > Supposing that problem were to be solved in an acceptable fashion--I am
      > wondering about the Cross-flow condenser itself. Given that the
      > cross-sectional increase is 2.25:1 (3-squared over 2-squared)
      >     * would I then want 2.25 times as much surface area in terms of
      >       coolant pipes?
      >     * if so, perhaps most simply implemented by using 2.25 times more
      >       pipes of the same size (smaller pipes yield greater surface area
      >       per volume than larger ones) and
      >     * presumably this would mean a correponding increase in pump power...
      > (I assume I can sort out the question of the liebig adjustment without
      > too much problem using the handy calculator on the homedistiller site...)
      > Thanks
      > R


      There's a lot of "fudge factor" built in to a 2" crossflow.  Increasing the coolant flow volume is the easiest way of removing heat and ramping up performance of any existing condenser.  Because there is little restriction/resistance in the crossflow's multi-tube coolant arrangement (parallel flow), you can increase the coolant flow considerably to suit the amount of vapor being fed in.

       That's a decided advantage over coils, which must be designed to suit the particular rig's vapor capacity.  Coolant flow in coils has limited adjustability due to high friction (requires high-pressure pumping).

      It's not unusual to have coolant flows of 6+ litres per minute in a 2" crossflow.
      However, if for some reason you don't want to up the coolant flow, and you want to design a larger one specifically for your volume & velocity of vapour flow, then you could start by studying the following basic math and parameters.  It ain't as simple as people think.

      regards Harry




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