45356Re: Cross-flow adaptation
- Jun 2, 2009
--- In Distillers@yahoogroups.com, Rasputin Paracelsus <rasputin@...> wrote:
> 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
> 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...)
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.
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