Be aware that
AC evaporators are designed for much lower flow rate of a completely different
fluid. It is fortunate that some cores make relatively effective coolant
radiators. But before using one you (or someone) should check the
pressure drop with the fluid we use; either water of or 50/50 water/EG, at the
flow rate you need. Be particular careful about connecting 2 units in
series.
A 5/8” dia
provides only about 1/3 sq in of x-sectional area for flow. On a 2-rotor
you’ll want flow capability of at least 25 gpm. In a 5/8 dia opening
this is a flow velocity of about 25 ft/sec. That is high, and results in
significant pressure drop. The pressure drop in an AC core can also be
high depending on the design.
Connecting 2
of these in parallel can work, a la Tracy
Crook et.
al. Putting all the flow through one (and one that no one has tried
before), or two in series is not a good idea, certainly not without doing some
flow testing first.
Go to
Griffin, or other
custom radiator vendor with your heat load, coolant and air flow rates, and
configuration constraints and have them quote you a radiator.
Just my
opinion, of course.
Al
Subject: [FlyRotary]
Re: evap core versus radiator
Tracy and I are using 5/8"
inlets and 3/4" outlets.
4 1/2" is about 1" thicker than what we
use.
Finn
sqpilot@earthlink wrote:
Hi, fellow rotary
enthusiasts.....I am confused regarding radiator versus evaporator cores. Ed
Klepeis can make a radiator for me that measures overall 16 x 10 x 4 1/2, by
sandwiching two 2 1/4" thick cores together. Unfortunately, there are two 2"
wide tanks on each end, which reduces the cooling fin area to 12" x 10" x
4 1/2". I calculate that to a total area of around
540.
I have
found an evap. core that measures 9 x 13 1/2 x 4 5/8" thick. I believe
that comes out to a total area of around 561. That would fit perfectly
in the cowling with even less modifications to inlets, etc. (Read that as
less work for me). I have heard on this forum that evap. cores are a
good choice for cooling, as they can take high pressures. Is there
anything else I should consider regarding radiator versus evap core for
cooling? Inlet and outlet tubes look to be around 5/8". The core looks just
like one from a GM Safari or Astro Van except for the size
difference. I don't know if the 5/8" inlet/outlet tubes would be too
restrictive to flow compared to a radiator that would be made with 1" NPT
inlet/outlets? My guess is that once the water gets inside either the
evap core or the radiator, flow is going to be restricted by the tubing
sizes inside the cooling device regardless of the inlet/outlet
sizes? I know that Ed Anderson,
Tracy and
others have had success with evap cores. Any possible pros and cons
would be much appreciated. Thank you for your time and opinions.
Paul Conner