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