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Hi Bill,
No I keep mine at a small private airport called
GooseCreek (28A), but Monore is only about 4 miles from home.
Ed
Sent: Sunday, December 19, 2010 4:54 PM
Subject: [FlyRotary] Re: Fw: Water temps
Ed,
Do you keep your plane
at the Munroe
Airport?
Bill
B
From:
Rotary motors in aircraft
[mailto:flyrotary@lancaironline.net] On
Behalf Of Ed Anderson
Sent: Sunday, December 19, 2010 4:10
PM
To: Rotary motors in aircraft
Subject: [FlyRotary] Re: Fw: Water
temps
Looking at it from Q =
MDt*cp. We know that the coolant mass
flow ( M ) through the system (both coolant and air) is going to be a
constant at some specific power setting and air speed. With an oil/coolant
heat exchange as part of the system - then the waste heat (Q) must be exchanged
with the air through the radiator. Therefore the efficiency of the
radiator in discharging heat to the air is an important consideration. The
more efficient - the smaller the radiator required and lower cooling drag
possible.
So since we want to get rid of the
same total Heat Q and since mass flow and Specific heat is constant that only
leaves Dt as a factor to play with. So all else being
the same, the configuration that produces the greatest Dt between coolant and air will be
the most efficient and require the smaller
radiator.
So if the coil cooler exchange is
placed on the Hot side of the radiator, that would increase the temperature of
the coolant going into the radiator and provided a larger Dt (more efficient) than if it
were placed on the Cool side of the radiator. If placed on the
cool side there is a greater transfer of oil heat to the coolant , since
the coolant has already passed through the radiator and is lower temp, but that
results in a higher temperature coolant going back into the engine.
To keep the coolant temperature at the same level prior to inserting the
oil/coolant exchanger into the circuit requires (as Tracy pointed out)
you to lower the coolant temp even more before it goes into the
oil/coolant exchanger by using a larger
radiator.
Since the objective is to remove
heat most efficiently from the engine (and hopefully keep cooling drag down), it
would appear that the oil/coolant heat exchanger being placed on the hot side of
the radiator offers an overall advantage from that perspective. Clearly
either way, it can be made to work.
Edward L. Anderson
Anderson Electronic
Enterprises LLC
305 Reefton
Road
Weddington, NC
28104
http://www.andersonee.com
http://www.eicommander.com
Sent: Sunday,
December 19, 2010 3:39 PM
Subject:
[FlyRotary] Re: Fw: Water temps
"no
matter which leg of the coolant system you pick up the heat from the oil cooler,
you raise the temp of the coolant loop by the amount of additional heat; so the
rejection temp of the rad is higher either way."
Not so
fast! Here's my take on it.
Yes,
the total heat rejection of the
rad has to end up being the same. BUT with the cold side oil cooler, to
keep the engine coolant inlet temperature (and temperature of the engine block)
the same requires a 33% larger rad (compared to what we needed a separate air to
oil cooler). Actually, the rad has to be even bigger than this
because we have to have the rad outlet temp even lower to compensate for the
rise in coolant temp due to temp rise of oil cooler. That means the
median temp of the rad is lower and therefore less efficient.
If you cool
the oil on the hot side of the coolant circuit, the inlet temp of the rad
is now higher than in the cold side scheme and the required rad size and/or the
airflow through the rad size increase is smaller due to the higher delta T
between air and rad. This results in less cooling drag.
That's my
story & I'm stick'n to it : )
Tracy
On Sun, Dec 19, 2010 at 12:13 PM, Al Gietzen <ALVentures@cox.net>
wrote:
For maximum cooling
of the oil from an oil/water HX (heat exchanger) you’ll want to plumb the oil
from engine out to the cooler; and plumb the cooler between the radiator and the
engine return. And I’m not quite sure about Tracy’s point because no matter which leg of
the coolant system you pick up the heat from the oil cooler, you raise the temp
of the coolant loop by the amount of additional heat; so the rejection temp of
the rad is higher either way. The assumption is, of course, that you have
sufficient capacity to keep the coolant exiting the engine below boiling for
extended high power.
On my Velocity 20B
installation I have a primary radiator in the cowl, and a secondary in the wing
root; plumbed in parallel. The wing root rad has an in-line 170F thermostat, and
generally only comes on line during extended climb. No thermostat in the engine
that would restrict flow and add a potential failure
mode.
I have an oil/air
cooler and an oil/coolant HX, also plumbed in parallel. The oil/coolant HX is
plumbed to the exit of the primary rad. The oil temp runs about 20F higher
than the coolant (measured at oil return and coolant out). I could probably
reduce that difference by restricting flow to the oil/air cooler forcing more
through the oil/coolant HX; but I’m quite happy with the way things work.
Over 200 hours and
lovin’ my rotary more all the time.
Al
G
----- Forwarded Message
----
From: "CozyGirrrl@aol.com" <CozyGirrrl@aol.com>
To: keltro@att.net
Sent: Mon, December 13, 2010 4:05:31
PM
Subject: Re: Fw: [FlyRotary]
Re: Fw: Water temps
Thanks Tracy for the adjustment
in my thinking. I don't want to target temps unrealistically.
Where does that leave
us with our pick up and return points for the oil/water cooling system? If the
oil were being cooled with water only and we wanted the best possible chance at
that, wouldn't we want to feed it the cooler water from the high pressure side
of the pump prior to entering the block?
Whatever space we
would use for an oil/air cooler takes away from potential coolant radiator
space. Putting the two side by side becomes less efficient spacewise for both
due to losses for structure etc. If it is not possible to cool the oil
adequately with water alone then we'll need to back up a little and make other
layout plans. I remember Richter's Cozy III with three P-51 scoops, it got the
job done but was like dragging a parachute in
drag.
Kelly, to your comment
below, while I am sure we'd have no problem putting adequate heat into the oil,
I am very concerned about keeping any more than just enough out of it. Much
easier going one way then the other =)
In a message dated
12/13/2010 2:49:02 P.M. Central Standard Time, keltro@att.net writes:
My own opinion is that after warm up and in flight the oil temp leaving the
engine before the
coolers (air or
water to oil) will almost always be well above
160-180 F..............If it is not
this
high then
the oil to water cooler will actually help warm it to a more efficient
temp.........IMHO
Somebody correct me if this is a fallacy
!!.......................<:)
Kelly
Troyer
"DYKE
DELTA JD2"
(Eventually)
"13B ROTARY"_
Engine
"RWS"_RD1C/EC2/EM2
"MISTRAL"_Backplate/Oil
Manifold
"TURBONETICS"_TO4E50
Turbo
From: "CozyGirrrl@aol.com" <CozyGirrrl@aol.com>
To: keltro@att.net
Sent: Mon, December 13, 2010 12:52:06
PM
Subject: Re: Fw:
[FlyRotary] Re: Fw: Water temps
This is where I get
confused:
-ideal water temp =
160*~180*F
If we are cooling
oil with water that is at best hotter than the ideal temp of the oil, then are
we not adding heat to it rather than removing it?
If we are trying to
cool oil, why would we feed the highest temp water to the oil/water cooler
rather than the coolest temp water by tapping into the pump housing where it
enters the block?
Based on feedback,
the water entering the block may be as low as 150*~160*F, would this be cool
enough to do an adequate job of cooling the
oil?
Also, which model of
Mocal is being used?
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