X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from fmailhost03.isp.att.net ([207.115.11.53] verified) by logan.com (CommuniGate Pro SMTP 5.3.11) with ESMTP id 4647264 for flyrotary@lancaironline.net; Sun, 19 Dec 2010 16:55:33 -0500 Received-SPF: none receiver=logan.com; client-ip=207.115.11.53; envelope-from=bbradburry@bellsouth.net Received: from desktop (adsl-85-147-11.mco.bellsouth.net[98.85.147.11]) by isp.att.net (frfwmhc03) with SMTP id <20101219215456H03002ved4e>; Sun, 19 Dec 2010 21:54:56 +0000 X-Originating-IP: [98.85.147.11] From: "Bill Bradburry" To: "'Rotary motors in aircraft'" References: In-Reply-To: Subject: RE: [FlyRotary] Re: Fw: Water temps Date: Sun, 19 Dec 2010 16:54:57 -0500 Message-ID: <65C578A2EF3946ED8EA3B9D6AD090269@Desktop> MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_0006_01CB9F9D.78644470" X-Mailer: Microsoft Office Outlook 11 Thread-Index: AcufwSK1oCdDZnn5QYeY+Ek+6R2bKgABgdJA X-MimeOLE: Produced By Microsoft MimeOLE V6.0.6001.18049 This is a multi-part message in MIME format. ------=_NextPart_000_0006_01CB9F9D.78644470 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit 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. Ed Edward L. Anderson Anderson Electronic Enterprises LLC 305 Reefton Road Weddington, NC 28104 http://www.andersonee.com http://www.eicommander.com From: Tracy Sent: Sunday, December 19, 2010 3:39 PM To: Rotary motors in aircraft 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 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" 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 =) ...Chrissi In a message dated 12/13/2010 2:49:02 P.M. Central Standard Time, keltro@att.net writes: Chrissi, 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" 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: said previously, -ideal water temp = 160*~180*F -ideal oil temp = 160*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? ...Chrissi ------=_NextPart_000_0006_01CB9F9D.78644470 Content-Type: text/html; charset="us-ascii" Content-Transfer-Encoding: quoted-printable

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 =3D 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.

 

Ed

 

Edward L. Anderson
Anderson Electronic Enterprises LLC
305 Reefton = Road
Weddington, = NC 28104
http://www.andersonee.com
http://www.eicommander.com

 

From: Tracy

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 =3D)

...Chrissi=

 

In a message dated 12/13/2010 = 2:49:02 P.M. Central Standard Time, keltro@att.net writes:

Chrissi,

    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

"TURBONETIC= S"_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:

 

said previously, =

-ideal water temp =3D = 160*~180*F

-ideal oil temp =3D = 160*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?

 

...Chrissi=

 

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