X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from cdptpa-omtalb.mail.rr.com ([75.180.132.123] verified) by logan.com (CommuniGate Pro SMTP 5.3.11) with ESMTP id 4647232 for flyrotary@lancaironline.net; Sun, 19 Dec 2010 16:10:13 -0500 Received-SPF: pass receiver=logan.com; client-ip=75.180.132.123; envelope-from=eanderson@carolina.rr.com Return-Path: X-Authority-Analysis: v=1.1 cv=Inhw+Jdt7z1D3BivGPfn2aw54OvUEJw5lAn/booRZkE= c=1 sm=0 a=cVHxHVjsHKoA:10 a=rPkcCx1H5rrOSfN0dPC7kw==:17 a=arxwEM4EAAAA:8 a=r1ClD_H3AAAA:8 a=kviXuzpPAAAA:8 a=3oc9M9_CAAAA:8 a=HZJGGiqLAAAA:8 a=9zHzPgpmZgbvQfGTi6kA:9 a=MD7P_mqiYhWNm4fh32gA:7 a=xkBm_alQi_KDlQ0z9ihuNSS8GM8A:4 a=pILNOxqGKmIA:10 a=4vB-4DCPJfMA:10 a=U8Ie8EnqySEA:10 a=HeoGohOdMD0A:10 a=UretUmmEAAAA:8 a=Ia-xEzejAAAA:8 a=_LGeA95ZCwNYBZgtKoEA:9 a=iT4n484cfjLKd6J_RScA:7 a=3ux0YGp2CRPpMO7ZNOKjoH05WWkA:4 a=iVkDmfvjeKcA:10 a=EzXvWhQp4_cA:10 a=rPkcCx1H5rrOSfN0dPC7kw==:117 X-Cloudmark-Score: 0 X-Originating-IP: 174.110.167.5 Received: from [174.110.167.5] ([174.110.167.5:56609] helo=EdPC) by cdptpa-oedge04.mail.rr.com (envelope-from ) (ecelerity 2.2.3.46 r()) with ESMTP id 3F/1C-13137-1947E0D4; Sun, 19 Dec 2010 21:09:38 +0000 Message-ID: <798B350A69B3423AA867A1ABFA9225F3@EdPC> From: "Ed Anderson" To: "Rotary motors in aircraft" References: In-Reply-To: Subject: Re: [FlyRotary] Re: Fw: Water temps Date: Sun, 19 Dec 2010 16:09:37 -0500 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_01B0_01CB9F97.22154B10" X-Priority: 3 X-MSMail-Priority: Normal Importance: Normal X-Mailer: Microsoft Windows Live Mail 14.0.8117.416 X-MimeOLE: Produced By Microsoft MimeOLE V14.0.8117.416 This is a multi-part message in MIME format. ------=_NextPart_000_01B0_01CB9F97.22154B10 Content-Type: text/plain; charset="Windows-1252" Content-Transfer-Encoding: quoted-printable 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=20 Sent: Sunday, December 19, 2010 3:39 PM To: Rotary motors in aircraft=20 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. =20 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.=20 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=92ll want to plumb the oil from engine out to the cooler; and plumb = the cooler between the radiator and the engine return. And I=92m not = quite sure about Tracy=92s 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=92m quite happy with the way things work. =20 Over 200 hours and lovin=92 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.=20 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=20 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,=20 -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?=20 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_01B0_01CB9F97.22154B10 Content-Type: text/html; charset="Windows-1252" Content-Transfer-Encoding: quoted-printable
Looking at it from Q =3D MDt*cp.  We know that the  coolant = mass flow (=20 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=20 heat exchange as part of the system - then the waste heat (Q) must be = exchanged=20 with the air through the radiator.  Therefore the efficiency of the = radiator in discharging heat to the air is an important = consideration.  The=20 more efficient - the smaller the radiator required and lower cooling = drag=20 possible.
 
So since we want to get rid of the same total = Heat Q and=20 since mass flow and Specific heat is constant that only leaves Dt as a factor to play with.  So all else = being the=20 same, the configuration that produces the greatest Dt=20 between coolant and air will be the most efficient and require the = smaller=20 radiator.
 
So if the coil cooler exchange is placed on the = Hot side=20 of the radiator, that would increase the temperature of the coolant = going into=20 the radiator and provided a larger Dt (more = efficient)=20  than if it were placed on the Cool side of the = radiator.   =20 If placed on the cool side there is a greater transfer of oil heat to = the=20 coolant , since the coolant has already passed through the radiator = and is=20 lower temp, but that results in a higher temperature coolant going back = into the=20 engine.  To keep the coolant temperature at the same level = prior to=20 inserting the oil/coolant exchanger into the circuit requires (as = Tracy=20 pointed out) you  to lower the coolant temp even more before it = goes into=20 the oil/coolant exchanger by using a  larger=20 radiator.
 
Since the objective is to remove heat most = efficiently=20 from the engine (and hopefully keep cooling drag down), it would appear = that the=20 oil/coolant heat exchanger being placed on the hot side of the radiator = offers=20 an overall advantage from that perspective.  Clearly either way, it = can be=20 made to work.
 
Ed
 
Edward L. Anderson
Anderson Electronic = Enterprises=20 LLC
305 Reefton Road
Weddington, NC=20 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=20 leg of the coolant system you pick up the heat from the oil cooler, you = raise=20 the temp of the coolant loop by the amount of additional heat; so the = rejection=20 temp of the rad is higher either way."


Not so fast!   Here's my take on=20 it.  

Yes,   the total heat=20 rejection of the rad has to end up being the same.  BUT with the = cold side=20 oil cooler, to keep the engine coolant inlet temperature (and = temperature of the=20 engine block) the same requires a 33% larger rad (compared to what we = needed a=20 separate air to oil cooler).   Actually, the rad has to be = even bigger=20 than this because we have to have the rad outlet temp even lower to = compensate=20 for the rise in coolant temp due to temp rise of oil cooler.   = That=20 means the median temp of the rad is lower and therefore less=20 efficient.

If you cool the oil on the hot side of the coolant=20 circuit,  the inlet temp of the rad is now higher than in the cold = side=20 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=20 results in less cooling drag.

That's my story & I'm stick'n = to it :=20 )

Tracy

On Sun, Dec 19, 2010 at 12:13 PM, Al Gietzen = <ALVentures@cox.net> = wrote:

For = maximum cooling=20 of the oil from an oil/water HX (heat exchanger) you=92ll want to = plumb the oil=20 from engine out to the cooler; and plumb the cooler between the = radiator and=20 the engine return.  And I=92m not quite sure about = Tracy=92s = point because no=20 matter which leg of the coolant system you pick up the heat from the = oil=20 cooler, you raise the temp of the coolant loop by the amount of = additional=20 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=20 coolant exiting the engine below boiling for extended high=20 power.

 

On my=20 Velocity 20B = installation I=20 have a primary radiator in the cowl, and a secondary in the wing root; = plumbed=20 in parallel. The wing root rad has an in-line 170F thermostat, and = generally=20 only comes on line during extended climb. No thermostat in the engine = that=20 would restrict flow and add a potential failure = mode.

 

I have an = oil/air=20 cooler and an oil/coolant HX, also plumbed in parallel. The = oil/coolant HX is=20 plumbed to the exit of the primary rad.  The oil temp runs about = 20F=20 higher than the coolant (measured at oil return and coolant out). I = could=20 probably reduce that difference by restricting flow to the oil/air = cooler=20 forcing more through the oil/coolant HX; but I=92m quite happy with = the way=20 things work. 

 

Over 200 = hours and=20 lovin=92 my rotary more all the time.

 

Al=20 G

 

----- Forwarded Message = ----
From: "CozyGirrrl@aol.com" <CozyGirrrl@aol.com>
To: keltro@att.net
Sent: Mon, December=20 13, 2010 4:05:31=20 PM
Subject: Re: Fw: [FlyRotary] = Re: Fw:=20 Water temps


Thanks=20 Tracy for the = adjustment=20 in my thinking. I don't want to target temps unrealistically.=20

Where does = that=20 leave us with our pick up and return points for the oil/water cooling = system?=20 If the oil were being cooled with water only and we wanted the best = possible=20 chance at that, wouldn't we want to feed it the cooler water from the = high=20 pressure side of the pump prior to entering the = block?

 

Whatever = space we=20 would use for an oil/air cooler takes away from potential coolant = radiator=20 space. Putting the two side by side becomes less efficient spacewise = for both=20 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=20 layout plans. I remember Richter's Cozy III with three P-51 scoops, it = got the=20 job done but was like dragging a parachute in = drag.

 

Kelly, to = your=20 comment below, while I am sure we'd have no problem putting adequate = heat into=20 the oil, I am very concerned about keeping any more than just enough = out of=20 it. Much easier going one way then the other = =3D)

...Chrissi

 

In=20 a message dated 12/13/2010 = 2:49:02=20 P.M. Central = Standard=20 Time, keltro@att.net=20 writes:

Chrissi,

   =20 My own opinion is that after warm up and in flight the oil temp = leaving the=20 engine before the

coolers = (air or=20 water  to oil) will almost always be well above=20 160-180 F..............If it is not = this

high = then=20 the oil to water cooler will actually help warm it to a more = efficient=20 temp.........IMHO

 

  =20 Somebody correct me if this is a fallacy=20 !!.......................<:)

 

Kelly=20 Troyer
"DYKE = DELTA=20 JD2" = (Eventually)

"13B = ROTARY"_=20 Engine
"RWS"_RD1C/EC2/EM2
"MISTRAL"_Backplate/Oil=20 Manifold

"TURBONETICS"_TO4E50=20 Turbo

 

 

From: "CozyGirrrl@aol.com"=20 <CozyGirrrl@aol.com>
To: keltro@att.net
Sent: Mon, = December 13,=20 2010=20 12:52:06=20 PM
Subject: Re: Fw: [FlyRotary] = Re: Fw:=20 Water temps

This is = where I=20 get confused:

 

said = previously,=20

-ideal = water temp=20 =3D 160*~180*F

-ideal = oil temp =3D=20 160*F

 

If we = are cooling=20 oil with water that is at best hotter than the ideal temp of the = oil, then=20 are we not adding heat to it rather than removing it?=20

 

If we = are trying=20 to cool oil, why would we feed the highest temp water to the = oil/water=20 cooler rather than the coolest temp water by tapping into the pump = housing=20 where it enters the block?

 

Based on = feedback,=20 the water entering the block may be as low as 150*~160*F, would this = be cool=20 enough to do an adequate job of cooling the = oil?

 

Also, = which model=20 of Mocal is being used?

 

...Chrissi


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