Home » Public Forums » GMCnet » Cooling Efficiency
| Cooling Efficiency [message #311649] |
Wed, 28 December 2016 17:08  |
jhbridges
Messages: 8412
Registered: May 2011
Location: Braselton ga
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For the thermodynamics gurus present. How efficient is liquid to liquid heat transfer - as in our oil and transmission coolers relative to air to liquid as in the radiator itself? I know it's more so, but not how much more so. Twice? power of ten or more? My only experience is with vapor phase cooling in UHF television transmitter klystrons. They generated so much heat due to electrical inefficiency the only way you could remove it was by heat of vaporization. Is there any great value in the outboard transmission coolers? Are we taking aim squarely at our foot if we bypass the radiator cooler?
--johnny
Foolish Carriage, 76 26' Eleganza(?) with beaucoup mods and add - ons.
Braselton, Ga.
I forgive them all, save those who hurt the dogs. They must answer to me in hell
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| Re: Cooling Efficiency [message #311651 is a reply to message #311649] |
Wed, 28 December 2016 17:41  |
JohnL455
Messages: 4447
Registered: October 2006
Location: Woodstock, IL
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Other than "more" it would depend on the temp differential of the 2 liquids. (Duh) I think the rad cooler provides some temp stabilization both directions as the mass of each system can store heat till it can be dissipated (scratch each others back). I don't like the in front of radiator coolers as they are more like Harleys and Volkswagens (air cooled) when it's hot out the trans is hot, and in winter it runs too cold.
John Lebetski
Woodstock, IL
77 Eleganza II
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| Re: [GMCnet] Cooling Efficiency [message #311652 is a reply to message #311649] |
Wed, 28 December 2016 18:10 |
Dave Mumert
Messages: 272
Registered: February 2004
Location: Olds, AB, Canada
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Hi Johnny
Here is a table that may give you an ideal of the difference
http://www.engineersedge.com/thermodynamics/overall_heat_transfer-table.htm
Air cooled heat exchangers look to be 100-130 for water
Tubular heat exchanger liquid to liquid looks to be 25-200
Plate heat exchanger liquid to liquid looks to be 150-700
A google search of "radiator heat transfer coefficient" will return enough hits to keep you entertained for several hours.
Hope that helps
Dave Mumert
> -----Original Message-----
> Subject: [GMCnet] Cooling Efficiency
>
> For the thermodynamics gurus present. How efficient is liquid to liquid heat transfer - as in our oil and transmission coolers
relative to
> air to liquid as in the radiator itself? I know it's more so, but not how much more so. Twice? power of ten or more? My only
> experience is with vapor phase cooling in UHF television transmitter klystrons. They generated so much heat due to electrical
> inefficiency the only way you could remove it was by heat of vaporization. Is there any great value in the outboard transmission
> coolers? Are we taking aim squarely at our foot if we bypass the radiator cooler?
>
> --johnny
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| Re: Cooling Efficiency [message #311653 is a reply to message #311649] |
Wed, 28 December 2016 19:06 |
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Matt Colie
Messages: 8547
Registered: March 2007
Location: S.E. Michigan
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Johnny Bridges wrote on Wed, 28 December 2016 18:08For the thermodynamics gurus present. How efficient is liquid to liquid heat transfer - as in our oil and transmission coolers relative to air to liquid as in the radiator itself? I know it's more so, but not how much more so. Twice? power of ten or more? My only experience is with vapor phase cooling in UHF television transmitter klystrons. They generated so much heat due to electrical inefficiency the only way you could remove it was by heat of vaporization. Is there any great value in the outboard transmission coolers? Are we taking aim squarely at our foot if we bypass the radiator cooler?
--johnny
Johnny,
Ready? Take a leak, grab a drink and Hang ON....
To answer your question straight up, Yes But Expect you might like to know why. Vapor phase cooling is a very different animal and I will tough on that at the end.
Air is handy for cooling only because there is some much of it available. But, eight pounds of air gets you about 100 cubic feet. Eight pounds of water gets you about one gallon (0.133cuft). You have to have the mass to transfer the heat. This is just one reason that the coolers in a radiator tank are so small. And there is an advantage to be had by cooling with the temperature controlled engine coolant. If you go to an air cooled heat exchanger not only does it need to be a lot larger, but it should include some kind of control as neither engine lubricating oil or transmission fluid like being too cold. Both for the same reason and that is moisture control. An engine can't avoid it because they make water as a product of combustion and some ends up in the lubrication. The transmission is a passive thing that is the result of heating and cooling.
Transmissions need a cooler because the torque converter makes about 15Hp (38kBTU)of waste heat just dragging you down the road.
So, if I have a Toronado with a 455, where is the lubricating oil cooler for that??
Good Question:
Did you ever try to run with the valve gear (rocker) cover removed? There is oil all over the place and it is on top of the combustion chamber cooling jacket and when it finally gets out of there it gets to run down the push rod grooves that are also on the outside of the cylinder cooling jacket until it gets to the pan where it can get some cooling by hanging out in the airflow under the vehicle.
Now, lets look at your vapor phase cooling for a moment. This is something steam engineers know about. A BTU is the amount of heat it takes to raise one pound of water one degree Fahrenheit. At the pressures you deal with that heat of fusion is 970 BTU/lb. So, if you can boil water and take away 970 with no (little) change in temperature, isn't that just one hell of a good idea? This is why I made a living boiling water.
Now, I hope I didn't loose you here somewhere, but if I did and you can sort of tell me where, I will be glad to try to clear it up.
Matt
Matt & Mary Colie - Chaumière -'73 Glacier 23 - Members GMCMI, GMCGL, GMCES
Electronically Controlled Quiet Engine Cooling Fan with OE Rear Drum Brakes with Applied Control Arms
SE Michigan - Near DTW - Twixt A2 and Detroit
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| Re: Cooling Efficiency [message #311654 is a reply to message #311649] |
Wed, 28 December 2016 19:11 |
jhbridges
Messages: 8412
Registered: May 2011
Location: Braselton ga
Karma: -74
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OK, the short of it is, use the radiator coolers, they work better than fins in the wind. The move for an outboard cooler would be outboard first, then through the radiator cooler and you'd feed the transmission or engine oil that's at a fairly constant temp - 180 degrees or so.
Thanks,
Johnny
Foolish Carriage, 76 26' Eleganza(?) with beaucoup mods and add - ons.
Braselton, Ga.
I forgive them all, save those who hurt the dogs. They must answer to me in hell
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| Re: Cooling Efficiency [message #311656 is a reply to message #311654] |
Wed, 28 December 2016 22:19 |
Ken Burton
Messages: 10030
Registered: January 2004
Location: Hebron, Indiana
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There is no way the the trans fluid temperature cooler should be anywhere near 180 degrees leaving the radiator. You put 180 to 190 degree coolant in the top (or one side in the case of cross flow radiators) and get much cooler coolant out the bottom (or other side). The trans cooler is always located in the cooler side of the radiator where the coolant temperature is lower. My trans fluid temperature in the pan never exceeds 150.
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana
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| Re: Cooling Efficiency [message #311662 is a reply to message #311649] |
Thu, 29 December 2016 08:37 |
jhbridges
Messages: 8412
Registered: May 2011
Location: Braselton ga
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OK, it becomes clear. It looks as if p'raps only the radiator transmission fluid cooler is the move, unless you tow a lot in hilly country in the summer, then p'raps an outboard cooler in front of the radiator cooler. And Matt, the vapor phase cooling is one thing I do understand. Given the really poor efficiency (Electricity to RF energy) of an analog UHF transmitter, it's about the only way you can carry the generated heat away from the thing. We were steamfitters, among other things.
Thank, guys.
--johnny
Foolish Carriage, 76 26' Eleganza(?) with beaucoup mods and add - ons.
Braselton, Ga.
I forgive them all, save those who hurt the dogs. They must answer to me in hell
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| Re: Cooling Efficiency [message #311669 is a reply to message #311649] |
Thu, 29 December 2016 12:39 |
jhbridges
Messages: 8412
Registered: May 2011
Location: Braselton ga
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I'd think you'd want just the opposite... do you not want the fluid going back to the transmission at a relatively stable temp, 150 - 200 degrees, regardless of the outside temp? If it sees the radiator cooler last before returning would it not then be at that stable temperature, either cooled or warmed by the radiator coolant as necessary?
That cooling fan system has gone through several changes in its development, the current one looks to be the best answer for our needs. As an interest6ing aside, all the electronic clutches have a speed sensor built in, for use by the vehicle computer. Since our coaches have no computer beyond the driver's laptop or tablet, it isn't iterated for our use, but the potential exists to run a fan tachometer if one wanted to do so. Tom Pryor had a tach on the demo setup in Mannsfield.
Foolish Carriage, 76 26' Eleganza(?) with beaucoup mods and add - ons.
Braselton, Ga.
I forgive them all, save those who hurt the dogs. They must answer to me in hell
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| Re: Cooling Efficiency [message #311673 is a reply to message #311649] |
Thu, 29 December 2016 14:52 |
Chris Tyler
Messages: 458
Registered: September 2013
Location: Odessa FL
Karma: 7
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Every aftermarket tranny coolers instructions I have ever seen has you routing the fluid downstream from the radiator. They also often cover eliminating the rad cooler due to a leak.
I forget which one, but one had a rather lengthy writeup on the [or at least their] theory of why this was the most efficient. Short version is the water to fluid TF was more efficient as long as the coolant was in operating range and the ext cooler is best utilized as a second stage.
In the HP world, high stall converters create a lot of heat and its common to add addl cooling. Also, on a car with marginal radiator cooling, eliminating the rad heat exchanger and going witha larger external cooler is common.I had problems with my suercharged Monza and dropped 20F by doing so.
However, too big a cooler mays restrict airflow to the radiator and AC condenser. I try to mount them away from those.
I suppose in very cold weather there would be such a thing as overcooling the fluid [Not a problem in FL] but as pointed out previously, the coolant would tend to help stabilize that.
76 Glenbrook
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| Re: [GMCnet] Cooling Efficiency [message #311675 is a reply to message #311669] |
Thu, 29 December 2016 16:50 |
emerystora
Messages: 4442
Registered: January 2004
Karma: 13
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I feel that the external cooler should be between the cooler in the radiator and the line back to the transmission. Mine has been like this for about 35 years now and it works fine.
Why would you want to cool the transmission fluid and then warm it back up in the radiator?
Emery Stora
77 Kingsley
Frederick, CO
> On Dec 29, 2016, at 11:39 AM, Johnny Bridges via Gmclist wrote:
>
> I'd think you'd want just the opposite... do you not want the fluid going back to the transmission at a relatively stable temp, 150 - 200 degrees,
> regardless of the outside temp? If it sees the radiator cooler last before returning would it not then be at that stable temperature, either cooled or
> warmed by the radiator coolant as necessary?
> That cooling fan system has gone through several changes in its development, the current one looks to be the best answer for our needs. As an
> interest6ing aside, all the electronic clutches have a speed sensor built in, for use by the vehicle computer. Since our coaches have no computer
> beyond the driver's laptop or tablet, it isn't iterated for our use, but the potential exists to run a fan tachometer if one wanted to do so. Tom
> Pryor had a tach on the demo setup in Mannsfield.
> --
> '76 23' transmode Norris upfit, 76 26' Eleganza(?) with beaucoup mods and add - ons.
> Braselton, Ga.
> "The road goes on forever, and the party never ends" --Robert Earl Keen
>
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| Re: [GMCnet] Cooling Efficiency [message #311681 is a reply to message #311675] |
Thu, 29 December 2016 18:22 |
Ken Henderson
Messages: 8726
Registered: March 2004
Location: Americus, GA
Karma: 9
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Emery,
The "Chevrolet P-30 Chassis Owners' Manual" agrees with you -- put any
external cooler in the return line. Incidentally, that manual discourages
the use of such coolers, and suggests an easy way to determine whether one
is likely needed. They do included a note that it may have to be covered
during cold weather. It's worth mentioning that they suggest installing
any temperature gauge at the outlet of the converter (where the cooler line
TO the radiator exits the transmission) and that the minimum recommended
operating temperature is 150*F. 350*F there is cause to run the engine at
1200 rpm in Neutral to bring the temperature down.
That manual, which Chevrolet would, 'way back, send for free to any P-30
owner on request, is, IMHO, an excellent reference for many GMCMH topics.
Examples: Sections on Vapor Lock and corrective actions; Battery
information, including why NOT to always use the Boost Switch;
Troubleshooting for many common systems, including the Electromotor Cruise
Control some of us have installed; Detailed information on ATF, etc.; and
much more which should be studied by most of us.
At one time Billy Massey had that manual on his web site, but I couldn't
find it to provide the URL here. Billy?
Ken H.
Americus, GA
'76 X-Birchaven w/Cad500/Howell EFI & EBL,
Manny Brakes & 1-Ton, etc., etc., etc.
www.gmcwipersetc.com
On Thu, Dec 29, 2016 at 5:50 PM, Emery Stora wrote:
> I feel that the external cooler should be between the cooler in the
> radiator and the line back to the transmission. Mine has been like this
> for about 35 years now and it works fine.
> Why would you want to cool the transmission fluid and then warm it back up
> in the radiator?
>
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Ken Henderson
Americus, GA
www.gmcwipersetc.com
Large Wiring Diagrams
76 X-Birchaven
76 X-Palm Beach
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| Re: [GMCnet] Cooling Efficiency [message #311683 is a reply to message #311682] |
Thu, 29 December 2016 18:56 |
Ken Henderson
Messages: 8726
Registered: March 2004
Location: Americus, GA
Karma: 9
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For some reason, that one didn't work for me, but this one, provided by
Google in response to the error on that one, did:
http://www.bdub.net/manuals/manuals/P30.zip
Thanks, Billy.
Ken H.
On Thu, Dec 29, 2016 at 7:44 PM, Billy Massey wrote:
> http://bdub.net/manuals/manuals/P30.zip
>
>
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Ken Henderson
Americus, GA
www.gmcwipersetc.com
Large Wiring Diagrams
76 X-Birchaven
76 X-Palm Beach
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| Re: [GMCnet] Cooling Efficiency [message #311684 is a reply to message #311682] |
Thu, 29 December 2016 18:53 |
Guy Lopes
Messages: 499
Registered: April 2004
Location: Sacramento, CA
Karma: 3
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That link didn't work for me Billy
Guy Lopes
76 Birchaven "Orion"
Sacramento, CA
W6TOL
www.GMC-Guy.com
-----Original Message-----
From: Gmclist [mailto:gmclist-bounces@list.gmcnet.org] On Behalf Of Billy
Massey
Sent: Thursday, December 29, 2016 4:44 PM
To: gmclist@list.gmcnet.org
Subject: Re: [GMCnet] Cooling Efficiency
http://bdub.net/manuals/manuals/P30.zip
On Dec 29, 2016 6:24 PM, "Ken Henderson" wrote:
Emery,
The "Chevrolet P-30 Chassis Owners' Manual" agrees with you -- put any
external cooler in the return line. Incidentally, that manual discourages
the use of such coolers, and suggests an easy way to determine whether one
is likely needed. They do included a note that it may have to be covered
during cold weather. It's ... Snip ...
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Guy Lopes
76 Birchaven "Orion"
Sacramento, CA
W6TOL
www.GMC-Guy.com
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| Re: [GMCnet] Cooling Efficiency [message #311685 is a reply to message #311681] |
Thu, 29 December 2016 19:14 |
emerystora
Messages: 4442
Registered: January 2004
Karma: 13
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Senior Member |
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Ken
The P30 manual can be found on the GMCMI.com site at
http://www.gmcmi.com/wp-content/uploads/2014/05/P30-Chassis-Manual.pdf
Emery Stora
> On Dec 29, 2016, at 5:22 PM, Ken Henderson wrote:
>
> Emery,
>
> The "Chevrolet P-30 Chassis Owners' Manual" agrees with you -- put any
> external cooler in the return line. Incidentally, that manual discourages
> the use of such coolers, and suggests an easy way to determine whether one
> is likely needed. They do included a note that it may have to be covered
> during cold weather. It's worth mentioning that they suggest installing
> any temperature gauge at the outlet of the converter (where the cooler line
> TO the radiator exits the transmission) and that the minimum recommended
> operating temperature is 150*F. 350*F there is cause to run the engine at
> 1200 rpm in Neutral to bring the temperature down.
>
> That manual, which Chevrolet would, 'way back, send for free to any P-30
> owner on request, is, IMHO, an excellent reference for many GMCMH topics.
> Examples: Sections on Vapor Lock and corrective actions; Battery
> information, including why NOT to always use the Boost Switch;
> Troubleshooting for many common systems, including the Electromotor Cruise
> Control some of us have installed; Detailed information on ATF, etc.; and
> much more which should be studied by most of us.
>
> At one time Billy Massey had that manual on his web site, but I couldn't
> find it to provide the URL here. Billy?
>
> Ken H.
> Americus, GA
> '76 X-Birchaven w/Cad500/Howell EFI & EBL,
> Manny Brakes & 1-Ton, etc., etc., etc.
> www.gmcwipersetc.com
>
>
> On Thu, Dec 29, 2016 at 5:50 PM, Emery Stora wrote:
>
>> I feel that the external cooler should be between the cooler in the
>> radiator and the line back to the transmission. Mine has been like this
>> for about 35 years now and it works fine.
>> Why would you want to cool the transmission fluid and then warm it back up
>> in the radiator?
>>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
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| Re: Cooling Efficiency [message #311695 is a reply to message #311649] |
Fri, 30 December 2016 08:03 |
jhbridges
Messages: 8412
Registered: May 2011
Location: Braselton ga
Karma: -74
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Senior Member |
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OK, the brain trust - including the folks at GM Truck and Coach - say outboard cooler last. I has again learnt something valuable in the Forum. Now, if I can just figure out why the new transmission was installed with two of the four coolers unused and the temp sender not connected, I will of learnt even more. Sigh.
--johnny
Foolish Carriage, 76 26' Eleganza(?) with beaucoup mods and add - ons.
Braselton, Ga.
I forgive them all, save those who hurt the dogs. They must answer to me in hell
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| Re: Cooling Efficiency [message #311700 is a reply to message #311649] |
Fri, 30 December 2016 09:07 |
JohnL455
Messages: 4447
Registered: October 2006
Location: Woodstock, IL
Karma: 12
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Senior Member |
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Keep in mind with an all stock system you also have 6 gallons of fresh watter in the water heater (48 pounds appox) as heat sink ballast tank which tends to help stabilize temperatures. This slighly mitigates the temp rise speed pulling a hill, and slighly slows the cooling of the entire system as you decend the grade. I would think since all 4 systems are linked by their own loops ( coolant, water, engine oil, Dexron) the whole thing should track as one system and be more stabile.
John Lebetski
Woodstock, IL
77 Eleganza II
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| Re: Cooling Efficiency [message #311703 is a reply to message #311649] |
Fri, 30 December 2016 12:36 |
jhbridges
Messages: 8412
Registered: May 2011
Location: Braselton ga
Karma: -74
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Senior Member |
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Matt - at this point I'm not sure who did the install, or under what constraints. Consequently, they'll be anonymous until 'all precincts is heard from' to paraphrase Ring Lardiner Jr. We've seen the kind of pecking party here which can evolve from real or imagined improper work, I've no intention of hosting one. The transmission failed after something over 6 thousand miles of proper operation. I've directions from Manny on how to accomplish some diagnosis, I've had a miserable cold for most of a week and consequently haven't been up to doing the tests and observations. As of a couple of days ago, I have a trolley to remove it, and ramps to put the coach up on to ease the removal. Step one is pull the pan off and see what I find. Dipstick investigation isn't much of a help. The fluid appears normal. I can't smell with a cold, but it didn't smell burnt when the coach came home on the hook either. In that it's synthetic, it could get surprisingly hot and still appear and smell normal.
I can't think of any failure which would produce the symptoms which won't require R&R so it's kind of moot - except that Manny asked to remove and check the pan to see what's in it first, a simple enough task. Ferrous metal, aluminum, friction material, or a clean pan and filter would it seems all be indicators of one or more specific problems.
Time will tell.
--johnny
Foolish Carriage, 76 26' Eleganza(?) with beaucoup mods and add - ons.
Braselton, Ga.
I forgive them all, save those who hurt the dogs. They must answer to me in hell
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