Author Topic: Cooling drum evaporation  (Read 24366 times)

rbodell

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Cooling drum evaporation
« on: February 09, 2008, 01:50:35 PM »
Just a thought on cooling.

Quite a bit of water is lost from the cooling drum each day. With $150 in antifreeze evaporating away along with it, I was thinking, what if I was to put enough diesel fuel on top of the water to to make a coating, wouldn't that slow down the evaporation?

Years ago before ecology came into being, we used to put oil on standing water to keep mosquitoes out and it seemed to take forever for it to dry up.
The shear depth of my shallowness is perplexing yet morbidly interesting. Bob 2007

Stan

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Re: Cooling drum evaporation
« Reply #1 on: February 09, 2008, 03:33:49 PM »
Does the antifreeze really evaporate?  I'd take a hygrometer reading and then let it "cook" down aways and then take another hygrometer reading.  I'd think the glycol type antifreeze mixtures will concentrate when the H2O evaporates off.  Don't really know, but the old Science teacher in me says this hypothesis needs a fun type experiment to prove.  ;D  You could do the same experiment in a small pot on the stove indoors if your weather outside is like mine.  Snow, Snow and more Snow.
Stan

dieseldave

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Re: Cooling drum evaporation
« Reply #2 on: February 09, 2008, 06:32:34 PM »

  I have a locally built coal stoker furnace. It has a vent on the top using 1" pipe. Screwed into the top of the pipe is a 1 litre plastic pop bottle. What happens is that the vapours that come out,condense on the inside of the pop bottle and drip back into the expansion tank. The 'boiler' runs at 165 F,so it really isnt a boiler as such. I top up with water 1 time a year,about 1 quart.

   So you would have to put a lid on the cooling drum with a hole at the top for the 'pop bottle condenser'

   What about an oil slick consisting of vegtable oil?

Stan

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Re: Cooling drum evaporation
« Reply #3 on: February 09, 2008, 06:58:12 PM »
The whole point behind "evaporative cooling" is the BTU's lost to the atmosphere due to evaporation. Go to Northern Alberta, get yourself soaking wet and stand outside in a 30 mph wind at -40 deg F to find out about this phenomenon.  Ask me how a supposeidly frozen dugout helped me to find out about this :D  (please people, no long rambling mathematical posts proving you have an old engineering text book).  Doesn't that mean you lose cooling capacity if you prevent evaporation ???
Stan


I know, I know, I made a spelling mistake, now ask me if I care.

« Last Edit: February 09, 2008, 07:02:12 PM by Stan »

Doug

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Re: Cooling drum evaporation
« Reply #4 on: February 10, 2008, 12:50:30 AM »

Yes.....
It's a Good Life, If You Don't Weaken

draganof

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Re: Cooling drum evaporation
« Reply #5 on: February 10, 2008, 01:37:21 AM »
I know this is not a scientific test but I use a radiator on my Changfa 195. The system is not pressurized and I carry some heavy loads so I lose about 1 pint of liquid through evaporation every 8 hours. I run a 50-50 antifreeze mixture and replace the boiled off coolant with pure water. The mixture has remained at -45 degrees protection level for the past 150 hrs. I am very sure only the water is evaporating from the coolant on my system. I do not run a water pump so the coolant boils heavily on high loads.

John
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rbodell

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Re: Cooling drum evaporation
« Reply #6 on: February 10, 2008, 06:35:46 AM »
MMMM lots to think about here, thanks for all the input here.

Draganof:
Evidently the antifreeze does not evaporate as I thought, But Just for funzies, I am going to boil off some on the stove. As Stan says, it would be a fun experiment and I love science.

Dieseldave:
I like that idea with the soda bottle. I do have a top on the drum to keep trash out and I leave the small bung open to relieve any pressure it might build up from expansion. I just went out and opened the big bung and a soda bottle fits just rite. I have to do a little fenegeling so the wind doesn't blow it out, but that should work fine.

Stan:
As for going to Northern Alberta, I have a friend who has the perfect answer to the cold weather up there ... he comes to visit me for the winter. I will take your word for it.

I did consider loosing some cooling by adding oil to the top of the drum, but I usually have plenty to spare. Last summer unless it was over 100 degrees, I didn't worry about it and then it still had a long way to go between 180 and 200 as it heated up so slow. By the time it got over 180, the sun was going down and the tank was in the shade. This year the tank will be in the shade all day long since I built a shed around  Dilbert and the tank is on the north side..

Well, the cat is telling me the dog wants in. Stupid ass dog just stands by the door and whines. The cat goes to the door and howls till I open it for the dog.
The shear depth of my shallowness is perplexing yet morbidly interesting. Bob 2007

oliver90owner

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Re: Cooling drum evaporation
« Reply #7 on: February 10, 2008, 10:27:36 AM »
rbodell,

Ethylene glycol is just a tad toxic.  Has been used illegally, in small quantities, as a sweetener in wine before - with fatal results.  I would take care if you are inhaling it.  Some antifreezes are based on methanol and these do evaporate.  Not much of that type  about these days.  Methanol is also toxic.

Ethlene glycol boils near 250 degrees Celsius.

If you want something that is non-toxic, go for the propanol version - dipropyl glycol - it is used as a food grade chemical and should be used for all heat exchange systems for frost protection, where there is any possibility of contaminated domestic water, should there be a leak any time in the future.

Regards, RAB

rbodell

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Re: Cooling drum evaporation
« Reply #8 on: February 10, 2008, 04:23:44 PM »
rbodell,

Ethylene glycol is just a tad toxic.  Has been used illegally, in small quantities, as a sweetener in wine before - with fatal results.  I would take care if you are inhaling it.  Some antifreezes are based on methanol and these do evaporate.  Not much of that type  about these days.  Methanol is also toxic.

Ethlene glycol boils near 250 degrees Celsius.

If you want something that is non-toxic, go for the propanol version - dipropyl glycol - it is used as a food grade chemical and should be used for all heat exchange systems for frost protection, where there is any possibility of contaminated domestic water, should there be a leak any time in the future.

Regards, RAB

Yeah I pretty well asumed that if for no other reason than I wasn't sure either way.

When I was a kid they said i shouldn't huff gasoline but it didn't hurt me none

hurt me none

hurt me one

Did I tell you that when I was a kid I used to huff ... what was I going to say?
The shear depth of my shallowness is perplexing yet morbidly interesting. Bob 2007

listerdiesel

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Re: Cooling drum evaporation
« Reply #9 on: February 10, 2008, 04:57:37 PM »
As Doug pointed out, if there is no evaporation, then there's no cooling effect, other than warming up the water in the tank to engine temp.

The heat required to evaporate water into steam is many hundreds the amount required to warm water up in the first place, that's why a boiling saucepan will never get above 212 Deg F or 100 Dec C, no matter how much heat you pour into it. The cooling effect is proportional to the amount of water evaporated, and the surface area of the tank open top affects how fast it goes.

Look up "Latent Heat of Evaporation".

Lister's sold more tank-cooled engines than anything else, and that goes for the Petrol engined models as well.

Peter
 

oliver90owner

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Re: Cooling drum evaporation
« Reply #10 on: February 10, 2008, 06:12:18 PM »
 listerdiesel and list,

For those that want to know, it requires 530 times more energy to evaporate a given amount of water than heating that same water by one degree Celsius.  At the other end it requires 80 times the energy to melt ice.

Regards, RAB

Stan

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Re: Cooling drum evaporation
« Reply #11 on: February 10, 2008, 06:17:00 PM »
Pe'ter....That's a standard grade 8 Science experiment, boiling water with a thermometer in it and keeping a graph of the temperatures.  What you have to remember is that at 4000', it is nearly impossible to get the water above 91 deg C due to air pressure gradient.  At the 10,000' level on top of a local mountain,  I once boiled a small pot of water and was able to keep my finger in it for an extended period of time.  It makes lousy coffee and I would guess tea too!
Stan

ronmar

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Re: Cooling drum evaporation
« Reply #12 on: February 11, 2008, 01:57:21 AM »
From what I have calculated from available information, a 55 gallon drum is just adequate for a 6/1 with the top off to allow full evap.  Here is a link to the engineers toll box for heat loss from open tanks both thru walls(with and without insulation) and from evap.  As the temp closes on 210F, the loss thru evap is nearly 10 times that lost thru the tank walls per SQ/IN of surface area.

http://www.engineeringtoolbox.com/heat-loss-open-water-tanks-d_286.html

Wanna conserve coolant, use an adequately sized radiator or heat exchanger with a header tank, which if properly configured, will have virtually no evaporation.  It has a side benefit of requiring far less coolant volume. 

Want to continue to use a drum for cooling?  Then evaporation is an essential evil...

Ron
PS 6/1 - ST-5.

Stan

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Re: Cooling drum evaporation
« Reply #13 on: February 11, 2008, 04:02:07 AM »
The one caveat to using a radiator is that is will cost horse power.  The original lister with radiator (rt click on my avatar)  run by a direct drive fan costs 1/3 hp.  I would imagine (and i'm sure someone with an engineering text book can elaborate ad nauseum) driving an electric fan driven one also costs an approximately similiar amount of hp.  Some of the guys here and on the Lister csog have large radiators sitting on a slant that allows for a free flow of air to pass through for adequate cooling.

I've always been intrigued by somehow diverting with fins, the air moved about by the flywheels to flow through a radiator.  You'd have to do a lot of diverting if you want to keep the water flowing by convection rather than installing another hp stealing water pump.
Stan

rbodell

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Re: Cooling drum evaporation
« Reply #14 on: February 11, 2008, 01:14:19 PM »
ooling.

I've always been intrigued by somehow diverting with fins, the air moved about by the flywheels to flow through a radiator.  You'd have to do a lot of diverting if you want to keep the water flowing by convection rather than installing another hp stealing water pump.
Stan

I was thinking about that too, until I finally gave up on the radiator and went back to the cooling drum. It's pretty hard to inprove on proven technology. When I had the radiator I worried about the fan or the temperature switch not working, I tried a mechanically driven fan for one day and because of the HP involved or worrying about the belt breaking, gave up and went back to the cooling drum. Now if I could just get rid of the thermostat.

Lister had a pretty good system worked out. It seems like every alternative to the original setup is either HP stealing, more costly or more danger of failure. The thermostat is only an improvement for those who run their engine occasionally. If they were never shut off, the thermostat failure would probably over ride what little life expectancy and fuel economy that would be lost by not having it.
The shear depth of my shallowness is perplexing yet morbidly interesting. Bob 2007