Cooling drum evaporation

[mike90045]

What would happen with a "closed top drum" with a "plastic soda bottle vapor recovery system" under moderate conditions, with anti-freeze?  The boiling point has been raised to 240F - from the antifreeze.  That implies more heat radiated from the tank walls.

Can the O rings take the extra 30F ? rise? 

 Will a "slow boil" in the water jacket provide enough cooling, or will the soda bottle melt into goo  ?

I can't see even a 24/2 getting an entire 55gal drum to a rolling boil, just the water jacket, and then cooler water flows in from the tank.

[Stan]

Bob, I'm not worried about a broken belt causing undue problems with a Lister.  The belt drive mechanism itself is very skukum (sp??) and the belt isn't under a great deal of stress, much less tension than a generator drive belt.  If it does break, the water circulation continues, and the engine automatically becomes a reservoir based system and will sit and boil merrily away for hours.  There's lots of water in the large reservoir built into the top of the of the rad, which isn't under any pressure at all,  so I don't think it will be a problem.

It's not like we live in a tropical climate (he said as he just finished shovelling yet another dump of snow). 
Stan

[listerdiesel]

Lister did produce an early high-speed J type petrol engine with fan blades cast into the flywheel. This was for a generating set and the speed was higher than normal, I think it was called a JL, but I#d have to go read an article to be sure.

Peter

[rbodell]

Bob, I'm not worried about a broken belt causing undue problems with a Lister.  The belt drive mechanism itself is very skukum (sp??) and the belt isn't under a great deal of stress, much less tension than a generator drive belt.  If it does break, the water circulation continues, and the engine automatically becomes a reservoir based system and will sit and boil merrily away for hours.  There's lots of water in the large reservoir built into the top of the of the rad, which isn't under any pressure at all,  so I don't think it will be a problem.

It's not like we live in a tropical climate (he said as he just finished shovelling yet another dump of snow). 
Stan

I wasn't using a lister radiator. In fact the one I was using had very little room in the top. I did have a gravity feed refill line with a 5 gallon supply to take care of any leakage.

All that aside, I have a tendency to worry about the little things. I know I shouldn't, but I still do. That is why I sometime overdo things. I guess that is a good thing anyhow.


I would probably loose it if I found my drum in a rolling boil LOL.

[Stan]

You'd have to be worried about all that black smoke from your exhaust from all that hard work if you found your 6/1 was  bringing 45 gallons of water to a rolling boil 
Stan

Have a look at this little engine bubbling away!

http://www.youtube.com/watch?v=7GBoGAs0FQg&feature=PlayList&p=993BD6D4E9BE0043&index=0

[lendusaquid]

Rig something up over the tank to condense the steam and allow it to drop back into the tank.Something with lots of fins.It wont catch everything but will slow down the water loss abit. As for oil on top of the water,i boiled up a filter bag to clean it the other day and had a layer of oil on the surface.When i moved some of the oil out of the way i got a face full of steam.That oil was a very effective insulator.

[ronmar]

Rig something up over the tank to condense the steam and allow it to drop back into the tank.Something with lots of fins.It wont catch everything but will slow down the water loss abit. As for oil on top of the water,i boiled up a filter bag to clean it the other day and had a layer of oil on the surface.When i moved some of the oil out of the way i got a face full of steam.That oil was a very effective insulator.

LOTS of fins...  A 55 gallon drum lid is 22" in diameter and has about 380 SQ/IN of surface area.  At 200 plus degrees, the evap carries away 8-10 times more heat than that same 380SQ/IN radiates.  If you inhibit the evap, you need to replace it with the equivalent radiant surface area or 380 X 8 or 10 = 3040-3800 SQ/IN...  If you don't put enough surface area into whatever you cover the drum with, the vapor will not re-condense(without forced air circulation) as the surface will be heat saturated because it is receiving far more energy than it can radiate.

The soda bottle over the lid mentioned earlier is a "heat pipe" which is a very effective thermal transfer device.  The vapor rises up the pipe away from the source, just like in thermosiphon and transfers it's energy to the skin and recondenses the vapor into liquid which runs down the wall of the pipe.  They use these on the Alaskan pipeline(with Amonia) to keep the tundra frozen beneath the heated pipeline.  The new type vacume and glass tube solar collectors also use this principal to transfer heat collected to the water circulated in the header pipe.  Water doesn't actually flow down into each collector tube.  They use a dry socket with a heat sync compound which allows a single tube to be removed and replaced without having to drain the system.

A 2" diameter pipe 50" long has 314 SQ/IN of surface area not including the end cap.  11 of these pipes would equal the surface area on top of a drum + the 8x multiple to make up for the loss of evaporation.  A 22" drum lid could easilly support 12-15, even 20 2" tubes spaced evenly around the top to act as heat pipes and still leave a good portion of the original 380 SQ/IN of drum top surface area,  which you aren't really loosing as it is equaled by the top caps on the 2" tubes.  This would transfer/remove the heat from the drum thru evaporation, but recycle the water back into the drum.  You have an expansion tank plummed into the system below the water level of the drum to allow for expansion, but not allow any vapor to escape.  This tank would also allow you to monitor the level in the drum without removing the lid.  Of course your cooler is now nearly 7' tall, but it will have the same equivelent dissipation capacity as a 55 gallon drum with the lid removed for evap... Would kinda look like this only with twice as many longer tubes on top.

  
  

Ron

[Stan]

And the Atomic Energy commission would be after you to apply for a permit to operate it 
Stan

[dpollo]

How about an expansion tank up on the roof, or in an attic space if freezing is a problem. The  altitude of the water in the partially filled expansion tank and the pipe leading up to it would pressurize the system slightly...  if it is six feet up... that would be roughly 3 lbs..... which raises the boiling point at engine level.  The upper part of the expansion tank would condense any vapour that collects there and an overflow pipe can be run outside.  The hot water heating system in our old farmhouse uses this sort of expansion system and it is rarely necessary to add water. The tank itself is a 22 gallon range boiler standing upright in the attic. It has been up there at least 60 years.  The system is topped up by running water in through a manual valve from the domestic supply at the boiler drain until the overflow at the top of the expansion tank lets the excess water out. Simple. I think it would serve an engine cooling system well, but it might be necessary for the lower cooling tank to be slightly more substantial than a fuel drum.

[ronmar]

How about an expansion tank up on the roof, or in an attic space if freezing is a problem. The  altitude of the water in the partially filled expansion tank and the pipe leading up to it would pressurize the system slightly...  if it is six feet up... that would be roughly 3 lbs..... which raises the boiling point at engine level.  The upper part of the expansion tank would condense any vapour that collects there and an overflow pipe can be run outside.  The hot water heating system in our old farmhouse uses this sort of expansion system and it is rarely necessary to add water. The tank itself is a 22 gallon range boiler standing upright in the attic. It has been up there at least 60 years.  The system is topped up by running water in through a manual valve from the domestic supply at the boiler drain until the overflow at the top of the expansion tank lets the excess water out. Simple. I think it would serve an engine cooling system well, but it might be necessary for the lower cooling tank to be slightly more substantial than a fuel drum.

I don't inderstand how an expansion tank up high would help.  With proper radiating surface, only a small expansion tank is needed and that just because of the huge difference between running temp and shut off temp.  You don't need to resist boiling, as with enough surface area(or enough evaporation), to dissipate the heat being added by the engine, the coolant will never boil... 

Where does the heat in this heating system you described go?  Are there radiators around the house to distribute the heat?  My guess as to the reason you don't need to add water is that the water is kept below boiling as the heat is drawn off in the radiators.  The system also maintains a realitively static temperature as heat is taken out thru the radiators, as fast as it is put in?  Probably the only reason it needs an expansion tank is to accomidate the differences between run and shutdown volumes. 

Ron

[Stan]

Dp....watch out trying to up the pressure in a Lister(oid).  Some on here have tried it and found out they leak!  Head gaskets too, even.  They weren't designed for a pressurized heating system.
Stan

[dpollo]

My thoughts on the elevated expansion tank were to slightly pressurize the system without actually closing it and to provide a cold surface to recapture evaporated cooling water.  As Stan points out, pressurization may not be a good idea, and of course evaporated coolant can be recaptured by other means.

The heating system I described is a marvel of thermo-siphon simplicity with a wood fired boiler and radiators in the rooms above. It does occasionally boil if the fire is not damped . Having sufficient radiation of any type is essential in any heating  or engine cooling system but the advantage of (passively) recapturing water results in less corrosion as the water frees itself of contaminants and dissolved air.

[ronmar]

Having sufficient radiation of any type is essential in any heating  or engine cooling system but the advantage of (passively) recapturing water results in less corrosion as the water frees itself of contaminants and dissolved air.

Exactly, and that is the problem that Bob originally posted about.  The use of, I am assuming, a 55 gallon drum, dosn't have enough surface area to dissipate the heat from a 6/1 at full load with the lid closed.  It needs evap, or more surface area and increased internal circulation efficiency(keeps the hottest fluid against the coolest surface) to be a closed system.  A farm of heat pipes on top would I believe passively accomplish this and cut evap water losses to basically nothing.  Each 2" X 50" pipe would add 318 SQ/IN to the radiation surface.  A 55 gallon drum top has about 380 SQ/IN of surface.  So adding twenty 2X50 pipes would be like adding 16 drum lids of additional surface area to which the hottest vapor would rise into and transfer it's heat to... 

Ron 

[dpollo]

Thanks, Ron, your comments on this subject and the area numbers should help members set up a system which will work. Someone once said, "Simplicity is the hallmark of good engineering".   I think that can be applied here.

 I'm kind of glad at the moment that my Lister is air cooled, I believe water cooled designs are superior but therein lies a whole new set of challenges.   dp

[oliver90owner]

Sorry, but it beats me to fathom why a bog standard ball valve on a water supply could not be used to replenish evaporation losses if you are that worried about it.

Regards, RAB