what size cooling tank

[old bob]

I have a 1940s lister cs 6hp which is used for pumping water and is sometimes hooked up to a small generator in times of power outages, for these purposes the engine is cooled by using a 45 gallon tank, but as I am a member of my local vintage society I now feel compelled to take the engine to local vintage shows, I have no problem lifting the engine onto a 4 wheel trolley but I am unsure what size water tank to take with me for an afternoon on the showfield . In recent years I have seen a variety of different size tanks used, these range from a 9 litre fire extinguisher, a 15 litre air compressor tank and several using either 12k propane gas bottles or the slightly smaller version, obviously I would prefer to take the smallest tank possible for healthy running with no load, if anyone takes their engine to shows I would be interested to know what size tank they use or if anyone has a suggestion please let me know

[Tom]

I think the answer to your question has to do in part with how hard the engine will be working at the show. It would add interest to go on the small side so steam would rise from the tank.

[38ac]

Hi Bob, welcome to the site 

You will have to convert my USA gallons to your liters but here is what I have learned from taking my engines around to shows.  A CS engine that has no loading and running a bit less than working RPMs will run for 2-3 hours before it gets too warm on just a 5 gallon tank. I also had a CS that I used to run a small generator and the loading was just a fan or two on hot days. It would run 5-7 hours on a 15 gallon water tank.  Best thing I did for cooling and for the show was to build a screen cooler. Takes less water than a tank, engine warms up quicker and will run all day without getting hot  and best of all  people are fascinated by it.

[BruceM]

Hey Butch, I always enjoy learning from you posts, thanks!  Do tell, what's a screen cooler? 

[broncodriver99]

Do tell, what's a screen cooler?

Here is an example. It is a form of evaporative cooling.

https://www.youtube.com/watch?v=jCKz1aAcISE

[BruceM]

Interesting.  Much more interesting to watch than a big tank!

[BruceM]

I used a big automotive radiator outside the generator shed with no fan on my 6/1 Listeroid all for about 5 years. it was vertical but oriented so that the prevailing breeze would go through it.  I only got some boiling when it was dead calm in the summer and had long 3/4 load runs.  Now I use the induced draft of the exhaust to pull cooling air through the radiator, and have all but about half a square foot of area of the radiator covered.

The smallest, single row Honda Civic radiator (or whatever you can find that's cheap and small) will do the trick with a couple muffin fans, I think. Ronmar has a nice setup with 3 surplus computer DC muffin fans on two thermostats, I think.

On my neighbor's 8/1 propane conversion, we use an 8 foot tall, 14" diameter pipe with wind turbine, and a 3 row, aluminum Honda Civic radiator above the engine with just convection flow.  The combination works fine with even the slightest breeze or lower loads if still.  A auto radiator fan on a thermostat is used for for backup.  It's only been on a few times in 1000 hrs of running.

[LowGear]

OK;  This is just dreaming but;

How about a tub at the base of the engine and setting up a faucet near the upper water connection and just letting the water fall into the tub instead of running it over the screens.  The cooling effect on the screens is really neat but just water running into one of those old copper water tubs that are oblong would be quite an effect.  It's a show.

Casey

Oh wow;  How about one of those nozzles that put a hollow in the stream?

[Hugh Conway]

Nice ideas here for a show machine!
The two here are workers and even then they do not heat water all that fast.
Used a 30 gallon tank for the listeroid and in 2 hours of running under heavy load, the top of the tank got warm. I changed over to an old house radiator (9 or 10 fin) It works well for a hard 2 hour run. The other engine (Dursley) uses an old galvanized milk can of about 15 gallons. That one is about right for the same run time and load. With the top removed, the large surface area can help dissipate heat if necessary on longer runs. Looks cool too! Both use thermosyphon. I am in a fairly moderate climate on the Northwest Pacific coast, so no really running hot days.
The fountain idea for shows sounds fun and could provide a bit of spectator cooling if they're downwind.
Cheers,
Hugh

[ronmar]

The ammount of cooling you need has a direct corrolation to the ammount of fuel you burn.  At idle, not much fuel, not much cooling.  Any load and both these numbers go up.  Basically you need to dissipate about 1/3 the ammount of the BTU content of the fuel burnt. 

An open tank cooler heat dissipation is completely dominated by evaporation.  As an example in 60F still air with 210F coolant the surface area of the water will shed around 3240 BTU per SQ/FT while the tank side will only loose around 360 BTU per SQ/FT.  In 80F still air the evap number drops to around 2700-2800 BTU per SQ/FT.  You could dissipate all the heat you need from a large surface area low volume pan.  The screen cooler is a wonderfull example of this.  The drawback is that it might be a little tricky to get a low volume pan to thermosiphon, so you may need a pump.

My 6/1 at full load(a little over 3KW on the generator) needs to dissipate around 18,000 BTU/HR.  In 80F air, a 6.5SQ/FT pan should be able to handle it.  1/2 load 3.2SQ/FT, 1/3 load 2 SQ/FT ECT...       

[old bob]

thanks for the replies everyone, it started to get really interesting with the later posts, the idea of using a screen of some sort appeals but at the moment I think I will settle for a 13 gallon (UK) drum as  I will probably hook up something for the shows that does not require full load, my next search is to find a good product to coat the inside of the old oil drum, as it is only made from mild steel the dreaded rust will start to take effect quite quickly, here in the UK there are several paint like products on the market but no one seems to have any great confidence in any of them, maybe it is my age or maybe it is just poor companies selling sub standard products, forty years ago you could buy stuff from a hardware store and it always did what it said on the tin!

[mikenash]

Y'know Bob, heaps of folks just use a cut-down copper hot water cylinder inner.  Never rust; polish up nice if you like that kind of look, easy to put fittings into etc

[dieselgman]

It is really the phase change that accounts for the extra energy dissipation... when a substance goes from solid to liquid, and from liquid to gas, (or vice versa) the energy change is not linear but rather takes a big jump at each change in phase. The evaporative cooling systems are moving the coolant from liquid to gas - thus the large energy transfer.

dieselgman

[dieselgman]

I remember traveling in India and many of the 500-year-old + palace grounds and residences were constructed with evaporative water "walls" for the purpose of air-conditioning. At a time when there was no technology, they knew the finer arts of making a hot climate bearable with some basic physics. Of course, they had to have many servants doing the hard manual work of transporting water from reservoir to elevated cisterns, but the rest of those systems were durable and permanent as the rest of the stone those palaces were constructed from.

dieselgman

[BruceM]

I've likewise been impressed at some of the techniques for motorless evaporative/thermosiphon cooling used in Persia and other desert climes.  I'm toying with the idea of adapting them for a solar greenhouse. If evaporative cooling pads or spray is used at the top of a 20 foot tower, with large opening (4x4), for example,  5000CFM of cooled air can achieved without a fan motor. The ancient Iranian use of tower cuppolas with wind flaps to either pressurize or evacuate air with wind power alone is also impressive.