Cooling with radiator gone wrong

[Jedon]

Nice! Is that about the right height to mount the radiator? My ST-5 is on the other side so maybe I"ll mount the radiator right in between that and the engine.

[cujet]

That rad mount was a temporary thing that was designed to work for "testing" the engine. I has been like that for years now.

A 6-1 can get away with a really tiny rad if done properly with a fan and pump. I would hesitate to hard mount the rad up high on the engine itself. It might vibrate to death.

In the above pic, the rad vibrates a touch, but the fan vibration is out of control.

[veggie]

cujet,

I'm curently building my 6/1 generator and I too will be going with a pump/radiator system.
I agree that the cooling system can be quite compact due to the relatively small amount of BTU's being rejected by the engine.

2,545 BTU's per HP X 6HP = 12,725 BTU

or

3.5 KW elec. output X 3414 BTU/hr. = 11,949 BTU

So, a radiator sized for 15,000 btu heat rejection should be adequate.
That's a very small radiator. Something in the range of 10" X 10" with a single pass.
(Of course it depends on the amount of air passing over it and the ambient temperature of the air.)
I'm intending to build a super compact radiator type cooling system for two reasons.
1] Space availability
2] In future the rad will be a secondary heat dump used after the primary water heat storage tank is up to temp.

I suspect a small motorcycle radiator (and a very powerful fan) should do nicely.

Cheers,
Veggie

[lowspeedlife]

It seems I remember ome one using a Honda Goldwing motorcycle radiator on thier 6-1 & it supposedly worked well & had a fan attached too.
   Scott R.

[Jedon]

If you have space wouldn't a really large radiator with a smaller or less powerful fan be more efficient?

[veggie]

I think the answer to that question is not so simple.
In the end, I think one is as good as the other provided they have the same BTU transfer rates.
In your case the size of the radiator looks quite adequate.
Did you get a chance to to hook up the fan yet?
Looking forward to the video.  chug....chug.....chug....chug (My poor impression of a Lister at 650 rpm) 

Cheers, Veggie

[BruceM]

My favorite cooling system approach is the inducted draft method, using the exhaust to draw air through a modest sized radiator.

Some duct work but no fan needed.  No extra load on the generator, and useful for guys like me that sometimes run something other than the generator.

I haven't converted my setup to this yet, but I will one day.

Andy Hall posted about this on another forum, quite some time ago. The photo is also his, of the Rumley Oil Pull tractor, which used this cooling method.

[Jedon]

Okay I changed the cooling system around but it's still not working quite right.
I removed the 1" heater hose altogether and moved the radiator close to the engine and not as high.
I put in a 1" iron pipe with a T for the temp gauge and then put a 4" pipe on that in order for it to be higher than the radiator and thus be used to fill the system as well as burp the air.
After it was running for a but I screwed the temp sensor in to prevent water from coming out.
I was getting circulation this time and after it got warm I turned the fan on.
As it got hot it started filling the overflow tank and when it got full I shut it off, this caused the water to boil and spill out of the overflow.

http://picasaweb.google.com/lh/photo/V9ShBTrvkV9KIf79KmQNig?feat=directlink

http://picasaweb.google.com/lh/photo/aAXDDV6e6KqdRugqi8sXNQ?feat=directlink

Any ideas?
Thanks!
-Jedon

[Jedon]

Thanks! Geesh this is all harder than I thought it would be, maybe I can just find a 50g metal drum around here somewhere!  
How would I increase volume? Some kind of reservoir inline on the hot side?

[Ronmar]

Jedon
 It looks like in the pictures your radiator is twisted/rotated to the right/clockwise slightly when looking from the engine toward the radiator.  Or put another way, the end where the upper hose is connected(nearest the camera) is lower than the other end(farthest away from camera).   Is this correct?  Setting this way, your radiator would have a huge air bubble in the top tank, with the only radiator coolant tubes under coolant being along the edge directly below the upper inlet hose connection. If this is the case, you may have only had coolant flow thru perhaps 25-30% of your radiator coolant passages, the ones nearest the camera in your pics.   And those passages are not in front of the fan...

I can't tell where your expansion tank is connected, but it does not appear to be connected to the top of the system.  The expansion tank serves double duty.  It allows the fluid somewhere to go when it expands, but it also allows air to exit the system, and replaces that air with more coolant.   In order to do this, it MUST be connected to the highest point in the cooling system.  In a cooling system air does not flow down thru water...  You can fix this 2 ways.
1.  Find the highest point on the radiator top tank and drill a hole in it.  Epoxy in a small hose barb and connect the line UP to the expansion tank to that new hose barb.  Make sure your hose runs upward from head to upper radiator inlet.  This upward flow will carry the air to the radiator top tank and from there it will flow up to the expansion tank.  This will keep an air pocket from forming in the top of the radiator, and if there is fluid in the expansion tank, the rad must be full.  
2.  Rotate the radiator so the upper radiator inlet is at the highest point.  In the hose where it enters teh radiator put in a T pointing upwards with fittings to connect the expansion tank hose to.  I would also suggest a wider fan that covers more surface area.  Fans are not very good at blowing air thru a radiator.  they are good in conjunction with a shroud at pullijng air thru a radiator, the way most auto applications are configured.

Jens
 His expansion tank is perfect for this application.  So is his coolant volume, as long as his pump is working, Volume dosn't provide any additional cooling.  Cooling is about transfer surface area, and temp difference and flow in the transfer surface areas.  You will need to move the same ammount of water per minute in a given radiator/engine/load setup irregardless of the cooling system capacity.  You only need enough coolant to cover all the heat transfer surfaces, and be able to pump it.    

[Ronmar]

cujet,

I'm curently building my 6/1 generator and I too will be going with a pump/radiator system.
I agree that the cooling system can be quite compact due to the relatively small amount of BTU's being rejected by the engine.

2,545 BTU's per HP X 6HP = 12,725 BTU

or

3.5 KW elec. output X 3414 BTU/hr. = 11,949 BTU

Veggie
  Those are the direct conversion numbers, BTU-HP, KW-BTU ECT...  They are for 100% efficiency, which is not ever possible, and do not account for engine, generator or drive efficiencies. The actual numbers thru the cooling system are significantly higher.

As an example, my 6/1 with a 3KW electric load on the ST-5 generator head delivers pretty close to 17,000 BTU/HR of hot water out of the heat exchanger secondary loop.  There are of course radiant losses from the engine and heat exchanger surfaces, so the engine heat output thru the cooling system under such a load is probably in excess of 18,000 BTU/HR...  I plan on insulating my engine block/cylinder and plumbing and re-measuring the heat numbers, but I just havn't got around to it:)     

[Ronmar]

His tank was overflowing from the expansion of trapped air in the system pushing water out of the system.  Waters thermal expansion coefficient is not very high.  1 gallon heated from 40F to 200F would only become about 1.03 gallons.  That is about 4 OZ per gallon over that temp change, and that would be for pure water. A water-antifreeze mix expands even less.   I use a very similar expansion tank, and it's level varies perhaps 1/2" from 30F to 200F for my 2 gallon system.

Well if you loose colant thru evap and other losses, you will of course no longer have enough in the system:)   Mine has been setting in the shed happilly for close to 2 years now.  I would be hard presses to measure if there has been any level change in the resovoir from fluid loss...

If your system is incapable of dissipating the heat you generate for any reason, extra coolant capacity in the system is only delaying the inevitable and potentially causing a bigger mess to clean up...  That is what level and over temp sensors are there to prevent, because unless you are there to watch it 24/7, the odds of you catching the problem in the act are pretty low...

[veggie]

Ronmar,

17,000 BTU form your 6/1 system sounds a bit high. Here's my thinking:

Of the total heat value present in the fuel only approx. 30% is available for capture from the cooling system.
Assuming a diesel mechanical efficiency of 30%.... (try this with different % values if you wish).

Of the total BTU value of the fuel
30% - Mechanical energy
30% - Heat rejected through the cooling system
30% - Heat rejected through the exhaust system
10% -Other losses (Engine block heat radiation and noise)

So..... if we apply this to a listeroid 6/1 making the full 6HP (4.47 kw)

30% Mechanical = 4.47 kw (6HP)
30% Cooling system rejection = 4.47 kw or 15,250 BTU Max.
30% Exhaust system rejection = 4.47 ks or 15,250 BTU Max

So I would argue that my 6/1 (and yours) running at full load would reject 15,250 BTU's into the coolant.
And under normal conditions (say 80% loaded) the most you would get is 12,200 BTU's.

There is some ambiguity over the exact % of losses through each system for the 6/1 which can open up some debate about the above numbers, but these are the ones I use for my CHP system component sizing.

Cheers,
Veggie

[BruceM]

No mentioned it so I guess I will. 

In the picture, Jedon's temperature sensor is at the top of a riser, the highest point in the whole system.  This seems unlikely to work due to air in the top of the riser. If this is what turns on the fan, this could be part of the problem.

[Ronmar]

I skip the 10%.  I Think those energies can be accounted in the other fields.  A straight 33%, or "rule of thirds" is pretty close to correct, at least in the case of my listeroid genset.  My initial tests delivered 6 pounds of water raised 45 degrees in 1 minute from the secondary loop of the heatexchanger with a 3KW electrical load. That is 270 BTU/MIN or 16,200 BTU/HR.  I did some later tests that were slightly higher, but I cant find those exact numbers and the circumstances of the test. They were however very close to 17,000 BTU/HR, so that is the number I quote now for full load heat output. That is however not quite the full power output of the engine.