Engine Cooling Water Tank Sizing

[High Gear]

Re: Water Wetter...

We used it in the Arrow MC Streamliner both in the pressurized system, 24psi cap (engine and heat exchanger) .4gal.

And in the open (unpressurized) reserve coolant tank, 7.5gal.

(1) to inhibit corrosion, stainless tank, alloy heat exchanger & engine, steel clamps, etc.

(2) it raises the boiling point of water a few degrees.

We warmed the engine to approx 170deg prior to a run using a bypass thermostat system (credit to Rick Byrnes).

At the end of a 5 mile run the engine coolant temp was usualy around 220deg. and the reserve tank was too hot to touch, but the coolant was not boiling.

This with 200hp.

Good stuff in my opinion

[DanCarlo2009]

            You don't see on the instruction?


_________________
Scum suckin bot

[Dr Goggles]

Fiddle-sticks!!!!! darn instruction ,!!!!  of course! I no see on......how silly of me ............


Now,is it just me or do I smell a web crawler program that found "COOLING" , and came up with this?..........


a pox on your refrigerated water cooler I say

[Interested Observer]

In reviewing some of the foregoing calculations that followed from the information provided by Harold Bettes, there appears to be confusion arising from a slight misstatement of one of the formulas and the units of measurement required.  In hopes of clarifying this, they are restated below with a little more explanation of what they represent and the units required.

The first formula basically calculates the flow rate required to achieve a given temperature rise given a stated energy input.  That is, what flow rate is needed to keep the water temperature within desired bounds while going through an engine that is rejecting heat to the coolant at a particular rate. 

GPM = 5.089*(Hp)/((c)*(To - Ti))    where:

   GPM = gallons per minute
   5.089 = (42.44 Btu/min)/(8.34 lb/gal (for water))  conversion factor for units
   Hp = horsepower put into the coolant,  about 1/3 of the engine’s flywheel horsepower
   c = specific heat of the coolant (Btu/lb-F)  = 1.0 for water
   To = temperature of outflow (degrees F)
   Ti = temperature of the inflow (degrees F)

Using this to recalculate the example situation from before, (HP = 200, To=180, Ti=100) it is found that the flowrate is 12.72 GPM.  This is much more reasonable than the 106 result from before, as the 106 was not gpm, but lb/minute of water.

The second formula determines what volume of fluid is needed to keep its temperature rise within the desired limits given exposure to a heat input for a period of time.  How big does the reservoir need to be?

V = 5.089*(Hp)*t/((c)* (To - Ti))    where variables are as identified above and t is the time of exposure in minutes and V is volume in gallons.

   -or, if the variable quantities remain the same as the first formula, (and rather intuitively):

V = GPM*t

Again, using the example with t = 3 minutes, the volume is found to be 38.16 gallons, which agrees with the previously determined result.  Interestingly, this method effectively assumes that the reservoir volume is only circulated through the engine once, that no mixing occurs in the reservoir, and that no heat is lost out of the system piping or tank.

[panic]

..

[donpearsall]

I have run my water tank (no radiator) on my bike for two seasons now. I am pleased with how well it works and does not overheat even when running the full 5 mile course using about 300 hp. My tank is about 9 gallons and has a pressurized cap. When the run starts, the thermostat is probably just beginning to open due to idling and at the end of the run (about 3 minutes) the temp at the top of the tank is about 200 and 180 at the bottom (where it flows back to the engine).

There is a lot of air cooling going on, I am sure, so the formulas do not apply verbatim. Just thought I would chime in with some real world results.
Don

[panic]

I knew this was a mistake, and did it anyway.

[Interested Observer]

The use of absolute temperatures to the fourth power pertains only to radiant heat transfer, not conductive.

Panic’s points 4,5, and 6 are generally correct and as Harold stated in the beginning, the method he proposed is an easy to use approximation of the actual heat transfer problem, intended to get into the right ballpark on water volume, and is not a definitive analysis.  However, it does a pretty good job, as witness the correlation with actual as-used results of a number of lsr practitioners.

[jl222]

 
  Running loaded on the chassis dyno and putting out 2300 rear wheel hp it doesnt take the long to boil water in our 28 gal tank [ not full ] but at Bville where we can't apply full throttle untll in high gear and our last run that
ended after 3 miles at 294 mph we had no overheating problem and never have had a heating problem.
  Blown gas is the worse for heat, roots blowers more than others  [centrifugal for us] and alcohol runs much cooler.

  Using 880 hp and 1.5 min in the volume equation, the # is 84 gal, that might be right for the dyno but overkill for Bville. We use about 20 gals.

                   JL222
 

[WZ JUNK]

We did a test to see how much water would flow through the engine with our water pump in the time that the engine would run during a pass at Bonneville.  I made the water tank so that it would hold more water than we could pump through the engine in one pass on the course.  We kept a supply of water in our pits and we changed out the water if we wanted to make another pass.  I think it was a little over 30 gallons of water.  400 cubic inch, 871 blown engine on gasoline.  Actually I over estimated the amount needed as in the test we did not allow for the thermostat opening and closing.  I thought it was best to error on the safe side and the extra water was just ballast anyway.

John 

[saltfever]

The use of absolute temperatures to the fourth power pertains only to radiant heat transfer, not conductive.

Panic’s points 4,5, and 6 are generally correct and as Harold stated in the beginning, the method he proposed is an easy to use approximation of the actual heat transfer problem, intended to get into the right ballpark on water volume, and is not a definitive analysis.  However, it does a pretty good job, as witness the correlation with actual as-used results of a number of lsr practitioners.

Well I'll never know what his points of view were because he erased them faster than a speeding bullet. This is a good thread. I wish he wouldn't do that.    Why not give us the benefit of all points of view? 

IO thanks for spelling out the values of the constant. It is rare that anyone will be so considerate, or perhaps they don't know how the constant was derived. Anyway, it is great to spell out the argument because sometimes curious minds want to know more than the quick result.

[Interested Observer]

To assuage Saltfever’s sense of loss....

Panic’s points dealt with a more detailed  description of the cooling system operation.   One was that a given coolant flowrate would probably only be “correct” at one point during a run.  It would likely be excessive during the early part-throttle operation and then later somewhat deficient for extended full-throttle running.  Secondly, the mixing of hot returns in the reservoir could raise the reservoir water temperature some, making the absorbtion of heat from the engine less efficient.  And thirdly, made a case for using ice in the reservoir due not only to its low temperature but the latent heat of formation of ice which adds to the heat capacity available.

[Mr411Fan]

For anyone who's interested, there is an interesting article in the latest  Air Classics magazine Vol 46 number 12 pages 44,45 by Bruce Lockwood on cooling related to Reno air race unlimited aircraft.

[saltfever]

I.O.: Thank you for sharing what was erased by Panic. All good points and worth considering during the "design phase".

[Caveman]

I have run my water tank (no radiator) on my bike for two seasons now. I am pleased with how well it works and does not overheat even when running the full 5 mile course using about 300 hp. My tank is about 9 gallons and has a pressurized cap. When the run starts, the thermostat is probably just beginning to open due to idling and at the end of the run (about 3 minutes) the temp at the top of the tank is about 200 and 180 at the bottom (where it flows back to the engine).

There is a lot of air cooling going on, I am sure, so the formulas do not apply verbatim. Just thought I would chime in with some real world results.
Don

9 gal?!
Where does the tank FIT?   Under the motor?  or is it shaped like an amoeba?