Cooling system specifications

[manta22]

Harold & Hotrod;

Try re-doing the calculation based on a total loss (boil-off) system.

Regards, Neil  Tucson, AZ

[hotrod]

At normal temperatures and pressures it takes one BTU of heat energy to raise one pound of water 1 degree F.
That gives us 8.34 BTU per degree temperature rise per gallon of water in the cooling system.

If you boil water the phase transition from liquid water to steam is very energy expensive requiring 970 BTU per pound to convert liquid water to steam.
That means if you allow 1 gallon of water to boil off during the run, you will dump 970 x 8.34 = 8089.8 BTU as steam

That is the equivalent of raising 20 gallons of water (166.8 lbs) 48.5 degree F.
(boiling water to steam uses 970 x as much energy as raising that same amount of water 1 degree F)

That is one of the advantages of the radiator in a box systems. If you have a pressurized loop going through the engine, but the water in the box is at atmospheric pressure and can vent steam when it reaches the boiling point, you can use this to your advantage.

If some water can boil off, you have a huge energy reserve at the boiling point of fresh water (204 deg F at bonneville) where as long as there is enough water in the box to cover the pressurized loop radiator (so it can dump heat to the unpressurized loop) it will cap the temperature rise at the boiling point of water as that unpressurized water boils off.

You can see this effect in use at NASCAR where they have the blow off vent from their pressurized cooling systems that allow it to blow off steam at high temperatures. This gives them perhaps one or two extra laps before they kill the engine if they have a cooling problem due to debris blocking the radiator or some other over heat problem.

[manta22]

Thanks, Hotrod. I just wanted everyone to see the advantage of a boil- off cooling system over a conventional one.

Regards, Neil  Tucson, AZ

[tauruck]

You lost me at Technical Discussion>.

[Hot Rod Lincoln]

You lost me at Technical Discussion>.

You too ?     

I'm going have to sit down and run the numbers on our current system.


Jon

[Rex Schimmer]

At normal temperatures and pressures it takes one BTU of heat energy to raise one pound of water 1 degree F.
That gives us 8.34 BTU per degree temperature rise per gallon of water in the cooling system.

If you boil water the phase transition from liquid water to steam is very energy expensive requiring 970 BTU per pound to convert liquid water to steam.
That means if you allow 1 gallon of water to boil off during the run, you will dump 970 x 8.34 = 8089.8 BTU as steam

That is the equivalent of raising 20 gallons of water (166.8 lbs) 48.5 degree F.
(boiling water to steam uses 970 x as much energy as raising that same amount of water 1 degree F)

That is one of the advantages of the radiator in a box systems. If you have a pressurized loop going through the engine, but the water in the box is at atmospheric pressure and can vent steam when it reaches the boiling point, you can use this to your advantage.

If some water can boil off, you have a huge energy reserve at the boiling point of fresh water (204 deg F at bonneville) where as long as there is enough water in the box to cover the pressurized loop radiator (so it can dump heat to the unpressurized loop) it will cap the temperature rise at the boiling point of water as that unpressurized water boils off.

You can see this effect in use at NASCAR where they have the blow off vent from their pressurized cooling systems that allow it to blow off steam at high temperatures. This gives them perhaps one or two extra laps before they kill the engine if they have a cooling problem due to debris blocking the radiator or some other over heat problem.

One comment about Hot Rods thinking, if you are boiling the "box" water in a "radiator in a box" system then the water temp in the radiator has to be quite a bit above the local boiling temp as it is the temperature differential between the radiator water and the box water that transfers the heat. I personally don't like seeing engine water temps at sustained temperatures above 190 deg F much less the 240 to 250 deg F it would probably take to boil the box water I would much prefer making the "box" or reservoir water temp to be at 32 degrees with lots of ice and use a good three way thermostat to control engine temp. It takes about 145 btu/lb to convert ice to water, certainly a lot less than water to steam but much easier on engines and to live with IMO.

Rex

[tauruck]

Rex your explanation is one a layman like myself can grasp.
The one point that interests me is the three way thermostat.
My motor of choice is a pretty obscure one. Ford 351C and people over here
have bad mouthed them for years. The problem is related to overheating.
Thermostats in the Ford parts bin here in SA show the same part # for 302, 351C and 351W
but the 351C has a water bypass and the correct thermostat is unique to that motor.
The other Ford units don't block off the bypass.
Finding a three way thermostat for a Cleveland might be a problem.
Can you please elaborate?. My understanding of thermostats is that the wax melts at a set temp and
it opens etc. I've never heard of a three way thermostat but it is very important for me to get schooled.
Sorry if I jacked this thread but I think we can learn a lot here.

[Ron Gibson]

I'll check to be sure, but I think the Ford 351/400 M's had by-pass or three-way thermostats. There was a hole in the block under the thermostat for re-circulation that was closed when the stat was fully open.

Ron

[John Burk]

All engines with thermostats I know of have a passive bypass circuit . Otherwise hot water would never flow past the thermostat to open it  . Even when the thermostat is open a small % returns directly to the pump inlet .

[Harold Bettes]

Thanks Rex for your comments,

When I first tossed out some easy ways to calculate the problem solution, the initial purpose was to keep it simple and A) Rate of flow and B) Water mass required seemed to be the best way to analyze the problem. This was done not to oversimplify, but to keep it simple yet have good solutions at hand.

Although one can use a radiator in a box as one solution, it has its own inherent problems. It is quite often better to keep things as simple as possible. Fewer parts makes for fewere nooks where problems can arise.

Mr. Tauruck, Yes, yess, yesss (my best imitation of a South African accent):
I agree with Rex for a number of reasons. Way up on the hit parade of problems with cooling systems is to carry heat away from the backside of the combustion chamber as it is an easy way to keep some control of inducing detonation (rattling the engine). That should be the driving thought process of an engine cooling system. I would encourage you to simlify the dependence on complex thermostats, but that is yet another level of system analysis.

In short (after the previous rant), I strongly support the philosophy that complex is arrogant and simple is elegant.

Best Regards to All that like this kind of stuff,
HB2

[Hot Rod Lincoln]

Rex your explanation is one a layman like myself can grasp.
The one point that interests me is the three way thermostat.
My motor of choice is a pretty obscure one. Ford 351C and people over here
have bad mouthed them for years. The problem is related to overheating.
Thermostats in the Ford parts bin here in SA show the same part # for 302, 351C and 351W
but the 351C has a water bypass and the correct thermostat is unique to that motor.
The other Ford units don't block off the bypass.
Finding a three way thermostat for a Cleveland might be a problem.
Can you please elaborate?. My understanding of thermostats is that the wax melts at a set temp and
it opens etc. I've never heard of a three way thermostat but it is very important for me to get schooled.
Sorry if I jacked this thread but I think we can learn a lot here.

Something you just might have to order a couple from the States or have someone ship you a couple:

[Rex Schimmer]

I have used the 77-83 3 series BMW thermostat, about $15.00. On a high flow system you need to run two of them in parallel. They are line mounted and I think the three connections are 25-30 mm dia. Again I got on to these from Stu Van Dyne at Van Dyne Engineering, he uses them on engines that he adapts his Offy water pump to. You can find them on the internet just Google 77-83 3 series BMW thermostat.

Almost all two way thermostats have a small hole drilled in them to let some water circulate but that water goes to the radiator (or water tank) and then back to the water pump, the 3 way style blocks flow to the cooling system and recirculates full water pump volume through the engine until it opens. It then closes off the circuit that recirculates through the engine when the set temp is reached and runs the water to the radiator (or water tank).

Rex

[Paolo Castellano]

I think that you are missing something in Harold's equations. The delta T (the difference between the water temperatures) is the difference between the water temp going into the engine and the temp of the water coming out of the engine. Not the temp of the total water in the system. If you look at it this way then you get very different numbers. Using the example of the 400 hp engine with 132hp going to heat you probably really only wanting a delta T of say 15 degrees which would mean a flow rate of around 45 gpm,which goes along with the rule of thumb that you should have 10 gpm of water flow per 100 horse power(this is per my good friend Stewart Van Dyne, Van Dyne Engineering). You need high flows to maintain turbulent water flow through the engine for maximum cooling efficiency and if you are using a radiator you definitely want high flow rates to maintain turbulent flow.
Rex

Hello all, I have been absorbing what I can from various threads on many topics.... It has been very informative and made me think of a lot of things I would have never considered.

How does this 10 gal/min/100Hp work with higher HP engines making 1500-2500 HP?

Do streamliners making 1500-2500 HP have/need 150-250 gal/minute belt driven water pumps? With a 250 gal/min water pump, a 25 gallon tank of water would go through the motor every 6 seconds??? Seems like overkill.

I do understand the big power cars are not running full power until later in the run, but what do these vehicles do for proper cooling?

I am not grasping the exact flow path for the radiator in a box setup as opposed to running the stock front cover driven water pump maintaining the usual cooling system pressure supplemented by say a 30 gallon water tank for additional heat sink capacity.

Does anybody have any idea of a range of how much an OEM water pump flows?

Thanks and best regards, Paolo

[RichFox]

The streamliner I have most recently observed has a billet block and no water in it. Burns alcohol with plenty of boost. Seems OK.

[Sumner]

....I do understand the big power cars are not running full power until later in the run, but what do these vehicles do for proper cooling?...

Also once they are full power they are covering a mile in 8 sec and as Rich pointed out possibly running a fuel that also cools vs. gas.

....I am not grasping the exact flow path for the radiator in a box setup as opposed to running the stock front cover driven water pump maintaining the usual cooling system pressure supplemented by say a 30 gallon water tank for additional heat sink capacity...

Are you asking how to set the flow path up in a rad-in-a-box situation or why do it or both?  One reason to do it that I like is you can warm the motor and the water in the radiator but keep all the water in the main tank cool and turn that on at the start or during the run.

I don't think there is 'one' rad-in-a-box setup as some have the radiator in the main tank.  For our use I personally don't like that as then again you are warming your main cooling water while warming up the motor. 

As for the flow in our case I mimicked (pretty much copied what I had learned from Sparky) and used a ....



.... 2 pass radiator that is connected to the motor normally but the cooling water enters the ...



... box on the bottom and flows through the bottom half of the radiator, up the other side and back through the top of the radiator and then back to the main tank.  Lots more on it here....

http://purplesagetradingpost.com/sumner/Hooley%202013/13%20-%20construction%20menu.html

Sumner