Cooling of engine

[Ove]

Hi...
I am looking for a formula to calculate how much pipe I will need to remove a certain amount of KW in an outboard cooler.
Known data is how many KW I need to cool.
The water temperature.
Water flow in the cooling pipes.
Dimension of cooling pipes (outer diam. and wall thickness) and I nee dto calculate how many meter of a given pipe I will need to cool the given effect.

Can somebody help me with a formula for this ?

Thanks.....

[TeddyDiver]

A quote from old thread..

Originally posted by Apex1

Make it easier Teddy (and safer),

as I said before, 100hp require 2m² in Alu, 6m² in steel, and that is what the engine manufacturers tell us (the industry).

A optimized flow* of the coolant, or tubes make a better result than a flat panel, of course.
*entrance of coolant is always at the aft end, forcing the fliud to flow against the seawater flow.
But both rules of thumb (Gerrs and ours) are worth nothing, when the area is calculated to the minimum, and one runs the engine for hours in warm waters at anchor.
Barnacles and marine growth do their part to make a minimal setup insufficient.
So, that should be done with a nice safety margin. Hence my larger figures.
And Gerrs "under 8kn" is a fault. It should be better saying at 8kn, because under 8 you slowly (pun intended) run into the insufficient range.

Regards
Richard

A quote in a quote in a quote...
and the original thread in case you might enjoy how to bend it so to speek..
kool keel diesel engine

[Ove]

Thanks, but I was more looking after a way to calculate the heat transmission in a keel cooler. I also have a number of experience figures but I wish to calculate it with the real figures of heat needed to be cooled, water temperature, waterflow, dimension of pipes, wall thickness etc.

If any one can help me I would be grateful....
Regards
Ove

[MikeJohns]

Have a look here


Keel cooling

converting from fresh water cooling to keel cooling

[CDK]

Ove, there is no formula because there are too many variables.
What you want to know is the thermal efficiency, expressed as delta t/ kW, for a heavily painted, barnacle festered keel cooler in a motionless sea. I'm afraid nobody can tell you that.

But you could use TeddyDiver's data as a starting point. 6 m2 for 100 hp translates to 0.08 m2 for 1 kW. That is approx. 1 meter of 1 inch steel pipe for every kW of the engine rating.

[pistnbroke]

and why would you want to do this on an outboard? if its that nasty impeller you dont like why not an external pump ? I can see how you can get the water into the outboard but how are you to stop it mixing with the exhaust ?

[Mr Efficiency]

Originally Posted by pistnbroke

and why would you want to do this on an outboard? if its that nasty impeller you dont like why not an external pump ? I can see how you can get the water into the outboard but how are you to stop it mixing with the exhaust ?

I think he means outboard as in 'external', not an outboard motor.

[pistnbroke]

Yes I miss read it ..its the cooler that is outboard not an outboard cooler Dooh .....