"Schertz, William W." wrote:

Paul, this was an interesting paper. I think Figure 17 (attached) is

very

relevant, it shows the effect of coolant properties.  Pure water  is of
course the best, but one should strive for as low an ethylene glycol
concentration as is compatible with the freezing point you expect.

Example:
At 180 F coolant temperature;
38% glycol requires a flow rate of 1.5 times that of pure water,
70% glycol requires a flow rate of 2.25 times that of pure water,
97% glycol requires a flow rate of 3.3 times that of water,

just to keep the same temperature difference between the gas side temp

and

the coolant (in other words to keep the cylinder head the same

temperature).

Figures 13-16 all show that increased flow has a direct effect on the
cylinder or head temperature.  Another reason you don't want to cut down

the

flow rate through the engine.

Bill Schertz

I knew you would find that one interesting Bill. Thanks for downloading
it and reviewing it.

Paul Lamar

>From working with the heat transfer guys on rocket engines, the bottom
line is velocity, velocity, velocity. These things have heat flux values
measured in BTU's per square inch seconds. The SSME (shuttle)
engine is over 90 BTU/in sq sec - with hydrogen (the worlds best
coolant screaming along the backside copper at .06 thick is starting
to melt on the surface. Vance J

 
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