Dual Radiators

[Robert Harris]

> > Gentlemen, a question came up on another list about which routing
(paralell
> >  or series) is better for cooling an engine (fuel injected
ofcourse)equiped
> >  with dual radiators. 
> George, I think the answer is this: Makes no difference in regards to
thermal
> properties.  This is why:
> 
> Two smaller radiators in parallel would dissipate 1/2 of the fluid, but
all
> the heat each, down to whatever level.
> 
> Two smaller radiators in series would dissipate 1/2 the heat from all the
> fluid, also bringing it down to whatever level.
> 

2 cents.  The amount of heat rejected to a cooling media is dependent upon
delta temp and the length of time.  

The higher the difference between the product and the cooling media, the
faster the rate of heat rejection. This is not a linear function and
raising the delta significantly raise's the rate of rejection.  Placing two
radiators in series divides the delta temp between them, with the first
doing more of the work than the second because its effective delta temp is
much higher - thus far more efficient.  In series, you do not double the
cooling by adding a second identical radiator because they are working at
different cooling levels. In parallel you do. You also gain by lowering the
coolant velocity and giving entrapped cavitation and steam bubbles more
time to collapse out before being recirculated. At high rpm and load your
coolant is more foamlike than liquid like - not unlike your lube oil.  


If the first ingredient ain't Habanero, then the rest don't matter.
Robert Harris <bob at bobthecomputerguy.com>


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