John,
Optimum with respect to what? With respect to heat dissipation by the
radiator to the ambient, a delta T of zero degrees is best, but the
difference between zero and ten degrees is negligible (ca. 5%) and the
extra energy consumed by the water pump to reduce the delta T below ten
degrees would begin to eat up the gain in heat dissipation. If Chris
improves the air flow and that produces a twenty degree temperature drop,
the heat dissipation will be doubled. If the temperature difference between
the radiator and ambient is 100 degrees, then a ten degree drop in
temperature (average of five degrees across the radiator) will decrease the
efficiency by only 5%; not a big deal, but if it's too much (I would say
30 or 40 degrees is probably too much), then a better water pump or less
restrictive radiator is needed. If Chris puts on a better fan, then maybe
he can increase the delta T at idle to fifteen degrees, which would solve
his problem and be considered "ideal" in this case.
Bob
At 09:12 AM 5/9/00 -0400, Carmods@aol.com wrote:
>In a message dated 5/9/00 2:54:14 AM Eastern Daylight Time,
>CVaught@Hawaii.rr.com writes:
>
><< what is a good delta T? >>
>
>The optimum delta T across the radiator, with the thermostat open, on the
>road is ten degrees.
> John Logan
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