I now have two spare 93/94 copper/brass rads!

[IdahoDoug]

Agree. But I have a b/g that includes some test design and statistics, so here's how I see it.

With airflow at zero, it will have the same negative impact on cooling for both units. I agree its a major factor in real world performance, but I'm going to assume that more airflow would benefit both radiator designs equally. I agree that ideally there'd be some flow, but it would be difficult to get the same flow on a unit in Texas (or wherever) and mine, and an airflow variation would introduce a very large testing variation.

In essence, my theory would be that the static radiant heat loss of a radiator is highly correlated with its dynamic heat loss (real world). Further, that a % difference in the static radiant heat loss between two different radiators would correlate highly with their dynamic performance (real world). So, if one radiator type ends the test 15% cooler each time, then I'll be able to state with reasonable certainty that that type is more efficient. Not 15% more efficient neccessarily as that would require a lot of testing and statistically valid sample sizes, but it would give one or the other the nod. If it's only 4% cooler each time, I'd be more likely to say that it's too close to call due to the casual nature of the testing.

What do you think? Do you feel that performance on a static test is valid enough for a dynamic (real world) performance comparison if there's a marked difference?

DougM

 

[IdahoDoug]

Semlin,

Blockages are only a big issue if we tried dynamic testing. Deposits will also impact static radiant heat loss, but to a much smaller degree than they would if they were reducing coolant flow speed and volume. My point is that dynamic testing probably introduces variations from the testing itself that will be larger than the variations in results themselves.

DougM

 

[Rich]

My understanding is that the fin & tube design has a major impact of the performance of a radiator and that the relative performance between different radiator designs, I.E 3 row copper/brass versus 2 row aluminum can vary greatly with different rates of airflow.

Regarding the black paint: a bit of further reading tonight indicates that at the temps auto radiators operate radiation cooling is not a major factor. The majority of heat transfer is accomplished by conduction. So the better radiation characteristics of the black coating are not significant. The primary purpose of the paint is apparantly to help control the corrosion of the copper.