Koolance's Response to Hardware Labs "The Copper Radiator Myth"

[Cathar]

Two factors that may or may not be worth considering are compression and friction.

Air will get slightly compressed entering the radiator, then heated to up a maximum of the water inlet temperature, then decompress on exit thus lowering exhaust temperature.

Dunno if there is any noteworthy friction coefficient at these airspeeds, if there is it could heat the exhaust past water inlet temp.

Not relevant. It starts at standard pressure, and leaves at standard pressure.

Besides, even if it was relevant, the pressure changes we're talking about are just 100-120Pa (from the results), or ~1/1000th that of atmospheric pressure. The amount of temperature rise from that size of pressure change, starting at a standard atmosphere pressure would be absolutely miniscule.

Also, frictional heat from the airflow wouldn't show up in the calculated heat dissipation, since that's calculated purely from the water delta and water flow-rate. Air-flow friction warming the air up would make the air hotter, yes, but only hotter above the amount required to absorb the rated heat-load from the water.