Copper vs. Aluminum
There's more to heat transfer than just the conductivity of the material. With a vehicle radiator there's the heat exchange of the fluid to the tubes, and then the conduction of the heat through the tubes and the finsm and finally the heat exhange with air. The last is largely convective and will involve both the tubes and the fins. I remember being surprised in one class excersize that the fins can be designed so that they will make the heat exchange worse! IIRC that was a passive convection excersize. My point is only that aluminum's disadvantages can be largely overcome in this particular regard. That doesn't make the observation of the differences in coduction any less interesting - its certainly an important factor
Exactly this, actually. Read on.
Get an infrared thermometer, I used it on my engine block and my radiators. The one with the high-efficiency radiator proved to be the coolest.
These cars weren’t designed to run too cool.
Use an infrared camera, not a thermometer. I have one on my phone because I literally pay my mortgage by building large scale heat exchangers. It's a game changer when it comes to understanding these things.
Aluminum the material is not superior to copper (Brass is harder to nail down, there's many types of brass) in regards to heat transfer. That said:
Most radiators, including the OEM in our cars, were BRASS, which isn't that great. Copper radiators aren't great, primarily due to cost, but also because copper has other manufacturing requirements that make it less desirable. Brass is terrible at heat conduction.
Aluminum allows the use of different tube sizes to make a more efficient radiator, via thinner tubes and fins....and it's lighter to boot.
-If your radiator is too thick (where the air passes through), you end up with virtually no change in temperature by the time the air reaches the tubes in the back, and it's just wasted coolant and radiator at that point; you're either going wider or taller.
-If the tubes are too small, you can't flow enough coolant and you end up needing more tubes to get your flow back, and then you run into my previous sentence about the radiator being too thick.
-If you have to make the walls of the tube thicker to resist the pressure, wind load, vibration, and other conditions of the application, you either lose air flow between the tubes, or have to space them so far apart that....my previous two sentences start shaking your tree.
And remember, unless you take the Thermostat out of the car, most of the time your flow is partially regulated to the radiator anyway. The new Rams have (tried?) that active grille to regulate airflow over the radiator because it wasn't needed all the time and they were trying to increase aero efficiency. If the radiator is spec'd to handle your car at its' most severe requirements, you're basically done. Bigger/better radiators beyond your max need aren't going to make you faster, better, or smoother with the ladies, and your radiator isn't used to capacity except in the worst of cases.
It's a radiator, and the rule of diminishing returns still applies.
Remember, all this talk about material-this and conductivity-that is moot. You have to look at the
system. I have heat exchangers with stainless steel tubes, and they work great
for the system and the application.
For most street cars, a properly designed aluminum radiator will be superior, and more importantly.....Just Fine For What You're Doing.
