This is borderline electronics, but I think many more of us here have done this kind of studies.
I'm heating an aluminium plate with an Aluminium clad power resistor by mounting it on it and applying 25W of power, just like on the following schematic: Note the thermal equivalent model I think it corresponds to, including the temperature nodes.
- What is the 0°C terminal of the power source connected to in that case? Ambient (as usual), or aluminium plate? How do we know?
- I can estimate R3 (0.5K/W) and I have a rough calculation of R4 (4.7K/W which I find really really odd*), but on the datasheet of the resistor I'm using I don't know if the thermal impedance is R1+R2 (junction to ambient) or R1 (junction to case). Numbers seem to point to R1+R2, but how do I know R1 then?
Goal: Calculate the temperature T of the aluminium plate at equilibrium.
*: Addendum: I've used the 0.225m².K/W value of this link together with the surface of my plate to find that, which means a 360x131 mm² plate radiates less than the resistor heatsink?