theetruscan
several different terms used
"C/W" in quotes is the die to coolant inlet temp difference รท Watts
it is in quotes as it includes the TIM joint offset which is not actually part of the wb, and also because the "C/W" is related to the flow rate
T/W has been used to denote the thermal resistance of the wb itself and was experimentally obtained with a TC or RTD in a hole in the bp 0.52" off the bp face
- this had some problems with the hole placement verification
but this data was used to try to quantify the TIM joint thermal resistance (a 'correct' C/W as it is a constant, for a given mounting)
C/W will appear again shortly in a writeup on ThermalDesign rads,
and in another article on rad and fan selection
- this C/W will use the difference between the air and the mean coolant temp (heat exchangers normally use the log mean temp difference but with the small deltaTs it is not worth the effort)
it is NOT correct to say that the TIM joint has a C/W of 0.05
my data suggests a value of perhaps twice that (the 0.05 value was in a 'what if' discussion)
(perhaps Les recalls the threads on OCAU where this was thrashed out - to no definitive conclusion)
Aavid has some good papers describing the calorimeter setup to make such measurements, mine is not really suitable
|