Quote:
|
Originally Posted by unregistered
but sufficient to understand that our efforts are not in a vacuum
|
or are as the case may be
Thermal Contact Resistance Measurments under Vacuum @ U of Waterloo 2003
via Stanford S.T.E.P.
pretty much your first link
Quote:
Experimental Apparatus & Proceedure
All measurements were performed using the thermal interface material test apparatus at the MHTL shown in figure 1. This apparatus, as described in the publication included in the Appendix of this report uses a pair of calibrated heat flux meters with equally spaced RTD elements to measure the total heat flow rate through the joint. Heating is provided by 4 cartridge heaters in a copper block at the bottom of the test column, a liquid cooled cold plate at the top of the column acts as a heatsink for the system. Loading is perfornmed using a linear actuator connected to a lever system, and a 1000lb load cell is used to measure contact pressure at the joint. The entire measurement apparatus is contained in a vacuum chamber, and all tests are performed under vacuum conditions, p<5Pa (0.037torr). A Keithley 2700 data aquisition system is used to perform all the measurements, and data logging and control of the experiment are performed using Labview v.5.i software running on a Windows-based PC.
|
Quote:
|
Two approaches are traditionally used to stabilize or eliminate heat losses, i) a guarded heater where surrounding conditions are controlled through a secondary heater and ii) a vacuum environment where conduction and convection heat losses are minimized and radiation heat losses can be controlled through a radiation heat shield.
|
the construction notes in the appendix are quite detailed
and relating to the actual question they used Aluminum 2024 for the flux meters
it looks like because of the tight dimensional control of the flux meters they are able to measure the temperature gradient and with the thermal conductivity of the Al 2024 determine the heat flow rate.
larger size of the flux blocks to get that gradient being the reason I assume they opted for a vacuum over the added complexity of insulation and secondary heaters when employing the RTDs
so provided the same data is available for other alloys and they are truely homogenous...