In the August 2003 issue, the Technical Data column was devoted to emissivity in practical temperature measurements. But what about the emissivity value that should be entered in your numerical model? Can we use the measured values as discussed in the column mentioned? Let me summarize the main points of it: Emissivity is not only a material property but also a surface … [Read more...]
Heat of Vaporization
Thermal energy transfer associated with a change of phase can be a valuable phenomenon for engineers designing systems for electronics cooling. Solid to liquid phase change materials were described in the May 2005 Technical Data column and the topic for this issue is liquid to vapor phase change. The energy required to change a substance from a liquid state to a vapor state is … [Read more...]
Thermal Conductivity Of Liquid Metals
This column deals with the thermal conductivity and melting points of liquid metals. Thinking about liquid metals, many people associate them with high temperatures. It is not widely known that some metallic alloys are liquid below 0�C, with the exception of course of mercury which was already known in ancient times. China's first emperor is said to have been buried in rivers … [Read more...]
Thermal Properties Of Building Materials
Previous Technical Data columns have covered thermal properties for many of the materials that are common to electronics packaging. The Technical Data for this issue is broader in scope and addresses common building materials, some of which are used in heat transfer laboratory environments, in addition to their usual construction applications. Knowledge of thermal conductivity … [Read more...]
A Practical Implementation Of Silicon Microchannel Coolers
Introduction More than twenty-five years ago, Tuckerman and Pease first described the use of silicon microchannel cooling for very high power densities [1]. However, the coolers could not be fabricated easily and pressure drops were very high. As chip power densities are now increasing beyond air cooling limits, a variety of liquid cooling methods are being investigated. Due to … [Read more...]
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