Thermal transport from a heat sink creates a unique condition in heat transfer and fluid flow once it is placed on a PCB in an unducted fluid flow delivery system. Although a heat sink may appear structurally simple, the fluid flow through its fin field and thermal coupling between it and the surrounding create a rather complex problem. As a result, heat sinks are often … [Read more...]
The Weakest Link in Air Cooling
So far, this 21st Century has been a big disappointment. I grew up on the science fiction of the 1950's and 60's. Plus I knew that the stories of Jules Verne and H. G. Wells had turned out to be amazingly accurate predictions of real technological advances. So I was expecting that, if I lived long enough to see the 21st Century (no way - I'll be in my 40's!), I'd be … [Read more...]
Thermal Capacitance
When time enters the equations, the ability of a material to store or release heat becomes a crucial parameter. This issue's technical data column is devoted to a basic understanding of thermal capacitance. Thermal capacity (or heat capacity) is defined as: Cth = V � � cp [J/K] where: V =Volume (m3) = Density (kg/m3) cp = Specific heat (J/kgK) at constant pressure (the … [Read more...]
A Few Design Techniques On How To Reduce The Power
There will always be the need to get heat out of high power circuitry, but with a little extra design effort up front, we may be able to reduce overall power needs. Here are two techniques that can help do that. Turn Idle Circuits Off A circuit that is not always used can be turned off until needed. This is a technique widely used in battery powered electronics, but it can be … [Read more...]
Challenges In Thermal Control Of Military Electronics Systems
Thermal design engineers working in defense electronics are facing many challenges, some of which have been around for a long time and some that are more recent. Worldwide climatic extreme temperatures are reasonably constant and there are many military electronic systems that function in these extremes. As a result, there is significant design history available for … [Read more...]
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