Ever since the advent of the automotive alternator, or claw-pole alternating current generator, in the 1960's, there has been an ever-increasing thermal design challenge to cool the power electronics in these machines. Figure 1 depicts a typical cutaway section of a modern day alternator. At first glance one may think that cooling the diodes in a rectifier bridge of an … [Read more...]
Estimating Natural Convection Heat Transfer for Arrays of Vertical Parallel Flat Plates
A simple formula to estimate the natural convection heat transfer coefficient on a flat plate was presented in a preceding column [1]. If, instead of a single plate, we wish to consider a closely spaced array of vertically oriented parallel flat plates, a different formula is required. The geometry to be considered appears in Figure 1 and is typical of that for a vertically … [Read more...]
Diamonds are a Thermal Designer's Best Friends
Different forms of carbon, such as processed natural graphite, pyrolytic graphite, diamond-like carbon, and synthetic diamond, offer lots of possibilities for maximizing conductive heat transfer.Synthetic diamond has already found its place as a common solution for heat spreaders inside semiconductor laser components, where temperature stabilization is of utmost importance for … [Read more...]
The Role of Natural Graphite in Electronics Cooling
Graphite is available as a variety of different material forms, the most useful in the electronics cooling market being pyrolytic graphite, graphite fiber reinforced carbon and polymer matrix composites, graphite foams and, the subject of this brief, natural graphite. The basic structure of graphite is shown in Figure 1. Figure 1. Structure of graphite crystal. The … [Read more...]
Use of Naphthalene Sublimation Technique for Obtaining Accurate Heat Transfer Coefficients in Electronic Cooling Applications
The naphthalene sublimation technique has been demonstrated by a number of investigators to be an excellent method for obtaining heat transfer results [1,2] and a few have applied this technique to applications focused on electronic cooling [3-6]. These investigators have found that the mass transfer process can be set up with cleaner boundary conditions and can be studied more … [Read more...]
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