ライブラリ登録: Guest

ISSN Online: 2377-424X

International Heat Transfer Conference 12
August, 18-23, 2002, Grenoble, France

The Generalized Leveque Equation (GLE) and its use to predict heat and mass transfer from fluid friction

Get access (open in a dialog) DOI: 10.1615/IHTC12.2620
6 pages

要約

A new type of analogy between frictional pressure drop and heat transfer has been discovered that may be used in chevron-type plate heat exchangers, in tube bundles, in crossed-rod matrices, and in many other periodic arrangements of solids in a fluid flow. It is based on the Generalized Leveque Equation (GLE).
Available experimental data on heat transfer in packed beds of spherical particles of diameter d had been collected and empirically correlated earlier by Gnielinski. His correlation provides a simple way to test the GLE for its applicability in predicting packed bed heat or mass transfer from pressure drop.
It was found that using a friction factor ξ = xf ξtotal leads to a very reasonable agreement between the analogy predictions and the experimental results. The fraction xf of the total pressure drop coefficient ξtotal that is due to fluid friction only, turned out to be a constant over the whole range of Reynolds numbers in many cases. For the packed beds of spheres, Ergun's equation, or more appropriate equations from the literature may be used to calculate the total pressure drop.
The new method can also be used in external flow situations, not only for internal flow as shown so far. This is demonstrated here for a single sphere as well as for a single cylinder in cross flow. In these cases, however, the frictional fraction xf of the total drag coefficient is not a constant over the range of Reynolds numbers. Nevertheless it is easily obtained from standard correlations of drag coefficients.
The successful application of the GLE also in cases of external flow seems to confirm, that this new type of analogy has a broad range of applications and may lead to a better understanding of the interrelation between fluid flow and heat or mass transfer in general.