Читать книгу Agitator Design for Gas-Liquid Fermenters and Bioreactors - Gregory T. Benz - Страница 45

The Nusselt number is the ratio of the convective heat transfer coefficient times a reference length divided by the thermal conductivity of the fluid. The reference length dimension depends on the heat exchange surface. For a vessel jacket, that will normally be the tank diameter. For tubes inside the tank, it would normally be the tube OD. Expressed in terms of tank diameter, we have:

(3.8)

It is used in heat transfer calculations, to determine the convective coefficient, h. It is a function of impeller type, Reynolds number, Prandtl number, and various geometric factors, as well as the ratio of local viscosity to bulk viscosity.