C3 Typical Values of Overall Heat Transfer Coefficients
The empirical values listed below are intended for the preliminary design of heat exchangers. The lower values apply to comparatively adverse conditions, e.g., low flow velocities, viscous liquids, free convection, and fouling. The higher values are valid for particularly favorable conditions, e.g., high flow velocities, thin fluid layers, optimum mass flow ratios, and clean surfaces. In special cases, values may fall below or exceed the given range. Therefore, the figures must be regarded critically and with the necessary caution. The given k values do not take additional heat conduction resistances of insulation and protective coatings into account.