Local heat transfer coefficients in a model “falling film” scraped surface exchanger

Utilization of an accurate technique to measure the local heat transfer coefficient in thin falling film scraped surface exchangers yields results which indicate that the local heat transfer coefficient is dependent on N0.5 and, above a certain rotational speed, independent of axial flow rate. Both of these observations are in agreement with the theoretical penetration model. The results, however, are generally lower than would be expected from the theory, and as a result, heat transfer may be described by the penetration model in combination with an empirical factor, f. This term is based on the liquid physical properties and gives a measure of the intensity of cross sectional mixing within the liquid, i.e. where f, is defined as