Minimum Wetting Rates for Falling Films on Stainless Steel

Abstract

AbstractThe minimum wetting rate is defined as the minimum mass flowrate per unit circumference that is required to maintain of complete falling film of liquid on a surface. In this work minimum wetting rates in a 48 mm i.d. stainless steel tube were determined jor water, 50% sucrose solution, and reconstituted skim milk under isothermal and heat transfer conditions. It was found that initial distribution of the liquid at the top of the tube was critically important. The minimum wetting rates under isothermal and heat transfer conditions ranged from 0.22 kg m−1 s−1 for 50% sucrose at 20% to 0.12 kg m−1 s−1 for water az 70°C. Nearly all rates decreased with temperature. Equations in the literature did not accurately predict the results obtained.