Factors affecting heat transfer in falling film evaporators

A pilot scale single-tube falling him evaporator (2 metres length of heating tube) was used to gain some understanding of the mechanism of evaporation in this type of evaporator. Results obtained from commercial milk evaporators were used to select operating conditions on the pilot evaporator. The study was carried out using the Newtonian liquids: water and sugar solutions. The overall heat transfer coefficients were affected mainly by temperature difference between the liquid evaporating and the steam condensing temperatures, evaporating temperature, irrigation density, Liquid viscosity, and the heating tube length, but the Prandtl number was also significant.