Determination and correlation of heat transfer coefficients in a falling film evaporator

The aim of the work was to determine the heat transfer parameters of a single effect evaporator under different operating conditions, in order to extrapolate them to a multiple effect unit. The falling film evaporator consisted of 12 stainless steel vertical tubes, 1″ OD and 3 m long, having an evaporation capacity of 240 kg/h. In this unit the conditions of each effect of a multiple effect evaporator were simulated, varying the feed concentration and the pressure, setting in this way the saturation temperature and the transfer regime. Obtained values were correlated by means of an equation that links the heat transfer coefficient with the fluid properties, geometric parameters and flow conditions. Comparison with existing correlations was carried out.