Performance evaluation of falling film evaporators in the dairy industry

Artikel i vetenskaplig tidskrift, 2017

Falling film evaporators constitute an essential part of dairy powder production facilities. Evaporation belongs to the thermal separation processes; consequently, the evaporation plant is fundamentally energy intensive. Hence, improvements to its operation can have a significant impact on the energy usage. A simulation tool that is based on experimental correlations developed at conditions similar to the industrial scale is presented to provide insight into the fundamental mechanisms occurring along the heat transfer surface of industrial evaporators. The model includes the complex interaction between the produced vapor and the liquid flow. The results demonstrate that the pressure drop, through its influence on the saturation temperature, is of high importance in the performance of evaporators. The tool can be used to investigate different design configurations, and it exemplifies how a change in the tube diameter for the same temperature difference and length of the surface will affect the maximum heat load per area as well as the pressure drop.