Impact of the geometric parameters on the thermal performance of a large-scale falling film evaporator for desalination

Abstract

Based on a validated distributed parameter model, the thermal performance of a large-scale falling film evaporator was simulated under different geometric parameters including the tube length and the row-column ratio of the tube bundle. On considering that the falling film evaporators applied in the multi-effect evaporation are operated under small temperature difference thus sensitive to the temperature variation inside the evaporator, the variation of the local temperature difference is presented in detail. The distributions of the local heat transfer coefficient and heat flux were also exhibited under different geometric parameters. Results show that both the tube length and tube bundle row-column ratio have significant impact on the distribution of thermodynamic parameters in the falling film evaporator. The maximum value of the average heat flux of the evaporator is obtained when the length of the tube is 7 m. The maximum heat flux of the evaporator is obtained when the tube bundle row-column ratio is 2.5.