The falling film flow has attracted much attention recently due to its advantages of low temperature difference, low flow rate, high heat transfer coefficient and high heat flux density. In this paper, a series of experiments were carried out to investigate the falling film flow and heat transfer characteristics outside the vertical tube based on the established experimental system. Flow patterns, the trend of heat transfer coefficients along the tube as well as the falling film breakdown phenomenon were described. Two new correlations were obtained to predict the heat transfer coefficient and falling film dry burning based on experimental data, and the maximum deviation between the experimental data and predicted values were -13.36% and 16.81%, respectively. The new correlations can provide a reference for the design of the heater in the Mechanical vapor recompression systems.

Mechanical vapor recompression; Falling film; Heat transfer coefficient; Falling film breakdown; Correlation

Technical Institute of Physics and Chemistry, Chinese Academy of Sciences; University of Chinese Academy of Sciences