Flow behaviors and heat transfer characteristics of liquid film during the pyrolysis process of molten plastics using OpenFOAM.

Highlights • The traditional VOF model was modified by considering the interphase drag force. • The surface of the liquid film is a wavy structure. • The liquid film presents a comprehensive flow pattern of film, rivulet and droplet. • In the severe pyrolysis region, the change in the bulk temperature is insignificant. • The apparent heat transfer coefficient at different temperatures were discussed. Abstract Falling film pyrolysis can improve the quality of pyrolysis products of waste plastics. The pyrolysis process of molten plastics is a complex process and the interphase force has an important influence on the flow and heat transfer process of the liquid film. Based on OpenFOAM® and considered the interphase drag force, the flow behaviors and heat transfer characteristics of the liquid film during the falling film pyrolysis of molten plastics were numerically simulated by VOF (Volume of Fluid) method. The results show that the surface of the liquid film is a wavy structure and the liquid film presents a comprehensive flow pattern of film, rivulet and droplet. With the increase of pyrolysis temperature, the length of liquid film and the average apparent heat transfer coefficient decrease, and the average thickness increases slightly. With the increase of the liquid film inlet velocity, the liquid film thickness and the average apparent heat transfer coefficient increase. [ABSTRACT FROM AUTHOR]