Investigation of boiling heat transfer process in the barrel of a gravity heat pipe type extruder.

• Elucidation of the nucleate boiling process in different positions of the barrel. • Research on the boiling phase change heat mechanism of the machine barrel. • The tail vortex disturbance enhances the boiling heat transfer from the barrel. • The rounded bottom of the barrel can improve the thermal capacity of the barrel. Gravity heat pipe barrels produce gas films during the processing of thermoplastic materials, which affect the heat transfer, so there is an urgent need to study the nucleate boiling process and mechanism at different locations in the barrel. The results showed that the local heat flux at the vapor-liquid-solid three-phase contact was the largest, and different process conditions had different effects on the departure diameter and departure time of boiling bubbles. The tail vortex disturbance generated by bubble departure drives the merging and growth of bubbles to departure, which in turn improves the heat transfer. The rounded bottom of the barrel reduced the air film and increased the heat transfer efficiency compared to the horizontal bottom of the barrel. This study can deepen the understanding of the mechanism of bubble boiling heat exchange in gravity heat pipe-type barrels and provide theoretical support for more relevant application scenarios. [ABSTRACT FROM AUTHOR]