PREDICTING THE COOLING CONDITIONS AT BLOWN FILM EXTRUSION LINES BY MODELING THE COOLING AIR STREAM

摘要

In order to develop a process model for the cooling air stream in blown film extrusion, an experimental analysis of the cooling conditions such as air velocity, temperature and pressure, was carried out. Thereby, a fundamental correlation between the cooling conditions and the resulting film temperatures was found and has been transformed into a theoretical description, whereat the air stream is described as a steady-state, two-dimensional, turbulent wall stream. With help of this model, the calculation of the air velocity and pressure along the bubble is possible. As a result, the temperature distribution in the bubble inflation area can be calculated by a dimensionless heat transition law.