Analysis of a high temperature heater in a false twist texturing process

The production of textured filament yarns by false twist texturing is an important commercial method that requires heating. In this study, the transient two dimensional modeling of the yarn, heated by high temperature heaters in a false twist texturing process was developed in order to investigate the influence of various heating conditions on the yarn temperature distribution and to quantify the relative contribution of thermal radiation to the total heating. The surface temperatures and the residence time of yarns of different diameters were measured and compared with the simulation results. The temperature distribution in the cross-section of the yarns was calculated for various yarn speeds and for different heater temperatures. The temperature difference between the surface and the center of different types of yarns along the heater was found. For a yarn in a heater, energy is transferred from the heater surface to the yarn by both convection and radiation. As the yarn approaches its heat setting temperature, the total heat rate decreases. However, the calculated results show that the relative contribution of radiation increases up to 60% of the total with yarn temperature and diameter. (C) 2002 Elsevier Science Ltd. All rights reserved.