Numerical simulation of flow and heat transfer characteristics in the extrusion and stretching process of non-Newtonian fluid in microchannel

Abstract

The quality of polyacrylonitrile (PAN) precursor fibers is crucial for improving carbon fiber performance, with dry-jet wet spinning as the primary production method. Here we numerically simulated the spinning process of PAN/dimethyl sulfoxide (DMSO) solution, comprehensively investigated the effects of spinneret structures and process conditions on fluid flow and heat transfer. Additionally, we evaluated temperature uniformity and introduced the Micropore Uniformity Coefficient (MUC) to assess velocity distribution uniformity. Results showed that the length-to-diameter ratio and taper angle influenced Micropore Uniformity Coefficient by changing the fully developed length of the velocity profile and flow stability. The volumetric flow rate had the most significant impact on temperature uniformity. The maximum radial temperature difference outside the spinneret accounting for 5% of the temperature difference between the spinning and the ambient temperatures. Comprehensive analysis indicated that a spinneret design with a length-to-diameter ratio of 3–4 and a taper angle of 50°-100° is optimal.