Experimental and numerical investigations on a high-density polyethylene (HDPE) blown film cooling with a new design of the counter-flow/radial jet air-ring

Abstract

This study experimentally and numerically investigates a typical HDPE blown film production process cooled via a single-lip air-ring. The processing observations are considered for the proposed subsequent modifications on the air-ring design and the location relative to the die to generate a radial jet, directly impinging on the bubble. Measurements are performed to collect the actual operating parameters to set up the numerical simulations. The radiation heat transfer and the polymer phase change are considered in the numerical simulations. The velocity profile at the air-ring upper-lip is measured via a five-hole Pitot tube to compare with the numerical results. The comparison between the measurements and the numerical results showed that the simulations with the STD [Formula: see text] turbulence model are more accurate with a minimum relative absolute error (RAE) of 1.6%. The numerical results indicate that the peak Heat Transfer Coefficient (HTC) at the impingement point for the modified design with radial jet and longer upper-lip is 29.1% higher than the original design at the same conditions. Besides, increasing the air-ring upper-lip height increased the averaged HTC, which is 13.4% higher than the original design.

Blown film cooling numerical and experimental investigations

“…It was found that only the Muslet & Kamal heat transfer model was correctly able to capture the physical characteristics of the heat transfer between the bubble and the cooling air, especially in the case of a very high FLH. Moreover, Ismail, ME [43] performed numerical and experimental investigations on the external cooling of an HDPE bubble with a new design of a counter flow air ring design. The performance of four different two-equation-based turbulence models is compared to the experimental results of the measured air velocity via a five-hole pitot tube.…”

A Novel Mandrel-Free Blown Film Die with Ultrashort Flow Distance and Uniform Discharge: Theoretical Modeling and Simulation

“…The uniformity of film thickness is mainly affected by two aspects: the structure of the blown film die, and the air blowing process . Numerous studies have investigated the aerodynamic phenomena resulting from different cooling rings on the cooling efficiency in blown film extrusion. , In contrast, reports of improvements in the structure of blown film die are seldom seen in recent decades. The development of blown film die structure is almost at a standstill.…”