Water spray cooling of polymers

S.B. Tan, P.R. Hornsby, M.B. McAfee, M.P. Kearns, M.P. McCourt

Research output: Contribution to journalArticlepeer-review

5 Citations (Scopus)

Abstract

The cooling process in conventional rotomolding is relatively long due to poor thermal conductivity of plastics. The lack of internal cooling is a major limitation although rapid external cooling is possible. Various internal cooling methodologies have been studied to reduce the cycle time. These include the use of compressed air, cryogenic liquid nitrogen, chilled water coils, and cryogenic liquid carbon dioxide, all of which have limitations. However, this article demonstrates the use of water spray cooling of polymers as a viable and effective method for internal cooling in rotomolding. To this end, hydraulic, pneumatic, and ultrasonic nozzles were applied and evaluated using a specially constructed test rig to assess their efficiency. The effects of nozzle type and different parametric settings on water droplet size, velocity, and mass flow rate were analyzed and their influence on cooling rate, surface quality, and morphology of polymer exposed to spray cooling were characterized. The pneumatic nozzle provided highest average cooling rate while the hydraulic nozzle gave lowest average cooling rate. The ultrasonic nozzle with medium droplet size traveling at low velocity produced satisfactory surface finish. Water spray cooling produced smaller spherulites compared to ambient cooling whilst increasing the cooling rate decreases the percentage crystallinity.
Original languageEnglish
Pages (from-to)1069-1080
Number of pages12
JournalPolymer Engineering and Science
Volume52
Issue number5
Early online date30 Dec 2011
DOIs
Publication statusPublished - 01 May 2012

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