Optimizing heating patterns of PET preforms with microwaves (Appl. Therm. Eng, 2022)
Explore our new method for heating PET preforms with microwave energy optimized for the blow moulding process in our latest study, ” Focusing dielectric slabs for the optimization of heating patterns in single mode microwave applicators,” published in November 2021 in Applied Thermal Engineering, Elsevier.
Heating PET preforms is a crucial step in the blow moulding process, which is the predominant technique for producing containers utilized in the packaging, transportation, and storage of beverages. This procedure requires heating a cylindrical PET preform to a flexible state before the blow moulding phase, ensuring that the resulting plastic bottles possess the necessary mechanical properties. In this process, the preform temperature profile is one of the critical parameters for manufacturing a bottle with the desirable mechanical strength.
In this study, a novel approach utilizing adjustable dielectric slabs has been introduced to act as near-field focusing elements inside a single-mode microwave applicator, aiming to modify the temperature profile of PET preforms during microwave heating.
The approach was evaluated through numerical simulations and experimental results in a TE101 rectangular cavity at 915 MHz.
The experimental results demonstrated the significant impact of the slabs on the electric field distribution, thus allowing for highly flexible optimization of heating patterns.
This concept could potentially be applied to other microwave cavities, allowing the temperature profile to be tailored to different types of loads with specific local temperature needs.
