Temperature profile prediction within selected materials heated by microwaves at 2.45GHz

This work presents a three-dimensional mathematical model to simulate temperature profiles inside a material heated by electromagnetic waves (EMW) at 2.45GHz. COMSOL-Multiphysics was used to simulate transient temperature profiles of pinewood, carbon, Pyrex, and combinations of such under different conditions. The model predicts that, upon exposing an 86mm wooden cube to 2.45GHz EMW for 300 s, the core temperature reached 595 K at a setting of 60 K/min, while the outer surface 365 K at 15 K/min. By mixing 50% carbon with the wooden block, the model anticipated the cube core to reach 990 K at 140 K/min, compared to 1350 K at 212 K/min with 75% carbon at the same power and after the same time. By inserting a 125cm3 carbon cube inside the wood cube, the core reaches 3200 K, while the outer surface was 375 K and 636 K for free convection (FC) and perfect insulator (PI), respectively. Placing the same volume of carbon on the surface of the wood cube yielded a maximum temperature of 660 K under FC, compared to 1280 K with PI. Changing the material of the core cube from Carbon to Pyrex yields a temperature of 324 K in the core, with 365 K and 605 K on the outer surface in the case of FC or PI, respectively. The average percentage relative error between the measured and the predicted temperatures was ±4% and ±15% inside the pinewood and carbon respectively.