Modelling a single-mode 915 MHz microwave applicator for low-moisture food treatment: comparison between COMSOL Multiphysics ^® and CST Studio Suite ^®

Two computational models were developed by using COMSOL Multiphysics® and CST Studio Suite® to simulate the microwave heating process of paprika and to compare the electromagnetic results obtained from each modelling software. The dielectric properties of paprika were initially measured at room temperature using the cavity perturbations technique and then estimated as a function of temperature. Experimental validation was performed in a rectangular waveguide with iris openings of 125 (Configuration 1) and 88 mm (Configuration 2). The impact of variations in both dielectric constant and dielectric loss on temperature prediction was examined, along with the sensitivity of the results to the positioning of probes. Simulated and experimental temperatures were compared at two positions inside the product: the centre (T1) and the bottom (T2). Additionally, the distribution of the electromagnetic field and the microwave reflected power were examined. The results highlight the strong impact of dielectric property variations on local temperature prediction and provide valuable insights for optimizing industrial microwave heating processes for food powders.