Experimental study of the effect of dielectric and physical properties on temperature distribution in fluids during continuous flow microwave heating

Temperature data was collected at multiple locations in tap water, saltwater, and carboxymethylcellulose (CMC) solutions heated in a continuous flow microwave system by use of custom made temperature measurement system employing a single fiber optic probe. Tap water, 3% saltwater and 0.5% CMC solution were pumped through a 915 MHz continuous flow microwave system operating at 4 kW at three flow rates of 1 lit/m, 1.6 lit/m and 2 lit/m. Saltwater absorbed most power (3940 W) out of the 4000 W incident power, followed by CMC solutions (2690 W) and tap water (2626 W). Cross-sectional temperature distribution patterns showed that saltwater had the most uniform temperature distribution followed by tap water; CMC exhibited a non-uniform temperature distribution due to viscosity changes and thermal runaway effects. The study was very useful in enhancing the understanding of continuous flow microwave heating process for a variety of material properties and flow rates.