Experimental investigation of the combined translational and rotational movement on an inclined conveyor on radio frequency heating uniformity

The objective of this study was to explore the possibility to improve radio frequency (RF) heating uniformity by subjecting the food to RF energy on a moving inclined conveyor and horizontally rotating it about its central axis at the same time. To do this, wheat flour in a rectangular container was heated on a rotating turntable moving on an inclined conveyor using a radio frequency oven operating at 27.12 MHz and a maximum power of 2 kW. A fixed electrode gap setting of 165 mm was employed. Heating experiments were also conducted without rotating the sample both on inclined conveyor and on horizontal conveyor positioned at two different heights between the RF electrodes. Temperature at four different internal locations was continuously measured using fiber optic probes. Temperature at the top surface and the mid-layer was also measured using an infrared camera immediately after heating. The combined translational and rotational movement of sample was found to reduce temperature gradients within the rectangular volume allowing to reach the target temperature in a more controlled manner. The proposed approach can be easily implemented in the industry to improve uniformity of heating.