Scalable electrohydrodynamic drying configuration for dehydrating biological materials at industrial scale

Abstract

Electrohydrodynamic drying (EHDD) is an energy-efficient and novel method for non-thermal dehydration of plant-based foods, especially fruits and vegetables. Upscaling EHD drying to dry biological materials like fruits and vegetables at an industrial scale is a current challenge of this technology, which hinders the implementation in industry. This paper experimentally evaluates the scalability of an optimized electrode configuration for EHD dryers. Unlike conventional EHDD studies, in which the collector electrode is a metallic plate, we employ a new design with a mesh with few conductive wires as a collector. This design was selected based on an in-silico optimization study aiming to improve energy efficiency. The performance of this novel emitter-collector configuration is characterized and compared with the conventional EHDD setup. Drying kinetics and energy consumption in different fruit loading densities are quantified as performance indicators to evaluate the scalability of different EHDD configurations. In addition, the overall performance of all EHDD configurations is compared with a commercial hot-air dryer from energy consumption and drying kinetics perspectives. Our experiments show that the new EHDD design leads to more uniform dehydration than the conventional EHDD configurations employed in previous studies. In addition, it significantly improves the specific drying rate by more than 65% and energy consumption by more than 60% for loading densities higher than 0.5 kg m-3. Compared to the commercial hot-air dryer, the novel EHDD configuration is 2.6 times more energy efficient. However, the drying rates of the EHDD configurations are lower than the commercial hot-air dryer. These significant improvements of the EHD dryer with the optimized and up-scalable mesh collector could provide the push needed to finally implement EHDD as an industrial unit in full-scale.