Abstract
Microwave (MW) assisted convective drying of clipfish (cured cod) was investigated at different intensities. The determined kinetics show that the drying time can decrease by over 90% at a microwave intensity of 155 W kg-1. However, quality aspects limited the microwave application to maximum intensities of 65 W kg-1, where the drying time is still decreased by 35%. The determined drying kinetics where used to model a 40 ton tunnel dryer for clipfish in a dynamic simulation. The energy consumption of a 200 kW heat pump drying system (HPD) and a heated ambient air drying system (HAAD) were investigated for different microwave intensities. The energy consumption for the HPD system was 171 kWh t-1 and it was 445 kWh t-1 for the HAAD system. For the microwave assisted drying systems the energy consumption increased up to 4465 kWh t-1. Microwave hybrid drying of clipfish is therefore considered uneconomical despite the faster drying kinetics. Economical energy levels for MW-HPD would have to be below 1.6 W kg-1 and 6.2 W kg-1 for MW-HAAD, at a drying time reduction of 50%. Copyright © 2013 Published by Elsevier Ltd.