Model and process simulation of microwave assisted convective drying of clipfish

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 kW h t−1 and it was 445 kW h t−1 for the HAAD system. For the microwave assisted drying systems the energy consumption increased up to 4465 kW h 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%.