Combined Energy Supply Drying of Fish Eggs and Lecithin Clot Based on Dehydration Kinetics: Mathematical Model Adaptation

Removing moisture from biological materials has many advantages since reduced volume means lower processing costs, and drying prevents microbial growth and spoilage. Despite the fact that different drying methods pursue the same goal, they differ conceptually and require modification/adaptation, depending on the biomaterial. The article describes the kinetics and optimal dehydration modes that increase the drying efficiency of quasi-liquid products (roe and skein complex) using physical and mathematical modeling of heat and mass transfer and moisture removal. The existing mathematical model for drying with combined energy supply was adapted to fish eggs and lecithin clot. The dehydration kinetics made it possible to understand the temperature distribution inside the dried biomaterial and estimate the drying time. A gas mix served as a drying agent. The calculations were compared with the experimental drying tests for similar biomaterials. The materials were subjected to dehydration in the mode of conductive-convective heat supply in an original laboratory drying unit. The authors identified the kinetic patterns and rational mode parameters to increase the performance. The rational operating parameters included the intensity of the coolant movement (3.50 m/s); the height of the dried layer (0.01 m); the surface temperature of the dried material and the temperature of the heating plate (313 K); the initial temperature (283 K); the final moisture content (0.10 kg/kg). Under these parameters, the specific productivity was 7.610 kg/(m2·h), and the drying time to 0.1 kg/kg humidity was 150 min. The rational operating parameters of the lecithin clot included the coolant feeding rate (2.50 m/s); the layer height (0.003 m); the surface temperature of the dried material and the temperature of the heating plate (343 K); the initial temperature (328 K); the final humidity (0.130 kg/kg). In this case, the specific productivity was 13.630 kg/(m2·h), and the drying time to 0.130 kg/kg humidity was 40 min. Heat and mass transfer modeling increases the accuracy of calculation, making it possible to realize the energy saving potential without preliminary experiments while maintaining the quality of the dried product. In this research, the kinetic patterns, optimal dehydration modes, and drying models can be applied to heat and mass transfer processes under different production conditions, as well as to design new drying units for fish eggs and lecithin curd.