Cold thermal energy storage with low-temperature plate freezing of fish on offshore vessels

Abstract

This paper presents the results of a numerical and experimental study of freezing time for fish in plate freezers, and the potential for improvement by altering fish block thickness and lowering evaporation temperature. Furthermore, the benefits of implementing cold thermal energy storage (CTES) in the system are presented. The numerical freezing model relied on the apparent heat capacity method and was validated experimentally with an industrial plate freezer. The freezing model demonstrated good agreement with experiments. Results suggested an increase in fish production capacity by 66 % when using -50 °C systems compared to -30 °C. Another 13 % increase in production capacity is possible if 50-mm thick fish blocks are used instead of 100-mm. Implementing CTES suggested a reduction in freezing time of 3.2 %, by maintaining constant plate temperatures during freezing. Reduced evaporating temperature, thinner fish blocks and implementation of CTES proved to be beneficial for freezing processes on offshore vessels.