Abstract
Pelagic fish is one of the most valuable food products due to its high content of marine fat and proteins. The
Norwegian pelagic fish industry processes almost 900 000 tonnes of herring and mackerel annually. The
main volume is packed in carton boxes and frozen on shelves in batch freezing tunnels. Most of the
refrigeration systems in this industry use ammonia as refrigerant. It is challenging to ensure even freezing of
the products and to achieve filling – freezing – emptying ("turn over") of tunnels in less than 24 hours. The
tunnels and packing that is used today require tunnel temperatures below -30°C. Low compressor efficiency
at part load, non-optimal use of fans and bad air flow distribution lead to low energy efficiency. A screening
of existing tunnels and refrigeration systems to investigate the main challenges in operation and management
has started, and will be the base for further improvement of freezing systems and equipment and refrigeration
systems, compressors etc. and improved management. Results will be given and discussed in the paper.
Norwegian pelagic fish industry processes almost 900 000 tonnes of herring and mackerel annually. The
main volume is packed in carton boxes and frozen on shelves in batch freezing tunnels. Most of the
refrigeration systems in this industry use ammonia as refrigerant. It is challenging to ensure even freezing of
the products and to achieve filling – freezing – emptying ("turn over") of tunnels in less than 24 hours. The
tunnels and packing that is used today require tunnel temperatures below -30°C. Low compressor efficiency
at part load, non-optimal use of fans and bad air flow distribution lead to low energy efficiency. A screening
of existing tunnels and refrigeration systems to investigate the main challenges in operation and management
has started, and will be the base for further improvement of freezing systems and equipment and refrigeration
systems, compressors etc. and improved management. Results will be given and discussed in the paper.