BLAST FREEZERS (Part 1) R717 VERSUS R717 / R744 CASCADE

摘要

An ammonia / carbon dioxide (R717/R744) cascade model was designed to be able to simulate the freezingprocess of pelagic fish. The modelling language Modelica was applied and it was implemented in thesimulation environment Dymola Control. Various simulations were performed for a typical design of thefreezing tunnel. The total energy consumption of the R717/R744 cascade unit was compared to a state of theart two-stage R717 system. The results show that the R717/R744 cascade system architecture, when properlydesigned, offers comparable overall energy performance at a reduced freezing time, compared to theconventional ammonia system.What is more, the cascade offers the possibility to reduce the evaporation temperature in the R744 bottomcycle to further reduce the freezing time.