Here, it should be noted that in the under studied
ammonia cycle the chillers operating pressures would
determine the refrigeration temperature levels. Therefore,
by changing the chillers’ operating pressures, the targeted
refrigeration levels can be achieved. Thus, to access the
required pressure and also by the aim of confirming the
retrofitted result, the refrigeration cycle is simulated by
HYSYS software before and after retrofit. Refrigeration
temperature levels and pressure variations of the chillers,
before and after retrofit are recorded in Table 9.