engleski

Ice bank as a means for fast chilling of water

An operation of an ice bank silo is studied by the use of a computer model. A vertical cylindrical silo tank is assumed as a stack of several equal modules. Tube coils spirally wound within each module are the part of the secondary coolant loop, using ethylene glycol or propylene glycol or modern low viscosity secondary coolants for heat removal during ice building. Water to be frozen or to be chilled flows outside the tubes, perpendicular to them, agitated by a propeller. Two basically different operating modes are analyzed: ice building (compressor working without warm water input) plus subsequent ice melting (with compressor stopped and warm water input) as a first mode, and as a second mode a simultaneous and continuous operation of compressor and warm water input. Different and time varying operating conditions are considered. The results show that in the first mode an ice bank can be used as an effective means for fast (albeit of limited duration) chilling of large amount of water, for relatively small installed power of a compressor. By properly choosing the operating parameters for the second (continuous) mode of operation, one can achieve water outlet temperature to be practically constant and almost equal to 0  C regardless of the water inlet temperature and its flow rate. Furthermore, using the ice melting and building as a buffer, the variation of required compressor power is smaller than the variation of the heat load usually imposed by the incoming water.

ice bank; water freezing; ice melting; mathematical model; Ice on Coil; Phase change material (PCM); Cold thermal energy storage

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