Page 52 - Low Temperature Energy Systems with Applications of Renewable Energy
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40 Low-Temperature Energy Systems with Applications of Renewable Energy
The following ways of storing cold thermal energy are known: accumulating ice on
the surface of submerged tubular heat exchangers filled with a circulating anti-freeze
solution; directly on refrigerant evaporator surfaces; within small containers, usually
made of plastic and spherical in shape; or simply a large volume of chilled liquid water.
A system for using a cold thermal energy storage unit is shown in Fig. 1.22 [31]. Dur-
ing periods of off-peak electricity pricing (typically overnight), the system operates in
the charging mode (A). The chiller is driven to provide 25 F( 3.9 C) heat transfer
fluid (water-antifreeze mixture) to the ice storage unit. This causes the water in the tank
Fig. 1.22 Modes of operation for cooling with a thermal energy storage system. (A) charge
cycle; (B) discharge cycle.
Redrawn from [31].
