Yuma Proving Ground, Arizona, has successfully operated an external-melt ice-on-coil storage cooling system with nominal tank storage capacity of 1050 ton-h (3692 kWh) for the past 12 years. The system cools Building 506, which consists of two perpendicular, three-story wings with a total floor area of 86,100 ft² (7999 m²). The ice storage system was a retrofitted “add-on” to the existing chilled water system and consists of one 220-ton (774 KW) centrifugal chiller and one 80-ton (281 KW) reciprocating chiller. The system’s design objective was to eliminate the electrical demand of the 220-ton (774 KW) chiller during the peak window of 1200-1600 hours. Yearly net savings of $22,450 in electrical utility costs paid back the construction cost of $144,969 in 6.5 years. This paper discusses system operation and maintenance and unanticipated benefits gained from operation in a changing deregulatory environment.

Units: Dual