The concept of thermal storage takes many guises that range from cold- water storage to ice creation and storage. Some systems have a dedicated ice-creating chiller operating with a glycol solution, while others use existing chillers and air-water systems. Most work in a conventional HVAC air-distribution system, although some newer arrangements are coupled with a cold-air system to optimize the entire system.
The objective of thermal storage is to cool water or build ice in the off-peak, nighttime hours. The chillers can then be turned off during regular business hours. The system thereafter uses only fan and pump horsepower to cool the facility. This reduces the peak daily energy use, and thus the demand surcharge. In many cases, the peak demand savings alone are sufficient to justify installation of a thermal-storage system. Further savings are possible because the chiller is operating during the cooler nighttime hours, so it’s able to run more efficiently by rejecting heat to a colder heat sink than during the daytime. As a result, the system not only lowers the peak demand charge but also reduces the energy use itself.
Ice-harvesting systems are available in skid-mounted assemblies that have pre-engineered pumps, chillers, storage tanks, and controls. They’re compact, efficient systems that take a minimum of piping and design to incorporate into an existing system. They’re available in a range of capacities and can be custom-designed to suit the needs and capabilities of the existing systems by the manufacturer’s staff, who are expert and experienced in the design of ice-storage facilities.
__________
Excerpt from Energy Conservation Projects.