Air Agitated Latent Heat Storage Units or Ice Builders store refrigeration in the form of ice.
The Latent Heat Storage Unit or Ice Builder produces ice. Large quantities of refrigeration can be stored in a relatively small space. The ice can be produced during periods of low demand for refrigeration or electrical energy. It can be used later in the form of 32° F to 34° F (0° C to 1.1°C) cooling water. This concept is ideal for leveling out refrigeration loads that are not constant throughout the cooling period, and for high refrigeration loads of a relatively short duration. Since the refrigeration compressors and related equipment are not required to be sized to meet peak load requirements, energy consumption is reduced to accommodate manual or automated loading.
Additional energy savings can be realized by building ice to store refrigeration during times when electrical demand for other uses is low, thus holding down demand charge rates. Many utility companies are also imposing time of day rates with lower rate during periods of low general demand; therefore, ice can be built during these periods to take advantage of the lower rates.
Another advantage of these thermal energy storage systems occurs when working from a reserve, the system capacity is not lost should a compressor breakdown. Latent Heat Storage Unit or Ice Builder can have a split evaporator with two compressors separately connected. In this way, if one fails, there is another to give at least 50% capacity (more by running it longer), until the failure has been remedied.
For certain heating, ventilating and air conditioning applications, the units can be used for storing cold and heat. The cold is stored as both latent and sensible heat while the heat is sensible heat only. This is accomplished by using the ice building coil as a condenser to heat the water in the tank.
Once the ice has been built on the coils to store the latent heat or thermal energy, it must be melted off evenly to provide as low and even a temperature as possible to the outgoing water. There are many methods of attempting to do this that eliminate the baffles and bypasses. Low-pressure air distribution lines between each vertical bank of coils at the bottom of the tank provide complete uniform agitation. Warm water returning at one end of the tank is instantly mixed with the ice water, resulting in a uniform ice melting temperature with no agitation dead spots or ice blocks. Ice water exits at the opposite end of the tank so the return water must pass through the entire ice bank.
Some imitators have cut corners and supply baffle and bypass systems and do not supply air agitation lines between each vertical bank of ice coils. This results in an uneven pattern of agitation over the tank area with dead spots where unwanted ice buildup can occur.
International Thermal Systems supplies an optional compact, highly efficient, low-pressure air blower for agitation with each Ice Builder. The air agitation is needed only when ice is being melted. The air blower motor starter should be interlocked with the customer supplied ice water circulating pump motor starter. The air agitation lines in the Ice Builder are easily removable for maintenance.