Hi,

I am working with a large factory that has an ammonia refrigeration plant. The plant has multiple screw compressors and an economizer. The refrigerant plant cools an ethanol-glycol-water solution to -7 deg C (19 deg F) into large holding tanks. The -7 deg C ethanol-glycol-water solution is then recirculated around the factory to cool jacketed product tanks to set temperatures.

There is interest in shifting more refrigeration plant operation to off-peak periods when electricity is cheaper. Phase change thermal storage is an option being considered. To save money on freezing-point suppressants, the factory is interested in the option of a simple water-ice storage system that could utilise an existing large tank at the factory that is available for much of the year. This ice-water couldn't be used directly for cooling because it is at 0 deg C (32 deg F) and the coolant is at -7 deg C.

To make use of the stored 0 deg C ice-water, there was interest in whether the ice-water could be heat-exchanged with the ammonia from the condensers, and the economizer bypassed.

Does anyone know of this having been done before?
Do you think it is possible?
Are there any potential negative operational/efficiency outcomes?

Thanks for your help. Any thoughts/advice is much appreciated.