Cascade System

Hi,
I would like to design warehouse refrigeration using Ammonia-Carbon Dioxide cascading sytem. From my calculation,the CO2 compressor power is 13kw and the Ammmonia compressor is 1660kw. Is my design OK?If not,what should I do to select the more logical for both compressor power ?

 

[RJVAN]

Depending on system specifics, CO2 vapor has 6-10 time as much cooling capacity PER CUBIC FOOT than NH3 vapor. That is, for a given number of BTU/min fed to the liquid refrigerant, CO2 produces fewer CFM of vapor. (Conversely, NH3 has better BTU/lb than CO2 because its vapor is less dense). It's therefore conceivable that the NH3 compressors are consuming more energy than the CO2's because they're pumping more CFM.

I'd like to hear what others say.