In large cold storage plants ammonia is used as refrigerant at what conditions?

The operating conditions of ammonia in commercial refrigeration are important for competitive exams. Low pressure and high temperature is the condition of the EVAPORATOR side where ammonia absorbs heat and becomes a low pressure gas. This high pressure liquid ammonia then expands through a valve dropping to low pressure where it evaporates at very LOW TEMPERATURE absorbing heat from the storage area. The cycle requires high pressure in the condenser section. Ammonia refrigeration systems typically operate at pressures of 10-20 bar on the high pressure side. Normal atmospheric pressure would not be sufficient for an effective refrigeration cycle. The boiling point of ammonia at 1 atm is minus 33 degrees C which would require very cold surroundings to condense it. Very high temperature would defeat the purpose of refrigeration. Refrigeration requires low temperatures inside the storage area.