Two-Stage Ammonia (R-717) Refrigeration Calculator
Optimize intermediate saturation pressure (P_i = √(P_e · P_c)), flash economizer subcooling, and booster/high-stage compressor mass flow and COP.
Operating Temperatures & Capacity
-30°F ≈ 13.9 psia (deep freeze)
95°F ≈ 196 psia (evaporative condenser)
1 TR = 12,000 BTU/hr (3.517 kW)
Two-Stage Performance Results
System Coefficient of Performance (COP):
—
Total Compressor Power:
—
Optimal Intermediate Pressure (P_i):
—
Intermediate Saturation Temp:
—
Low-Stage / High-Stage Pressure Ratios:
—
Power Savings vs Single-Stage:
—
Two-Stage Ammonia (R-717) Thermodynamics
For low-temperature industrial freezing applications below $-15^circ ext{F}$ (blast freezers, cold storage), single-stage ammonia compression results in excessive pressure ratios ($> 8:1$), driving compressor discharge temperatures above $275^circ ext{F} - 300^circ ext{F}$ and breaking down lubricating oil.
Equal Pressure Ratio Principle
P_intermediate = √(P_evaporator · P_condenser)
Balancing the pressure ratios across the low-stage booster and high-stage compressor minimizes total electrical shaft power, while flash intercooling desuperheats the booster vapor to saturation.