In an ammonia system, one evaporator is to provide 180 kW of refrigeration at -30°C, and another evaporator is to provide 200 kW at 5°C. The system uses two-stage compression with intercooling and is arranged as shown in Fig. 1. The condensing temperature is 40°C. Sketch the process on T-s and P-h diagrams. Calculate the mass flow rate of refrigerant through the high-stage compressor, in kg/s.
State | T (°C) | h (kJ/kg)
1 | -30 | 1403.75
2 | | 1599.88
3 | | 1447.06
4 | | 1588.84
5 | 40 | 371.35
6 | | 371.35
7 | | 203.27
8 | | 203.27