5. An ammonia compressor is connected to an evaporator at -40°C with a cooling c

5. An ammonia compressor is connected to an evaporator at -40°C with a cooling capacity of 220 KW. The
system employs a single-pass shell-and-tube water-cooled condenser operating at 40°C. The liquid
ammonia leaving the condenser is saturated liquid while the ammonia vapor entering the compressor is saturated
vapor. The compressor has 4 cylinders, is operating at 60 rev/s, and has a percent clearance of 8% and an actual
volumetric efficiency equivalent to 88% of its clearance volumetric efficiency. Compression is not isentropic,
while expansion is isentropic. The compression efficiency is 82% and the stroke-to-bore ratio is 1.2. The
condenser water is discharged at 25°C through a pipe having a diameter of 10 cm. The condenser water
temperature rise is 7°C. The condenser is designed in such a way that water is the shell fluid and ammonia
is the tube fluid. The film coefficients of heat transfer on the inside and outside of the condenser tubes are 450
W/m2 k and 150 W/m2⋅ k, respectively. The condenser tubes are 22 mm nominal diameter and 2 m long.
Compute the following:
1. The temperature of the superheated vapor leaving the compressor, °C.
2. The mass flow rate of ammonia in the system, kg/s.
3. The clearance volumetric efficiency of the compressor.
4. The bore and stroke of the compressor, mm.
5. The power requirement of the system, kW.
6. The condenser heat rejection rate, kW.
7. The overall heat transfer coefficient in the condenser, kW/m2⋅ K.
8. The condenser heat transfer area, m2 .
9. The number of condenser tubes.
10. The amount of condenser cooling water, kg/s.
11. The velocity of water in the condenser discharge pipe, m/s.
12. The coefficient of performance of the system.

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