Propane (1000 kg/hr) is to be liquefied following a two-stage compression. The inlet gas is to be at 300 K and 0.1 MPa. The outlet of the adiabatic compressor I is 0.65 MPa, and the propane enters the interstage cooler where it exits at 320 K, then adiabatic compressor II raises the propane pressure to 4.5 MPa. The final cooler lowers the temperature to 320 K before it is throttled adiabatically to 0.1 MPa. The adiabatic compressors have an efficiency of 80%.

(a) Determine the work required by each compressor.

(b) If the drive motors and linkages are 80% efficient (taken together), what size motors are required?

(c) What cooling is required in the interstage cooler and the final cooler?

(d) What percentage of propane is liquefied, and what is the final temperature of the propane liquid?