Example 6.23: Liquefaction of Nitrogen

Nitrogen is liquefied in the process shown in Figure 6-16. Nitrogen gas is fed at 25 °C, 1 bar (stream 1). The gas is compressed to 180 bar in a compressor with an efficiency of 85%. The precooler uses ambient water as the cooling medium and cools the nitrogen to 30 °C. The precooler uses cold vapor from the separator as the cooling medium; this vapor leaves the precooler at 20 °C (stream). Perform the energy and entropy balances on the basis of 1 kg/s of liquid nitrogen produced.