Question

A two-part compressor operates with steady state conditions. The exit of the first part of the compressor is also the inlet of the second part of the compressor. In the first part of the compressor, air is compressed from 1.5 bar, 350 K to 5.5 bar with a mass flow rate of 7.2 kg/sec. In the second part of the compressor, air is compressed from 5.5 bar to 9.5 bar with a mass flow rate of 5.8 kg/sec. Each unit of mass passing from inlet to exit undergoes a process described by pv^1.36=constant. Heat transfer occurs from the air at a rate of 53.0 kJ/kg of air, to cooling water circulating in a water jacket enclosing the first part of the compressor. An additional heat loss from the second part of the compressor air also occurs to the surroundings in the amount of 91.0 kJ/kg of air. If kinetic energy and potential energy changes are negeligable, determine the compressor power in kW. Use table A-22 for ideal gas air properties, assuming that specific heats are variable with temperature, and are not constant.

Answer 1