Nitrogen gas is compressed at steady state from a pressure of 14.2 psi and a temperature 60o F to a pressure of 120 psi and a temperature of 500o F. The gas enters a compressor with a volumetric flow rate of 1200 ft3 /min. The magnitude of the heat transfer rate from the compressor to its surroundings is 5% of the compressor power input. Using the ideal gas model (with variable specific heats) and neglecting kinetic and potential energy effects, determine (a) The compressor power input (in horsepower). (b) The volumetric flow rate at the exit (in ft3 /min).

An external consultant recommends that a plant installs a bank of capacitors for power factor correction. this will reduce the peak electrical demand charges by an average of 93 kw every month. the plant current pays $13 per kw in peak demand charges. the capacitor bank will include 223 kw of fixed capacitors, and 183 of variable capacitors. the fixed capacitors cost $59 per kw, and the variable capacitors will cost $65 per kw. the consultant charges 21% of the equipment costs to install the capacitors. because this project will reduce the demand for the electric utility, they are prepared to provide a one-time rebate of $42 per kw of reduced demand. what is the simple payback period for this project (in years)?