The purification of hydrogen gas is possible by diffusion through a thin palladium sheet. calculate the number of kilograms of hydrogen that pass per hour through a 4.3-mm-thick sheet of palladium having an area of 0.38 m2 at 500°c. assume a diffusion coefficient of 4.7 × 10-8 m2/s, that the concentrations at the high- and low-pressure sides of the plates are 2.3 and 0.34 kg/m3 of hydrogen per cubic meter of palladium, and that steady-state conditions have been attained.

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)?