Water vapor enters a valve with a mass flow rate of 2 kg/s at a temperature of 320 degrees Celsius and a pressure of 60 bar and undergoes a throttling process to 40 bar.
(a) Determine the flow energy rates at valve inlet and exit and the rate of exergy destruction, each in kW.
(b) Evaluating exergy at 8.5 cents per kW*h, determine the annual cost, in $/year, associated with the exergy destruction, assuming 8400 hours of operation annually.