In a hydroelectric power plant, 65 m3/s of water flows from an elevation of 90 m to a turbine, where electric power is generated. The overall efficiency of the turbine–generator is 84 percent. Disregarding frictional losses in piping, estimate the electric power output of this plant.

An electric motor is rated at 10 horsepower (HP) and costs $800. Its full-load efficiency is specified to be 85%. A newly designed, high-efficiency motor of the same size has an efficiency of 90%, but costs $1,200. It is estimated that the motors will operate at a rated 10-HP output for 1,500 hours a year, and the cost of energy will be $0.07 per kilowatt-hour. Each motor is expected to have a 15-year life. At the end of 15 years, the first motor will have a salvage value of $50, and the second motor will have a salvage value of $100. Consider the MARR to be 8%. (Note: 1 HP= 0.7457kW.)(a) Determine which motor should be installed based on the PW criterion.(b) What if the motors operated 2,500 hours a year instead of 1,500 hours ayear? Would the motor selected in (a) still be the choice?

A refrigerator does 26.0 k) of work while moving 117 kJ of thermal energy from inside the refrigerator. (a) Calculate the refrigerator's coefficient of performance. (b) Calculate the energy it transfers to its environment. kJ

A new electric power plant has an efficiency of 37%. For every 100 barrels of oil needed to run the turbine, how many are essentially lost as waste heat (in barrels of oil) to the environment?