A farm of windmills supplies a power output of 2 MW for a community. Each windmill has blades 10 m in diameter. At the location of the windmills, the average velocity of the wind is 11 m/s and the average temperature is 20 ° C. Estimate the minimum number of windmills to be installed.

Steam-power plant

P6.1 In a steam-power plant, steam at 200 psia and 600 ° F enters a turbine and exits at 5 psia and 200 ° F. The steam enters the turbine through a 2.5-inchdiamateter pipe with a velocity of 11 ft/s and exits through a 9-inch-diamater.

Find the power in kW produced by turbine.

Chapter 6 Problem 11 A hot exhaust gas is heating a boiler to produce superheated steam at 100 psia and 400 ° F. In the meantime, the exhaust gas is cooled from 2500 to 350 ° F. Saturated liquid water (stream 1) at 14.7 psia enters the boiler with a flow rate of 200 lb/h. Superheated steam (stream 2) is used in a turbine, and discharged as saturated steam (stream 3) at 14.7 psia. Assume that the surroundings are at 70 ° F, and the heat capacity of the flue gas is C p =7.606 +0.0006077 T , where T is in Rankine and C p is in Btu/(lbmol R).

Determine the molar flow rate in mol/s of the exhaust gas needed and the maximum work produced in kJ/s.

P6.19 A steady flow adiabatic turbine receives steam at 650 K and 8200 kPa, and discharges it at 373.15 K and 101.32 kPa. If the flow rate of the steam is 12 kg/s determine

(a) The maximum work in kJ/s and

(b) The work loss in kJ/s if the surroundings are at 298.15 K.

P6.35 A steam power plant is using a geothermal energy source. The geothermal source is available at 220 ° C and 2320 kPa with a flow rate of 50 kg/s. The hot water goes through a valve and a flash drum. Steam from the flash drum enters the turbine at 550 kPa and 428.62 K. The discharged steam from the turbine has a quality of x 4 = 0.90. The condenser operates at 15 kPa. The water is a saturated liquid after passing through the condenser.

Determine the net work output in kW.

Chapter 6 Problem 42 In a hydropower plant, a hydroturbine operates with a head of 33 m of water. Inlet and outlet conduits are 1.70 m in diameter. If the outlet velocity of the water is 4.6 m/s

estimate the power produced by the turbine in kJ/s.

Chapter 6 Problem 46 A farm of windmills supplies a power output of 2 MW for a community. Each windmill has blades 10 m in diameter. At the location of the windmills, the average velocity of the wind is 11 m/s and the average temperature is 20 ° C.

Estimate the minimum number of windmills to be installed.