This is problem 5-17 from El-Wakil’s Powerplant Technology book -- consider a simple combination turbine with...

This is problem 5-17 from El-Wakil’s Powerplant Technology book -- consider a simple combination turbine with one Delaval impulse stage and one 60 percent reaction stage. The nozzle of impulse stage receives steam at 900 psia and 900°F and leaves it at 300 psia. The nozzle efficiency is 97 percent and its angle is 20°. The blade speed is optimum and its velocity coefficient is 0.95. The impulse stage is followed on the same shaft by the reaction stage which exhausts to 100 psia. The steam entrance angles for that stage are also 20°. The efficiency of the fixed blades (nozzles) is 90 percent. Because of different diameters of the impulse and reaction moving blades, the velocity of the reaction blade is 1.5 that of the impulse blade. (a) Determine all steam velocities and draw the velocity diagram of the combined turbine, (b) calculate the work of each stage, in Btus per pound mass, and (c) calculate the individual stage and the turbine efficiencies.

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samet mamat answered 2 years ago

This is problem 5-5 from El-Wakil’s Powerplant Technology book -- steam expands ideally in a turbine...

This is problem 5-5 from El-Wakil’s Powerplant Technology book -- steam expands ideally in a turbine from 2500 psia and 1000 degFahrenheit to 1 psia. Compare the maximum steam velocities and the number of stages required by (a) a velocity-compounded impulse turbine, (b) a pressure-compounded impulse turbine, and (c) a 50 percent reaction turbine if the optimum blade velocity may not exceed 885 ft/s in any of them. Take all nozzle angles to be 25°.

This is problem 6-6 from El-Wakil’s Powerplant Technology book -- consider a powerplant operating on an...

This is problem 6-6 from El-Wakil’s Powerplant Technology book -- consider a powerplant operating on an ideal Rankine cycle without feedwater heating. Steam enters the turbine saturated at 1000°F at the rate 5x106 lbm/h. The turbine exhausts to a surface condenser area of 402,467 ft2 and cooling water inlet temperature of 60°F. Calculate (a) the plant net power, in megawatts, (b) the plant efficiency, in percent, (c) the cooling water exit temperature, in degrees Fahrenheit, and (d) the water flow...

This is problem 8-13 from El-Wakil’s Powerplant Technology book – Consider a combined gas-steam turbine cycle...

This is problem 8-13 from El-Wakil’s Powerplant Technology book – Consider a combined gas-steam turbine cycle with both machines ideal. Air enters the compressor at 1 atm and 500 degree R. 200 percent theoretical air gases enter the gas turbine at 2400 degree R. The pressure ratio for both compressor and turbine is 5.624. No intercooling, reheat, or regeneration are used in the gas-turbine cycle. The turbine exhaust is used directly without supplementary firing and leaves to the stack at...

This is problem 6-9 from El-Wakil’s Powerplant Technology book -- consider for simplicity an ideal Rankine...

This is problem 6-9 from El-Wakil’s Powerplant Technology book -- consider for simplicity an ideal Rankine cycle with turbine inlet and exit steam at 2500 psia and 1000°F, and 1 psia, respectively, and no feedwater heating. The steam mass flow rate is 2x106 lbm/h. The plant has two-pass surface condenser with 45-ft-long 7/8-in 18-BWG-type 304 stainless steel tubes. Cooling water enters the tubes at 70°F and 7 ft/s. With no flows into the condenser other than turbine steam, find (a)...

This is problem 5-13 from El-Wakil’s Powerplant Technology book -- a 50 percent reaction stage in...

This is problem 5-13 from El-Wakil’s Powerplant Technology book -- a 50 percent reaction stage in a steam turbine undergoes a total of 20 Btu/lbm enthalpy drop. The nozzle efficiency and angle are 88 percent and 25°, respectively. The blades move at 420 ft/s and have Vr1 = 332 ft/s, Vs2 = 386 ft/s, and ? = 22°. The steam flow is 1.08x106 lbm/h. Find (a) the work done by the stage in horsepower and megawatts, (b) the blade efficiency,...

This is problem 7-12 from El-Wakil’s Powerplant Technology book -- it is desired to compare the...

This is problem 7-12 from El-Wakil’s Powerplant Technology book -- it is desired to compare the effect of two types of dry cooling tower systems on powerplant performance. The towers are of the indirect cooling type. One operates with a surface condenser with an 8 degrees Fahrenheit terminal temperature difference, and the other with a direct-contact condenser with 0 degrees Fahrenheit terminal temperature difference. Consider for simplicity a simple ideal Rankine cycle with inlet saturated steam at 1000 psia. Further...

This is problem 7-15 from El-Wakil’s Powerplant Technology book -- a spray pond is used to...

This is problem 7-15 from El-Wakil’s Powerplant Technology book -- a spray pond is used to cool a 200-MW powerplant that has a 39 percent efficiency. The condenser cooling water outlet temperature is 90 degF. The atmosphere is at 70 degF and 60 percent relative humidity. The spray nozzles have ntu = 0.15, r = 0.015 and f = 0.25. Determine (a) the number of spray modules required, (b) the flow per module, in gallons per minute, and (c) the...

This is problem 7-5 from El-Wakil’s Powerplant Technology book -- an included-draft cooling tower cools 90,000...

This is problem 7-5 from El-Wakil’s Powerplant Technology book -- an included-draft cooling tower cools 90,000 gallons per minute of water from 84 to 68 degFahrenheit. Air at 29.75 inHg absolute pressure, 70 degFahrenheit dry bulb and 60 degFahrenheit wet bulb, enters the tower and leaves saturated at 80 degFahrenheit. Find (a) the volume flow rate of air, in cubic feet per minute, and (b) the makeup water required, in pound mass per hour.

This is problem 7-3 from El-Wakil’s Powerplant Technology book -- a natural-draft cooling tower is 450...

This is problem 7-3 from El-Wakil’s Powerplant Technology book -- a natural-draft cooling tower is 450 ft high. Air enters the tower at 14.696 psia, 50°F, and 50 percent relative humidity and leaves in a saturated condition. The pressure drop in the tower is 0.015 psi. Calculate (a) the air exit temperature, in degrees Fahrenheit, and (b) the makeup due to evaporation, in pound mass per pound mass of dry air.

This is problem 7-6 from El-Wakil’s Powerplant Technology book -- a wet cooling tower receives 1.5x106...

This is problem 7-6 from El-Wakil’s Powerplant Technology book -- a wet cooling tower receives 1.5x106 lbm/min of condenser water at 96 degFahrenheit, and 1.25x106 lbm/min of air at 1 standard atmosphere, 62 degFahrenheit, and 50 percent relative humidity. The air leaves saturated at 82 degFahrenheit. Calculate (a) the exit water temperature, in degrees Fahrenheit, and (b) the percent condenser cooling water makeup due to evaporation.

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