Chapter 7, Problem 7.18P

A steam turbine at steady state is operated at part load by throttling the steam to a lower pressure before it enters the turbine. Before throttling, the pressure and temperature are, respectively, 1.5 MPa and 320°C. After throttling, the pressure is 1 MPa. At the turbine exit, the steam is at .08 bar and a quality of 90%. Heat transfer with the surroundings and all kinetic and potential energy effects can be ignored. Determine. (a) the temperature at the turbine inlet, in °C, and (b) the power developed by the turbine, in kJ/kg of steam flowing.

A steam turbine at steady state is operated at part load by throttling the steam to a lower pressure before it enters the turbine. Before throttling, the pressure and temperature are, respectively, 1.5 MPa and 320°C. After throttling, the pressure is 1 MPa. At the turbine exit, the steam is at .08 bar and a quality of 90%. Heat transfer with the surroundings and all kinetic and potential energy effects can be ignored. Determine. (a) the temperature at the turbine inlet, in °C, and (b) the power developed by the turbine, in kJ/kg of steam flowing.

Determin the exergy, in kJ, of the contents of a 1.5 m3 storage tank, if the tank is filled with: a) air as an ideal gas at 440°C and 0.70 bar b) water vapor at 440°C and 0.70 bar Ignore the effects of motion and gravity and let To = 22°C and Po=1 bar.

A pump operating at steady state receives 2.4 kg/s of liquid water at 50°C, 1.5 MPa. The pressure of the water at the pump exit is 15 MPa. The magnitude of the work required by the pump is 37.8 kW. Štray heat transfer and changes in kinetic and potential energy are negligible. Determine the work required by a reversible pump operating with the same conditions, in kW, and the isentropic pump efficiency.

Refrigerant 134a enters an insulated diffuser as a saturated vapor at 80 deg F with a velocity of 800 ft/s. The inlet area is 1.4 in^2. At the exit, the pressure is 400 lbf/in2 and the velocity is negligible. The diffuser operates at steady state and potential energy effects can be neglected. Determine the mass flow rate, in lb/s, and the exit temperature, in deg F.

answer 99 and 100

A pump operating at steady state receives 1.2 kg/s of liquid water at 50°C, 1.5 MPa. The pressure of the water at the pump exit is 14 MPa. The magnitude of the work required by the pump is 21 kW. Stray heat transfer and changes in kinetic and potential energy are negligible. Determine the work required by a reversible pump operating with the same conditions, in kW, and the isentropic pump efficiency. Step 1 Determine the work required by a reversible pump operating with the same conditions, in kW. W p.rev kW i Save for Later Attempts: 0 of 1 used Submit Answer Step 2 The parts of this question must be completed in order. This part will be available when you complete the part above.

7-54 A gas turbine operating at steady state is shown in Fig. P7.54. Air enters the compressor with a mass flow rate of 5 kg/s at 0.95 bar and 22°C and exits at 5.7 bar. The air then passes through a heat exchanger before entering the turbine at 1100 K, 5.7 bar. Air exits the turbine at 0.95 bar. The compressor and turbine operate adiabatically and the effects of motion and gravity can be ignored. The compressor and turbine isentropic efficiencies are 82 and 85%, respectively. Let T. = 22°C, p. = 0.95 bar. Using the ideal gas model for air, determine, each in kW, a. the net power developed. 725-5 b. the rates of exergy destruction for the compressor and turbine. 125-3, 138.6 -).964 c. the net rate exergy is carried out of the plant at the turbine exit, Py = 5.7 bar n₂=82% Compressor m₂ = 5 kg/s P₁ = 0.95 bar 1 T₁ = 22°C Qa Heat exchanger FIGURE P-64 P-5.7 bar 7,- 1100 K Turbine -n₁ = 85% PL-0.95 bar

Steam enters a turbine operating at steady state at 850oF and 450 lbf/in2 and leaves as a saturated vapor at 1.4 lbf/in2. The turbine develops 12,000 hp, and heat transfer from the turbine to the surroundings occurs at a rate of 2 x 106 Btu/h. Neglect kinetic and potential energy changes from inlet to exit. Determine the exit temperature, in oF, and the volumetric flow rate of the steam at the inlet, in ft3/s.