Chapter 7, Problem 7.85P

Figure P6.90 shows a simple vapor power cycle operating at steady state with water as the working fluid. Data at key locations are given on the figure. Flow through the turbine and pump occurs isentropically. Flow through the steam generator and condenser occurs at constant pressure. Stray heat transfer and kinetic and potential energy effects are negligible. Sketch the four processes of this cycle in series on a T-s diagram. Determine the thermal efficiency.

Figure 5.15 in the text gives a schematic of a Carnot cycle operating with a H2O liquid/vapor with a steady flow (constant mass flow rate) through each component. From the properties given below your cycle may or may not be a Carnot cycle. Kinetic energy and potential energy changes can be ignored in this problem. The cycle conditions are as follows: Process 4 – 1: constant pressure at 300 kPa from saturated liquid to saturated vapor Process 2 – 3: constant pressure at 30 kPa from x2 = 87.9% to x3 = 10.9% a) Determine the thermal efficiency using steam table data b) Compare the result of part a) with the Carnot efficiency using the boiler and condenser temperatures. c) State if the cycle is internally reversible, irreversible or impossible

Steam enters the first-stage turbine at 40 bar and 500 °C with a mass flow rate of 17.36 k9. Steam exits the turbine at 20 bar and 400 °C. The steam is then reheated at constant pressure to 500 °C before entering the second-stage turbine. Steam leaves the second-stage turbine at 0.6 bar. For operation at steady state, and ignoring stray heat transfer and kinetic and potential energy effects, sketch a T – s diagram of processes 1-4 and determine: (a) The entropy generated in the first-stage turbine [0.64 kW/K] (b) The isentropic efficiency of the first-stage turbine [89%] (c) The exit temperature of the turbine 2 if its isentropic efficiency is nT, = 0.85 [130 °C] (d) The entropy production in the reheater if the average boundary temperature is 600 °C [0.91 kW /K] Steam + P = 40 bar T = 500°C (AV), = 90 m³/min P4= 0.6 bar Power Turbine Turbine P2 = 20 bar T = 400°C Reheater P = 20 bar T3 = 500°C 2 Qreheater

Air is drawn into a gas turbine working on constant pressure cycle at 1 bar, 21 ℃ and compressed to 5.7 bar. The temperature at the end of heat supply is 680 ℃. Taking expansion and compression to be adiabatic where k = 1.4, calculate the heat energy supplied per kg at constant pressure. Select one: Air is drawn into a gas turbine working on constant pressure cycle at 1 bar, 21 ℃ and compressed to 5.7 bar. The temperature at the end of heat supply is 680 ℃. Taking expansion and compression to be adiabatic where k = 1.4, calculate the heat energy supplied per kg at constant pressure.   a. 489 kJ/kg b. 501 kJ/kg c. 472 kJ/kg d. 389 kJ/kg a. 489 kJ/kg b. 501 kJ/kg c. 472 kJ/kg d. 389 kJ/kg

Figure below shows a simple vapor power plant operating at steady state with water as the working fluid. Data at key locations are given on the figure. The mass flow rate of the water circulating through the components is 109 kg/s and isentropic turbine efficiency is 80%. Stray heat transfer and kinetic and potential energy effects can be ignored. Determine (a) the net power developed, in MW. (b) the thermal efficiency. (c) the isentropic pump efficiency. (d) the mass flow rate of the cooling water, in kg/s. (e) the rates of entropy production, each in kW/K, for the turbine, condenser, and pump. P-100 bar Ty-$60°C Power out Turbine Py-0.08 bar -80% Steam Cooling water in at 20°C generator Condenser P-100 bar T-60°C Cooling water out at 40°C 4. Pump 3 P= 0.08 bar Saturaied liquid Power in ww

The figure shows the schematic of a vapor power plant in which 100 kg/s of water circulates through the four components operating at steady state. The water flows through the boiler and condenser at constant pressure and through the turbine and pump adiabatically. Kinetic and potential energy effects can be ignored. Process data follow:Process 4–1: constant-pressure at 1 MPa from saturated liquid to saturated vaporProcess 2–3: constant-pressure at 20 kPa from x2= 88% to x3= 18%Determine the cycle thermal efficiency. Determine σcycle , in kW/K. Determine if the cycle is internally reversible, irreversible, or impossible.

As shown in the figure, Refrigerant 22 enters the compressor of an air conditioning unit operating at steady state at 40°F, 80 lbp/in² and is compressed to 160°F. 200 lb/in?. The refrigerant exiting the compressor enters a condenser where energy transfer to air as a separate stream occurs, and the refrigerant exits as a liquid at 200 lb/in², 90°F. Air enters the condenser at 75°F, 14.7 lb/in² with a volumetric flow rate of 1000 ft3/min and exits at 110°F. Neglect stray heat transfer and kinetic and potential energy effects, and assume ideal gas behavior for the air. Step 1 Compresser 1+R22 Hint Step 2 mg22 = 7.026 7-11 wwwww www Wa= 7₂=160 F P-200 7₁-4FF P-80² Your answer is correct. Determine the mass flow rate of refrigerant, in lb/min. Determine the mass flow rate of refrigerant, in lb/min, and the compressor power, in horsepower. * Your answer is incorrect. 2.125 -Condemer lb/min Determine the compressor power, in horsepower. Aus at T P 1471² (AV) 7₁-90°F Py = 200 m² hp P == 300…

6.110 Figure P6.110 shows a simple vapor power plant operating at steady state with water as the working fluid. Data at key locations are given on the figure. The mass flow rate of the water circulating through the components is 109 kg/s. Stray heat transfer and kinetic and potential energy effects can be ignored. Determine a. the net power developed, in MW. b. the thermal efficiency. c. the isentropic turbine efficiency. t2 d. the isentropic pump efficiency. e. the mass flow rate of the cooling water, in kg/s. f. the rates of entropy production, each in kW/K, for the turbine, condenser, and pump. P = 100 bar T = 520°C %3D Power out Turbine P2 = 0.08 bar 2 = 90% %3D Steam Cooling water in at 20°C generator Condenser Pa= 100 bar T= 43°C Cooling water out at 35°C 4. Pump 3 P3 0.08 bar Saturated liquid Power in FIGURE P6.110 2. www

As shown in the figure, Refrigerant 22 enters the compressor of an air conditioning unit operating at steady state at 40°F, 80 lb/in² and is compressed to 160°F, 200 lb/in². The refrigerant exiting the compressor enters a condenser where energy transfer to air as a separate stream occurs, and the refrigerant exits as a liquid at 200 lb/in², 90°F. Air enters the condenser at 70°F, 14.7 lb-/in² with a volumetric flow rate of 1500 ft³/min and exits at 110°F. Neglect stray heat transfer and kinetic and potential energy effects, and assume ideal gas behavior for the air. Step 1 I₁-110°F Compressor 1+ R22 at MR22 = www www T₂-160°F P₁-200 lbfin.² Condenser Air at T₁ P4-14.71bfin.² (AV), 7₁-90°F P-200 lbf/in² T₁=40°F Pi-80 lbfin.² Determine the mass flow rate of refrigerant, in lb/min, and the compressor power, in horsepower. Determine the mass flow rate of refrigerant, in lb/min. lb/min T₂ <- 60°F T₁ = 90°F T₁ = 40°F Pa = Pa = 200 bin² P-801brin²