Chapter 6, Problem 6.101P

Liquid water flows isothermally at 20°C through a one-inlet, one-exit duct operating at steady state. The duct's inlet and exit P2 = 4.8 bar T = 320°C diameters are 0.02 m and 0.04 m, Water vapor (AV)2 = (AV)3 respectively. At the inlet, the velocity is 50 m/s and the pressure is 1 bar. At the exit, determine the mass flow rate, in kg/s, and V, T A1 = 0.2 m? P1 = 5 bar 3 velocity, in m/s. P3= 4.8 bar T3 = 320°C

0.2 m³ of air at 4 bar and 130 °C is contained in a system. A reversible isothermally expansion takes place till the pressure falls to 1.02 bar. The gas is then heated at constant pressure till Temperature is 144 °C. Calculate: (i) Pressure, Temperature and volume of each state. (ii) The work done. (iii) The net heat supplied. Take cp = 1 kJ/kg K, cv = 0.714 kJ/kg K.

Saturated water vapor at 300°F enters a compressor operating at steady state with a mass flow rate of 5 lb/s and is compressed adiabatically to 700 Ibf/in.? If the power input is 2150 hp, determine for the compressor: (a) the percent isentropic compressor efficiency and (b) the rate of entropy production, in hp/°R. Ignore kinetic and potential energy effects.

C6 5.

Air with a mass flow rate of 2.5 kg/s enters a horizontal nozzle operating at steady state at 480 K, 350 kPa, and velocity of 5 m/s. At the exit, the temperature is 300 K and the velocity is 450 m/s. Using the ideal gas model for air with constant cp=1.011 kJ/kg K, determine: (a) the area at the inlet, in m²; (b) Calculate the work done by the control volume and the flow work, in KW; . (c) the heat transfer to the nozzle from its surroundings, in kW.

Carbon dioxide gas is compressed at steady state from a pressure of 20 Ibf/in? and a temperature of 32°F to a pressure of 50 Ibf/in? and a temperature of 120°F. The gas enters the compressor with a velocity of 30 ft/s and exits with a velocity of 80 ft/s. The mass flow rate is 2500 Ib/hr. The magnitude of the heat transfer rate from the compressor to its surroundings is 5% of the compressor power input. Use the ideal gas model with cp = 0.21 Btu/lb.°R and neglect potential energy effects. Determine the flow area at the inlet, in ft2, and the power required by the compressor to work, in horsepower.

Parvinbhai

Refrigerant 134a enters a horizontal pipe operating at steady state at 40°C, 300 kPa, and a velocity of 40 m/s. At the exit, the temperature is 50°C and the pressure is 240 kPa. The pipe diameter is 0.055 m. Determine: (a) the mass flow rate of the refrigerant, in kg/s, (b) the velocity at the exit, in m/s, and (c) the rate of heat transfer between the pipe and its surroundings, in kW.

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