Chapter 6, Problem 6.18P

6.14

3. thermodynamics

Steam enters a nozzle operating at steady state at 20 bar, 263°C, with a velocity of 52 m/s. The exit pressure and temperature are 8 bar and 162°C, respectively. The mass flow rate is 2.9 kg/s. Neglecting heat transfer and potential energy, determine the inlet area in cm2.

One-quarter Ibmol of oxygen gas (O₂) undergoes a process from p₁ = 20 lbf/in², T₁ = 500°R to p₂ = 150 lb/in². For the process W = -500 Btu and Q = -202.5 Btu. Assume the oxygen behaves as an ideal gas. Determine T2, in °R, and the change in entropy, in Btu/°R.

Steam enters a turbine operating at steady state at 850oF and 450 lbf/in2 and leaves as a saturated vapor at 1.2 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.

An oil pump operating at steady state delivers oil at a rate of 10 Ib/s through a 1-in.-diameter exit pipe. The oil, which can be modeled as incompressible, has a density of 100 lb/ft and experiences a pressure rise from inlet to exit of 40 Ibf/in?. There is no significant elevation difference between inlet and exit, and the inlet kinetic energy is negligible. Heat transfer between the pump and its surroundings is negligible, and there is no significant change in temperature as the oil passes through the pump. Determine the velocity of the oil at the exit of the pump, in ft/s, and the power required for the pump, in hp.

Air is compressed in a piston–cylinder assembly from p1 = 25 lbf/in2, T1 = 500°R, V1 = 9 ft3 to a final volume of V2 = 1 ft3 in a process described by  p⁢v1.30=constant.  Assume ideal gas behavior and neglect kinetic and potential energy effects.  Using constant specific heats evaluated at T1, determine the work and the heat transfer, in Btu.

Steam enters a turbine operating at steady state at 440°C and 30 bar and leaves as a saturated vapor at 0.08 bar. The turbine develops 9000 kW, and heat transfer from the turbine to the surroundings occurs at a rate of 590 kW. Neglect kinetic and potential energy changes from inlet to exit. a. Determine the exit temperature, in °C. b. Determine the volumetric flow rate of the steam at the inlet, in m³/s. T₁-440°C P₁=30 bar Qout 590 kW 2 X₂ 100%(sat.vapor) P₂=0.08 bar W turbine = 9000 kW

1. thermodynamics