Chapter 6, Problem 6.94P

T-9

Saturated water vapor at 300°F enters a compressor operating at steady state with a mass flow rate of 5 Ib/s and is compressed adiabatically to 650 lbf/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.

An ideal gas, initially at 30°C and 100 kPa, undergoes the following cyclic processes in a closed system: (a) In mechanically reversible processes, it is first compressed adiabatically to 500 kPa, then cooled at a constant pressure of 500 kPa to 30°C, and finally expanded isothermally to its original state. (b) The cycle traverses exactly the same changes of state, but each step is irreversible with an efficiency of 80% compared with the corresponding mechanically reversible process. Note: The initial step can no longer be adiabatic. Calculate Q, W, ∆U, and ∆H for each step of the process and for the cycle. Take CP = (7/2)R and CV = (5/2)R.

Steam at 50 bar and 600°C enters an adiabatic turbine and leaves as saturated vapor at 1.5 bar. The elevation of the entrance is 3 m above the exit. The velocities at the entrance and exit are 3 m/s and 0.3 m/s, respectively. a. What is the specific power produced in the turbine? Answer: 972.96 kJ/kg b. How much do potential and kinetic energies contribute to this power? Answers: Kinetic Energy Contribution = 4.6 x 104% Potential Energy Contribution = 2.98 x 105%

R-134a enters a compressor operating at steady state at -4°C, quality of 0.95 and exits at a pressure of 1400 kPa. If the exit temperature is 70°C, determine the (a) isentropic compressor efficiency in %, (b) the work input, in kJ/kg of refrigerant flowing and the (c) change in the entropy of the refrigerant, in kJ/kg-K. Heat transfer between the compressor and its surroundings as well as the kinetic and potential energy effects can be ignored.

How do I solve this in steps? What equations do I use?

Air at 200 kPa, 52°C, and a velocity of 355 m/s enters an insulated duct of varying cross-sectional area. The air exits at 100 kPa, 82°C. At the inlet, the cross-sectional area is 11.57 cm². Assuming the ideal gas model for the air, determine: (a) the exit velocity, in m/s. (b) the rate of entropy production within the duct, in kW/K. Part A Determine the exit velocity, in m/s. V2 = i m/s Save for Later Attempts: 0 of 1 used Submit Answer Part B The parts of this question must be completed in order. This part will be available when you complete the part above.

Steam enters an adiabatic turbine with a mass flow rate of 5 kg/s at 3 MPa, 600° C, and 80 m/s. It exits the turbine at 40° C, 30 m/s, and a quality of 0.9. Part A Assuming steady-state operation, determine the shaft power produced by the turbine. Use the PC flow-state TESTcalc to evaluate enthalpies at the inlet and exit. Express your answer to four significant figures and include appropriate units. HÀ ? Wext = Value Units Submit Request Answer

A turbine provides 5 MW of power. Determine the rate of heat transfer between the turbine and its surroundings if the operational conditions are as follows: The turbine operates at steady state. Water enters the turbine at 2 MPa and 360 C with a velocity of 100 m/s. Saturated vapor exits at 0.1 MPa and a velocity of 50 m/s. The elevation of the inlet is 3 m higher than at the exit. The mass flow rate of water is 15 kg/s. Let g= 9.81 m/s^2. Select one: a. -2315.2 kW b. - 812.2 W c. 1112.1 MW d. - 331.4 MW