Chapter 6, Problem 6.122EP

1. Steam at 10 MPa, 500°C has an ideal engine turbine that has one stage of reheat, K] exhaust is at 0.005 MPa and 85% quality. The work produced by the engine is 800 kg. Determine the thermal efficiency of the turbine.

! Required information NOTE: This is a multi-part question. Once an answer is submitted, you will be unable to return to this part. An adiabatic pump is to be used to compress saturated liquid water at 10 kPa to a pressure of 15 MPa in a reversible manner. P₁ 15 MPa Pump Calculate the errors involved in parts b and c. The error involved in part b is The error involved in part cis %. %.

4. Air at a temperature of 500 0C is compressed at a constant pressure of 1.2MPa from a volume of 2 m3 to a volume of 0.4m3 . If the initial internal energy decrease is 4820 KJ, find a. The work done during the reversible compression b. The heat transferred c. The change of enthalpy d. The average specific heat at constant pressure

2. An adiabatic steam turbine that you choose above takes steam at 500 kPa and 330 °C and expands to 10 kPa. Find the dryness fraction, enthalpy change and isentropic efficiency of the plant using the conditions given if ideal enthalpy is 3645 kJ/kg.k.

9. Helium is compressed in an adiabatic cylinder from 70°F, 10 ft³, 15 psia to 1 ft³ according to the relation pVK = c. Find the work nonflow, the final temperature and the change of enthalpy.

4. A) Wet steam at 200 deg C has a specific enthalpy of 2300 kJ/kg (in the 2 phase region). Determine the quality and specific volume and specific entropy of the mixture. B) Calculate change in entropy of an ideal gas that expands freely to twice its volume, assume isothermal reversible process. What is the work done in the process 2

Question 3: Superheated steam enters a turbine at 7 MPa, 550°C, and exits at 150kPa a. Draw the system. b. If the process is reversible adiabatic (isentropic), find the final temperature (T2), the final enthalpy (h2,) of the steam, and do the energy balance to calculate the turbine work (Wts). c. Using entropy balance, show that Sgen for the above process is 0. d. If the isentropic efficiency is 85%, find the actual final temperature (T23) and calculate Sgen? e. Plot process in (b) and (d) on a Ts diagram with proper labelling.

Compute for the work steady flow.

A refrigeration using R-410a has a capacity of 320kW of refrigeration. The evaporating temperature is -10C and condesing temperature is 43C. Calculate the fraction of vapor in the mixture before the evaporator. Use the properties of R-410a from refrigerants' table.