文档介绍：Thermal Energy Final Exam – Fall 2002
Do all eight problems. All problems count the same.
1. A system undergoes a reversible cycle while exchanging heat with three thermal
reservoirs, as shown below. Compute the magnitude and direction of Q3 and W.
2. A tank contains 2 kg of nitrogen at 100 K with a quality of 50%. Through a valve,
kg is now removed while the temperature remains constant. Find the final quality
inside the tank and the volume of nitrogen removed if the valve is located at:
a) the top of the tank,
b) the bottom of the tank.
Hint: a table for saturated nitrogen is given on page 5.
3. Saturated water vapor enters a reversible, adiabatic turbine at a pressure of 10 MPa.
At exit the pressure is MPa. A table for steam properties is given on page 6.
a) What are the inlet and exit temperatures?
b) What are the inlet and exit entropy per unit mass?
c) What are the inlet and exit qualities?
d) What is the turbine work per unit mass?
Suppose now that the turbine adiabatic efficiency is :
e) Draw both the ideal and non-ideal processes on T-s and h-s diagrams and
sketch isobars and isotherms through the inlet and exit states for the liquid
region, inside the vapor dome and for superheated vapor.
f) What is the turbine work per unit mass for the non-ideal expansion?
g) What is the exit quality for t