1.
A path of process is described by
p = 4/v - 1 + 0.8v2
If p = 4, using Interactive Thermodynamics, evaluate v. Plot v versus p by varying p from 0.5 to 10. Use step sizes of 0.5. Submit a copy of the program statements and the solution.
2.
Two intensive properties of a system consisting of ammonia are given in the following list. For each case use an appropriate phase diagram (e,g., P-T, P-u, T-h, P-v, etc.) to identify the phase or phases that exist in the system. Also, for each case, evaluated the properties asked to be found.
- T = 10 oC, p = 0.8 bar: Find v in m3/kg, u in kJ/kg, and h in kJ/kg.
- p = 2 bar, v = 0.3742 m3/kg : Find T in oC, u in kJ/kg, and h in kJ/kg
- p = 2 bar, v = 0.665 m3/kg: Find T in oC, v in m3/kg, u in kJ/kg, and h in kJ/kg
- T = 30 oC, h = 1488.06 kJ/kg: Find p in bars, v in m3/kg, and u in kJ/kg
- T = 2 oC, p = 100 bar: Find v in m3/kg, u in kJ/kg, and h in kJ/kg
- T = 12 oC, x = 0.6: Find p in bar, v in m3/kg, u in kJ/kg, and h in kJ/kg
3.
Use the IT software program to evaluate unknown properties in problem SP-3.2. Compare the results with your solution of problem Ext-3.2.
4.
Consider saturated liquid water at 80 oC undergoing an isothermal (constant temperature) compression process. For this process evaluate specific volume (in m3/kg), specific internal energy (in kJ/kg), and enthalpy (in kJ/kg) at pressures of 25, 50, 75, 100, 150, 200, 250, and 300 bar. At each state, evaluate the % deviation of property from the saturated liquid state. Discuss the results and explain what kind of conclusion can be made from the results. You may use an Excel spread sheet to evaluate % deviations from the saturation properties.
5.
The relationship
h (T,p) = hf (T) + vf (T) [p -psat (T)] (1)
is given for the approximation of enthalpy in the compressed liquid region. For the water in the compressed liquid region, compare the actual enthalpy data with those obtained from the approximation equation (Eq.1) along constant temperature lines 80 oC, 180 oC, 220 oC, 260 oC , and 300 oC, as pressure increases above the saturation pressure. In each case determine whether the correction term, vf (T) [p -psat (T)] improves the accuracy of approximation of h (T,p) over the approximation just by h (T,p) = hf (T).
6.
For superheated water vapor, plot (on a single graph) the values of h (in kJ/kg) as a function of temperature, for constant pressures of 1 bar, 0.7 bar, 0.35 bar, and 0.06 bar. What kind of conclusion can be made from the graph that you have constructed? Also, on a separate graph, plot the values of h (in kJ/kg) as a function of temperature, for constant pressures of 40 bar, 100 bar180 bar, and 320 bar. What kind of conclusion can be made from the graph that you have constructed in this case? You may use MS-Excel for this problem.
7.
Two tanks are connected by a valve. One tank (A) has a volume of 0.42 m3 containing 5 kg of Refrigerant-22 (R-22) at 3 bar. The second tank (B) contains 3.0 kg of R-22 at 20 bars and 100 oC. The valve is opened, allowing the refrigerant in two tanks to be mixed and reach an equilibrium state at 10 bars. During this process heat transfer occur at the surfaces of two tanks.
- Use the thermodynamics property tables in the textbook, find solutions to the following steps of problem (20 points)
- Determine what phase or phases are initially present in tanks A and B.
- Evaluate the volume of thank B, in m3.
- Calculate the total heat transfer, in kJ and the direction of heat transfer.
- Formulate and solve this problem, using the IT software .You must provide a hard copy of the formulation of the problem in IT and the solution (20 points)
- Evaluate the heat transfer values, in kJ, by varying the final pressure from 3.5 to 19.5 bars, with a step size of 0.5 bar. Plot Q versus the final pressure. You may use IT for this part of the problem (10 points).
Now consider that the two tanks are well insulated. The initial conditions of the two tanks are the same as before. The valve is opened, allowing the refrigerant in two tanks to be mixed until it reaches an equilibrium state. Determine whether the final state is, compressed liquid, superheated vapor, or a mixture of liquid and vapor at the final state. Evaluate temperature and pressure if the final state is a single phase; or temperature, pressure, and the quality, if the final state in the two phase region. Discuss the results.
8.
Consider two kg of ethylene undergoing a constant pressure process from T1 = 10 oC, P1 = 76.8 bar to T2 = 52.45 oC.
- Does ethylene behave as an ideal gas during this process? Provide justification for your answer.
- Evaluate V1 and V2, in m3.
- Calculate the work during the process. Explain whether the work is done on the system or by the system.