Problem 59
Steam is throttled slightly from \(2 \mathrm{MPa}\) and \(500^{\circ} \mathrm{C}\) Will the temperature of the steam increase, decrease, or remain the same during this process?
Problem 62
Demonstrate that the Joule-Thomson coefficient is given by $$\mu=\frac{T^{2}}{c_{p}}\left[\frac{\partial(v / T)}{\partial T}\right]_{P}$$, $$\mu=\frac{T^{2}}{c_{p}}\left[\frac{\partial(v / T)}{\partial T}\right]_{p}$$
Problem 63
Consider a gas whose equation of state is \(P(v-a)=\) \(R T,\) where \(a\) is a positive constant. Is it possible to cool this gas by throttling?
Problem 65
On the generalized enthalpy departure chart, the normalized enthalpy departure values seem to approach zero as the reduced pressure \(P_{R}\) approaches zero. How do you explain this behavior?
Problem 66
Why is the generalized enthalpy departure chart prepared by using \(P_{B}\) and \(T_{B}\) as the parameters instead of \(P\) and \(T ?\)
Problem 68
Determine the enthalpy of nitrogen, in Btu/lbm, at \(400 \mathrm{R}\) and 2000 psia using \((a)\) data from the ideal-gas nitrogen table and \((b)\) the generalized enthalpy chart. Compare your results to the actual value of \(177.8 \mathrm{Btu} / \mathrm{lbm}\).
Problem 69
Determine the enthalpy change and the entropy change of \(\mathrm{CO}_{2}\) per unit mass as it undergoes a change of state from \(250 \mathrm{K}\) and \(7 \mathrm{MPa}\) to \(280 \mathrm{K}\) and \(12 \mathrm{MPa},(a)\) by assuming ideal- gas behavior and ( \(b\) ) by accounting for the deviation from ideal-gas behavior.
Problem 71
Water vapor at \(1000 \mathrm{kPa}\) and \(600^{\circ} \mathrm{C}\) is expanded to 500 kPa and \(400^{\circ} \mathrm{C}\). Calculate the change in the specific entropy and enthalpy of this water vapor using the departure charts and the property tables.
Problem 75
Oxygen is adiabatically and reversibly expanded in a nozzle from 200 psia and \(600^{\circ} \mathrm{F}\) to 70 psia. Determine the velocity at which the oxygen leaves the nozzle, assuming that it enters with negligible velocity, treating the oxygen as an ideal gas with temperature variable specific heats and using the departure charts. Answers: \(1738 \mathrm{ft} / \mathrm{s}, 1740 \mathrm{ft} / \mathrm{s}\)
Problem 79
A \(0.05-\mathrm{m}^{3}\) well-insulated rigid tank contains oxygen at \(175 \mathrm{K}\) and 6 MPa. A paddle wheel placed in the tank is turned on, and the temperature of the oxygen rises to \(225 \mathrm{K}\) Using the generalized charts, determine ( \(a\) ) the final pressure in the tank, and ( \(b\) ) the paddle-wheel work done during this process.
