Due: Thursday, February 23rd

Problem 1. (15 points)

This problem concerns ammonia gas at 100deg.F and 200 psia.

For ease of comparison, use units of ft[3]/lbm for intensive volume, V, BTU/lbm for intensive enthalpy, H, and BTU/lbm R for intensive entropy, S. Show all units throughout your calculations.

A) (3 points) Calculate V using the Peng-Robinson EOS (This may be done on Maple). Compare this answer to the value given by Fig. 9.4 (p. 284) of S&VN.

B) (12 points) Estimate the residual properties V[R], H[R] and S[R] for ammonia in two ways and compare the answers you get from each method:

Method 1: Use the thermodynamic data for ammonia which can be found in Figure 9.4 (p. 284) and Table 9.2 (pgs. 285-6) of Smith and Van Ness.

Method 2: Use the generalized correlations.

Problem 2. (5 points)

A Mollier diagram (S vs. H) for steam is shown on the inside back cover of S&VN.

Find the slope of a line of constant P on a Mollier diagram as a function of P, V, T and Cp only.

Problem 3. (10 points)

A rigid vessel of 3.0 m[3 ]capacity contains 0.03 m[3] of liquid water and 2.97 m[3] of water vapor at a pressure of 101.33 kPa.

Step 1. Heat is added to the vessel until all of the liquid evaporates. What is the temperature and pressure in the vessel when the liquid water has just disappeared?

Step 2. Heating is continued until the pressure relief valve on the vessel opens. This occurs at a pressure of 40 bar. What is the temperature of the first steam which escapes?