Microsoft Word - Cengel and Boles TOC _2-03-05_.doc

Beattie-Bridgeman, and Benedict-Webb-Rubin equations of state is illus-
trated in Fig. 3–60. It is apparent from this figure that the Benedict-Webb-
Rubin equation of state is usually the most accurate.

Chapter 3 | 147

v, m^3 /kmol

T, K

300

200

100

0

0.01 0.1 1 10 100

20.7%

14.1%

2.1%

11.6%

6.3%

1.2%

3.2%

0.1%

1.0%

0.4%

0.1%

0.4%

0.1%

0.0%

0.2%

0.0%

0.0%

0.0%

0.0%

0.0%

0.0%

0.0%

0.0%

0.0%

5.7%

59.3%

18.7%

15.2%

74.5%

51.0%

7.9%

0.7%

5.2%

5.2%

0.6%

3.7%

3.3%

0.4%

2.5% 1.6%

0.2%

1.3%

0.8%

0.1%

0.8%

0.4%

0.1%

0.3%

>100%

>100%

>100%

0.9%

0.1%

0.1%

0.4%

0.1%

0.1%

20 MPa10 MPa 4 MPa 2 MPa 1 MPa 0.2 MPa0.1 MPa

0.0125 MPa

0.0%

0.0%

0.0%

0.0%

0.0%

0.0%

0.1%

0.0%

0.0%

0.5%

0.0%

0.0%

1.0%

0.1%

0.1%

1.9%

0.1%

0.1%

4.2%

0.1%

0.2%

4.7%

0.2%

0.2%

0.1%

0.0%

0.0%

0.1%

0.0%

0.0%

0.5%

0.0%

0.0%

0.5%

0.1%

0.0%

1.1%

0.1%

0.0%

2.3%

0.1%

0.0%

5.3%

0.1%

0.1%

3.7%

0.1%

0.4%

1.2%

0.1%

0.1%

2.8%

0.1%

0.1%

6.7%

0.7%

0.1%

2.9%

0.3%

0.7%

Van der Waals (top)

Beattie-Bridgeman (middle)

Benedict-Webb-Rubin (bottom)

FIGURE 3–60

Percentage of error involved in various equations of state for nitrogen (% error
[(|vtablevequation|)/vtable] 100).

EXAMPLE 3–13 Different Methods of Evaluating Gas Pressure

Predict the pressure of nitrogen gas at T
175 K and v
0.00375 m^3 /kg

on the basis of (a) the ideal-gas equation of state, (b) the van der Waals

equation of state, (c) the Beattie-Bridgeman equation of state, and (d) the

Benedict-Webb-Rubin equation of state. Compare the values obtained to the

experimentally determined value of 10,000 kPa.

Solution The pressure of nitrogen gas is to be determined using four differ-

ent equations of state.