## Chapter 3:

From Components

to Models

### Abstract

Read the abstract### Table of contents

See the table of contents### List of examples

- 3-1: Vapour pressure predictions of methane using different formulas
- 3-2: Quality evaluation of molar volume correlations
- 3-3: Evaluation of the ideal gas heat capacity equations for n-pentane
- 3-4: Quality evaluation of vapourisation enthalpy correlations
- 3-5: Comparison of second virial coefficient calculation methods
- 3-6: Comparison of critical points and acentric factor from different databases
- 3-7: Use of the group contribution methods of Joback and Gani
- 3.8: Diesel fuel characterization
- 3.9: Vapour pressures of di-alcohols
- 3.10: Find the parameters to fit the vapour pressure of ethyl oleate
- 3.11: Fitting of BIP coefficients for the mixture water + MEA with the NRTL model
- 3.12: Separation of n-butane from 1,3 butadiene at 333.15K using vapour-liquid equilibrium
- 3.13: Draw the heteroazeotropic isothermal phase diagram of the binary mixture of water and butanol at 373.15 K
- 3.14: Isothermal phase diagram using the Flory Huggins activity coefficient model
- 3.15: Use of an equation of state for pure component vapour pressure calculations

# Example 3-4: Quality evaluation of vapourisation enthalpy correlations

A comparison of enthalpy of vaporisation for two hydrocarbons is to be proposed. Differences between different correlations will be analysed. The various equations are the following:

### DIPPR form:

### Yaws form:

### PPDS form:

### Watson’s form:

In these relationships, the reduced temperature is defined as: and the parameter τ is deduced from: . Coefficients for the different equations are:

Equation |
T_{c} (K) |
A |
B |
C |
D |
E |
---|---|---|---|---|---|---|

DIPPR |
469.67 |
39.109 |
0.38681 |
0 |
0 |
0 |

Yaws |
470.08 |
39.1846 |
0.388985 |
- | - | - |

Equation |
T_{c} (K) |
A |
B |
C |
D |
E |
---|---|---|---|---|---|---|

DIPPR |
562.05 |
45.346 |
0.39053 |
0 |
0 |
0 |

PPDS |
562.05 |
0.00171484 |
0.0258604 |
-0.0243564 |
0.00740881 |
0.00680068 |

For the Watson equation, we can take = 33.6 kJ/mol at *T _{0}* =300K for benzene.

## Analysis:

- The properties are temperature and enthalpy of vaporisation.
- Components are respectively pentane and benzene, which are databank components.

## Solution:

### See complete results in file (xls):

Some help on nomenclature and tips to use this file can be found here.

A graph is constructed with the relative difference obtained by the various polynomials and compared against the DIPPR equation. The deviations between these different relations are weak and for this kind of compound are in agreement with the experimental deviation.

## References

R. L. Rowley, W. V. Wilding, J. L. Oscarson, Y. Yang, N. A. Zundel, T. E. Daubert, R. P. Danner, *DIPPR® Data Compilation of Pure Compound Properties*, Design Institute for Physical Properties, AIChE, New York, NY (2003).