Rarey/Nannoolal methods

Estimate the critical data of R227ea (CF3-CHF-CF3) with the Rarey/Nannoolal method. The normal boiUng point is given by Tj, = 256.73 K [10]. The molar mass is M = 170.027 g/mol. The number of atoms in the molecules is 10, where hydrogen is not counted. 

Vi is the number of occurrences of group i in the molecule. The values for the particular group contributions are listed on www.ddbst.com. The results for the representation of the data sets are reported to be superior to those obtained with other methods [12]. An evaluation with more than 2000 substances yielded average deviations of 16.5 K for the Joback method and only 1.5 K for the Rarey/Nannoolal method, which demonstrates the superiority of the latter one. 

Estimate the normal boiling point of pentylcyclohexane (Figure 3.2) with the Rarey/Nannoolal method. 

Estimate the dynamic viscosity of liquid R123 (CF3-CHCI2) at = 30 °C and 1 2 = 50 °C using the Rarey/Nannoolal method. The normal boiling point is Tfc = 300.97 K. 

Critical temperatures, critical pressures, and critical volumes can be estimated with group contribution methods. The most common ones are from Lydersen (1), Ambrose [2, 3), joback and Reid [4], and Constantinou and Gani (5). They are all explained in [6]. A recent development by Rarey and Nannoolal [7, 8) seems to be the most accurate one, but it is more difficult to apply. 

Recently, a new method has been developed by Rarey and Nannoolal [7,8]. Based on the Dortmund Data Bank, the method has made use of all the data currently available. It has overcome the difficulties of other methods for large molecules with more than 20 carbon atoms. The calculation equations are... 

A new group contribution method developed by Rarey and Nannoolal [72] performs significantly better. Its relative mean deviation turned out to be 15.3% for 813 components. The method is defined by the following equation ... 

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