Flash Comparison of Matlab and Aspen

A quick comparison of the results found by use of the Matlab programs with those found using Aspen for the ideal cases in Example 3.2 in BGW show a remarkable agreement as they should. Slight differences in the vapor pressure functions used in the two cases probably account for the differences seen in the third decimal places. Here is a summary of those results and those reported in BGW.

Example 3.2 Flash of an ideal Mixture

Case 1: P and Fraction of Toluene recovered in the vapor Specified

	From Matlab	From Aspen	From Authors of Text
Temperature in K	393.28	393.25	393
V/F	0.8720	0.8738	0.8715
C6H6 K/C7H8 K	2.2711	2.2749	2.305
C8H10 K/C7H8 K	0.3848	0.3863	0.381

Case 2: P and T specified

	From Matlab	From Aspen	From Authors of Text
Temperature in K	390.00	390.00	390.00
V/F	0.6604	0.6641	0.7602
C6H6 K/C7H8 K	2.2924	2.2967	2.305
C8H10 K/C7H8 K	0.3805	0.3818	0.381

Case 3: P and V/F specified

	From Matlab	From Aspen	From Authors of Text
Temperature in K	392.20	392.15	391.9
V/F	0.8000	0.8000	0.8000
C6H6 K/C7H8 K	2.2780	2.2822	2.305
C8H10 K/C7H8 K	0.3834	0.3848	0.381

Examples 7.3 & 7.4: Non-ideal Separations

Examples 7.3 and 7.4 offered more contrast between the simulations found with Matlab and Aspen, but most of the differences can be accounted for in activity coefficient models used in the different simulatiors. In this example T= 343K and P=1atm.

Example 7.3

	From Matlab (From Aspen) Ideal Package	From Matlab using Margules 2 suffix equation	From Aspen using Van Laar	From Aspen using Wilson with built in binary data
V/F	0.6575 (0.6661)	0.8660	0.6130	0.7511
MeOH liq mol frac	0.34885 (0.3453)	0.3334	0.3529	0.3190
n-propanol liq mol frac	0.36031 (0.3651)	0.4829	0.3431	0.4180
acetone liq mol frac	0.29084 (0.2897)	0.1837	0.3039	0.2631
MeOH K	1.2230 (1.2378)	1.2302	1.2175	1.3383
n-propanol K	0.3233 (0.3212)	0.3234	0.3195	0.3057
acetone K	1.5709 (1.5719)	1.5045	1.5157	1.6929

Example 7.4

	From Matlab (From Aspen) Ideal Package	From Matlab using Margules 2 suffix equation	From Aspen using Van Laar	From Aspen using Wilson with built in binary data
V/F	0.1356 (0.1535)	0.1532	0.1435	0.1669
Temperature K	338.92 (339.05)	334.35	339.65	336.35
MeOH liq mol frac	0.3976 (0.3966)	0.4030	0.3963	0.3955
n-propanol liq mol frac	0.22205 (0.2254)	0.2270	0.2234	0.2308
acetone liq mol frac	0.3804 (0.3780)	0.3700	0.3803	0.3737
MeOH K	1.0454 (1.0559)	0.9515	1.0649	1.0676
n-propanol K	0.2675 (0.2649)	0.2233	0.2712	0.2013
acetone K	1.3802 (1.3798)	1.5294	1.3603	1.4216