First, we start by loading start301 in Matlab

M A T L A B (R) 
(c) Copyright 1984-98 The MathWorks, Inc.
All Rights Reserved
Version 5.2.1.1420
Apr 30 1998


To get started, type one of these: helpwin, helpdesk, or demo.
For product information, type tour or visit www.mathworks.com.

>> start301
Copyright 1998 Rice University.  
All rights reserved
Welcome to CENG301's start301!! 
You have three choices, Please read them carefully.  
Then click on the appropriate choice in the menu bar:

1: Click (1) to start a new session
2: Click (2) to enter the name of a datafile from a previous session, in the current directory
3: Click (3) to use compound names not in the CENG 301 database
WARNING...if you hit (3) no compound data will be available

***CLICK ON (1)*** 

Now choose from the above menu

***CLICK ON 'Energy & Mass Balances'***

***CLICK ON 'CENG 301's'***

Please wait while loading database...
Which units do you want to use for temperature? 
Choose one from the menu

***CLICK ON 'Kelvin' since Temperature given in Problem is Kelvin***

Input the name of your new file: 16.4-1
The output file name is: 16.4-1
Input the number of compounds: 2
The number of compounds is: 2
Enter the name of compound # 1: Ar
Enter the name of compound # 2: O2
Enter the number of reactions: 0
Here are your compounds' formulae and names:
No. Formula  Name
----------------------------------------
 1  Ar       argon  
 2  O2       oxygen 


Here are your reactions:
----------------------------------------
No reactions given



Enter the number of streams: 1
 
The variables for your compounds have now been created, you may continue, or come back later and reload the same data.



Now, we use the program 'dcalc'



>> help dcalc



 Chapman-Enskog formula for mass diffusivity coefficient for binary mixtures
 
 function D = dcalc(p,T,index)
 
 Argument List:
 p [=] pressure in kPa
 T [=] temperature in the units of Tdeg
 index [=] index of 2 compounds in cnms whose Dab is to be found
 (If this argument is omitted, Dab will be found for the first 2)
 Returns:
 D [=] mass diffusivity in units of m2/s
 
 Ex: >> clear
 >> start402
 >> d = dcalc(0.0099, 298, [1 2])
 d =
 1.8961e-05 Created 3/21/95-2 Jim Lee
 



'dcalc' requires the pressure in kPa...Use convu to convert


long-eared% convu
 Give the NUMERICAL value to be converted.
1
 Give the NUMERATOR   of the OLD units.
atm
 Give the DENOMINATOR of the OLD units.

 Give the NUMERATOR   of the NEW units.
kPa
 Give the DENOMINATOR of the NEW units.

 To change from your old units to the new ones multiply by:   101.3250
  1.000000    atm   =  101.3250    kPa   
 If you want to convert another measure, reply: y
n




Back in Matlab, 'dcalc' can now be used to solve for Dab


>> dcalc(101.3250,293.2,[1 2])

ans =

   1.8818e-05



***'dcalc' returns answer in the units of m^2/sec***


***Thus, by multiplying by cm^2 (10,000), one gets: 0.188 cm^2/sec