MTDATA – Phase Diagram Software from the National Physical Laboratory

 

 

 

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ENTHCONT

Enthalpy countours for a composition triangle in a multicomponent system

This application is used for the calculation of iso-enthalpy contours on a triangular composition grid in a multicomponent system.

The application is number 29.

set user_v(application_code) = 29 !

Before initiating the calculations it is necessary to define a datafile for the system to be covered by the calculations, to classify any phases required to be absent or identified as giving rise to miscibility gaps and to specify the pressure. All this can be set up using the normal APPLICATION commands within MTDATA.

Firstly it is necessary to specify the number of steps in composition forming a grid on the triangular cut. A value of 20 might be appropriate although this can be adjusted for coarser or finer calculations.

set user_v(number_of_steps) = 20 !

and the temperature and pressure:

set press 101325 temp 1273.15 !

The application is designed for a multicomponent system (ie with at least three components). The following example, however, is for a three component system. To calculate sections in higher order systems it is necessary simply to add more components to the composition groups.

set 'A' 0.9998 0.0001 0.0001 !
set 'B' 0.0001 0.9998 0.0001 !
set 'C' 0.0001 0.0001 0.9998 !

The corners of the diagram should be assigned to the composition groups.

set user_v(group_lower_left) 'A' !
set user_v(group_top) 'B' !
set user_v(group_lower_right) 'C' !

Finally it is necessary to define the limits and the step interval for countouring the enthalpies. This is done by setting the appropriate user variables.

set user_v(contour_start) -20000 !
set user_v(contour_end) +16000 !
set user_v(contour_step) 2500 !

The results of the calculations are stored in a ".liq" file for subsequent replotting perhaps using the LIQSURF application which provides a three dimension perspective on the calculations.

 

Updated 5 May 2010