To: prospective users
Subject: Windows Based Phase-equilibrium Tutorial
August 25, 2000
Here is the documentation for the PC/Windows based phase-equilibrium tutorial. The PowerPoint
presentation's file name is "phase," but the actual title on the first page of the presentation is "Computer
Visualization of Binary, Ternary, and Quaternary Fluid-Phase Equilibria." This document differs from
the instructions for the Silicon Graphics workstation version of the software.
The tutorial can be run from a CD using the autorun feature. It can also be copied to a hard disk for
faster access. In the latter case, the user can run the tutorial by double clicking the file phase.bat.
Graphics programs called from the PowerPoint presentation allow the user to explore the phase diagrams
more fully. To run these separate programs, the user must choose to enable macros when asked in a
pop up window. We recommend running this on at least a Pentium II class machine with 32 MB of ram
running Windows 9x or NT.
This package has been distributed since 1998 for Silicon Graphics Workstations only. User
response has been enthusiastic, particularly after the software was reviewed in "Science" magazine. We
expect that the PC/Windows version will find even greater application. This is supported by the numerous
inquiries that we have already received from thermodynamics teachers in several countries.
Kenneth Jolls
Iowa State University
and
Walter G. Chapman
Rice University
COMPUTER VISUALIZATION OF BINARY, TERNARY, AND QUATERNARY FLUID-PHASE
EQUILIBRIA
Kong S. Tian* and Kenneth R. Jolls
assisted by Richard J. Campero
Department of Chemical Engineering
Iowa State University
Ames, Iowa
June 1998
Ported from Unix to Windows by
Jasper Yen, Hector Perez,
and Walter G. Chapman
Department of Chemical Engineering
Rice University
Houston, TX
August 2000
* Kong Tian is with HTRI, Inc., College Station, Texas
-------------------------------------------------------------------------Copyright © 1998
Copies of the information in this tutorial may be made for educational, nonprofit purposes only and must
be accompanied by a written statement recognizing the original authors.
-------------------------------------------------------------------------Copyright © 2000
The movable image routines in this software contain runtime libraries that have been licensed from
Silicon Graphics Incorporated. These libraries cannot be distributed without permission.
General Description
The philosophy behind this software is to give students of thermodynamics an introduction to the
subject of mixture phase diagrams by using the display and animation capabilities of powerful computer
graphics hardware. We hope that by using the program students will gain an appreciation of what the
diagrams mean in terms of physical-property behavior and also of the importance of visual thinking and
hyperdimensionality in understanding thermodynamics. But it is also important that they learn the
limitations of the drawings. In the interest of producing elaborate, global displays of P,T,x,y properties, all
data in this tutorial have been generated through the equation-of-state method by using the PengRobinson equation with common mixing rules as implemented in the ASPEN PLUS chemical process
simulator. Thus many of the subtleties of mixture thermodynamics are not touched upon in this
presentation and will have to wait for later sequels that have a different focus.
There is no suggestion that the drawings shown here represent the precise physical-property
behavior of the chemical systems considered. But they are qualitatively accurate and adhere rigorously
to the requirements of the Phase Rule. The deviations that do exist in no way detract from the value of
the tutorial as a teaching device.
This is our first attempt to produce a major, general-usage visualization product for instruction in
mixture thermodynamics. The only comparable precedent that we know of is the work of Keith Gubbins
and co-workers at Cornell in the early 1980s cited on page 58 of the tutorial. Those programs were very
different from this work and were focused more on fluid-phase critical states, but they were cleverly
conceived and well executed and they brought high-performance computer graphics firmly to bear on the
problem of teaching mixture thermodynamics and phase equilibrium.
The tutorial presents three kinds of displays:
Text slides
Fixed drawings with labels and identifying comments
Movable images that can be manipulated interactively
There are 64 slides containing text and fixed drawings, and these are contained in the
PowerPoint presentation itself. Page numbers appear in the lower right-hand corners.
Running the Software
Normal operation consists of paging through the presentation sequentially and calling up the
movable images (which in each case requires temporarily leaving PowerPoint) by clicking on the fixed
drawings or on the blue buttons in the slides that precede those images. PowerPoint is then re-entered
after each movable drawing by clicking on the X button in the upper right-hand corner of the movable
image window.
Paging through the tutorial may be done in one of two ways. You may click on the blue "forward"
or "backward" arrows in the lower center of each slide, or you may use the "page down" and "page up"
keys on the computer keyboard. The "home" and "end" keys give the title (1st) and final (64th) text
pages, respectively, from any point in the tutorial. Clicking on the "Open Book" icon takes you to the
Table of Contents where you can move quickly to any named section by clicking on the blue button
containing the section name.
There are 12 movable, interactive drawings. These are given below along with the number of the
fixed page (in parentheses) from which each can be called. The movables are not numbered sequentially
in the program and have descriptive titles somewhat different than those shown below:
1. binary P-T-x,y diagram (wireframe image with gray sectioning planes)
(11)
2. azeotropic binary P-T-x,y (enlarged wireframe image)
(15)
3. isothermal, ternary composition prism
(18)
4. ternary pressure-composition prism (shaded-surface
image pair with a gray intersecting plane)
(20)
5. isobaric ternary composition prism (image pair with
an isothermal intersecting plane)
(21)
6. isothermal ternary prism with a three-phase region and tie lines
(27)
7. complete isothermal ternary prism showing VLE, LLE, LLVE,
and LLE critical states
(31)
8. isothermal ternary containing a binary azeotrope
(32)
9. isothermal ternary: three binary azeotropes and
a ternary azeotrope (image pair, isobaric plane)
(35)
10. isobaric ternary: same as number 9 but with an
isothermal plane
(36)
11.isothermal saddle azeotrope
(37)
12. wireframe ternary dew-point surface showing data
points and triangular graphic elements
(43)
In movable image 1, the P-T-x,y phase diagram can be displayed either in wireframe or with surface
shading. Use the Boil and Dew switch buttons to toggle the two surfaces on/off. To view an isothermal or
isobaric slice of the phase envelope, first click on the arrow symbol in the upper right-hand corner and
then turn the surfaces on. Click and drag the three-dimensional arrow to move the isothermal or isobaric
sectioning planes. Note the agreement between the sectioning of the surfaces and the two-dimensional
red/green curves already drawn.
To be able to move either sectioning plane you must turn the diagram so that the controlling 3-D
arrow is directly visible, not "hidden" behind the drawing.
In all of the movable images mock thumbwheels appear in the margin of the display labeled Rotx,
Roty, and zoom. These may be "turned" by dragging the mouse cursor over a particular thumbwheel to
rotate or zoom the image. Rotation (and even sustained motion) can be imparted to the model also by
moving the hand-shaped cursor over the image with the left mouse button depressed. This may be
helpful in gaining a sense of the three-dimensionality of the drawings (and it may also be fun), but
accurate positioning [e.g., to generate precise top or side (2-D) views] is better accomplished with the
Rotx and Roty controls. These give movement around only one axis at a time. As an example, see the
comments on page 15 for two-dimensional positioning of the movable binary azeotrope.
Movable images 4, 5, 9, and 10 comprise two-parts each: a 2-D fixed view and a 3-D movable
view. The 2-D image is the view from directly above the cutting plane. The effect is to create a twodimensional triangular projection on the right side of the screen of the three-dimensional prism shown on
the left. The idea is then to move the intersecting plane up or down (which changes the pressure or
temperature of the section) and observe the bubble-point and dew-point curves on each side of the
display.
To move the cutting plane, first choose the arrow cursor by clicking on the arrow button at the top
right of the screen. Then click and drag the 3-D arrow to move the plane. In some cases, it is necessary
to hold down the "alt" key to allow smooth movement of the cutting plane.
We repeat that the movable drawings can be accessed only by clicking the mouse on the fixed
drawings or on the blue buttons in the screens that precede them. To return to the PowerPoint
presentation, click on the X in the upper right side of the window. This operation returns to the fixed page
that preceded the movable, after which one can continue through the tutorial in the forward or backward
direction using the blue arrows or the "page down/up" keys.
It is also possible to move back and forth quickly between a movable drawing and the fixed
text/image screen that precedes it. To do this use the the ctrl-tab key combination to switch windows.
This is particularly useful for the movables that follow fixed images directly. The movable images have
very few callouts (labels, numbers, comments, etc.) because the alphanumeric characters are often
bothersome as the drawing is moved around in 3-D space. But by switching quickly between the fixed
and movable drawings, numerical values, axis labels, and other text items can be remembered more
easily while changing from one type of display to the other. This operation gives access only to the
preceding text/image page. To reach any other fixed page the movable image should be closed
completely by clicking on the X in the upper right-hand corner of the window.
On each of the individual movable diagrams 3-5 and 8-11, clicking on the dew or bubble button
toggles that surface between transparent and opaque. When the movables first appear they are at less
than full-screen size and (in most cases) aligned with the screen coordinates. But as the images are
zoomed and rotated in 3-D space the transparent surfaces can become skewed with respect to the light
source. Some of their clarity can be lost, and the drawings can become confusing. Switching the
transparency off and on as the image is moved around can usually reorient the viewer as to what he or
she is seeing.
Using the Tutorial as a Teaching Device
One of the naive temptations of technology-assisted instruction is to try to let technology teach by
itself. That may be possible with elementary subjects but certainly not with phase-equilibrium
thermodynamics. To assimilate the meaning of the information in this presentation a student needs a
combination of both theoretical understanding and experimental perception. Technology has made it
possible for us to help with the latter -- we can generate large amounts of data, prepare those data for
computer-graphic manipulation, and display the visualized results in useful, interactive configurations.
Indeed we hope that this tutorial will enhance experimental perception. Once students connect the
drawings with the reality of a VLE system or of an azeotrope or of an immiscible liquid pair they should be
able to make good progress. That's what phase diagrams are concerned with -- they provide powerful
visual analogies of complex physical-chemical situations.
But if the connection isn't made, or if there is insufficient theoretical understanding, this tutorial
(and also the many fine print examples containing the same information) may not accomplish very much.
Heavy emphasis on "quantitative visualization" is new to many students of science and engineering
because right-brain methods are not stressed in our science education system. For some students it will
be necessary to explain carefully what the curves and surfaces in these drawings mean and how they
conform to our expectations based on the Phase Rule. This is especially true for the ternary and
quaternary examples. Hyperdimensionality is difficult for "practice-oriented" students to deal with, and its
role in thermodynamics, beyond a mere curiosity, is not easily appreciated.
The elaborate explanation on pages 44-46 of tetrahedral composition points for a quaternary
system is an attempt to address this problem. Not only is an internal composition point carefully
illustrated but the dilemma of having no spatial dimensions left to show other properties is noted also. For
the experienced chemical scientist this may be intuitively obvious, but for the novice it is not. Nowhere in
our chemical education system is it more appropriate than in phase-equilibrium thermodynamics to drive
home the concept of dimensionality and the advantages (but also the limitations) of using geometrical
analogs (models) of physical phenomena.
Students can practice visualizing elementary thermodynamic ideas using software on a CD-ROM
that accompanies the 3rd edition of "Chemical and Process Thermodynamics" [Benjamin Kyle, Prentice
Hall, 1998]. Macros from the original author's "Equations of State" program are included that produce 3-D
images of pure-fluid PVT surfaces using the van der Waals and ideal-gas equations. PC-executable
sequences show thermodynamic process paths on those surfaces and relate the paths to standard
process calculations and to the basic ideas of phase-equilibrium.
As for chemical/theoretical explanations, however, these are mostly absent from this work. The
text slides are largely descriptive of what the drawings show, how the data were generated and the
images produced, and how the visualizations could be made even more useful through a greater
emphasis on computer animation. But the word "chemical potential" appears only once in the text, and
only for the one immiscible ternary system is there any mention of Gibbs-energy minimization. We
assume that any course in chemical thermodynamics to which this tutorial is suited will provide that
background for the students who use it. The theory of phase equilibrium is well developed in several
popular textbooks and is usually an important component of any course dealing with the practical aspects
of the subject. The drawings we present will be most effective when students understand that the
physical behavior modeled is the result of "theoretical thermodynamics at work."
Acknowledgments
Most of the people and organizations who have contributed to this effort, either directly or by
providing financial support, are cited at the end of the tutorial. In addition we should recognize Holger
Glatzer, Iowa State University chemical engineering doctoral student of Professor L. K. Doraiswamy, who
obtained crucial, last-minute data from ASPEN PLUS for confirmations and for insertion on the fixed
drawings.
Rob Louden, Computer Publishing Specialist at the Iowa State University Printing Service, has
been a continuing source of technical information on graphics-file manipulation, and he also helped in
important ways with the preparation of the images for hardcopies and for sending to the various journals
announcing this software.
Ken Patton, former Graphic Designer in ISU's Engineering Publication and Communication
Services, produced and modified many of the fixed drawings using Adobe Photoshop software.
But additional credit is due in several of the cases mentioned specifically in the tutorial. Longstanding financial support for the original author's work on visualized thermodynamics has been provided
by the Department of Chemical Engineering at Iowa State. Direct support for Kong Tian during his M.S.
graduate study at ISU and for the many procedures involved in composing this presentation has come
from a grant to the author from the General Electric Foundation entitled "Improving Instruction in
Thermodynamics and Related Courses through Scientific Visualization."
Special thanks go to Perry Miller, computer graphics doctoral student of Iowa State Mechanical
Engineering Professor James Oliver and also consultant for Engineering Animation, Inc., of Ames. Perry
has been our "resident expert" on the niceties of using Showcase and Open Inventor graphics software
on the Silicon Graphics IRIS workstation and has also assisted with the PowerPoint version. He was "on
call" to the very last minute and is responsible in large part for our being able to make the SGI
presentation run in a seamless manner.
But the direct burden of the programming, organization, and day-to-day modification in this
project, following Kong Tian's graduation and departure in late 1997, was assumed by Dr. Richard
Campero, former ISU chemical engineering research student of Professor Dennis Vigil. Dr. Campero
worked with the author to take Mr. Tian's original thesis presentation, supplemented by contributions from
the other individuals cited, and produce a finished, automated software package that runs without the
annoying distraction of manual computer operations. Dr. Campero's skill and perseverance in these
matters permitted the author to function almost in the role of a movie director -- asking for "this effect to
happen," "that message to appear," and "these changes to occur" with the almost certain assurance that
those wishes would take shape without his having to deal personally with the minutiae of low-level
computer-graphics programming. This was a luxury that few project directors in academic research enjoy
and for which all concerned owe Richard a well-deserved "thank you!" We wish him a satisfying and
successful career in his position as research engineer with the Westvaco Corporation in Covington,
Virginia.
The porting of the program to the PC/Windows environment and enhancements to the
presentation are primarily the work of Jasper Yen, a sophomore engineering student at Rice University.
Support for Jasper's work was provided to Professor Walter Chapman by an Innovative Teaching Grant
from The George R. Brown Foundation and by a grant from the BP-Amoco Foundation.
We hope that users will learn from this software, and we welcome their comments and criticism.
Kenneth R. Jolls
Iowa State University
Walter G. Chapman
Rice University
August 25, 2000
License Information
The movable image routines in this software contain runtime libraries that have been licensed from
Silicon Graphics Incorporated. These libraries cannot be distributed without permission. To use the
software, the user must abide by the following licensing clause.
LICENSING CLAUSE
DISTRIBUTOR IS WILLING TO LICENSE THE ACCOMPANYING SOFTWARE TO YOU ONLY UPON THE
CONDITION THAT YOU ACCEPT ALL OF THE TERMS CONTAINED IN THE LICENSE AGREEMENT. READ
THE TERMS AND CONDITIONS OF THIS LICENSE CAREFULLY BEFORE USING THIS SOFTWARE. BY
USING THIS SOFTWARE, YOU AGREE TO BE BOUND BY THE TERMS OF THIS AGREEMENT.
IF YOU DO NOT ACCEPT OR AGREE TO BE BOUND BY THE TERMS OF THIS AGREEMENT, PROMPTLY
RETURN THE SOFTWARE UNUSED WITHIN FIFTEEN (15) DAYS OF PURCHASE FOR A REFUND.
License Grant and Title. Licensee is granted a non-exclusive and non-transferable, limited, personal
license to use the enclosed Software solely for internal business purposes and on a single computer owned, leased
or otherwise controlled by Licensee and for which an ID password has been issued. The Licensee's right to use is
limited by this license agreement. Licensee may copy Software only for backup purposes, only in machine readable
form, marked with every notice on the original. Ownership of Software remains exclusively with DISTRIBUTOR.
Licensee agrees not to assign, sub-license, transfer, pledge, lease, rent, or share Licensee's rights under this license
agreement.
2.
Confidentiality. Software is confidential and proprietary information of DISTRIBUTOR and/or its licensors.
Licensee agrees to take adequate steps to protect Software from unauthorized disclosure, copying, or use.
3. Limited Warranty. DISTRIBUTOR warrants that for a period of ninety (90) days from the date of purchase, as
evidenced by a copy of the receipt, the media on which the Software is furnished will be free of defects in materials
and workmanship under normal use. Otherwise, the software is provided ?AS IS? without a warranty of any kind.
This warranty extends only to the Customer as the original licensee. Customer's exclusive remedy and
DISTRIBUTOR's entire liability under this limited warranty will be, at DISTRIBUTOR's option, to repair or replace the
Software, or refund the license fee paid upon return of the Software.
4.
Disclaimer of Warranty. DISTRIBUTOR DISCLAIMS ALL OTHER WARRANTIES, EXPRESSED OR
IMPLIED WITH RESPECT TO SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
AND FITNESS FOR A PARTICULAR USE. DISTRIBUTOR SHALL NOT BE LIABLE FOR ANY SPECIAL,
INDIRECT, PUNITIVE, OR CONSEQUENTIAL DAMAGES RESULTING FROM USE OF SOFTWARE UNDER ANY
CIRCUMSTANCES. DISTRIBUTOR DOES NOT WARRANT THAT THE FUNCTIONS CONTAINED IN SOFTWARE
WILL OPERATE IN THE COMBINATION LICENSEE SELECTS OR THAT OPERATION OF SOFTWARE WILL BE
UNINTERRUPTED OR ERROR-FREE.
5.
Liability Limitations. DISTRIBUTOR's aggregate liability for damages to Licensee for any causes
whatsoever, regardless of the form of action, shall be limited to the amount of license fees paid DISTRIBUTOR by
Licensee under this license agreement.
6.
Licensee Indemnity. Licensee shall indemnify and hold DISTRIBUTOR harmless from all costs, including
attorney's fees, arising from Licensee's use of Software.
7.
Termination. This License is effective until terminated. Licensee may terminate this License by destroying
all copies of the Software including accompanying documentation. This License will terminate immediately without
notice from DISTRIBUTOR if Licensee fails to comply with any provision of this License. Upon termination, Licensee
must destroy all copies of Software.
8.
Export Regulations. Licensee shall (i) comply with all U.S. laws and regulations pertaining to security and
export controls, and (ii) not export Software without the required government approvals.
1.