2006 Thermosolver Thesis Presentation (1)

7/28/2019 2006 Thermosolver Thesis Presentation (1)

1/28

ThermoSolverAn Integrated Educational

Thermodynamics Software Program

Connelly Barnes


2/28

What is ThermoSolver?

Programmed by Connelly Barnes.

Software program used to teach Chemical

Engineering (ChE) thermodynamics.

Available for free from Web (Google it).

Allows students to "explore"

thermodynamics

make nontrivialcalculations, and compare different

thermodynamic models.


3/28

Motivation

Thermodynamic equations can become

complicated, must be solved by lookup

tables or computer algorithms.

Tables are available for a limited set of

pure species.


4/28

Motivation (continued)

Computer solutions: spreadsheets, scripts,

Computer Algebra System worksheets can

be used, but it's hard to let the student use

different number of species,

thermodynamic models, etc.

We would like students to not have the

burden of programming every solution,especially for routine calculations.


5/28

Objectives

Standalone educational software program.

Easy to use interface reduce all

"barriers" to using the software.

Research and develop algorithms needed

to solve equations.

Integrate with chapter problems inEngineering and Chemical

Thermodynamics by Milo Koretsky.


6/28

Use at Universities

At OSU, ThermoSolver used in ChE

thermo course, graduate reactors course,

plant design.

In plant design, ThermoSolver not

specifically named, but 10/39 students

used it.

Don't track usage by other Universities,

but Web search reveals it has been used

at Univ. Notre Dame, Indiana and Univ. of

Colorado at Boulder.


7/28

Features

Database, 350+ chemical compounds.

Calculate saturation pressure, temp.

Solve equations of state (LK and PR). Find pure, mixed fugacity coefficients.

Fit excess Gibbs energy models to

experimental data. Bubble point and dew point calculations.

Plot phase diagrams for binary systems.


8/28

Features (continued)

Calculate Keq for single chemical reaction.

Multiple chemical reaction equilibria.

Plotting. HTML docs provided, numerical methods

and equations described.


9/28

Tour of Program:

Saturation Pressure Calculator

Solve for saturation pressure or saturation

temperature.

Saturation pressure/temp determines

where liquid/vapor phase transition occurs.

Example problem: Find saturation

pressure of 1,4-dioxane (C4H8O2) at 50oC.


10/28

Tour of Program:

Equation of State Solver

Finds one of the state properties pressure,

molar volume, or temperature given the

other two, using the LK or PR equations of

state.

Example problem: Find molar volume of

propane at 35 bar and 50 oC. Compare w/ideal gas: 0.77 L/mol.


11/28

Tour of Program:

Fugacity Coefficient Solver

Finds the pure fugacity coefficient or the

fugacity coefficient of a species in a

mixture, using the LK or PR equation of

state.

i

i


12/28

Tour of Program:

Fugacity Coefficient Solver

i


13/28

Tour of Program:

Models for excess Gibbs energy

Fits activity coefficient models to

experimental data for binary Vapor-Liquid

Equilibrium (VLE) systems.

Objective function.

Example: Chloroform-heptane.


14/28

Tour of Program:

Bubble point / Dew Point Calculator

Dew point: gaseous system, when first

drop of liquid forms achieved by

decreasing temperature or increasing

pressure.

Bubble point: liquid system, when first

bubble forms.

Solver finds temp./pressure where first

bubble or dewdrop forms, and composition

of chemicals in bubble or dew-drop.


15/28

Tour of Program:

Bubble point / Dew Point Calculator


16/28

Tour of Program:

Binary Phase Diagrams

Make plots of phase transitions in binary

vapor-liquid systems.

Example: Plot pressure vs. liquid mole

fraction for methylcyclohexane-benzene

system at 50 oC.


17/28

Tour of Program:

Equilibrium Constant Solver

Finds KTat a single temperature, for a

single chemical reaction.

Plots KT

vs T.


18/28

Tour of Program:

Equilibrium Constant Solver


19/28

Tour of Program:

Multiple Chemical Reaction Equilibria

Gas-solid equilibrium.

Found by minimizing excess Gibbs energy.


20/28

Tour of Program:



21/28

Tour of Program:



22/28

Numerical Algorithms

Newton root finder with backtracking.

Downhill simplex method for minimization.

Iterative substitution.


23/28

Multidimensional Newton Method

Vector-valued function F: Rn -> Rn.

Newton step Iterate

n

nn

n

x

F

x

F

x

F

x

F

D

1

1

1

1

F

)()(1

iiD xFF x

xx ii 1


24/28

Newton Backtracking

Use full Newton step if norm ||F||2 is less

than its value at xi, otherwise try /2, /4,

/8, ... until ||F||2 is less than its value at xi.

This is guaranteed to happen, as is a

descent direction for||F||2.


25/28

Simplex Method

J.A. Nelder and R. Mead, "A simplex

method for function minimization,"

Computer Journal 7 (1965) 308-313.

Simple, derivative free method for finding

minimum of function of form F:Rn->R.

Does not use derivatives, so constrained

minimization possible by setting Fto

infinity.


26/28

Algorithms

Equation of state solver: Newton method.

Excess Gibbs energy model fitting: Simplex.

Bubble point / dew point: Custom iterative

methods based on those of Smith, Van Ness,

and Abbott.

Multiple chemical reaction equilibria: Newton

and simplex. Typically converges, howeverDr. Koretsky found a problem where this

method does not converge.


27/28

Conclusion

Objectives met?

User interface is straightforward to use.

Numerical methods converge with oneknown exception.

A practical tool integrated with problems in

a textbook.


28/28

Acknowledgements

Milo Koretsky, Mentor.

Rubin Landau, Computational Physics.

2006 Thermosolver Thesis Presentation (1)

Documents

Transcript of 2006 Thermosolver Thesis Presentation (1)