NGDE: Software for Solution of Nucleation, Surface Growth and
Coagulation Problems
A.
Prakash, A. P. Bapat, and M. R. Zachariah*
Departments of Mechanical Engineering and
Chemistry
University of Minnesota
ABSTRACT
A simple numerical method to solve the
General Dynamic Equation (GDE) has been described and the software made
available. The model solution described
is suitable for problems involving gas to particle conversion due to
supersaturation, coagulation, and surface growth of particles via
evaporation/condensation of monomers. The model is based on simplifying the
sectional approach to discretizing the particle size distribution with a nodal
form. The GDE developed here is an extension of the coagulation equation
solution method developed by Kari Lehtinen (Lehtinen and Zachariah, 2001)
wherein particles exist only at nodes, as opposed to continuous bins in the
sectional method. The results have been tested by comparison where simple
analytical solutions are available, and are shown to be in excellent agreement.
By example we apply the model to the formation and growth of Aluminum
particles. The important features of the model is that it is simple to
comprehend, the software which we call Nodal-GDE Solver (NGDE) is relatively
compact, and the code is well documented internally, so that users may apply it
to their specific needs or make modifications as required.
The software is
being distributed as freeware, with the request and expectation that
attribution be provided for work performed using the code.
NGDE CODE
The numerical algorithm has been implemented in C. The example
problem is specific for a growth of aluminum aerosol by the
evaporation-condensation method, however, the software is designed to allow the
user to apply it to other systems where property data such as saturation vapor
pressures and surface tension are known.
The program code performs four main types of calculations
1.)
pure
coagulation,
2.)
coupled
nucleation and coagulation,
3.)
pure
surface growth
4.)
unified
GDE containing all of the above.
The program execution consists of the
user inputting to the input file the necessary data about the aerosol material
properties and the process conditions. The output can be either viewed on the
console or directed to a file for storage.
The source code for the program has a modular structure.
Each section of the code is independent of other sections. The source is well
commented, and a list of variable names, and their units are documented within
the code to allow the user to make customized changes.
The NGDE package provided, consists of the source code in C, an instruction file readme.txt, and the sample input files for the example problem discussed in the AS&T paper.
DOWN
LOAD THESE FILES
Paper describing theory ( to appear in AS&T)
NGDE Software (written in C language)
DOWNLOAD ALL THREE INPUTS
The software
is being distributed as freeware, with the request and expectation that
attribution be provided for work performed using the code.