IAM Monte Carlo Code


Calculation of Incidence Angle Modifiers


Over the past several years, a family of computer programs to calculate the optical performance of cylindrical (and other non-symmetric) solar collectors have been developed at the Solar Energy Applications Laboratory at the Colorado State University. The programs use a three dimensional Monte Carlo ray tracing algorithm to trace a large number of "solar" photons through possibly many surface interactions until the photons are either absorbed by a surface or exit the volume of interest. The overall transmission-absorptance product ([tau][alpha]) of the collector is computed as the ratio of photons absorbed by all designated absorber surfaces to the number of photons incident upon an imaginary aperture plane defined by the user (in the absence of all other surfaces). The output of the calculation is a matrix of biaxial Incident Angle Modifiers (IAM's) suitable for use with available TRNSYS collector models. The IAM is defined as the ratio of a collector's performance ([tau][alpha]) at a particular angle of incidence to the collector's performance at normal incidence ([tau][alpha])normal.

This web page makes the program manual and computer code (Fortran 90 source code, sample input files, and executable binary files) available for general use. The files contained on this page are copyrighted by Colorado State University. They can be distributed freely as long as they are distributed completely including any copyright message.


IAM Program Version 3.0

Version 3.0 is the latest version of the IAM Monte Carlo computer code.

The following are links to text files. To view the files, simply click the link. If you would like to save these files to your own computer, after clicking on the link, choose "Save As" from your browser's "File" menu.

Program Manual

Example Input Files

Fortran 90 Source Code


The next three links are the executable files. If you click on the link, your browser will download the file to your own computer. Read the manual to learn more about executing the program.

Executable Binary Files


IAM Program Version 2.2

Version 2.2 is a previous version of the IAM Monte Carlo code.

Version 2.2 incorporates a number of bug fixes from version 2.1. The most significant was a correction in the way semi-specular surface reflection routine works. The semi-specular option should not be used in Version 2.1.
The following are links to text files. To view the files, simply click the link. If you would like to save these files to your own computer, after clicking on the link, choose "Save As" from your browser's "File" menu.

Program Manual

Example Input Files

Fortran 90 Source Code


The next three links are the executable files. If you click on the link, your browser will download the file to your own computer. Read the manual to learn more about executing the program.

Executable Binary Files


If you run into problems with this program, either downloading the files or executing the program, please e-mail to either Jeff Miller at:jm568432@engr.colostate.edu or Joe Ryan at:jryan@k12.colostate.edu
This page was last updated on June 26, 1998