Fin Fan Shortcut Sizing
iOS iPad Utilities
For heat transfer specialists--chemical engineering, mechanical engineering. For iPad only.
Fin Fan Shortcut Sizing allows you to take a quick approach to sizing a fin fan heat exchanger ("fin fans" for short) based on some high level data input. You don't need physical property data for this shortcut sizing technique, just the duty, temperature profile, and some other inputs described below, and you can hash out a starting size for a fin fan. This is great for high level engineering estimating of size.
I've used this routine for several years with great success, from concept (using this sizing technique only) to seeing the actual fin fans installed in the field. Results in early engineering phase estimates using this technique very closely matched the final design (typically within 10%).
You will need to enter the following, and don't worry, if you're not sure, the information contained within provides some guidelines and tips:
Duty (in million BTU/hr, or MMBTU/hr)
The overall heat transfer coefficient, U ( BTU/ (hr ft2 F) )
Process Temperatures in and out (degrees F)
Air temperatures in and out (degrees F)
Elevation of installation location (in ft. above sea level).
Relative Humidty input is optional, program defaults to 0%.
Then for the sizing part, you also input the following:
Number of fin fan bays that will be used (start with 1)
Number of tube rows you assume (start with 4)
Length of fin fan exchanger design (in feet)
Number of fans per bay
That's it--hit "calculate", then monitor the messages. The messages will guide you in what to change up or down for a preferred design. Recalculate with each new input value, and you will iterate down to a good solution. The guidelines suggested are from industry standards and experience.
This will be a valuable tool for those of you new to heat exchanger sizing, trying to understand some of the limitations, and give you some quick "classroom" type exercises in actually designing a fin fan that will work.
Considering the time it took to develop this, and the amount of guidance and information contained within, I think it's a bargain.
Future revisions of the program will include inputs for fin designs (program assumes a fixed fin design and tube outer diameter, so it's constrained a little).
Error messages checking for bad input are included.
Bad results? It checks for that too and reports it to you.
Check out the many screen snapshots I've taken to see what it can do for you. Feedback is appreciated.
Feedback is welcome.
Fixed a known bug--updated air face velocity to be corrected for the density of air at the elevation entered. Previous version (1.0) was incorrectly using a correction to the pressure, and the wrong ratio at that...now fixed.