I recently had the need to quickly build a fume extractor for soldering, and since at the place there was a ton of 80mm CPU fans lying around, I used those to build something like this (not to scale):
Where the components were (all airtight "sealed" with duct tape)
- Intake of an old clothes dryer hose (100mm diameter, a bit more than 1m long when extended, fixed to some big metal lump to have it stay in place). This is positioned dynamically to suck in soldering fumes
- the hose itself
- A cut off pyramid shaped cardboard construction
- A 3x3 stack of 80mm CPU fans. Directly behind it, the air comes out (future enhancement might be some coal filter)
So the airflow is from 1 to 4.
This thing did its job, but not in any terrific way. So I was wondering if anyone with experience in fluid dynamics could tell me how to improve it, or more specifically which of my ideas to improve it might make sense.
For the sake of this question, lets say the resources are limited to about the items described, reasonable additions that most people have in their workshop included (so e.g. hot glue is fine, but I am not looking for "add a bigger fan" kind of enhancements).
The items are:
- The hose (2m of it, 100mm diameter)
- Enough cardboard
- 10 fans, 80mm diameter, all assumed to be equal in performance
My ideas now included:
- instead of making 3x3 fan configuration, I take two 2x2 configurations and put them "in series" (that is, a box like 4 to its right, with reasonable space in between, whatever that space needs to be)
- at point 3, add an additional 80mm fan or
- at point 2, add an additional 80mm fan or
- at point 1, add an additional 80mm fan (all assuming for that additional point I would only have one last fan left in case of a 3x3 configuration)
Which of these ideas (or combinations of one additional fan and the other fan configurations) would noticeably improve the performance of the device (that is, move more air)?