Dude, you owe me $$$$$! Send it by paypal -
NOW!!
Your original question was very good. It did make me if an ~1F-20F super cap would help with a fan, and by how much. But, more important, after someone else asked about the CFMs of fans in some other thread (I think on the "other" site), it got me thinking of all of the "hearsay" and "I measured" stuff about fans. It brought back nasty memories about all of the incorrect info about springs (and there is still a lot!) that was "accepted as truth" because it was repeated in so many threads, and it may (or may not have) been based on what one person measured or said a zillion years ago.
The CFM of a fan in open space, may not be a good indicator of the CFM of a fan when it's connected to a radiator. Also, when people say "they measured the CFM", what EXACTLY does that mean? There are MANY variables! Without knowing the EXACT voltage and what EXACTLY was used to measure it, how it was measured, etc, etc, the CFM ratings that are repeated over and over could be off a lot!
So, my project for the Winter months:
Measure the "few electric fans" that I have.
Measure then in open space. Record the input voltage. Document exactly what I did, what I measured, etc. Take videos - see for yourself exactly what I did, what I measured, how I measured it, my test setup, etc. Also, put the fans against a new radiator, yes I have spare.
Keep the fan shrouds the same distance from the radiator(maybe 1/3"? I have to decide), take CFM measurements.
Measure the air velocity at a few points, see how consistent the airflow is from the outer top inner portion of the blade. Hey, check out the videos if you want that info. Too hard and too much work to try to make a general test and post results.
Also, take startup and steady state current measurements with a current probe and storage scope.
Maybe also take startup and steady state current measurements with a current probe and storage scope.
Throw results on the web.
I'm going to use an accurate hot wire anemometer. The twirly fan anemometer are fine for quick measurements. But, they suffer from bearing resistance, material accuracy, wear, etc.
So,
you owe me the money that I just spent on an anemometer! Don't worry, I take paypal.
Yea, I need little "projects" like this every year to keep me entertained.
Yea, I'm an engineer - 110%, or should that be 150%, or 200%, or some other stupid percentage people quote?
I love learning. I love seeing a question, looking to find answers (and determining the "basis and likely accuracy of the answers"
), and then seeing if I can somehow verify them myself.
Still, that does not mean that you don't
owe me for the hot-wire anemometer that I just bought.