Ray I know us chemical engineers are not too smart but I can read a pressure gauge. My city nominally supplies water at 80 psig, but I'm pretty far out on the system and my gauge varies from 50 psig during high usage times to 70 psig at night.
I have measured the output repeatedly with a can and a stopwatch since getting the unit over two years ago and it's 30 gal/day everytime...winter,summer,day, and night. I recently changed the RO element and guess what...30 gal/day brand new. There are no restrictions. It sits right next to the 250 gal. atmospheric pressure storage tank. It's supplied with a one inch water line and all internal and discharge tubing is that supplied with unit. The waste water tube dumps into a one inch pipe that carries it outside.
Anyway, I'm not complaining about the RO unit. I'm commenting on the fogger design that David is contemplating. He is looking only at the
ultimate evaporation (and humidity and cooling) attainable based on the humidity chart and not considering that mass transfer is a rate process dependent on the drop size and surrounding temperature conditions. He has limited height (and thus time) to get the necessary heat transfer into the drop and evaporate it completely before it reaches his foliage. The system is in reality its own worst enemy because both the increased humidity and reduced temperatures achieved by running it increase the difficulty and time required to evaporate more fog. Calculations can only provide a starting point for a system design. Unfortunately, testing it is the only way to completely evaluate it. I'm telling you that two systems much more likely to succeed that the one David is talking about (based on the inlet water pressure drops and water drop flight times available) fail to operate adequately and the GH designer has involved the fogger manufacturer to attempt to resolve the issues without success. As a result they essentially refused to install a fogger unit in my GH (unless I took full responsibility) and suggested the wet wall instead. That's cause for concern on David's part.
My only issue with the RO is that if he actually uses the water he is talking about it's going to cost an arm and a leg. I'm no where near California (Thank God), but I read about water usage restrictions there. I have no idea whether these effect him or not. I assume he knows the answer to that. I also do not not know the cost of his water, but it could not possibly be less than mine...at least I hope not. That would be a kick in the head.
I'm just letting you know that you have not properly considered all the variables in a fog system. Certainly whatever you do is up to you, but I assume you would not have posted the issue here unless you wanted some feedback. I'm apologize for ever mentioning Ray's RO system. What I get is what I get, but I assume that designing various chemical process systems over the last 40 years qualifies me to measure water flow while taking into account the controlling factors in that measurement. 30 gal/day is enough for my emergency use. I'm not complaining, just stating the facts.
Other than that ...How 'bout them War darn Eagles!!!
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