I launched a Kickstarter campaign for an efficient Venturi nozzle. What the heck does that have to do with permaculture? Well, it can be used to aerate the water in your fish ponds or aquaponic & hydroponic systems. Here's a link to the campaign: Kickstarter Campaign
The campaign is filled with all kinds of scientific stuff to show how much more efficient it is over standard nozzles. Plenty of charts showing how much dissolved oxygen is added to the water, how much water flow you need, and examples of how to use the nozzle.
For those of you who don't know me, years ago I was the guy that built the crazy rocket mass heater that ran on pellets. (Some say I'm the first to get this to work but we'll leave that argument to other people!) Rocket Mass Heater
yup. Some of the other videos show some of the measurements that I took during development. This new design injects twice as much air through the nozzle than a standard venturi. However, that doesn't necessarily mean there is twice the increase of DO in the water. I'm hoping to get a second DO sensor so I can do an actual side-by-side trial with this. Good DO sensors aren't cheap!
The original purpose is for the hydroponic folks to aerate the deep water culture beds. It's to replace the expensive regenerative air blowers and diffusion stones. These systems are expensive, loud, and the stones need cleaning. With this newer design, it will make it more cost effective to install and operate this setup. The real trick will be convincing an established industry that this is probably better. In my greenhouse I have a 100' long growbed that needs about 50 nozzles in it. The big growers could use 100's for their systems.
The aquaculture industry is a secondary market for putting them in the fish tanks. Not as many nozzles consumed but still a great use for them!
It probably would work fairly well. My fish tank is 1300 gallons and I'm using 3 nozzles in it running on about 60 watts. My total lift is about 5' so I have some loss of efficiency because of the lift. The aeration system I'm using in my deep water culture bed has 10 nozzles and is running at 88 watts because there's no lift.
I could try the laser sometime and see what it does. The testing that I have done does shows that the DO level increase away from the nozzles so that implies that oxygen is staying in the water column even away from the area of the nozzles.
The ceramic stones are cool. One thing they don't mention is how much power that devices uses. It needs both a fairly large water pump and some kind of air pump strong enough to force the air through the ceramic. They did mention that it was treating an area 100 square meters. That's usually large enough for most areas...but not very large for an ocean!
I'm not sure why no one else has made this but I would speculate it was the cost to make it. Most venturi's are a simple 1 piece. (A standard 2-part cavity mold with 3 side actions). This design is two parts which makes it more expensive to produce and assemble. It also looks like most on the market aren't really designed for efficiency...they just whipped them up so they could sort of work. When you're injecting soaps, chemicals, and fertilizers, they usually just regulate it with valves to adjust the flow.
I'm not sure why no one else has made this but I would speculate it was the cost to make it.
I've only seen the concept of the annular ring of holes used once before that I can recall. It was in the front stage of the Pursuit Marine Drive steam eductor, which was ironically the opposite of your purpose. It used a gas to move liquid, rather than a liquid to move gas. I think the air bubbles sucked through were compressed, and their expansion added to the thrust. I wonder if you made one like the rear stage, if it might suck even more air.
And he said, "I want to live as an honest man, to get all I deserve, and to give all I can, and to love a young woman whom I don't understand. Your Highness, your ways are very strange."