In this post, we will go through designing and building a pressurized nutrient supply.
But first, lets study why we use high-pressure aeroponics, and understand the key aspects of this method. Then we design and build according to the findings.
Why Aeroponics?
There is lots of information about what is high-pressure aeroponics and why it is better. Check the article from Maximumyield.com: Growing on Air: How Aeroponics Turns Less into More
There is also a YouTube video showing the difference, even the aeroponics systems in the video are just Low-Pressure Aeroponics.
And here from academic authority: (The benefit list is too long that you have to read by yourself)
Aeroponics systems can reduce water usage by 98 percent, fertilizer usage by 60 percent, and pesticide usage by 100 percent, all while maximizing crop yields. Plants grown in the aeroponics systems have also been shown to uptake more minerals and vitamins …
American Scientific Research Journal for Engineering, Technology, and Sciences (ASRJETS) (2017) Volume 27, No 1, pp 247–255
Here is the list of experts from Wikipedia: Aeroponics.
Oxygen (O2) in the rhizosphere (root zone) is necessary for healthy plant growth.
The increased aeration of nutrient solution delivers more oxygen to plant roots, stimulating growth and helping to prevent pathogen (virus, bacterial and fungus) formation.
Aeroponics can limit disease transmission since plant-to-plant contact is reduced and each spray pulse can be sterile.
Due to the disease-free environment that is unique to aeroponics, many plants can grow at higher density (plants per square meter) when compared to more traditional forms of cultivation.
Less nutrient solution is needed throughout.
It allows greater control of plant environment and improved nutrient feeding.
Key Factors
The key factor of root development in an aeroponic environment is the size of the water droplet. Based on researches, NASA has determined that high pressure hydro-atomized mist of 5–50 micrometres micro-droplets is necessary for long-term aeroponic growing.
Atomization (>65 pounds per square inch (450 kPa)), increases bioavailability of nutrients.
When an accumulator system is incorporated, the spray pressure is more stable. And by skipping the phase of activating pump to apply pressure, the cycle times can be further reduced to < ~1 second on, ~1 minute pause.
Maintaining a higher pressure when the nutrient is atomized will reduce the chances of nutrient salt accumulated on atomizing sprayers, thus lower the maintenance cost.
Goal and Design of Pressure Regulating Unit
In a typical closed-loop high-pressure aeroponics system, the nutrient delivery function can be demonstrated in the graphic below.
So, in the above diagram, the nutrient is sucked in to a booster pump and pressurized. The accumulator tank stores the pressurized nutrient and maintain the pressure in the delivery tubes. An optional pressure sensor monitors the nutrient pressure to prevent over/under pressurization. Solenoids control the nutrient delivery timing. The release valve is used to drain the system, normally in maintenance phases.
The design goal is to create a device that
is safe to use,
portable to fit indoor household spaces,
can boost the nutrient pressure,
can maintain the pressure without pump running all the time,
do not alter characteristics of nutrient,
can deliver nutrient with precise timing,
is modularized and easy to use.
Encapsulate the Implementation
Well, if you have read my previous blog posts, you would know that I like to modularize functions and encapsulate the detailed internal implementation. The result is simplified unit interface. And, this is important, it allows future upgrade of the unit without causing dependency issues, as long as the interface compatibility are maintained properly.
In this case, the unit is simplified as a box with one nutrient intake from reservoir, two pressurized nutrient outputs to nozzles, one recycle output back to reservoir, one folded drain tube, along with power/signal wires. It is much easier to maintain and operate.
Here it is the simulated rendering of the nutrient pressure control assembly:
Packaged View
