Pictures of my Hydro systems

[GpsFrontier]

I just thought I would post an update about the Idea of Liquid Nitrogen for cooling the nutrient solution.

Unfortunately this does not seem feasible. Although the temperature of Liquid Nitrogen is about -320 F, It rapidly evaporates/boils away when introduced to the atmosphere. The density of Liquid Nitrogen is lighter than water so like oil and water the Liquid Nitrogen does not mix with the water but just floats on top until it all evaporates/boils away. Even though I poured 1 Letter of Liquid Nitrogen directly into the nutrient tank for my strawberry's, the direct contact between the Liquid Nitrogen and water did not seem to transfer any of the cold temperature of the Liquid Nitrogen into the water before it all evaporated/boiled away (in about 5-7 min). I didn't have a thermometer to put into the nutrient tank but I felt the water temp before and after adding the Liquid Nitrogen to it, and unfortunately I didn't find that there was any difference in temperature.

The only way I can see to use Liquid Nitrogen to cool the nutrients is in a pressurized recirculation system (I don't have the funds to experiment with this right now). Because the Liquid Nitrogen would freeze any pump and make it unusable (I am sure), the system would need to be pressurized to be able to get the Liquid to flow through a set of metal coils that can be submerged into the nutrient tank. Because the direct contact with with metal will cause the metal to reach a temperature of something like -40 F, the metal coils would then directly cool the nutrient solution.

A system like this would need to consist of two holding tanks for the Liquid Nitrogen, with the coils between them to run the Liquid Nitrogen back and forth through. Each holding tank would need a pressure relief valve, a pressure gauge and an open and close valve leading to the coils. As well as a fitting for injecting the compressed air and a sealable opening for filling with Liquid Nitrogen. You would also need a air compressor to pressurize the system. It would also take some research to find out what pressure range to use, and the system of coarse would need to be able to withstand pressure higher than its intended use (this could be tricky because nobody has done it before).

Like me, this might be a bit much to invest in (time and money) but for larger operations, even commercial Hydroponic farms in very hot regions of the world it may be a reasonable alternative to other methods (once the bugs were all worked out). Although I am not sure how large operations are addressing this problem but I would imagen that the "Geothermal (underground)" method is probably still the most efficient.

As for me I am looking into better ways of insulating my Hydro systems, nutrient tanks, fill and drain lines. I am also considering renting a back hoe to dig into the the rockey ground here in the desert of Lake Havasu AZ.. But the nutrient tank would need to be deep enough and surrounded with dirt to get the best Geothermal affects. This makes it more perminate and hard to take out and clean with every nutrient solution change as well as making the pump need to pump the solution another 3-4 feet high. I will probably need another higher volume pump for that.

[Amigatec]

And better way would be find an old refrigerator and mount a coil inside of it, use a thermostat switch to turn the pump on and off to recirculate the solution through. With a big enough coil and enough insulation on the tank it should work nicely.

[GpsFrontier]

Originally Posted by Amigatec

And better way would be find an old refrigerator and mount a coil inside of it, use a thermostat switch to turn the pump on and off to recirculate the solution through. With a big enough coil and enough insulation on the tank it should work nicely.

I had considered that back in the summer also but unfortunately it would cost way to much to run the refrigerator, especially in the 128 degree days we have here in the desert during the summer. That's why we don't have a second fridge in the garage for food. I now have a few designs in the works, most revolve around geothermal energy, with coils at least 2 feet underground.

[Harlequin]

Originally Posted by GpsFrontier

I had considered that back in the summer also but unfortunately it would cost way to much to run the refrigerator, especially in the 128 degree days we have here in the desert during the summer. That's why we don't have a second fridge in the garage for food. I now have a few designs in the works, most revolve around geothermal energy, with coils at least 2 feet underground.

Would you consider using a system that possibly would use a lot of water? If not then I would use an evaporation cooling system. My understanding is that where you live is high heat low humidity in which case these systems work very very well.

What you need is a large surface area and then a thin flow of water over that surface area. The water will evaporate cooling the surface.

From wikipedia these are some rough temperature cooling rates.

Some rough examples clarify this relationship.

* At 32 °C (90 °F) and 15% relative humidity, air may be cooled to nearly 16 °C (61 °F). The dew point for these conditions is 2 °C (36 °F).
* At 32 °C (90 °F) and 50% relative humidity, air may be cooled to about 24 °C (75 °F). The dew point for these conditions is 20 °C (68 °F).
* At 40 °C (104 °F) and 15% relative humidity, air may be cooled to nearly 21 °C (70 °F). The dew point for these conditions is 8 °C (46 °F).

You could build this system one of two ways. One is a large radiator (truck radiator?) and simply pump water to the top of it and let it run down the outside with your nutrient being pumped through the inside. Or build yourself a swamp cooler which is simply a couple of sprayers infront of a fan and direct it at the radiator. The first way would consume less water as you would recirculate the water and only have to top up the reservoir of coolant water. The other method would probably be more effective.