Rider509: Two Thais & G13

[Archiweedies]

Hey, Archiweedies, good to see you! If you go back a page or so you'll see that I thought about a stainless coil doing just that. But after crunching some thermal transfer numbers it's apparent that it'd have to be a hella long coil, like... 100ft! LOL. I found a coil that has 100' of 3/8" O.D. and 20' of 1/4" O.D. 304 stainless for 150 bucks that would do the trick, but if I can drop the fridge coils right in the res I'd rather do that. I'm off to pull one of the fridges apart to see if it's even possible. I'll let ya know.

Ahh I wasn't completely caught up before commenting. Either way, I'm interested to see what you come up with. I'm always looking for ways to drop res temp even though I've yet to complete one hydro grow haha.

Do you think, given a large enough coil of garden hose, that my suggestion is feasible? I've no data to suggest one way or another, but my gut tells me it could work.

 

[Rider509]

Day Two in the system and everything's happy so far. Fingers crossed.

 

[Rider509]

I wonder if it would have enough effect to draw cold outside air into the reservoir using a couple of big area air stones and an air pump.
???

Great minds think alike. I've got two air pumps dedicated to the res that I'm going to put in the fridge and run it that way to see what effect it has. If that works I'll be so stoked.

 

[bignstrange]

Your set up is great, honestly makes me think about satisfying my needs with another system if you get my drift hopefully my tent never finds out XD

Can't wait to see what you come up with on the res chiller front .

 

[Rider509]

Rider509 - Two Thais & G13

I don't see why it wouldn't, Archiweedies. Def worth a shot. Sure would suck if your weed tasted like water from a hose though! LOL. J/k.

 

[Scrogdawg]

First off, the rate of cooling in the fridge has to exceed the rate of warming in the reservoir. Quick calculation says that 100 feet of 3/4" garden hose will hold 1 gallon of water. Lets assume 1 hour in the fridge will drop the temp 10 degrees. Now if that was pumped back into a 10 gallon reservoir every hour.....fuck it, I don't think it would work Archi.

 

[TheMadDabber]

I'm sure you already know but they have some cool temperature controlled timers avalible that would only pump the cool air when the temp rises above x degrees.

Also I know vex kept his res at 65° with a frozen 2 liter.

But sounds like this pirate has a sound plan for the job! Excited to see how it works. I'll be over here taking notes.

 

[Scrogdawg]

Great minds think alike.

"Great minds think alike" but "fools seldom differ". Just trying to keep myself grounded...lol.

 

[OntarioGro17]

First off, the rate of cooling in the fridge has to exceed the rate of warming in the reservoir. Quick calculation says that 100 feet of 3/4" garden hose will hold 1 gallon of water. Lets assume 1 hour in the fridge will drop the temp 10 degrees. Now if that was pumped back into a 10 gallon reservoir every hour.....fuck it, I don't think it would work Archi.

I'm running my nite through 20' of 1/4 inch tube into a cooler with frozen bottle and keeping 7 gallons cold no problem at approx 10 gal/hr. it works excellent and my plan was to scale up to my minifridge and keep a tub of water in it running the coils through that chilled water.

 

[TheMadDabber]

"Great minds think alike" but "fools seldom differ". Just trying to keep myself grounded...lol.

So long as you aren't the ground for a circuit

 

[Archiweedies]

First off, the rate of cooling in the fridge has to exceed the rate of warming in the reservoir. Quick calculation says that 100 feet of 3/4" garden hose will hold 1 gallon of water. Lets assume 1 hour in the fridge will drop the temp 10 degrees. Now if that was pumped back into a 10 gallon reservoir every hour.....fuck it, I don't think it would work Archi.

Haha well it sounds crazy enough for me to stay away from....for now. Maybe one day me, you, or someone will put it to the test. I don't have one of the little fridges .

 

[Rider509]

This is getting ridiculous. Air pumps are in the fridge now. Time will tell if cooling the air to the stones will be enough. Anticipating that it won't I ordered the 120' stainless coil. I refuse to be the ice bitch to my res again.

 

[Rider509]

I drained the system and flushed out all of the bat poop and worm castings. I'm not cut out for the Fox Farms organic route. Shit stinks!
So I'm back to using the Cutting Edge Solutions products. I dropped the mix down to 980µS since Scrogdawg has me freaked out that I was overdoing it. I should just buy the GH product line and copy his feed schedule because... have ya seen his grow!?

 

[Rider509]

In planning for the arrival of the 120' stainless coil I started crunching some numbers. Thermal dynamics is a quick trip to insanity. There are three thermal resistances on the heat transfer path that need to be taken into account: external convection from the air to the pipe, conduction through the wall of the pipe, and internal forced convection from the pipe wall to the water. The conduction through the pipe wall is negligible with thin-wall 304 stainless, but air movement over the coils plays a big role in altering external convection. I found the Nusselt number given the calculated Reynolds number but then had to integrate these relations along the pipe length because, shit changes. The biggest factor is the contact time of the water in the cooled pipe, which should be self evident, but the degree to which it impacts cooling of the water is mind-blowing. And then I had to factor in the resistance through the pipe to fluid flow, which is def not negligible, to determine pump capacity. This is about where my head exploded. So given a res temp of 72F and a fridge temp of 34F, water forced through a 120' 3/8" coil at 3gpm with a 7.2m/s fan blowing through the coils (it's one I already have and found the wind speed, measured with a Kestral 1000, on a site where fan geeks hang out) should produce a drop of about 4 degrees. All of THAT for four fricking degrees? Gaaaaah! Screw this. I'm going to send the coil and temp controller back and buy a commercial 1/4hp dedicated chiller. My sanity and peace of mind are worth it. So much for DIY.

 

[Rider509]

Time for a paradigm shift. Instead of relying on the inefficient exchange of heat from air to coil, what if we use the fridge to cool a glycol sump and pump glycol through the coil submerged in the reservoir?

It should work. Glycol has a lower heat capacity than water so better heat exchange. And a direct interface between the cold coils and the water is a better interface than an air/water exchange.

edit: and insulate the totes, dummy!

 

[TurboBucket]

Is the refrigeration unit in the mini fridge going to be big enough to meet your heat load?

 

[Scrogdawg]

You can't add cold, you can only remove heat. The heat needs to go somewhere. You would pull heat from the reservoir into the circulating glycol and then pull that heat into the glycol bath. From there the heat is transferred to the air in the fridge and all you've done is warm up the fridge. Now the beers warm and no one will come to visit anymore cuz who the fuck wants to drink warm beer.

 

[freakbudz420]

These commercial fridges are oversized to accommodate repeated opening of the fridge and effect quick pulldown of product temps. At about half way on the temp control it will freeze product. But, honestly, I don't know. I don't ever want to run hydrodynamic thermal calculations again. Just too damned many variables. It works or it doesn't.



LMAO, Scrogdawg, always the pragmatist! But no worries, I have beer on tap that's always 34F.

Your own beer tap! Damn, now I'm ultra jealous!!

 

[TurboBucket]

As scrogdawg said the heat has to be transferred somewhere. Imho I wouldn't bother with glycol, water will be just as good without having to deal with the glycol, unless you want your coil temp under freezing then obviously glycol will help but that's not needed for a 65°f system. Before you design a cooling system it helps to know your heat load.

 

[TheMadDabber]

Shit is there anything he doesn't have or build . It's a pirates life for rider!

Grandpa takin had what I thought was a quality chiller I was planning to recommend... Then it failed.

Ahh the joys of thermodynamics