cooling with fans

[dsb1829]

Okay, I am working on a couple of schemes for cooling down the reef tank using fans. As we all know the fan across the surface is a last ditch effort and is terribly inefficient.

I saw a setup at a local store that used a 6" clip fan plumbed to ABS tubing that was reduced to a 3" bulkhead. The bulkhead entered the sump at the wet dry chamber. This creates a more efficient cooler, but what if you don't want to use bioballs or a wet dry? It is a neat idea because it gets the fan away from the water and thus reduces the accident potential to nill.

I am thinking of a mod of this using a spray nozzle, and some ping pong balls to slow the water down and break it into smaller drops without all of the bacteria colony of bio balls. This should allow enough time in the cooling tower to drop the water temp before it re-enters the tank flow. Sound okay to me. What do you guys think?

Okay, the reason I posted this in the reef forum was also to see if you guys have any links on the subject of evaporative coolers. Not necessarily DIY. I am mainly looking for ideas to increase the efficiency. I have all of the standard DIY sites already (oz, sw aq, etc...). Thanks for reading.;)

[PerryinCA]

I know Joaco has some info on his page about a DIY evap cooler that seems to work well for him. Here's the link to his page:

http://www.wyx.com/iheo/tank/aquarium.htm

I think that if you have enough fans in the Canopy, you should be fine... If you plan of 3 or more 400's....then I don't know. But with running all the fans, you could probably save money by using a chiller.

I think the Ranco heat controllers are awesome, and will probably benefit you in your situation.

As for the ping-pong balls....wouldn't they float?

-Perry

[dsb1829]

I have joaco's site. Something about a single stream of water and a fan blowing on it don't strike me as incredably efficient. Yes, it does work for him. I think he is also in Buenos Aires or someplace like that. I don't know if humidity is more or less condussive to this type of cooling.

As far as the balls go it would be similar to a wet-dry, not submerged. Their only purpose would be to slow the water down and distribute it more evenly. Both of these would make for more contact time, cooler water, and higher efficiency.

The fans are really inconsequential in comparison to a chiller. Fans are generally .25A draw for the typical DC. A Chiller for 180g on the other hand will draw in the 7A range. It takes a lot of fans to draw 7A.

Yeah, gonna have 3 400s over this sucker. It will be bright, hot, and very dificult to keep any sort of temperature stability without a chiller. We just can't spent the $800 on one right now. All we need is something to get us through the next three months and then we are clear until next year. With the 2 400s over our 72g the temperature change in the 6.5 hour photoperiod is 6-10 degrees depending on how much room temp changes through the same period. It takes us about 3-4 hours after the MH go off to bring the temp back down to 80 or below. We have really had to pay attention to the weather in order to know if we need to open the stand and point a 16" fan at the sump for additional cooling.

The more I dig around I see that no one does cooling towers. Lots of dorm fridges that produce a claimed 10 degree drop off of 150btu. I am basically trying to build something that is out of the norm. Any ideas from fellow reefers are appreciated.

catch you later perry

[cod]

This is the most unique aquarium cooling idea I have ever seen. I think there is a saying about crazy notions becoming good ideas.(if there's not there ought to be);)

Mike

[dsb1829]

Yep, saw that one a while back. My appartment manager wouldn't appreciate it if I dug up the yard and burried tubing. Not to mention the esthetics of tubes draped across the walkway into our appartment. Man the neighbors would really think we are crazy:eek3:

[SupaJSK]

if you really get into a tight spot. you can fill two liter soda bottles and freeze a couple of them. drop one in your sump before you head out to work on a hot day.

[dsb1829]

no no no, you have me all wrong. I am not doing it out of desparity. I simply want to cool my tank witout a chiller or having it sound like the airport. That is kind of a tall order. Just figured I would poke around on the forums and see if I could drum up any experience or additional considerations.

[Joaco]

Originally posted by dsb1829
I have joaco's site. Something about a single stream of water and a fan blowing on it don't strike me as incredably efficient. Yes, it does work for him.

Read the link again, it's not just the single strike of water ;)

http://www.wyx.com/iheo/tank/cooler.htm



you have to point the stream of water against the glass, so that you create more surface for temperature exchange via air contact.
You can also do that by creating a small overflow in the sump, with a small waterfall you create the same effect without the pump. If you don't make the fall too tall, of the GPH to high, it will be very quiet.
if you want to improve it more, place the fan blowing up, not down (will come to that later)

I don't know if humidity is more or less condussive to this type of cooling.

Yes it is (will come to that later as well)

The more I dig around I see that no one does cooling towers. Lots of dorm fridges that produce a claimed 10 degree drop off of 150btu. I am basically trying to build something that is out of the norm.

About the dorm fridge idea, this is basically why I don't like it (take it with a grain of salt though, because I didn't try it myself):

http://www.cs.cmu.edu/~cap/raid/chil...dge/index.html

Just a quote from that link to give you an idea:

Air conditioners and commercial water chillers are rated in BTU/hour (in the United States), which is a measure of how quickly they can remove heat. A dorm fridge moves about 100 BTU/hour. A small window-mount air conditioner moves about 5000 BTU/hour (50 times as powerful as a dorm fridge). A 1/6 horsepower commercial water chiller sits in between these figures. It moves about 1500 BTU/hour. Therefore, it's reasonable to conclude that we might succeed in building a reef aquarium chiller from an air conditioner, but not from a dorm fridge. The fundamental heat moving capacity is just too low in the dorm fridge. If you convert a dorm fridge to a water chiller, the fridge will run constantly without making a significant dent in the water temperature, even if you hope to achieve only a few degrees decrease in temperature.

Ok, lets go on, adding the points I left out above. Check out this link:


http://www.ctdoc.com/Ch1.html

Thermal Characteristics of Cooling Towers

(very cool link, ok, some pun intended )


From the first link (I'm quoting for the people that are lazy to read the links, just go to the links for many more details)

Suppose you have a 125 gallon reef aquarium. Neglecting your sump, your 125 gallon tank has about 1000 pounds of water in it. One BTU is the energy required to change the temperature of one pound of water by one degree Farenheit. If a dorm fridge moves 100 BTU/hour, then it would take 10 hours to drop the temperature of your tank by just one degree, and that's if the tank has zero energy input, meaning no lights, no pumps, and perfect insulation from the room.

Now a longer quote from the second link: (it fills the gaps I left on the first answers. I added the bolds to the following text for clarity

Suppose someone was issued a bucket of water and told to make the water change to vapor as quickly as possible. Several strategies would likely develop.

One strategy might be to find a second empty bucket and pour the water back and forth to expose more of the water to air. The falling water could be made to splash into droplets to increase the surface area exposed to the air. Better yet, the bucket could be dumped out onto a large surface for maximum exposure to air.

Next, a fan could be added to flow air over the water to encourage moisture laden air to exit and be replaced with new air that is better able to accept more vapor.

Lastly, if the quality of air could be manipulated, ‘dry’ air- air that contains very little moisture- would be used because of its ability to accept greater amounts of water vapor.

If the scenario were modified such that:

- New water was added to replace that lost to evaporation, - The water was continuously recirculated over the surface, and, - The runoff was continuously heated...
We would have all the elements of an operational cooling system.

For each pound of water that a cooling tower evaporates, it removes somewhere near 1000BTU’s from the water that remains. The more evaporation that takes place, the more heat that is removed. Additional heat is taken away by the air by virtue of its temperature increase but this sensible heat exchange is minor compared to the latent component provided by the water’s phase change.

Still think it's not incredibly efficient? I would still give it a try before the dorm fridge option

Joaco

[nucleuscracker]

joaco -

you must be in hiding - man you have some time on your hands (after the length of that post. )

[organicreefer]

heres my idea:
fan(s) hanging inside stand blowing straight down on the sump and in between the sump and the fans a multilayered grid of small diameter pvc(or whaterve tubing is safe and provides the best heat exchange) with water being circulated through(small pump in sump)that way the fans are used for evaporative cooling at the same time the water in the pipes is being cooled.the more surface area of youre grid the more cooling you get.the only thing im not sure of is if it will work how much turnover would my grid need to make it worthwile (to see a temp drop) would the pump required for said turnover put more heat in the system than the tubes cool it (i doubt it) anyway you think it will work?any ideas on what tubing to usemaybe something flexible (to reduce head on pump)

[dsb1829]

Good lord Joaco! Wet bulb, dry bulb, and psychrometers. I don't have any intentions on revisiting that part of my engineering curriculum right now. I didn't like heat transfer, that's why I chose a design focus .

I went back through your site yesterday. I debated on editing to show that I did realize that it wasn't just a stream, but decided to let it slide. Guess you caught me.

I have read the dorm fridge article several times. That is part of the reason for my questioning the claimed cooling people say is achieved with them.

I wasn't claiming that your cooler doesn't work either. I simply want to design one that takes that idea to an extreme. By this I want to increase the contact time of the water with the passing air. The best way of doing this appears to be fabricating a small cooling tower. My thoughts are by using a spray bar in conjunction with some type of media (haven't decided what yet, will explain shortly) to slow the water and yet have a minimal effect on the air speed through the chamber. I want to use a small clip style fan, but may end up using a blower if necessary. It really depends on the results of some preliminary testing.

The media is something I was hoping I would get suggestions on. I already mentioned the desire to slow water and not air. There are other considerations as well. I need to be able to clean them well. If a slime coating develops on them the efficiency can drop as much as 50%(from online article, e-mail if you want it). Other than that it is pretty much open. I have been thinking ping pong balls, small loop mesh, plastic strand media, or some other type of plastic to distribute the water evenly.

Thanks for the article. I will read it more thoroughly this evening. The connection between lb of evaporated water and btu of cooling is very interesting. At 8lb per gallon that would mean that 8000btu of cooling is achieved per gallon approximately.

Keep the ideas coming!

[Joaco]

Sorry about the writting style in that last post, I was going to leave the office when I typed it

I just sent you an e-mail about the slime/water article, that would be some interesting reading material, thanks for sharing.

About the cooling tower:
as you say, maintainance would be an important point to consider, especially because the bacteria coating would grow fast on that surface that would be well oxygenated. Actually the surface would start working almost like a wet/dry filter, because of the aerobic bacteria, but that shouldnt be of concern if you are going to clean it often to keep it efficient (because of the slime topic).

Because of the surface/speed relation of air/water, I would think that a trickle system would be most efficient, but we are getting into the wet/dry thing again.

There was a good cooling tower design at OZ some months ago, but I just checked and the link is no there anylonger. Let me check tomorrow on my other computer to see if I downloaded the page on that hard disk.

Joaco

[PerryinCA]

Doug,

I think that if you put 4-6 4" fans in the canopy, that will take care of alot. What I just did recently was put a globe industries 6" High velocity fan on my sump connected to a Ranco controller. That and a single Icecap fan in the canopy keep the tank between 79 and 82 degrees, and thats with over 100 watts of lighting. I am wating for my other Icecap fan to come back (broke), but I bet that keeps it at around 80-81, where I want it. The fan is a little loud, but it only runs a few hours a day.

Having external pumps will help a LOT! Testing a Mag vs. Rio for my skimmer caused a 1-2 degree difference! (higher for the RIO).

The tower sounds like a good idea, but I think if you plan ahead and use large external pumps (didn't you get a Dolphin 3500?) you could cut back the heat by a bunch.

Look forward to seeing what you do.

-Perry

[dsb1829]

Hey Perry,

Yeah I got a Dolphin 3600. Definitely not an ampmaster, but it came with the deal so no complaints. I still have to plumb my tank. Right now the 180 is running with HOT 250s, fluval 404, sump, rio return@300-400gph through my uv sterilizer to try and reduce parasite transfer. So far, so good.

As far as my heat situation is concerned it should be far better than on the 72g. The new canopy is 18" tall and has holes for 5 4" fans. That should take care of a lot of the radiant heat preblems. I would like to run a couple of IC fans, but don't like hearing that they are always breaking down. That is the last thing I need, components that need to be regularly warrantied.

I have been busy with setup and also cleaning after the initial aftermath on Sunday, but will be trying out a couple of ideas before long. I will keep you all posted on the results.

[SHUMALA]

I've read on a board somewhere that someone used a 2L plastic coke bottle, filled with water, freeze in fridge, and put into their tank (sump). Extremely cheap.. All you gotta do is make sure there's no holes in the bottle and the seal is tight. When the photoperiod ends, put the bottle back in the freezer and do the same again next day.

Alan