Cooling Tower Project

[lfsmarineguy]

I think there are a lot of ways you can go with this. Nitrates are a concern for me too and I think adding anything into the tube that could potentially trap particles that would decompose is bad. I don't see there being a need to use any of that stuff if the design was tweaked.

 

[meschaefer]

You could also make a second tube attached to the first, essentially the same design, and both dumping into a common reservoir at the bottom, but the second would just be for recirculating, increasing the pull down where higher temps are an issue.

I am not sure if recirculating the water would be useful. You will only be able to pull the temp of the water down so far (limited to the wet bulb temperature). It would only be usefull if the first cooler couldn't bring the temp down to the wet bulb temperature. But I wonder if it gets harder to bring the water temp down the closer you get to wet bulb temps.

If you where to have two tubes, basically two tower coolers, I think that you wold be better off running tank water through both of them, it would pull the temp down faster although not necessarily farther.

 

[lfsmarineguy]

That's what I was talking about. If the first tower wasn't at max efficiency the second tower would be recirculating the water apart from the first. The introduction of tank water would be slower in the second allowing the second to pull down more than the first since there is less heat being introduced.

 

[boozeman]

If I am looking at this correctly it seems to be a confined evaporative cooler. you can get more ideas by looking up the term ''swamp cooler''. You can get better efficiency by having the water percolate thru mesh material(such as enkamat) to increse the surface area being evaporated by the fan. Also, look at the way Deltec does their evaporative cooling unit.

 

[meschaefer]

If I am looking at this correctly it seems to be a confined evaporative cooler. you can get more ideas by looking up the term ''swamp cooler''. You can get better efficiency by having the water percolate thru mesh material(such as enkamat) to increse the surface area being evaporated by the fan. Also, look at the way Deltec does their evaporative cooling unit.

I have looked at the use of mesh, and have even been to a website for a company that sells the mesh for commercial applications. The concern that I have with mesh is that I fear the mesh would become a site of Nitrate production.

The deltec units, as well as some of the other evaporative coolers I have seen on RC and other places (as well as swamp coolers) are all reliant on the use of the mesh (technically called "fill"). More often than not, these type of systems end up being a large box, with water sprayed over the top of the mesh/fill, and air introduced from the side. This is crossflow design.

Here is a RC build thread for a DIY using the deltec model

If not for my fear of nitrates, I think that this wold be the most efficient design. But since I want to avoid the use of fill, I am somewhat constrained to the counterflow design, which does not require mesh/fill, as air is forced against water falling from the opposite direction.

 

[boozeman]

I'm sure that you could swap out the fill ofthen enough to negate the growth of bacterial mulm ....or, how about if you use a nylon screen and culture algae (sort of a modified algal turf scrubber) to take care of the nitrates while a fan blows across to do the evap. ?

 

[Wes]

what about the mesh causes concern for "producing nitrates"

the fear of detritus buildup?

or do you think bacteria will colonize on the mesh and somehow result in high nitrates like the old wet/dry filters?

If it's the latter, i think it will be negligible. Im sure you already have the nitrate removal taken care of by other means. The bacterial mulm on the mesh can't create more nitrates, it just won't remove nitrates... You will still have the same amount of NH4 going in, so I don't think it's possible for the mesh to create any more. Just keep the mesh clean and you will be fine.

 

[meschaefer]

what about the mesh causes concern for "producing nitrates"

the fear of detritus buildup?

or do you think bacteria will colonize on the mesh and somehow result in high nitrates like the old wet/dry filters?

If it's the latter, i think it will be negligible. Im sure you already have the nitrate removal taken care of by other means. The bacterial mulm on the mesh can't create more nitrates, it just won't remove nitrates... You will still have the same amount of NH4 going in, so I don't think it's possible for the mesh to create any more. Just keep the mesh clean and you will be fine.

Yes I am concerned about bacteria will colonize the mesh. IMO, when bacteria produce nitrates far from the anaerobic bacteria that break it down, it is not as readily available to the anaerobic bacteria resulting in an inefficiency in the breakdown... and an increase in measurable nitrates.

 

[meschaefer]

As I said at the beginning of this thread there are some drawbacks to this type of system. I thought that I should take a moment to point those out.

1. This type of system works on evaporative cooling, much in the same way that allowing a fan to blow across your tank helps cool it. The amount of cooling that the system can perform is limited, and this limit is directly related to the relative humidity. The more humid it is outside, the less the system will be able to cool. No matter how big the tower, or powerful the fans, you will never be able to bring the temperature below what is called "wet bulb". Wet bulb temperature is always lower (unless there is 100% humidity) then air temp. Here is a link on how the wet bulb temp is determined.

2. As this type of system works on evaporation, it will increase the relative humidity in immediate vicinity of the cooling tower. If this humidity is trapped in the room the tank is in, or more importantly from the same location where the cooling tower draws fresh air, the efficiency of the system will drop as the system runs. Remember, as the humidity increases, the wet bulb temperature increases and the cooling capacity decreases. What is nice about this type of system, is that you can easily vent the humidity outside, assuming that you have a way to run the vent, and avoid this problem.

3. As this type of system works by evaporation, you will necessarily go though more top off water. If you are using RO/DI (and you should be using RO/DI) you will need to produce more water... going through filters, DI resin, membranes and waste water at a faster rate. It is not recommended to run a system like this without an ATO.

 

[Wes]

Yes I am concerned about bacteria will colonize the mesh. IMO, when bacteria produce nitrates far from the anaerobic bacteria that break it down, it is not as readily available to the anaerobic bacteria resulting in an inefficiency in the breakdown... and an increase in measurable nitrates.

yes but with the same amount of nitrogen going in, it is impossible to create MORE nitrates. Do you understand what I mean? Increasing nitrates will be impossible in this case unlesss you also increase the ammount of Nitrogen going into your system. It wont matter that there is no anaerobic bacteria in the mesh, because you have the same amount of ammonia being converted to nitrates with or without the cooler.

 

[wxl14]

If you are in NJ/NY and u say you have a basement setup. I would break the cement about a foot down lay the pipe and run the water through there. That way You get to cool your water for free. and all it cost you is a little cement and some backbreaking work. But this would be guranteed to work. just my two cents. Plus I would buy a dehumidifier for your basement. Just the normal evaporation of a tank that is 300 gallons has to be a lot. you dont want any mildue problems.

 

[meschaefer]

If you are in NJ/NY and u say you have a basement setup. I would break the cement about a foot down lay the pipe and run the water through there. That way You get to cool your water for free. and all it cost you is a little cement and some backbreaking work. But this would be guranteed to work. just my two cents. Plus I would buy a dehumidifier for your basement. Just the normal evaporation of a tank that is 300 gallons has to be a lot. you dont want any mildue problems.

While I appreciate the input, it nothing I haven't considered before and I want to keep the thread on topic.

 

[meschaefer]

yes but with the same amount of nitrogen going in, it is impossible to create MORE nitrates. Do you understand what I mean? Increasing nitrates will be impossible in this case unlesss you also increase the ammount of Nitrogen going into your system. It wont matter that there is no anaerobic bacteria in the mesh, because you have the same amount of ammonia being converted to nitrates with or without the cooler.

You absolutely correct, there will be no more nitrates than there where before. Ammonia in, nitrate out, the amount of nitrates produced is tied only to the amount of ammonia in. The idea of a "nitrate factory" is a misnomer at best. Perhaps it is better to think about the next step in the process, the production of Nitrogen, which uses up the nitrates.

Follow this, if the nitrates are not available to the anaerobic bacteria that break the Nitrate down into nitrogen, then the denitrifaction will not happen. IMO, the reason people with bio balls usually have high nitrate readings is because the production of nitrates is not taking place in close proximity to the anaerobic bacteria. The nitrates then need to make there way to the anaerobic bacteria before they can be broken down, this is inefficient.

When nitrates are produced in close proximity to the anaerobic bacteria (such as in live rock), they are readily available.... allowing for not only a higher population of dentirifying bacteria, but they are converted before they have an opportunity to "escape" into the water column.

Just a theory.

 

[wxl14]

Keeping on topic I doubt that one five foot tube will be able to keep the water cool. To be realistic about this project you would have to run and experiment. See how much cooler the water get after dropping from the tube with the fans on. The temperture at the top. Then the temperture at the bottom. You will have to have a very accurate thermometer. As I believe the cooling would be very small. Then you would have to see how many gallons you can pass through the system why still keeping the same cooling effect. I would be cautious as I believe to see any cooling at all you would have to have multiple tubes to cool. I don't believe one five foot tube will do it. Maybe 3 or 4 would do the trick. Also I believe by doing this you will be losing a lot more water and salt out of your tank do to evaporation and salt creep.
but keep us posted and if you have a digi cam take some pics so we could see what your working with.

 

[meschaefer]

Keeping on topic I doubt that one five foot tube will be able to keep the water cool. To be realistic about this project you would have to run and experiment. See how much cooler the water get after dropping from the tube with the fans on. The temperture at the top. Then the temperture at the bottom. You will have to have a very accurate thermometer. As I believe the cooling would be very small. Then you would have to see how many gallons you can pass through the system why still keeping the same cooling effect. I would be cautious as I believe to see any cooling at all you would have to have multiple tubes to cool. I don't believe one five foot tube will do it. Maybe 3 or 4 would do the trick. Also I believe by doing this you will be losing a lot more water and salt out of your tank do to evaporation and salt creep.
but keep us posted and if you have a digi cam take some pics so we could see what your working with.

Evaporation and salt creep are a concern. As indicated in my post of potential problems, I would not attempt this type of system without an ATO.

As to potential cooling effect, I am also concerned about this as well, and but for the extensive amount of research I have done I would have dismissed the idea completely.

In the link I posted to a thread on RC, found on the first page, a reefer in New Jersey built a much shorter version, about a 2 foot drop but with a 6" diameter pipe as opposed to 4" on my design. He was achieving temp drops approaching 12 degrees on a 72 gallon system. The 12 degree drop brought the system to 8 degrees below ambient room temp, on a system that normally ran +4 degrees above ambient room temp.

At 12 degrees cooling (or 8 degrees below ambient room temp) he reached the limit of the system, i.e. it wouldn't bring the temp down any further. The real question is whether the end temp was limited by the size of the device or if he had reached the wet bulb temp.

 

[wxl14]

I have an idea that incorporates the cooling of the system and some artistic merit. since its a bit of topic i will pm u the idea. It might come out pretty interesting.

 

[meschaefer]

I have an idea that incorporates the cooling of the system and some artistic merit. since its a bit of topic i will pm u the idea. It might come out pretty interesting.

Please do. I am open to most ideas, just want to keep the thread clean.

 

[wxl14]

Pm sent

 

[artie1209]

how about running the tube into a sealed 5 gal bucket and pluming the bucket back to the sump you can cut a hole in the top of the bucket and install a computer fan blowing in to create positive pressure or even a large air pump might accomplish the same effect.

 

[meschaefer]

how about running the tube into a sealed 5 gal bucket and pluming the bucket back to the sump you can cut a hole in the top of the bucket and install a computer fan blowing in to create positive pressure or even a large air pump might accomplish the same effect.

I am not 100% sure about what you propose.

If everything is the same, except for the fan placement and the addition of the bucket. It would work, but the bucket is kind of meaningless and possibly a determinate. In that case it would just be a reservoir where cool water would sit, (after falling from the tube) possibly heating up due to ambient air temperature before flowing back to the sump. The placement of the fan into the bucket, as opposed to into the tube, would possibly create more back pressure slowing the speed of the fan and therefore the amount of air flowing through the tube. Also less efficient.

If on the other hand, you intend to have the water just in the bucket (and not flowing through the tube) and the fan blowing into the bucket, with the tube acting as a chimney for the heat blown off the water. I don't think that wold work very well. It may work a little, but I would be surprised if it lowered your overall temp to a point where it was worthwhile. Comparatively, you have very little surface area.

The system works off of surface area, the point of the tower is two fold. One: the water surface area is increased as it is forced into streams or drops by the plate at the top of the tower. Two: the contact time with the air is increased as the air and water counter flow past each other through the tube. The more surface area (ie drops of water) and the more contact time, the more efficient the system will be in removing heat from the water.

I do not see any situation where an air pump would work better, or more efficiently, than a fan.