Adapting a bong cooler for 2 stage evap cooler

[GraywolfPrepper]

Hi guys. I'm hoping you can help. I also hope I'm in an appropriate forum for the question.

I'm working on a system that involves an adapted bong cooler. It won't be cooling a computer system but I guess it could be adapted to do something like that. Shuffling around the web, you guys have the most useful info and experience on the topic so I'd like to throw a few questions out there and see what you think. It dives into swamp cooler theory a bit but I should be good with that end. What I'm trying to do is make a pseudo volenti cooler tube and double that with cooling the air, which is the primary goal.

I'm trying to adapt an existing single stage evaporative cooling system for remote cooling of tents and shelters in desert regions. Their idea works fairly well but I'd like to make some improvements.

Instead of just using a container with a single output that has wet pads on the input (the direct stage), I'd like to precool the air going into the system by using a radiator (probably an auto transmission cooler or similar) to improve efficiency.

Here's a sketch of what I'm looking at at the moment

Essentially, The cooling tower will hopefully provide two functions. One, it'll be an evaporative cooler that cools the air inside the center tube by evaporating the water in the aspen padding surrounding it.

The water that supplies the shower/drip system will be cooled by the tower as well and will be pumped up to a transmission cooler at the dry air intake. The exit of that transmission cooler will supply the shower/drip system. The feed line up to the radiator will sit inside the tube to minimize heat gain.

I currently have a 3" inline 240 c.f.m. fan I'm gonna try, which will pull air out of the system (from inside the center tube, which will most likely be made of fencewire and aspen padding).

Depending on the heat gain of the air exhausted from the shelter (probably a lot from a tent), I may then feed back that air into the water reservoir on one side to exit out the other. That air is isolated from the cooling tower air by dropping the cooling tower into the reservoir and drilling vent holes under the water level for the return.

I have a few problems right now with the idea but I don't have all the parts yet to see if I'm right or how to correct them. I'm hoping to hone in on the design first and then adjust later (measure twice, cut once I guess).

1 - I don't know if I'm loopy with this idea
2 - I'm not sure about how much volume of air I'll need in the larger tube to ensure evaporation. Basically, can I pack it with loose aspen padding or does it need a lot of airflow.
3 - I'm thinking of starting with a 6' tower (arbitrarily) but I don't know what kind of pump I'll need to pull the volume of water that high for enough flow to keep the pad wet for maximum efficiency

I realize the water from the radiator will heat up but that should have a negligible effect on the energy pulled from the water as it evaporates down the tube. I'd like the cooled water to precool the air into the system (thereby increasing the efficiency of the evaporative process) without adding humidity to the system until it gets pulled into the center tube.



Anyone see issues right off the bat before I start fabricating?

 

[Bobnova]

It's certainly an interesting concept, one that I don't think anybody has tried before. Seems like it ought to work.

I'm not an expert on this sort of thing though.
I wouldn't recirculate the tent air back through, it'll be humid at that point so a second pass through likely won't do much for it.

 

[GraywolfPrepper]

Thanks bobnova

If I were to use the exhaust air from the shelter, it would be to indirectly cool the incoming air through some sort of a heat exchanger, similar to what I'm thinking of doing with the cooled water. Heat would transfer out of the incoming air but no humidity. Unfortunately I think that because it'd be out in inefficient conditions, the air would be close to ambient by the time it got to the heat exchanger, thereby just increasing complexity and cost without any real temperature change.

 

[Nimblor]

You had me at bong. I am not sure what a bong cooler is but I am familiar with the concept.

Seriously though, there have been several efforts on using swamp cooling, swamp type cooling, and bong cooling for cpus or cases and/or rooms.

Most infamously http://www.overclockers.com/nuclear-tower-water-cooling/

But also http://www.overclockers.com/forums/showthread.php?t=680115r

and http://www.overclockers.com/forums/showthread.php?t=627486

I.M.O.G. looks like he would be a good resource in your endeavor.

 

[GraywolfPrepper]

Awesome nimblor. I did some searching and spent hours reading the posts here but didn't see these ones. Great find!

 

[GraywolfPrepper]

Ooookay. After a bunch of coffees at starbucks and looking at a bunch more threads and other sites, I've decided that a modified sealed volenti dripping down as a tower into the lower chamber will be a lot more efficient and cheaper and easier to build. I'll just then run the water from the pump through an exhaust radiator on its way back up to replenish the volenti stacks.

Thanks for the help guys. Saved me a lot of rework.

 

[RnRollie]

Ooookay. After a bunch of coffees at starbucks and looking at a bunch more threads and other sites, I've decided that a modified sealed volenti dripping down as a tower into the lower chamber will be a lot more efficient and cheaper and easier to build. I'll just then run the water from the pump through an exhaust radiator on its way back up to replenish the volenti stacks.

Thanks for the help guys. Saved me a lot of rework.

I wanna see that work

The thing is: a "volenti" is still an OPEN evap "swamp" cooler.. which means that the "loaded" moist air still has to go somewhere, preferably outside the room. If you seal it and try to recycle the loaded air the humidy level keeps rising till evap just doesn't work anymore.

So, ok, if you want to re-condense it & "dry it out" before reuse there is another issue. Efficiency... condensing requires some energy... so much so that an airco unit is probably cheaper that an elaborate evap swamp cooler rigged up with a recondenser. Not to mention the size... water that changes from liquid to gas/vapor expands something like 1600 times in volume... meaning that if you evap 1 liter of water / hr, you need to "catch" 1600 liters of loaded air /hr to recondense it back to 1 liter of water. Thats about 8 bathtubs of air.. not a smal box

Just a few things to take into consideration..

TL;DR Physics: you need to spend +2kJ energy to compensate for the 2kJ that gets extracted from the water into the air

Dont get me wrong, you might have a more efficient way to get it done, and i'ld like to see the build and see you succeed.
But im pretty sure that you'll have to accept that certain things can only be done if you accept certain losses or allow for expensive solutions.... unless of course you manage to build a perpetuum

 

[coolingdude]

having dealt with 2 stage swamp coolers the key is you only moisten your working air once and that is in the last stage. basically you have 2 normal bong coolers used as it always would be except that the water from the first unit is pumped 2 some sort of a heat exchanger on the inlet of the 2nd unit. as the temperature difference between ambient air and the water is relatively small you will need a radiator larger than the inlet of the 2nd bong cooler to increase contact time with the air entering to allow sufficient exchange of heat... 2 stage evaporative cooling is only good for when you need to get to below the current wet bulb temperature. If you haven't already reached within a few degrees of that dont bother with 2 stage, you need a larger single stage.