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So I cannot sleep in heat and humidity. At all. I have designed a cheap tent air conditioner and dehumidifier based on the peltier effect. I haven't built it yet, I was hoping for some advice on it first. I will be glad to share my results with you all so you can also stay cool. It only needs a 12v power source.
Here are my plans, hopefully its not to confusing. I will use one of those cheap foam coolers to house it. Than put a tube maybe 6" wide through it. The peltier pads will be placed around this, the cool side facing toward the center tube. Basically one side of the pads gets really cold and the other side gets really hot when you apply a current to it. Heatsinks will be placed on both sides to increase surface area. A fan will blow cool air through the center tube, cooling the tent. The transferred heat will end up inside the cooler, which will be blown out an exhaust tube outside the tent. Place a bucket under it to collect the moisture it sucks out of the air onto the cold heatsinks. Here is a crappy drawing (yes, its ms paint, I just installed windows 7 rc1 and don't have photoshop up and running yet) Please give me your input on improving the design, or if you have any experience with peltier devices, as I only just discovered their existence maybe a week ago.
I think you are going to need a pretty large heat sink for the peltier pads to work efficiently you may even want to consider some water in the bottom of the cooler for this purpose. Also what is your power source going to be?
peltier pads don't use much power. The heat will be tremendous though. Foam coolers are allowed but highly frowned upon.
EDIT: I don't know if you will be able to produce enough condensation but if you were able to pump/spray/redirect the condensate onto the hot heatsinks you would greatly improve your ability to pull heat out of them.
What if you placed all of the peltier pads on the underside of the 'cold tube' so that the hot heatsinks were at the bottom of the cooler. Than set it up to drain all condensate into the cooler so the heatsinks would be sitting in the puddle of condensate. if you make the cold tube short and wide, it wouldnt really matter if peltier pads were on all sides of it...it would probably make it more efficient
Sorry to report but it will not work. You would need tons (one tone = 12,000 BTU's) of cooling to cool down a tent in hot and humid weather. There is absolutely no insulation properties in tent material. The heat load would be tremendous even if your tent was in the shade.
It doesn't have to be a foam cooler, I just went with that because I figured it was cheap. And I will try to redesign it to utilize the condensation to help cool the hot side. Also I will be using one of those portable 12v power packs kinda like a car battery. Maybe one with a solar panel to recharge it.
I realize something like this will not cool off my entire tent that much. I am more interested in having a cool stream of air blowing on me for a few hours as I try to fall asleep, and maybe in the morning to squeeze in a few more ZZZ's after the sun comes up.
He could definitely get something going if he threw heatsinks on either side of those pads. Even if it was a small jet blowing directly onto his head, it would be refreshing. Definitely would need a tank of water that was doing a spray on the hot heat sinks the more I think about it though. It would be overkill for a small payback but doable.
yes its kind of elaborate for basically a fan blowing cold air but I am worried I would not be able to sleep in those conditions. My apartment is kept around 68 degrees at night. (all utilities are included in my rent I pay same price regardless how much the AC is used) And I am always building odd things like this so I would enjoy the project, I don't really consider it a hassle or anything.
Another question: would it be more effective to have the hot side of the heatsinks submerged in water, or use small amounts of water dripping or sprayed so it can evaporate? the re humidified hot air would stay in the hot side of the chamber and blown out of tent.
haha so I just re read this thread and had this image of a bunch of hippies munching on corn reading this scratching their heads going wtf is he talking about?
Not that I'm saying I think this forum is full of hippies, but I realize maybe this would be better suited in a forum full of engineering students. Just thought I would share with my fellow Rooers a project that will help the next 40 days go by just a little faster.
That's an awesome idea, I would love to have that at roo. My solution to that has usually been drink the beer faster before it gets warm, but if I wasn't broke and actually bought descent beer I would definitely consider doing something like that.
I think if you got a good fan to blow on you in the morning and at night it would be much easier and get the same job done. The air wont be cooled but with the heat you will more than likely have at the very least a layer of moister on you regardless. So just a fan blowing on you would be fairly cool.
The drip/spray will work better than submerged in water. The phase change will remove large ammounts of heat. If you are going to submerge it in water than you probably need to throw water blocks on the hot side and pump the water through a radiator. On a side note, 68 degrees!? Ironically enough, AFTER Bonnaroo I finish out the summer with the windows open and no AC, I've just gotten used to it at that point.
A simple fan may do the trick as well, but that's not nearly as fun. I have already committed myself to building some sort of cooling device and I am too stubborn to give it up. If it doesn't work, not much is lost. But if it does, it will be that much more of a pleasant surprise.
Even though I don't expect the temperature to drop that much at all in my tent, since it is waterproof wouldn't it drop the humidity significantly?
I'm not tryin to give you a hard time or anything, so please don't take it that way... but honestly I would just learn to deal with the heat for a few days. This or something similar probably will not work... the humidity will overwhelmingly overpower this device.. a tent just doesnt serve as any sort've temperature/humidity barrier.
The farm cools down SIGNIFICANTLY after dark.. it actually gets quite chilly sometimes. Just plan on the sun waking you up, or rent an RV.
I am tremendously averse to humidity. Just reading this thread makes me sweat. I have managed to sleep quite easily until the sun comes up at Roo.
If you are up until late night (which you should be), its not too bad at night (you will also be exhausted). The Hell-Furnace that commences when the sun hits your tent in the a.m. is probably impossible to combat. You would probably get more results rigging shade up over your tent.
That said, if any of you engineering guys comes up with tent AC, let me know.
If I were to build any sort of cooling system, I would just go with such...
A closed loop system comprised of a coil of metal tubing in an ice chest that is plumbed up to another coil or grid of metal tubing that is strapped to a fan. Put a small pump in line between the fan grid and the coil to cycle what ever fluid you choose to fill the system with. A 60/40 mixture of anti-freeze/water would probably work well, and might even stand up to having a block of dry ice in the cooler with the coil without freezing solid.
I'm not sure how often you'd have to recharge your cooler with ice, but this would probably make some fairly cool air.
I'v looked at a few simple solutions involving water. the best one I came across is like a better version of the one in the video a few posts up, but instead of just blowing over the top of the ice, I would pipe a metal tube into the cooler filled with ice, kinda like a reverse radiator. I just figured an electric based design would require a lot less maintenance at roo, traded for the hastle of building it.
Well unfortunately I haven't made much progress yet. Well actually none at all. I have been a lot busier lately than I planned (put a business start-up on hold in favor of finishing college and decided to study abroad in New Zealand at the last minute, I'm leaving 2 weeks after roo!)
Anyway, I will most likely be going with a much simpler and even cheaper ice based system, will post a drawing shortly. I've scoured the internet and took the best parts of every ice based cooling system, as well as everyone's advice from here, and put it together into a simple but effective design
