cooling your tent or van

[FIGJAM]

Make a 120 volt version for the house.

Box fan from walmart and an ac pump from HF and you know the rest.

[Jackass]

A GFI outlet wouldn't hurt either...

[Adi052]

Dude, you are my hero du jour. I was trying to think of a way to build something along these lines and it hadn't come together in my head. I will gladly steal your design.

[FIGJAM]

Dude, you are my hero du jour. I was trying to think of a way to build something along these lines and it hadn't come together in my head. I will gladly steal your design.

[captain mcguiver]

So on Esplanade around 4:30 they had an ask a physicist booth. Of course I waited my turn and brought up the subject of swamp coolers and the ol' "where does the heat go?" question we couldn't get straight at cooler con. Anyway, after about 20 minutes all I got out of the conversation was something about the change of states of water to vapor "taking" the heat.

A little more research and I got the clearest answer I could come up with:

heat cant go, it is a form of energy and can only be tranformed into other types of energy. the heat energy is transformed into kinetic energy in the water molecules.

So basically, everything is cool, the only thing changing is the water to water vapor which "takes the heat" and leaves us with cool air and cool water.

I guess it makes sense. Hope that clears some things up for some of you who cared.

[FIGJAM]

I think I remember the term "phase change"?

[Snow]

The simplest way is to think of boiling water. When you boil water to make steam (a phase change) it takes heat to excite the molecules enough to cause a phase change. Same think happens when you evaporate water, it takes heat to make it happen. This heat comes from whatever the water is "on" this case the air (to keep it simple). thus the evaporation cools the air and also increases the humidity (and density-but thats a tangent). Same thing happens when you sweat, a dog pants, or you pour rubbing alcohol on your skin.

[FIGJAM]

I knew it was magic all along.

[Noboundaries]

Thanks for Figjam for the ideas and the original design. Worked great but we took a bit of a different route for their use.

I built two AC Bucket swamp coolers because we were going to be taking a quiet gennie anyway (Champion 2000 watt inverter generator). The gennie runs for 9-10 hours on one gallon of gas on the econ setting (550 watt output). Had to modify the bucket design and make it a double level evaporator due to the AC factor and size/depth of the cheap ($15) AC fan. One of the swamp coolers was for evaporating greywater and the other for tent cooling using meltwater. Even though the tent cooler worked great, put out 185 CFM airflow at 68 degrees at 20% humidity into a 460 CF tent, we were actually more comfortable taking our siestas in the afternoon breeze under our white monkey hut laying in our anti-gravity chairs (the white MH always stayed cool to the touch, even during the hottest part of the day). Consequently we ended up just using them both for greywater evaporators to the open air, not for tent or closed space cooling. We had a giant funnel with a screen filter in it to catch food particles/hair/etc that we threw in our trash before we loaded the evaporators. Playa dust didn't make any difference at all.

One of the evaporators had a 92 gph pump and the other a 252 gph pump. The smaller pump evaporator could evap about 3/4 gallon per hour and could draw the water down to about 1/2 inch in the bottom bucket. The 252 gph pump version was evaporating twice as much due, probably due to better element saturation but could only draw the water down to about 1 1/4 inches before it started sucking air. We were evaporating 3.5 to 4 gallons of grey water a day so the gennie only ran for less than two hours a day. Typically we waited until the RVs around us turned on their LOUD generators in the afternoon before we turned on our quiet one. Couldn't even hear ours with the RV generators running.

We ended up bringing about 1.5 gallons of greywater home. Next year I'll add a third level to the evaporator, putting the larger pump in a small sump that will maximize the water catch, leaving only a cup or less of unevaporated greywater.

[FIGJAM]

Another mild year heat wise.

[sharpstick]

Kinda makes you realize what an incredible deal that HF pump was! I'm seriously kicking myself for not grabbing one a week ago.

i avoid harbor freight. that incredible deal isn't so good when that POCC(piece of chinese crap) dies midweek on the playa. maybe get two for redundancy. how good does that deal look now?

[sharpstick]

Thats a great plan. I misunderstood.

I think the bleach will take care of any bacteria.

that's fine if you don't mind the smell. no personal experience, but i've heard stories . . .
i have very clean cooler water since i started loading my ice into gallon ziploc bags, also any open perishable food, either in bags or sealed containers. now what water does seep into the bottom of my coolers is fresh and clean, although a bit dusty.

[unjonharley]

Kinda makes you realize what an incredible deal that HF pump was! I'm seriously kicking myself for not grabbing one a week ago.

i avoid harbor freight. that incredible deal isn't so good when that POCC(piece of chinese crap) dies midweek on the playa. maybe get two for redundancy. how good does that deal look now?

Anyone else try a HF pump

[FIGJAM]

The Harbor Fraight solar fountain pump is OK for the bucket cooler and I have'nt had any reports of failure, but any cloudiness or dust on the panel and they quickly become inefficiant.

[sharpstick]

The Harbor Fraight solar fountain pump is OK for the bucket cooler and I have'nt had any reports of failure, but any cloudiness or dust on the panel and they quickly become inefficiant.

YMMV. HF products in general are inferior. I've had too many defective products from them to consider the savings worth it. Chinese factories can make good merchandise, but they only bother to when they are contracted by a real brand name who has to stand by the products and requires the quality.

[Noboundaries]

Both the pumps mentioned above in the coolers used for grey water evaporators were HF pumps. Grey water was, well, grey water, though filtered to remove particles, and there was a ton of dust in the evaporators. The HF pumps worked perfectly all week. I had one spare 92 gph spare just in case. It is still a spare.

[FIGJAM]

If you build the taller evaporator you will need a pump with more head.

[usurpedus]

i wish we could find a premade container with the ideal 15x15x24in dimensions for the unicooler

[FIGJAM]

You can, but I was trying to keep it cheap to build.

http://www.acrylicdisplaymfg.com/html/d ... cubes.html


http://www.interiorplantscaper.com/buy_flashy_box.htm

[Canoe]

Couldn't get dura-cool pads at HD Reno this year.
Manager of section said they stopped reordering them (and other cooler parts/supplies) partway through the summer, so they're usually long gone by mid August.

Lowe's in Fernley was another story. Pads & rolls in stock. Photos taken on Sept. 3rd.

duracool sm.jpg

[HandJamMasterC]

I've replaced my Harbor Freight solar pumps ( the solar panels were too small and dust sensitive ) with this - Remote Controlled Solar Water Pump Kit with LED lights - 211GPH

http://www.1000fountains.com/remote-con ... 16614.html

Wow, does this thing move the water. Plus, it's remote controlled. I had to increase the plastic tubing size to get the increased flow. Should work really well, plus the battery back up and bigger solar panel is awesome.

[missprism]

hi! figjam, i am so looking forward to trying the bucket cooler.

question 1) what is the best way to cut the hole in the lid to place the fan? will just a box cutter do?

question 2+) i am a total idiot when it comes to batteries. can someone please? explain in the simplest of terms how to get power from a battery to the pump and fan? what equipment is needed? do you have to solder?

MUCH appreciated. MANY thanks!

[FIGJAM]

Yes a box cutter will work.

The easiest way to connect to the battery would be alligator clips.

I spliced the fan to the pump wire by just cutting the wires, twisting them together, and sealing them with shrink tubing.

This leaves one long cord to go to the battery.

[missprism]

Perfect! Thanks!

[Roark]

While researching the physics needed to evaporatively cool a 30 foot dome, I found something I would like to share. The total cooling effect is 890 btu per pound of water evaporated. A gallon of water is 8.3 lbs. So for the folks who are getting a gallon per hour of evaporation, you are creating 7,400 btu of cold.

Put another way: Figjam's V2.0 is creating the same amount of cooling as a small A/C unit from Homeless Despot.

Pretty impressive.

Something else to throw into the communal hat for when Figgy gets the itch to experiment again: insulate the water reservoir. The heat gain into an uninsulated reservoir accounted for 6-7% of overall losses in an experiment at the Univ of Idaho.

[FIGJAM]

The heat gain into an uninsulated reservoir accounted for 6-7% of overall losses in an experiment at the Univ of Idaho.

Can you link that experiment?

Outside air temp of 98 degrees.

Cooled air comeing from the bucket, 68 degrees.

Water temp in the bucket, 58 degrees.

Where does the 6-7% lose happen?

I've never seen a manufactured evap cooler with any insulation of any kind, and I've seen MANY brands.

A 30 degree drop in temp is optimim according to the charts in this thread.

Adding extras to the design just adds to the cost of a simple to build project.YMMV

[Roark]

Its a pdf doc I downloaded. I am on the ipad and dont have it available but will find the URL and post it. You might find it interesting.

As I recall the context of that 6-7% was in the form of a loss compared to the best-case theoretical scenario.

From memory the average swamp cooler reaches about 85% to 89% efficiency. Of the 15 to 19% lost, 6 to 7% was due to an uninsulated pan, and the rest was due to the heat input of the motor and pump.

A back-of-the napkin calc however does not show this to be in the ballpark. A 1/3rd horsepower motor draws about 300 watts (1023 btu). A typical recirc pump draws about an amp (340 btu) for a total of 1360-ish btu. Add-in that 6-7% for uninsulated loss for another 680-ish btu and you have about 2040 btus of lost cooling capacity. If we figure this loss to be 13% of our total output,(overall system eff is 87%, splitting the difference here) then total cooling output would be 15,692 btu. That cant be right. Its LOW.

Realworld specs on a commercial unit are 4.3 amp draw, 4500 cfm, and a 25F drop with 5 gph used. Just calculating the theoretical btus gives you 36,935 btus at 100% efficiency. That is off by half. Not even close. If we assume the advertisements are right, that 4500 cfm with a 25F drop would take 135,000 btu. Again, a huge disconnect.

I think I need to go beat myself with a psychometric table and see where the errors are. i'm just confusing myself here...

Edit: BINGO! I found the motherlode. See: http://www.piec.com/formulasdef.htm

[FIGJAM]

I don't know all the science.

I'm speaking strictly from practical experience, so I'm not hampered by facts when I start a project!

Your example is for a full sized cooler and the heat from the motor and pump may affect efficiancy.

For all practical purposes, the fans and pumps we're useing here are creating so little heat that it is effectivly 0.

My point here is to keep this so simple that anyone wanting to build a cooler won't be discouraged by fiddeling details.

The fact that they report a 25 degree temp change makes me suspicious, as my thrown together designs consistantly get 30.

[missprism]

i know using grey water from food use isn't recommended... but how about using shower water? would the soap suds affect anything? i think i might make my space smell nice

how are people securing the endless breeze fan to their boxes? is it heavy?

[unjonharley]

i know using grey water from food use isn't recommended... but how about using shower water? would the soap suds affect anything? i think i might make my space smell nice

how are people securing the endless breeze fan to their boxes? is it heavy?

You shower to get the crud off your body.. Why would you want to spray it back into your air.. Dead skin and stuff like that start to rot with in hours.. Your tent could smell like a dead person..