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Post by woodyz on May 30, 2014 20:44:08 GMT -7
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Post by geron on May 31, 2014 17:16:36 GMT -7
I think he mentions this but doesn't work well at all in high humidity. We often run 90% and better. 93% humidity with ambient temp at 71° outside as I type!! Running a dehumidifier in the house and humidity is down to 41% inside.
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Post by woodyz on May 31, 2014 17:30:48 GMT -7
It works off evaporation of the water in the bucket, so the higher the humidity is the less effective it is. He had a note at the bottom saying it works better in direct sun. Running it will also increase the humidity inside whatever you run it too.
Growing up a water cooler wasn't what you kept your beer in, it was that big box hanging out side the window, swamp cooler, whatever. They did make it bearable to sleep on a hot night.
Somewhere on here is a post I made using the same evaporation process, without any fan or battery to keep fresh food or refrigerated meds like my Son's insulin cool enough in the summer and warm enough in the winter.
This was where I started but I wanted to use the same technology in something I could carry. I will try and find the post.
OH! It does work too.
zeer pot is the name most used, instead of cooling the air and pushing it out, you are cooling the inside of the container.
they use sand I am using perlite and anti-freeze.
Oh yeah! I remember now, we all already have a pretty good start on one if you have a hand crank ice cream maker. You can't count on ice, but you can rig the hand crank to circulate water/anti-freeze through the moister retaining material. I got it down to the size of the one cup soup thermos we used to carry. It is now a emergency refrigerator for his insulin, you can prolong the cooling my shaking it to redistribute the media from dry to wet. Then I use a series of small clay pots to rejuvenate the cup sized fridge when in a camp.
Running water is a big plus but just a source of water you can pour over is required, doesn't have to be potable water. In fact I was working on a model where I could filter water and "charge" the cooler in the same process. keeping it warm is the opposite, but the media changes from perlite and anti-freeze to mineral oil. Where the mineral oil is warmed with heated water in a coil wrapped around the container holding the meds. The anti-freeze wasn't retaining heat as well as it was cold. I have already tested this.
But I am going to try and distill water from a tea pot through the coil, so I am heating the mineral oil and distilling water at the same time, but I will have to cool the mineral some after as it makes it too hot.
I can keep six vials in one container, that's a little more than four months, so there would have to be a cooled and heated cache somewhere. Cooling isn't so hard stopped using a running water supply and hiding it under the water. Heating is different, it can't get to0 hot. A root cellar a 45 constant temp would be ideal.
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Post by marc on Jun 2, 2014 7:26:22 GMT -7
As you pointed out, Geron - evaporative cooling schemes are limited to places that do not have too much humidity. In your example of 71F at 93%, the best possible evap cooling system would cool the air down by only 1 degrees – and push it up to almost 100% RH – causing condensation problems. Your dehumidifier is the way to go for comfort!
Under very low humidity desert type conditions, evaporative coolers (and Zeer pots) can help a lot – it only depends upon your expectations. I bring this up only to point out that it is not a replacement for refrigeration for things like meat or vaccines, when it’s hot outside.
The best you can do under any condition, is to get within a few degrees of the wet bulb (saturation) temperature. Regardless of claims posted on the internet, you can never get colder than the saturation temperature with conventional evaporative cooling with water.
For quick estimating purposes, with a very well designed Zeer pot, with high winds blowing across it - add 4-6 degrees to the wet bulb, to get your interior pot temperature.
So in the examples below:
100 degrees at 30% relative humidity, you should expect to see 78 degrees in your Zeer pot.
90 degrees at 15% could get you to about 63 degrees in the pot.
80F at 60% RH = 70 wet bulb
80F at 30% RH = 57 wet bulb
80F at 15% RH = 53 wet bulb
90F at 60% RH = 77 wet bulb
90F at 30% RH = 65 wet bulb
90F at 15% RH = 58 wet bulb
100F at 40% RH = 77 wet bulb
100F at 30% RH = 73 wet bulb
100F at 15% RH = 66 wet bulb
Generally, in areas that are not “bone dry” - evaporative cooling schemes are least effective when you need it the most.
Disclaimer: All of the above numbers are approximated for ease of use and for the purposes of this discussion!
Marc
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Post by hunter63 on Jun 2, 2014 8:11:43 GMT -7
Like most of these kinda of projects....that actual performance will be varied all over the place.
So the question becomes "Is it worth the trouble?"
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Post by garret on Jun 3, 2014 7:16:08 GMT -7
from my experiance with evap cooling it is best started before the heat of the day build and tends to act more like a heat barrier than a cooling system, it certainly works well in melbourne where we dont have much humidity as long as it is used correctly, if you wait for the heat to build it struggles to work well
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