Coolers how good or bad?

[ericmark]

Tried to buy an AC everywhere sold out, hardly surprising in this weather, I was offered a cooler instead, as far as I can see you cool a pack in freezer then fit to cooler, thought was AC around 2 kW and freezer around 80 W so it would not work for long, before freezer full of packs waiting to be cooled. However in the time while waiting for AC's to be back in stock seems a reasonable option.

So every empty pop bottle and milk bottle filled with water and put in the freezer, two days latter ready to give it a go, So 4 bottles, not full so around 7 litres of frozen water placed on a tray to catch any condensate in front of a fan, if it worked then repeat.

Well loads of condensate, had to empty tray twice about two mugs full of condensate, however it did not seem to cool the room by even 1°C in fact not even 0.1°C it was worse than without the bottles as without the fan was set to move side to side but with bottles aimed direct at bottles, I did not expect a massive drop, but did expect to be able to measure it. Room thermometer started at 27.9°C and 20 minutes latter it was 28°C the bottles took some 2 hours to fully turn back to water, but temperature remained at 28°C. It did to be fair feel cooler, likely due to lower humidity, but at 61% now outside it was not that high anyway.

So if I had bought a cooler which had done that, I would have taken it straight back, they are sold, so one assumes they must work better than may simple bottles in the room, windows and doors kept closed of course.

So what do these coolers do, that my 4 two litre bottles of frozen water did not? what have I missed?

Now trying to cool house ready for tomorrow, my idea is, if cool to start with, I have a chance of keeping cool all day, but 23:20 now and room at 25.8°C outside 18.5°C and garage at 21.2°C windows open and fans running but curtains closed to stop attracting moths. Want to see house at 20°C before morning.

I have banned use of oven, OK still use microwave, kettle and induction hob, and during day no computers. The latter really helps. But back to are these so called coolers any good, and if so what do they do which my frozen bottles did not do.

 

[big-all]

the trouble you have the heat must be exchanged this can only happen via the bottle surface
you may get better results with a damp towel as you have a greater surface to evaporate the water
ideed you will loose far more heat iff you wet your skin and blow the fan to dry as the 28degree air is cooler than body temperature by about 9degrees
indeed an open window back and front may cool far quicker regardless off inside temperature

 

[ericmark]

I did consider larger surface area, however it only lasted 2 hours before all ice melted, increase surface area and time would reduce.

 

[big-all]

ice is a very inefficient way to cool an area as you have to pump that amount off heat to make the ice into the building in the first place
where as water evaporation with an open window uses heat to evaporate the water for little more than a few watts to run a fan

 

[ericmark]

ice is a very inefficient way to cool an area as you have to pump that amount off heat to make the ice into the building in the first place
where as water evaporation with an open window uses heat to evaporate the water for little more than a few watts to run a fan

That may be correct, however my mother at 92 objects to being sprayed with water to cool her down. The idea of a metal or other good conductor where the open window is with a pump dribbling water down a towel on the outside, with two fans one inside and one outside would likely cool down the room using latent heat of evaporation, however it would not be easy to set up.

 

[big-all]

you pass the air through the damp cloth or towel no spray no water droplets just hopefully cooler air but with more moisture