Although cellophane is nearly impermeable to air and liquid water, it is permeable to water vapor, aka humidity.

Because of that, it should be usable as a key component of a dehumidifier (or perhaps an atmospheric water generator), using the following simple setup:

First, fresh air passes through a dust filter, then across the top surface of our cellophane filter, then between the heat sink fins of the hot side of our peltier effect heat pump, then it's discharged out into the room.

Meanwhile, humidity moves through the cellophane film into a pressure vessel, then goes between the fins of the heat sink fins of the cold side of our peltier effect heat pump, and then is removed from pressure vessel by way of a pump which can handle both gas and liquid.

The discharge of the pump goes into a bottle, where liquid will remain, but from which air can escape.

The efficiency of the device will depend in large part on the surface area of the cellophane filter. To maximise this area, without making the entire device huge, can be done by shaping the cellophane into a spiral.

Some of you reading this may wonder what is the advantage of this over using the peltier effect heat pump by itself, and the answer is that it eliminates the need to chill the nitrogen and oxygen in the air, and allows it to only chill the water vapor. This is very important, since even at 100% relative humidity, air only contains a few percent water vapor.

You might also be thinking that the efficiency of the pump must inevitably be low, but that will only be true when it's starting up and removing air. When the system is in a steady state, it will only be removing liquid water, which shouldn't require much power.
-- goldbb, May 15 2017

A review of membrane-based air dehumidification http://journals.sag...77/1420326X13500294
[xaviergisz, May 15 2017]

Oh cellophane, not cellphone... never mind.
-- popbottle, May 16 2017


Industrial air drying systems using silica gel, which is much more durable and efficient than cellophane, have been using this technique for decades.

Baked and WKTE.
-- 8th of 7, May 16 2017


ugh.. There's a bunch of prizes and "projects for Africa" type things dedicated to getting water out of the air. I suspect the energetics will never work out for the hotter places. Where I grew up they'd fund any project that promised to put the water back.
-- bs0u0155, May 16 2017


// water out of the air. //

Is this not what you humans refer to as "rain" ?

Perhaps you should consult the aboriginal inhabitants of wales, where the phenomenon is observable 24/7/365 ?

Mind you, a nation of eyebrow-ridged mouth-breathing taffs probably lack the ability to comprehend the absence of rain, their primitive linguistic system lacking the capability to express abstract concepts such as "clean", "dry", "friendly" and "it's wrong to have sexual relations with close family, even if they do have thick, woolly coats and communicate by bleating"*

*Yes, your mother is included in this. Get over it.
-- 8th of 7, May 16 2017


Ah Wales - Land of my Father's gardener.

The strange thing is that many Welsh people are opposed to independence. I think Westminster will just have to insist.
-- MaxwellBuchanan, May 16 2017



random, halfbakery