1. Principle : listen to the audio file Evaporative coolers (billet du 24/09) source : The Economist, Keeping cool and green (extract), July 15th 2010

2.  Advantix Systems (formerly called DuCool) LDAC

• Watch these videos : Liquid Dessicant Air Conditioning  (see transcript below) + Process overview
• Read : Advantix Systems overview, p. 16/17 : How it works.

– can be used as a « transcript » of the second video.

3. NREL DEVap system :

– NREL video  (Have a look at the NREL website – The National Renewable Energy Laboratory is a laboratory of the US Department of Energy)
Called the « Oscars of Innovation », the R&D 100 Awards recognize and celebrate the top 100 technology products of the year.  2012 R&D 100 Winner : DEVap.

Read the article   An energy-saving air conditioner (MIT Technology Review)

Browse through NREL’s technical report (esp. p. 12-13, fig. 2-9 : description of the process).

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Transcript :

Advantix Systems Liquid Dessicant Air Conditioning (LDAC)

It reduces utility bills by 30 to 80%,
improves comfort,
naturally cleans and disinfects the air,
and does not cost more ?
How does liquid dessicant air conditioning work ?
0:32 – Simple ! You see,
our unique technology uses nature’s drive for balance,
also known as equilibrium,
to reduce humidity in the air while cooling it at the same time.
To ilustrate how our liquid dessicant works
let’s look at some simple concepts from nature.
0:51 The first concept is absorption.
Let’s take a cup of ater and add salt to it.
Initially the salt dissolves in the water
due to the attraction between the salt and water molecules.
Then if we’ve added enough salt
the salty solution will begin to pull moisture from the surrounding air
because salt is a natural dessicant.
1:14 – A dessicant ?
– A dessicant is a material that attracts and absorbs moisture.
In this case the attraction is so strong
that the salt will attract moisture from the air
even though it’s already dissolved in water.
– So the salt is trying to balance its attraction to water
by drawing even more water into the solution ?
– That’s right.
1:35 Now let’s look at the second concept of diffusion.
Let’s take a second cup of water
and connect it to the first cup with a tube.
The salt from the first cup will gradually diffuse into the other
until the concentration of salt is balanced in both cups.
That’s the natural equilibrium.
1:55 Now let’s see how the two concepts of absorption and diffusion work together.
Imagine that we have one cup outdoors and the other cup indoors.
Inside the salty water is pulling moisture from the air as before.
Outside, if a heat source is warming up the water,
some of it evaporates.
The remaining water becomes even more salty.
Again the concentration in the two cups tries to achieve balance.
Only this time it is water molecules that need to diffuse from the inside cup
to the saltier outside cup.
As long as heat is applied to the outside cup this process will continue,
drawing water from the inside of the building to be evaporated outside.
2:40 – So the cups are actually treating the air in the room
and making it more comfortable
using only salt and small amount of heat applied to the outside cup ?
– Precisely. And using the same absorption and diffusion process,
Advantix Systems equipment can utilize unused heat
to efficiently treat the air and cut utility bills.
– Wait. I see how it treats humidity
but I thought Advantix Systems technology both dehumidifies and cools.
– That’s right. Click Next and I will gladly show you how.