Naked Science Forum

General Science => General Science => Topic started by: akashray on 16/02/2014 14:00:36

Title: Custom Made Dehumidifier Vs AC
Post by: akashray on 16/02/2014 14:00:36

      I am planning to create a school project about the use of dehumidifiers instead of ACs to decrease energy consumption.Now,decreasing humidity actually makes higher temperatures much more tolerable.

Check out http://en.wikipedia.org/wiki/Heat_index to know more about this.

Now,conventional dehumidifiers work in pretty much the same way as AC s do.So,what if I use silica gel or clay absorber as the moisture absorbing substance and use it to make a dehumidifier.

         Now,will this work especially in Asian countries like India?Can this really keep the apparent temperature at a comfortable zone?

Title: Re: Custom Made Dehumidifier Vs AC
Post by: CliffordK on 16/02/2014 22:20:42

It might work.  You'd have to drive the moisture out of the silica gel which you could accomplish in 1 of 2 methods, heating, or lowering the pressure. 

I could imagine using some kind of a solar cooker to cook your silica, perhaps with one batch cooking while the other one was drying the air.

You would likely need a fan to circulate the air through your desiccant. 

Clay may be dusty.

Title: Re: Custom Made Dehumidifier Vs AC
Post by: alancalverd on 17/02/2014 08:57:54

It's worth considering the original Electrolux refrigerator principle, using solar heat to drive a closed cycle system with no mechanical parts.

Whatever you use, you still need to circulate the air through your dehumidifier, and in the case of a gel or powder desiccant it's a good idea to rake it from time to time to expose new dry material.

It's definitely worth doing some calculations in advance. Air weighs about 1 gram/liter so there's about 20 kg of air in a small room. It becomes unpleasant if there is around 10% water in the air, so you need to extract about a liter of liquid water from a bedroom or office to make it worthwhile. Now consider how many air changes per hour are needed to keep the place smelling fresh - up to 5 changes per hour if it is "just comfortably" occupied (like an aeroplane or a classroom). And add the amount of water exhaled or perspired by the occupants: maybe 0.1 - 0.2 liter/hour per person. It's quite a task for a passive absorber, so you need to maximise the exposed surface area.