DIY solar dehumidifier

[jeff5may]

Here is a regenerator that is said to have a thermal COP of 1.0 or better when used with gas:

http://ailr.com/our-technology/two-stage-regenerator/

The cool thing about this one is that it takes advantage of the natural stratification of the saltwater solution. Since the strong solution is denser, it naturally descends in the tank.

[AC_Hacker]

The waterfall idea looks pretty interesting to me.

Has anyone found info about the percentages of dissolved CaCl2 in water to make this thing work? Seems there should be some kind of chart that would indicate the range of CaCl2 per water that would be effective in a 'waterfall' setup.

This waterfall setup with solar drying, would be a good combo for areas with abundant sun AND excessive humidity... it would suit quite a few EcoRenovaters!

* * *

BTW, CaCl2 has also been used in some of the more successful Phase Change Material thermal energy storage studies... but that would be a topic for another thread.

-AC

[jeff5may]

Originally Posted by Ross D

The idea of dehumidifying the air before it is circulated through the building is to reduce the moisture content of the air.

You're on the right track here.

If outside air is used as the building cools at night, it will eventually reach the dew point of the air and the building will become damp, condensing on the cooler surfaces and equipment stored in there.

Not if it is being dehumidified on the way in. The wheel or liquid actually absorbs more water vapor when it gets colder.

By recirculating the internal air during the day, dehumidifying it and heating it, the overall moisture content within the building will reduce. Which will reduce any condensation overnight, it should also contribute to overall higher temperatures within the building.

Ross

The incoming dry air stream will tend to evaporate the water out of the room: furniture, walls, plants, people, everything with moisture content. This will tend to cool the objects within the room due to evaporation. The net heating of the condensation is taken away by the dessicant wheel or liquid solution. This assumes a forced-air setup.

With the waterfall or fountain setups, it has been found that run continuously, they can over-dry the air, wreaking all manner of havoc on woodwork and interior furnishings. Misting systems are being used to provide additional evaporative cooling and make-up humidity, especially in solar-powered systems.

[MN Renovator]

What happens to the woodwork and internal finishings?

[NiHaoMike]

Originally Posted by jeff5may

With the waterfall or fountain setups, it has been found that run continuously, they can over-dry the air, wreaking all manner of havoc on woodwork and interior furnishings. Misting systems are being used to provide additional evaporative cooling and make-up humidity, especially in solar-powered systems.

Easy fix for that is to use a humidity sensor to either turn off the dehumidifying setup or turn on an evaporative cooler.

[jeff5may]

MN,

Just imagine something being left in the desert for a few weeks. Woodwork shrinks and warps. Plants drop their flowers or leaves. People develop dry skin and sinus infections.
When the indoor RH goes much below 40% for long, people and objects acclimated to high humidity take notice. Some of these systems, especially those that utilize temps above 190 degF, claim that their systems can lower RH down into the teens and twenties.

AC,

Now that you mention it, this solar dessicant dehumidification system could easily be bent to become a high-capacity thermal store. Say one were using an evacuated tube collector on the roof, with the batch tank filled with CaCl2 brine solution. With a temp diff controller and a few sensors here and there, one could direct the hot brine solution to a DHW tank or a hydronic loop or tank to cool the solution. It could then top off the fountain to dehumidify if necessary.

[jeff5may]

A good video describing operation:
http://www.advantixsystems.com/video1.php

And here it is on youtube:

http://www.youtube.com/watch?v=WNvxkXyKwGw

Another image I could just not resist to doubt:

[Daox]

That is weird, but really cool.

[AC_Hacker]

Originally Posted by jeff5may

MN,
Now that you mention it, this solar dessicant dehumidification system could easily be bent to become a high-capacity thermal store. Say one were using an evaporated tube collector on the roof, with the batch tank filled with CaCl2 brine solution. With a temp diff controller and a few sensors here and there, one could direct the hot brine solution to a DHW tank or a hydronic loop or tank to cool the solution. It could then top off the fountain to dehumidify if necessary.

There was a guy named George Lane, that worked for Dow chemical doing extensive work on phase change material.

HERE'S HIS PATENT

...and then there is Carl Venner's Dissertation.

There's so much to be said about this stuff that it should be continued on another thread.

-AC

[AC_Hacker]

It is a shorter route to comfortville, but there remains the issue of easily & effectively removing the water.

With a de-humidifier, you dump the reservoir out, job done.

Here, we're only half way home.

-AC