My Experience Designing, Building, And Operation Of A Successful ‘’Solar Regenerated Desiccant Air Conditioner’’(SRDAC) For Our Passively Heated Solar Home.

This WebPage (With Links To Photos Having Extensive Descriptive Captions), Will Help You Understand How My SRDAC System Works, How & When It Was Built, And Report How Well My System Performs.

A Brief Introduction To My Desiccant Air Conditioner (SRDAC), With Mention Of My Preliminary Pilot Project Home Built SRDAC.
…My First Preliminary Pilot Project Home Built SRDAC, was constructed starting ~ May 2011: Experiments (with Data Measurements) were completed ~July 2011: These showed that the Home Built SRDAC had promise of success for our area of South Carolina!! From this relatively simple Home Built SRDAC, I have gradually evolved (and constructed) a suitably economical design for a Full-Scale Solar Regenerated Desiccant Air Conditioner (SRDAC) for our house. The next paragraphs, say why I am doing this, describe my efforts. Included also is a link to a newspaper article about our solar house, with photos.

I’m doing this SRDAC Research & Development, not only to cut down on the ever growing $$ cost of our AC Electrical Power for Summer Time Dehumidification, but also to minimize our contribution to Global Warming: With our ever growing awareness of the On-Coming Catastrophe of Global Warming, we view with regret, the past years of our contribution to World Carbon Dioxide emission, through our use of any Electrical Power. So it is that, for our home dehumidification. we want to end our use of Electric Company’s Electrical Power: This use has been for ~34 years, since we moved into this home in ~1980.

Clearly, because of Global Warming, and our desire to stop our unnecessary use of electrical power (and $ money $), we should have obtained some form of SRDAC back in the 1980’s: But back then I did not have any reserve emotional energy, nor the available time. Nor did I know how, or even have the gumption to start the needed research effort!! Nor did I have even any idea how this might be done, let alone the needed “good idea”. So it was that this project had to wait for:

My SRDAC Design Is, Of Necessity, Somewhat Adapted To Our Henry & Suzanne Gurr, Passively Heated (and Cooled) Solar Home.
…This Passively Heated (and Cooled) House, has about 150 ton of passive heat storage, mainly reinforced concrete, which is augmented with a large amount of direct “earth contact.” The latter was done not only to increase the effective tons of passive heat storage, but also to use “earth contact,” gain free heat in winter, and free cooling in summer! Because of this, the SRDAC design will need to create a comparatively minimal amount of cooling, and mainly supply moisture (humidity) removal. This is because the infiltration of humidity into our house (and other forms of humidity creation) in our house is comparatively rather low: This comparatively low infiltration of outside humid air, is in part, a nice consequence of infiltration being blocked by the “earth contact” areas, which have a good moisture barrier

I) A Brief Description of My Preliminary Experimental Pilot Project Home Built SRDAC, Is Given With These Photos:
My First Experimental & Exploratory Pilot Project Home Built SRDAC, started (May 2011), is shown in this (and next 4) photos of June 2011 (As you study these photos, please pay attention to where I mention “underground pipes”: You should realizing where these are, and this will help in you understanding of the discussion at A) next below.)
Experimental measurements on this Pilot SRDAC (and other similar tests), showed that the Home Built SRDAC had promise of success for our area of South Carolina!!

II) Based On What I learned From My (Above-Mentioned) Preliminary Pilot Project Home Built SRDAC, A Full-Scale Working Desiccant Air Conditioner (SRDAC), Has Been Built & Successfully Used

Building on the experience gained from my (above mentioned) Preliminary Pilot Project, I have gradually evolved a suitably economical design for a Solar Regenerated Desiccant Air Conditioner (SRDAC) for our house. This design was constructed ~ June / July 2012, and this system (with many-a-modification), is essentially what I am still using as of the writing, late July 2014.
. My Full-Scale Working Desiccant Air Conditioner (SRDAC) is shown in this (and next 3) photos of 8 August 2012.

The Full-Scale Desiccant Air Conditioner (SRDAC) shown in the above-mentioned photos, has been used, with varying success starting the Summer Of 2012, and continues thru the date of this writing 21 July 2014:

Except For Cloudy Days, I Have Been Able To Somewhat De-Humidify The Lower Level of Our Two Story Home, As Explained In The Following “Season-By-Season Stories & Explanations”:

A) Summer 2012, Using 250 Lb Of Saw Dust As Desiccant, Was Minimally Successful During:

Explanation: In May ’12, I was feeling pretty happy by my relatively successful good de-humidification of our house’s lower level. But in July this good performance evaporated!! Suddenly Gone!! This was, of course, deeply mysterious & troubling, not to mention very confusing & very confounding!! . I exhausted a great amount of time and thinking and experimental testing: And finally, only after eliminating all possible other explanations, I finally concluded this => During May the underground pipe (14” ID Steel Culvert ~ 25’ long) was actually cooing lower-level house air entering the sawdust, to below ~74 °F. However, by July this temperature had gone up to over ~77 °F, eliminating the ability of sawdust to remove humidity from lower level air itself, which is typically at ~75 °F. This “failure to remove”, is essentially because, the “moisture grabbing power” of sawdust, is about equal to that of the our house lower level contents, such as: Carpet on our floors, cloth & wood on our, furniture, paper, books, cardboard, wood door frames, etc, etc.
…SUMMARY: In essence the lower-level house air entering the sawdust must be 2 – 3 °F colder than the temperature of our lower level, to be able to grab the moisture from our lower level contents!! Such colder conditions, were only available here in SC, up thru late May.

Three Additional Important Observations, Which Apply To most SRDAC Systems:

…AND IN SUMMARY, the sawdust SRDAC was somewhat successful, and showed it was relatively safe, to spend up to $1000, to purchase and ship Silica Gel, for my next full-scale SRDAC tests.

SIDE NOTE: How I Became Sufficiently Sure Of Success, To Justify Spending $752 To Purchase 330 Lb. Of Silica Gel, For My Full-Scale SRDAC Testing Program?
…First off Silica Gel is widely used in de-humidification applications generally, and the successful use of Silica Gel, is well documented: Examples include medicine, industrial & food drying, and more specifically for human comfort in their living quarters & buildings. Examples of this validated use of Silica Gel, even for human living spaces is clearly evident in all of the WebPages, listed at the bottom of this page, under “Useful Information Re Solar Regenerated Desiccant Air Conditioning (SRDAC).”
…And just to be double sure, Silica Gel would work, I did special sealed 5 gallon bucket “mock-up” test => I solar heat recharged ~5 lb of Silica Gel Packets, by placing them on the hot metal roof our house, for one hour. (These packets were collected from various medicine jars, computer shipping boxes, etc.) Then with a humidity gauge mounted inside the lid of the bucket, I placed successively: 1) ~7lb of miscellaneous Xerox paper and cardboard, which had the typical moisture level of our house lower level. Then 2) Quickly added the recharged Silica Ge. And 3) Quickly closed the bucket with its sealed lid, and placed it in the lower level of our house, so the test would done at appropriate house temperature. After one day, I removed 2) and re-closed the bucket, and recorded the % Relative Humidity of the bucket insides, which of course included the paper. Satisfactory drying of the paper showed on the Humidity Gauge, and stayed there at the same from % Relative Humidity for the next several months. Conclusion? Ok to spend up to $1000 to purchase and ship 330 lb of Silica Gel, for my full-scale SRDAC !!! (Unfortunately I do not remember the data results, nor can I find these data records.)

B) Early Summer 2013, I Saw Again The Same Above-Mentioned Relatively Good Performance Go From, Good To Bad, As May Turned To July. -(( This Forced Search For A Better Desiccant: My Search & Study Yielded The Following =>
…As discussed 1) > 5) above, any organic desiccants were not effective enough: The best (non organic material) alternative to sawdust, seemed to be the highly proven Silica Gel Desiccant: Industrial grade Silica Gel, is relatively available, and of acceptable cost $752 for the 330 lb. I purchased. I arranged for my (private car) pick-up near Lake Zurich IL on June 26, 2013, and loaded the first 110 lb into my system on 29 June. The Silica Gel I purchased, comes nearly dry at 1.5% water by weight: So to see how well this Silica Gel would de-humidify, I used the blower of my SRDAC, to move our house’s lower level, thru this 110 lb. I was able to de-humidify "best ever”, for two days, before the 110 lb’s drying ability was “used-up”!! '''
C) Thus: My “Full Scale Test Runs” (July 1 thru July 21, 2013) Were With 220 lb of Silica Gel Desiccant loaded in My SRDAC System, in place of the earlier 250 lb of sawdust. In my system Silica Gel was found FAR more successful than wood sawdust, for following reasons: Successful de-humidification of our house’s lower level with Silica Gel, since it did not require the relatively cool evenings of late May. BUT still, an average day collector air temperature over ~ 115 deg F was required, for successful de-humidification of our house’s lower level. Since my existing collector achieves performance, only those rare days which were I started to search for methods to get higher Collector Air Temperature.

D) Late July 2013 thru to Mid September 2013, by Google Searches, I discovered the idea to use Black Colored Insect Screen to make a Solar Hot Air Collector: I added 2 layers of screen (black). and did indeed get higher collector air temperature, but de-humidification performance was still barely good enough:( And, since some old clear polyethylene plastic was available, I also added an “Air Pre-Heat, The Air Pre-Heat was achieved by placing 5 foot wide clear plastic on BOTH sides of my 4’ x 24’ collector, arranging that the Sun-Heated Air under this plastic, would flow under the plastic cover of the collector, and subsequently thru the two layers of screen. With the Air Pre-Heat, I did get higher collector temperature air output, but still really not good enough: There are too many cloudy (or partly cloudy) days, or days where the heat from the sun is reduced by too much thick haze.

E) Late May 2013 thru to date of this writing, 20 July 2014. My SRDAC remains mostly configured as discussed above. I continue to use it, although as yet, my system is only partly successful.
...And, when additional de-humidification of our house’s lower level is needed, I run (night time only) our Small One Room Air Conditioner. (( This 6000 BTU Haier Paragon ESAD4066, was purchased July 2008: This model was chosen, because it was listed as the Highest Electrical Efficiency in US Government Energy Star Ratings.!! This Haier, has always been mainly used for de-humidification of our house’s lower level.))
…Even after I am able to build a satisfactory SRDAC Hot Air Collector, I still will have this Haier for Back-Up purpose, on days our SRDAC System can’t be recharged: Such as rainy-cloudy days, or days with too much haze or too many clouds.

Well … this has been “My Story” told “Season-By-Season, With Explanations”!!

And with this, you are up-to-date on My Experience Designing, Building, and Operation of a somewhat successful ‘’Solar Regenerated Desiccant Air Conditioner’’(SRDAC) for our Passively Heated Solar Home.

Thanks for visiting, and being with me in spirit, as you read this page!!

Sincerely Henry Gurr,
USCA Professor of Physics Emeritus.

An Invitation For Persons To Contact Me To Share Ideas And Information Concerning Solar Regenerated Desiccant Air Conditioners For Home (or Commercial) Applications.

I am especially interested in discussing Solar Regenerated Desiccant Air Conditioning (SRDAC), with persons who have experience in (or have information about) this field, or related ideas. Therefore, any person who wishes to share ideas and information should contact me concerning:

1) Solar Regenerated Desiccant Air Conditioning generally, or
2) Solar regenerated desiccant processes, or
3) Ideas concerning air conditioning (or dehumidification) of solar homes.

You are invited to contact me at HenryG__USCA.edu. My full contact information (& a lot more info about me & my other projects), by typing Henry Gurr into Bing or Google.

DATE-LINE: July 23, 2023. Current Status Our ‘’Solar Regenerated Desiccant Air Conditioner (SRDAC) System, For Our Passively Heated Solar Home”. by Henry Gurr.

…As was mentioned above, it was my son David Gurr; who originally suggested the SRDAC Idea. And sometime in Summer 2014, seeing that I did not get high enough collector temperature air output, suggested how I could greatly increase my collector temperature, but at the penalty of much harder construction. I have spent considerable time thinking how to do David’s suggestion: For example use contact cement to attach the Silica Gel or using two closely sandwiched collector sheet metal plates.
….But unfortunately, my life priorities, since summer of 2014 have prevented any more progress on my SRDAC Project. :-((
…However this is not as bad as it might seem. In the June 2018, we installed a Solar Electrical Power System, and this is now used to power our above-mentioned Small One Room Haier Paragon Air Conditioner. And, when additional de-humidification of our house’s lower level is needed, and only when there is enough sun, I run the Haier.
…At least this way we achieve our above-mentioned goal of not using the Electric Company’s Electrical Power for Home Dehumidification.

Some Useful Information Re Solar Regenerated Desiccant Air Conditioning (SRDAC) .

Here is some relevant information I have found via Google, as of July 2012:
Currently, my design ideas have been influenced by the discussion of the following two links. Although my literature search is (so far) rather incomplete, these .two pdf documents A) & B) seem most suitable as a guide for designing my system.

Looks like the SAME above A) Article Is Available Click Here.

NOTE: The above are for Industrial & Large Institutions, but Munters and other companies also offer Desiccant Wheel Air Conditioners, as smaller units designed for home installations.

Solar Regenerated Desiccant Air Conditioning (SRDAC) is most easily adaptable to the extreme desert areas, because of the near total availability of intense sun!! All day!! Every day!!!. ''' Bing or Google searches for Solar Regenerated Desiccant Air Conditioner will find many articles, where solar desiccant cooling / dehumidification application is part of the discussion. For example, I have found lots of information (In English) coming out of Jeddah, Saudi Arabia!!

Written by Henry S Gurr & Edited by D Matos, 14 Jul 2012. Major revised by HSG 21 July 2014 + Minor Rev 23-4 July 2023.
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