SolCool scam or not? [RE-wrenches]

[Jeffery Wolfe, Global Resource Options]

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Evap cooling is great in hot, dry climates. There are a few of those in the US (say, southwest US). Water quality is of course a problem. In the correct application, these can be great, but are always higher maintenance (scale, corrosion, etc.).

With proper water treatment (which may or may not add a significant energy load), the units can be good. Using evap cooling to precool the air before the condenser certainly can save some energy, and combines the best and worst of both DX refrigeration and evap cooling. It also allows you to use the unit in areas where evap cooling alone does not cut it due to humidity. However, at some point you need to ask if the added maintenance, added pressure drop through the evap cooler surface, reduced coil life due to increased corrosion, and reduced coil efficiency as the coil corrodes, are worth the increase in efficiency gained by the evaporative effect. My guess is that once you get very far out of the desert, it does not.

An additional point to note is that these units do use WATER. That can be a pretty rare resource in areas where there is not much humidity. There are exceptions, but it needs to be considered.

Air conditioning is tough. Best solution I've found is open windows, energy efficient fans, shades and light shirts. Second best is a whole house fan to flush the house at night at high volume, and shades drawn closed during the day to keep the sun out. Third best is either geothermal coupled cooling systems or super efficient DX (direct expansion, typical air conditioner refrigerant cycle). And if you use DX, make sure that the condenser is not put on top of the black roof where the temps are 40 deg hotter! Also, best to run the DX unit at night, when the ambient temperatures are usually lower, resulting in higher efficiency. (although that does decouple it from direct solar, but it substantially cuts the energy use.)

It's fascinating to me that air conditioning was only invented in about the 1920's, and that most houses did not get air conditioning until the 1970's. How did people live before then? We may find out!

Jeff Wolfe

Global Resource Options, Inc., Solar Energy Solutions

-----Original Message-----

From: Joel Davidson [mailto:joeldavidson at earthlink.net <mailto:joeldavidson at earthlink.net> ] 

Subject: Re: SolCool scam or not? [RE-wrenches]

 

In the 1980s Wm. Lamb Company made a PV powered swamp cooler that was attached in front of the condenser of a conventional air conditioner. The cooler uses a 24 VDC Pitman motor direct powered by 2 each Arco 30-watt 30-cell modules and also required water plumbed to it. Within 2 years, scale built up in the cooler and the painted sheet metal body rusted. The additional moisture on the air conditioner caused it to rust. The principle underlying direct evaporative (adiabatic saturation) cooling is the conversion of sensible to latent heat. Nonsaturated (low humidity) air is cooled by exposure to free and colder water, both thermally isolated from the other influences. Swamp coolers will work in Athens Greece, not Athens Georgia.

The Second Edition of Evaporative Air Conditioning Handbook by Dr. John R. 

Watt P.E. copyright 1986 had 450 pages of more than I ever wanted to know about the subject.

Do any wrenches or your customers use a swamp cooler?

Joel Davidson


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