1936 Air Washing Machine

[RebeccaJHB]

I have plans for a theatre built in 1936. These are architectural plans and the engineering is sketchy to say the least. The plans show outside air being drawn through an "air washing machine" and through a huge wooden duct to the auditorium. What the heck is this? Is it like a mini water tower with the air being exposed to water to cool it? The heating system seems to be a completely separate system. There is a coal fed boiler with cast iron radiators heated by steam. So was the air washer only run in summer to cool the air? Or was it also run in winter to purify the stale inside air. (At that time smoking was allowed inside theatres.)

Rebecca

 

[Yorkman]

An air washer is a fancy name for an evaporative cooler (swamp cooler), depending on the design, they may have used city water to a sump to spray over the media. Some are designed to spray heated water over the media to achieve heating and humidification in the winter. While others use chilled water to produce cooling and de-humidification. Yours being 1936, centifugal chillers had only been around about 12 years, mechanical refrigeration for comfort cooling was still a pretty new idea. I would bet it was run for cooling only in the summer. Where is this building if the WB temperatures are too high it wouldn't be too effective for cooling. As far as air purification I doubt it.

I'm not a real engineer, but I play one on T.V.
A.J. Gest, York Int./JCI

 

[danw2]

My dad lives in Arizona and cools his house with an evaporative cooler, (water that dribbles/sprays onto canvas) so someone is still making the stuff.

 

[imok2]

Rebbeca do some research:

http://en.wikipedia.org/wiki/Evaporative_cooling

 

[RebeccaJHB]

Thank you all for answering. My friend intends to renovate this theatre. Of course, he will install a new, modern HVAC system, but I was just so curious about the original system. The drawings that he has just shows a "black box" with the air flowing through it. In 1936, what exactly would that have been? It doesn't even call out a manufacturer.

It is located in Kingsport, Tennessee. We have some hot and humid days in the summer, but usually just the upper 8o's or lower 90's, Fahrenheit. The reason I asked about purification is that the theatre was advertised as having "clean air."

Would the water recirculate or would there be a constant supply of fresh water? If it recirculated, wouldn't it need to be cooled? If it was constant fresh water, wouldn't that be expensive? City water and sewer is expensive now and the town wasn't very old then. It seems that they would have still been paying for a water treatment plant at that time.

Rebecca

 

[Yorkman]

The cooling effect is imparted to the air through the latent heat of evaporation of the water. The water was most likely recirculated over the cooling media (like a cooling tower) but more surface area, the supply air was drawn from the outside through the media exchanging sensible heat for latent heat, following a line of constant enthalpy. In other words the temperature of the air was dropped but the humidity of the air went up. This was a once through system for the air (it; the air was not recirculated). Water usage would be the rate of evaporation, any blow down to control disolved solids and a little loss to drift. If you live in the southwest Colo., Ariz., Utah these are very common, as our outside air is hot but very dry. Yesterday in Colo. where I live it was 97 degrees and 12%Rh, running an evap cooler at 70% efficeintcy we could get 73 to 75 degree air at about 50 -55%Rh.

I'm not a real engineer, but I play one on T.V.
A.J. Gest, York Int./JCI

 

[MedicineEng]

But as pointed out before, if your climate is hot and humid, the evaporative cooling is not much of an help...

 

[quark]

Suspended particles and some gases in air can be washed with water (just like the scrubbing) and this comes as a complement with the evaporator coolers. I know some liquid desiccant dryer manufacturers guaranteeing particulate cleanliness, upto some extent, due to this liquid washing effect.

The basic principle of evaporative coolers, as already explained in detail by Yorkman, is that the latent heat required for evaporation of water is extracted from sensible heat of air and thus air gets cooled down.

It doesn't matter, much, if we are circulating hot water or cold water, as the ratio of latent heat of water to specific heat of water is phenomenolly high.

 

[nh3iceman]

I believe Carrier built some of the air washers during that time. Buffalo Forge was another if I'm not mistaken.

My guess is they used city water for whatever cooling effect was achieved, and just let the water run down the drain. This was fairly common back then.

If you get the opportunity to see this in person you might look for a large water storage tank. I have also heard of some air washer systems that used ice blocks to provide cooling. An early form of thermal storage, so to speak.

 

[RebeccaJHB]

I wondered about a water storage tank, too; but I don't think there is one. There could have been one in 1936, though. Every time I study the plans, I see something I missed before. I was wondering if there was a condensation problem on the outside of the ducts or if the wood was insulation enough. I found a detail of the duct. There is 2-inches of wood with 1/2-inch of "Masonite ins" inside. I am assuming that this means "Masonite insulation," but I never heard of Masonite being used for insulation and 1/2-inch doesn't seem like much. Anybody else heard of this?

You guys are the greatest! Maybe "WE" should write an article for "Invention and Technology" magazine.

Rebecca

 

[KiwiMace]

If the air is not being cooled to the low temperatures found in a/c supply air conditions, there is much less likelyhood of condensation on the outside of the duct - the air supplied from a swamp cooler will be higher than the dewpoint temp of the surrounding air.
Heat transfer will also be a lot less with a lower thermal gradient.

Masonite is wet felted wood fibre, can be made into low density insulation panels, or hardboards as you may be mroe familiar with.

 

[AbbyNormal]

Sorry to re-hash an ancient thread.

The old air washer was an interesting alternative to a cooling coil if my memory serves me correct. Air was passed through a spray of cold water.

The temperature of this spray water was lower than the dewpoint of the air it was cooling and it dehumidified the air. Kind of interesting, dehumidifying by using water.

Its one advantage, low pressure drop.