No.4 Effect of trees

I have explained that we are able to cool outdoor temperature by utilizing fog and mist with small environmental load. But if it doesn't continue and becomes hot again immediately, we may not feel that effectively works.

Outside is actually exposed to sunshine and wind, then the temperature soon becomes hot if it does not continue generating fog. The environmental impact is small even though continuing generating fog, but people may think it wastes natural resources. Therefore it is also important how to keep cool during stopping generating fog.

My solution was to properly spray the fog on trees. It was effective to spray the fog on leaves. If there are suitable trees, it is quite effective because these can prevent blowing fog away by wind.
As I introduced in "No.3 Evaluation & measurement", temperature falls well around trees. Even if it was not dry mist, it was not stuck to trees so much. But whole trees got wet as like after raining when I continued spraying for around 20 minutes. It stayed enough cool for a while afterwards even if I stopped fog. However, it became hot sooner if there was no tree.I did not strictly measure it, but it became hot within 5-10 minutes in strong sunshine if there was no tree, and the cool was kept for 20-30 minutes when there were trees.

Because continuance effect is such a level in strong sunshine, it can last longer for 40-50 minutes in shade. I scattered fog around a fragrant olive tree in east side of my house. It was enough to spray for 20 minutes each three or four times until evening because the east side is in shade in afternoon.

No.3 Evaluation & measurement

I report an effect of the fog cooling this time. According to various reports, the cooling effect by the fog seems to be able to cool around 3-5 degrees than ambient temperature. By this experiment, it was confirmed. But temperature greatly rises on sunny and hot day in summer. For example, it is not unusual to become more than 40 degrees on urban asphalt street though the ambient temperature is still 30 degrees.

The next photographs show a result of the temperature change measurement performed at 9:30 AM on July 31st, 2005. The sunlight of the summer was quite shiny in southern front of my home facing to a parking lot. The ambient temperature of the morning was around 29 degrees, but the temperature under the sunshine easily exceeded 30 degrees because the weather was so nice.

******Before cooling****** *******After cooling*******

On the left photograph, the red part indicates it was strongly lighted and reached around 33 degrees. The yellow part shows it was shadowed by my neighbor's house, but still reached 29 degrees as well as the ambient temperature. Although my plants prevented the heat, after all the inside of the room became hot by radiant heat.

The right photograph shows measurement result after cooling with fog for 20 minutes. It cooled 3-4 degrees down and the temperature became 27-28 degrees around the trees. It also reached to 25-26 degrees on the ground under the trees. The photos don't clearly show because covered with a tree, but the temperature was 27.5 degrees in the living room behind the trees then. I could feel coolly if blowing soft wind.

The shower heads were installed on a tree branch in the middle of the photo and on a house wall behind the trees. The mists flew around my house with evaporating at the most direction of wind rather than wetting the trees. I installed one more shower head in the east side, then the whole house cooled down considerably if all ran at the same time.

By the way, I could easily measure temperature in the high place because I used a radiation thermometer. But I sequentially measured points where I defined beforehand because it could not widely measure. Because the photographs were composed from the data, there may be some errors.

I will report about the effect of the tree next time.

Motion picture

The next motion picture is created to easily explain my concept.

Please enjoy watching it.

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No.2. Selection of nozzles

Let me explain about nozzles to generate fog and mist. As I described in the previous section, I have tried to use several kinds of shower head that were usually available to purchase at a do-it-yourself store. I also found a problem that flowing water quantity was too much, though the fog was generated.
Then the heads were modified to decrease water quantity without lowering hydraulic pressure. I tried several ways, and found that was the best to close all the discharge holes with glue except only one. And the remaining hole was narrowed to minimize spraying area by inserting a piece of metal wire.

I felt that it still wasted water though I modified nozzles because puddle was created on ground by operating for half hour. Therefore, I looked for other nozzle with smaller water consumption, and I found G530 of Takagi Ltd.. Water consumption was decreased to 0.4 liters/a minute without any modification of the nozzle. I also felt the size of the mist became smaller than the previous nozzles. The actual sales price of G530 is about 1300 yen in internet.

http://www.takagi.co.jp/en/

If mist size becomes smaller than 10 microns meter, it doesn't get wet nor adhere because it becomes so-called "dry mist". Since mist is able to invade into room and to make laundry wet in the vicinity according to wind, it is important how to avoid wetting.
This solution can be enough practical in case of right installation of the nozzles. Although the real dry mist cannot be created by using such a gardening nozzle. To cool down the air, it is effective to wet surrounding trees and wall to some degree when using it in garden at home.
Although a real dry mist generator was installed and replaced in 2008 July, I found it also actually made wet. This topic is to be explained later.

By the way, nozzles are soon damaged if left without covers between autumn and spring. At least, nozzles should be detached or be protected with a plastic bag apart from piping. In my case, all the nozzles were covered between 2004 autumn and 2005 spring, but one piece was broken. Durability might be this level.

I will report how effective it was next time.