[Equest-users] How do you think about the no electricity Eco-Coolers from Bangladesh

Wed Jul 20 05:28:58 PDT 2016

My observations are that the air does heat up when compressed then cooled when it decompresses. For example, if you have a large take of compressed air used to fill a small tank, the small tank heats up as it is filled and the large tank cools off as it does the filling of the small tank.

That would lead me to believe that, in the end, the air would be roughly the same temperature after it went through the compression then decompression as it traveled through the bottles from outside to inside. The bottles might absorb some of the heat from the compressed air and then you would have a wall that is warmer than room. In the end, I don’t believe there would be much change in temperature in the room.

Christopher Jones, P. Eng.
Rowan Williams Davies & Irwin Inc.
Consulting Engineers & Scientists
901 King Street West, Suite 400, Toronto, Ontario, M5V 3H5
T: (519) 823-1311 ext 2052
M: (416) 697-0056

From: Equest-users [mailto:equest-users-bounces at lists.onebuilding.org] On Behalf Of Joe Huang via Equest-users
Sent: Tuesday, July 19, 2016 8:54 PM
To: equest-users at lists.onebuilding.org
Subject: Re: [Equest-users] How do you think about the no electricity Eco-Coolers from Bangladesh

I saw today the same technology also promoted on the CIBSE Bulletin Board even with a video "explaining" how it works (the plastic bottles supposedly "compresses and cools the air")

( https://www.linkedin.com/groups/75555/75555-6160367729091100672?midToken=AQF3zdCi1vKWLA&trk=eml-b2_anet_digest_of_digests-hero-8-view%7Ediscussion&trkEmail=eml-b2_anet_digest_of_digests-hero-8-view%7Ediscussion-null-bc6m0%7Eiqtrhngl%7Eh3 )

To me, this seems more like wishful thinking.  My comment posted on the CIBSE Bulletin Board was:

I don't understand how this would work from a thermodynamic point of view. There has to be some air velocity to begin with, in which case I can see how the bottles might channel the air flow resulting in higher air velocities coming out of the bottle openings, but wouldn't the total amount of air flow be the same, or less than through the window opening with no obstruction? Also, someone explain to me how compressing the air will cool it?? I've always thought that compressing the air would heat it up, although in this case the effect would be extremely minimal either way.

Joe

Joe Huang

White Box Technologies, Inc.

346 Rheem Blvd., Suite 205A

Moraga CA 94556

yjhuang at whiteboxtechnologies.com<mailto:yjhuang at whiteboxtechnologies.com>

http://weather.whiteboxtechnologies.com for simulation-ready weather data

(o) (925)388-0265

(c) (510)928-2683

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On 7/14/2016 7:22 PM, 冷面寒枪 via Equest-users wrote:
Recently,I read the news about the zero air cooler,which is made with re-purposed plastic bottles.And the new claims that it helps reduce indoor temperature by 5 degrees centigrade.
The making process is shown as following:
[cid:image001.jpg at 01D1E260.7C354A20]
[cid:image002.jpg at 01D1E260.7C354A20]
I dout that very much.

the Joule-Thomson Coefficient for air (mostly nitrogen) at 300K (27°C/80°F) is about 0.36K/bar. This means that at 300K a 1bar change in pressure equates to a 0.22K. The change in pressure required to get the 5°C (5K) reduction would therefore be:

5 / 0.22 = 22.7bar

[cid:image003.jpg at 01D1E260.7C354A20]
So I think it is impossible the temperature drop will be up to 5  degrees centigrade after the air through the bottle.

What do you think?

------------------
Yongqing Zhao
Changsha Green Building & Energy Saving Technology CO.,LTD
NO.438,Shaoshan Road,Changsha,Hunan,China
Telephone:13574805636
Email:zhaoyongqing1987 at 126.com<mailto:Email:zhaoyongqing1987 at 126.com>
         503271081 at qq.com<mailto:503271081 at qq.com>

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