Talk:Yakhchāl

untitled

this article begins right, but then starts to read like it was copied from a book (mostly because it repeats what is said in the "introduction" as if it wasn't connected to it) I lack sufficient knowledge on this subject to make changes--164.77.106.168 12:08, 13 November 2006 (UTC)

Night sky cooling

In Murray Leinster's the Planet Explorer he says the Babylonians were able to cool stuff to below ambient temperature via radiation to space at night by insulating it from ground heat and protecting it from convection currents. Is he just nuts? Is this an old theory that has now been discounted? the wind towers article says this is not possible, but it seems to make sense if you think about it really hard. Anybody know anything about this? Puddytang 01:53, 17 April 2007 (UTC)

It looks true. It's circulating again, with a handful of sites making a big deal about it. Water freezes at night in the winter. A few intuitive optimizations can conserve ice, and help produce more ice, on more nights of the year. The Persians placed ponds for ice production next to the ice houses for easier transportation to storage. They must have placed the pool in the shadow of the ice house, so that it received less heat during the day. (I assume they kept some water in it during the day so that it stayed a little cooler by evaporation, to get a small head-start for cooling at night.)

The Persians might have discovered that low-lying water is more likely to freeze at night in the winter. On cloudless, windless winter nights, water at or below ground level is more likely to freeze at night, even when elevated water does not freeze. That is, even when the ambient a few feet above ground is a few degrees above freezing, many surfaces radiate heat into the sky, become cooler than ambient, and produce some air that is (OH MY GOD) a few degrees below freezing, which collects at ground level and especially in depressions, depositing hoarfrost and freezing small puddles. See Radiative cooling#Nocturnal surface cooling. (Heat radiation from the water itself is probably minor to the effect.)

Knowing the explanation for the effect has no connection to exploiting it, but knowing more details of the effect is helpful in exploiting it. If the Persians noticed that low-lying water is more likely to freeze, they would optimize for it by placing the pond low (but that is kind of a "given"). We can look for other optimizations: If they knew that a small valley helped, they would try to place the complex at the bottom of a small valley (though a valley is also kind-of a "given", for availability of water, and more shade). If they surmised that heat from the ground countered the freezing, they might try to insulate the pond from the ground (as mentioned above) with straw, like they insulated the ice house. (If we tried this today, we might want to raise the pond a few inches above ground level, to let air cool it from below as well as above.)

So, when they got more ice on more nights, they were exploiting "night sky cooling", knowingly or not. Several sites cite this TED talk by Aswanth Raman. He claims the pool outside the ice house made ice at night, even when ambient was +5 °C = 41 °F. He says we see "frost" (hoarfrost) at night even when the air temperature is above freezing. Aaswath Raman: How we can turn the cold of outer space into a renewable resource | TED Talk

Cited by: The Process of Freezing Ice in the Desert According to Physicists tecped.com, How People Created Ice in the Desert 2,000 Years Ago

This page independently credits radiation: "A clear night sky has a very low temperature, and on clear nights surfaces facing the sky radiate heat into the sky. In this way the temperature of the water in the pool could drop below the temperature of the air, and on cold nights it would drop below 0°C, thus creating ice."

This page incorrectly credits the yakhchāl: "Once water is stored inside the yakhchāl, it's able to freeze into ice because of the extremely low temperatures that the structure creates."

This page seems to imply that the ice makes more ice and freezes water "all year round". - A876 (talk) 04:37, 23 August 2018 (UTC)

Parallell this to how ice caves form naturally in Lava tubes in New Mexico

This is a great example. Of course it works! This is another great example of harnessing Passive energy. THere is an Ice Cave, the Bandera ice cave, that must work the same way as a natural formation. —Preceding unsigned comment added by Mariecamille (talk • contribs) 01:59, 2 June 2010 (UTC)

global/merger tags

globalise and merge tags were placed on this article, but no discussions were started on the talk page. the reason given in the edit is that the article focuses "particularly on Iran, for no cost clear reason." Recognising the inherent selectivity of such a question, i disagree. My reasoning for why yakhchals are notable enough in their own right so as to warrant their own article separate from the generic ice house is the same reason why Egyptian pyramids are not merged into the mausoleum article. I will remove the tags... they should only be added back if engaging in discussion. Firejuggler86 (talk) 10:54, 18 August 2020 (UTC)

some yakhchāl in Iran

I believe this part is useful and should be added to the article

 08:38, 12 May 2021 (UTC)

Some of the historical Iranian yakhchāl (Ice house):

1. Yakhodan Moayedi of Kerman, the Seljuk period
2. Chahar Borj Mashhad,
3. Bam has been registered in the list of national heritage NH of Iran under number 6759.
4. Yakhodan Ravar
5. Meybod in Yazd province,
6. Kowsar Gonabad
7. Haj Agha Ali Rafsanjan city,
8. Paveh in Paveh village of Semnan province registered NH in 2007 with the number 20157.
9. Yakhodan Karimabad Mashhad
10. Sabzevar triple refrigerators located at the western exit of Sabzevar city towards Shahroud
11. Farooj
12. Radkan Glacier in Radkan village of Chenaran city related to Afsharian period, Kashmar Frutgeh Glacier related to Qajar period, #Khairabad Dargaz
13. Abarkuh, Abarkuh ,
14. Islamshahr, Jafarabad yakhchāl of Islamshahr,
15. Zarsif Kerman yakhchāl,
16. Nimour in Khomein-Delijan
17. Pakhtaghan
18. Aliabad Varamin
19. Behroud Firoozeh
20. Biarjamand Semnan
21. Varamin
22. Rafsanjan, [1]

Working on adding more to this, but the direction is unclear

This paper has an image of a map on page 4 of 7 that suggests a relationship with the type of ice house constructed in a place and where it lies in Iran. I am wondering if these places would also be considered yakhchāls, as they are pits with ice in them, just with different architecture around the pit. Robrobrob2 (talk) 00:25, 25 September 2021 (UTC)

Todo..

There's a lot of great things to add into this article from this paper regarding the physics of these places. Also, it would really be nice if there was a cc version of this picture that we could use in the ice pools section of the article. I might eventually get to adding the stuff from the paper into the text, but I don't have the skills to make the diagram. Fephisto (talk) 03:53, 30 April 2023 (UTC)

I've placed a request. Fephisto (talk) 15:44, 7 May 2023 (UTC)

Which has now been completed, thanks to MingoBerlingo. Along with this page, I also put the image on the radiative cooling and passive cooling pages as well to try to help explain the topic. Fephisto (talk) 11:59, 8 May 2023 (UTC)

Question: does Yakhchāl refer to just the adobe hut? Or does it refer to the entire complex (adobe hut+qanat+bâdgir+walls+ice pools)? Fephisto (talk) 04:11, 30 April 2023 (UTC)

The paper linked above suggests it's the whole complex. Fephisto (talk) 21:11, 1 May 2023 (UTC)

 Done, but maybe this source should be added, too? Fephisto (talk) 15:44, 7 May 2023 (UTC)

Found some sources to include in the article:

• General source, breaking down Yakhchals into the shading walls, pools, and the main storage hut. I think maybe the design section should be subsectioned in a similar way, possibly.

 Done Fephisto (talk) 15:44, 7 May 2023 (UTC)

• a lot about the importance of the mortar/subterranean construction

Need to check all the sources and do a better job placing the sources inline as well. Fephisto (talk) 15:58, 8 May 2023 (UTC)