Stoneware water coolers...

[Externet]

Greetings.

Those 19th century water coolers were made with porous ceramics or stone for the evaporation to lower a bit the temperature, is that right ?

Then, the vessel surfaces were not to be glazed, as such would impair evaporation; is that right ?

 

This shiny one may not be a genuine cooler, right ?

Seen perhaps two in my life; and do not remember being glazed...

Were their outside walls always moist when 'working' ? 

[Mordred]

Not sure on those ones but my 1920's textbook mentions using a small ceramic bowl in a larger ceramic bowl filled with water in the larger one. The cooling results from the expansion from the smaller bowl to the larger bowl.

What effect the glaze itself would have on evaporation I wouldn't know but the example I provided didn't require glazing except for water proofing.

Edited August 6 by Mordred

[exchemist]

1 hour ago, Mordred said:

Not sure on those ones but my 1920's textbook mentions using a small ceramic bowl in a larger ceramic bowl filled with water in the larger one. The cooling results from the expansion from the smaller bowl to the larger bowl.

What effect the glaze itself would have on evaporation I wouldn't know but the example I provided didn't require glazing except for water proofing.

Intriguing, how does that work?  What is this expansion from the smaller vessel? Water doesn't expand, surely? Is it not something to do with evaporation?  

[Mordred]

Simply through the increase in surface area. Much like refrigeration by taking air from a small tube to a larger chamber the mean density/kinetic energy decreases resulting in cooling.

Here is a basic table covering linear expansion cooling coefficients for different materials.

https://courses.lumenlearning.com/suny-physics/chapter/13-2-thermal-expansion-of-solids-and-liquids/#:~:text=The dependence of thermal expansion,which varies slightly with temperature.

If you think about it heat sinks are simply increasing surface area.

Now with the above your better equipped to consider glaze vs no glaze ( ceramic is rather pitted greater surface area) as opposed to smooth.

Though you would also need the conductivity of ceramic as opposed to glaze as well

Edited August 6 by Mordred