I think there’s a typo (since it couldn’t be an error) in Cecil’s article about ice harvesting/sale. Describing ice houses:
The problem is that latent heat is the heat/energy required to convert 0 ºC ice to 0 ºC water - it’s heat you add, not heat that’s released. cite.
Forgot link:
And I will tell you what is was like to use a 7 place table of logarithims!A slide rule is just fine for ordinary engineering calculations.
When higher precision is required you either have to get a 20 ft. slide rule with 4 signifigant digits or turn to logarithms.
To multiply you add and to divide you subtract, to raise to powers you multiply, and to extract roots you divide. Sounds confusing,doesn’t it?
And all the time keep track of the mantissas and the characteristic of each term.
That’s why I’ve put all my money in buggy whips!
I would not presume to answer for the Master, but it is fairly clear that he intended to say the following: An opening at the top allowed evaporation (from the melted water clinging to the ice) to draw off any latent heat of melting that could melt the ice further (i.e. evaporation, encouraged by the vent, cooled the still-solid ice block). An obvious typo.
Yep. The last ice house in Kankakee County, Illinois, burned down in the early '70s–while it was being demolished.
I remember the ice in hot Australian country towns in summer coming from icehouses which used evaporative cooling wooden water towers to make the ice. It seemed to work very well, with the water cascading down the outside.
This is just the kind of Cecil column I like. It answers an interesting question that I would have never thought to ask in an entertaining way.
I’m letting my SDMB subscription lapse next month, but I reckon I’ll keep reading Cecil’s columns as long as he can crank out ones like this.
The buggy whip industry is doing quite well.
Buggy driving nowdays (except for the Amish & similar) is nearly all for a hobby, and participating in horse shows & eventing.
People of the past, who used buggy driving as ordinary transportation, would spend as little as possible on buggy whips. But compared to them, people will spend much more on their hobby, on high-quality, fancy looking buggy whips. To say nothing on the spending on really fancy whips for shows!
That is very interesting!
Wasn’t there some kind of refrigeration machinery that used the water from the evaporative cooling tower(s) to actually freeze the ice?
There is no “latent heat of melting” to further melt the ice. The change of state due to melting absorbs heat. I agree that evapororative cooling could have been the reason for the vents. Or perhaps a vent design that draws air along the surface of the roof to prevent it from becoming too hot.
If there is a Latent Heat of Condensation, and I know that there is, because it is a term that was drilled into my head once, it stands to reason that there would also be a latent heat of freezing. Melting and evaporation would cause cooling, then.
Then, too, liquid water in the vicinity of the ice would have a tendancy to defeat the insulation and allow the ice to couple more efficiently with the ambient thermal environment. That ambient thermal environment being a hot summer’s day.