Why not cool with radiators?

ArthurPeabody

I read this article in the NY Times about Qatar cooling its stadiums with cold water: https://www.nytimes.com/2022/12/13/sports/soccer/qatar-world-cup-stadiums-air-conditioning.html and I remembered staying in an old hotel that had an 'ice water' tap at its sinks.

EBEBRATT-Ed

They use chilled water fro chillers and run the chilled water through air handlers or fan coils. They have been doing that for 100 years. Now they are cooling with "chilled Beams" condensation is an issue

mattmia2

Chilled beams work if you have circulation that dehumidifiers the air. Not sure how much work is done by the dehumidification vs the beams.

I'm curious about this ice water faucet.

JakeCK

Cooling with radiators in a desert might work. Cooling with my radiators when the humidity is 75% outside is a very very bad idea.

ArthurPeabody

EBEBRATT-Ed said:

TNow they are cooling with "chilled Beams" condensation is an issue

I've never heard of 'chilled beams'.

mattmia2 said:

I'm curious about this ice water faucet.

This was the '60s. I was a teenager. An older fellow said it was a luxury in hotels in the olden days. The water in this hotel was no colder than the regular cold water.

JakeCK said:

Cooling with my radiators when the humidity is 75% outside is a very very bad idea.

Why? You get a latent heat of evaporation released for every molecule of water condensed, so that's in the equation. AC already deals with this. In a building that already has AC, would radiator cooling decrease its load enough to save money? Otherwise one would have to add dehumidification - it might be cheaper than adding AC.

Jamie Hall

Two problems. The biggest is condensation. In an air conditioner, the condensation occurs in the coils, and the condensate is caught in a pan and routed out to somewhere where it hopefully won't cause too much damage. A dehumidifier is nothing more than an air conditioner put to a different purpose, often with some temperature recovery. If you try to cool air with a radiator, if you manage to get it to the dewpoint -- 65 F for 75%RH air at 75 F to begin with -- it will condense. All over the floor or the carpet or what have you. And perhaps worse, that condensation releases heat, and the end resullt is that you really can't cool the air much below the dewpoint.

Second, there is the matter of heat transfer, which is related to temperature difference. Let's say you are circulating cold water -- perhaps 45 or so -- and the space temperature is 75. 30 degrees F. There will be much less heat transfer than if you are circulating steam at 212 degrees in the same space -- temperature difference of 137 or so. over 4 times the heat transfer rate.

Now if you have enough water, the best way to cool in a arid climate dry is what is called a swamp cooler. Just evaporate water in the air, and it will coo. These have been used in one form or another for the last 3,000 years, at least. If you don't have enough water, or the air is moist to begin with, mechanical refrigeration or, in the bad old days, melting ice.

hot_rod

Some additional information here

https://www.caleffi.com/sites/default/files/file/idronics_28_na.pdf

GGross

@ArthurPeabody

Chilled beams are pretty cool (that's a pun) They are all the rage with engineers, they don't cool a space by just being a cold beam though, they do distribute air as well.

For a better understanding of why we don't run chilled water through the radiators do a little experiment. On a hot summer day, in an unconditioned space, get a glass full of ice water and sit it out, wait 20 minutes and look at the glass, if it is covered in water so to would your radiators be, except much more mass so much more water, enough to damage a house. This method also would not dehumidify the air in the space which oftentimes is a primary factor in comfort

that being said radiant cooling is used sometimes, usually in commercial applications just as you mentioned to decrease the load in the space. Generally not with traditional radiators though

aircooled81

Worked on a building 5 or 6 years ago, 4 stories, every floor was a 1 mile walk - the building was round. All glass, curved actually, glass on exterior was 40 feet long!
The ceiling was made from Terazo, and had tempered chilled water which would turn the terazo into a heat sink. Lightly cool the terrazo, lightly cool the air, the cool air would fall and warm air rise.
Now that's the largest chilled beam system I've ever seen.