Cooling Towers

[supersurgilator]

I was just wondering how much less energy a cooling tower and chiller use over a traditional air conditioner? My school has a cooling tower and it sucks because they have to wait until there is no more chance of cold weather before they can turn it on. So since it has been in the 70's this week, it has been 80+ inside the buildings. It just seems that most commercial buildings and restaurants use traditional AC units, so I was just wondering about how much they are saving by not using them/

 

[hydralique]

Hard to say . . .

Cooling towers are expensive to make because they have to have pumps and float valves, and can be difficult to deal with in cold weather as noted. They're also maintenance hassles, and prone to rust over the years. For these reasons they're pretty much restricted to large commercial installations where a cooling plant is used to produce chilled water which is then piped through a building. Cooling towers can be used for both electric compressor driven systems and gas-fired absorbtion systems.

Efficiency ratings are a product of the entire system, so it's pretty much impossible to say how much is gained by one over the other unless you're looking at two specific systems. The advantage of cooling towers is that a good one can exchange heat pretty efficiently and so can take up less space than an equivalent air to air condensor. If the condensor is large enough and has enough air flow, then the system can be as efficient as a cooling tower.

 

[toggleswitch]

As previosuly stated, the total energy consumed to do a job depends on

1- The energy source used to drive the chiller or compressor.
2- The ease by which the heat removed from the air-conditioned space can be dispersed into the outdoors.

Water and air are technically both fluids, but water can hold and transfer heat more efficiently than air can. This is why heating a home needs only a 1-inch wide water pipe containng hot water going around to the radiators/convectors, but also why the main ducting of a forced warm-air heating system can be one foot square (30cm X 30cm), or the like.

Chiller and towers tend to be used in systems much larger in overall capacity than a typical air-cooled condenser coil.

Chillers can also be used with steam or mechanically driven motors/engines instead of electricity which may be pricey or not avaialble for use during peak-demand periods. (Say as in Manhattan during heat-waves. Heat waves here are defined as "x" number of days over 95*F outdoors).

Cooling towers tend to be maintenance intensive. There is a tendency to use many smaller air-cooled systems in a larger buidlng so that if one unit dies, there will not be a total loss of cooling.

 

[maytagbear]

Sorry for being dense, but

the only cooling towers I know are the odd things at nuclear power plants.

Could someone please link a picture or something?

Thank you,

Lawrence/Maytagbear

 

[tolivac]

Just about all large Govt buildings use Chiller systems-the transmitter building I am in now(mid shift) has such a system and the chillers run all year-for humidity control.The chillers we have are 250ton capacity each-they use a dry condensor unit-like a commercial AC unit.The chillers have two compressors each-work on demand-if the load is light one compressor runs-if heavy both run-and the two chillers one is for the front office part of the building-the other for the transmitter area.more the half of the building is unconditioned-unheated or cooled.Just the occupied and office areas are conditioned.And the place has two fuel oil boilers for heat-and can use transmitter heat as well.Not all chillers use the outdoor water injected "cooling towers"another building I worked in used them-the chillers only ran during the spring-summer.600ton and 1200 ton capacity.The studios were cooled-like the transmitter site with 250 ton chillers-4 in all.

 

[sudsman]

stand alone cooling tower

Used alone or in 2 3 4 or 5 units depending on the tonage needed

 

[toggleswitch]

Lawrence:

Cooling "towers" use water/anti-freeze mixture just as a car radiator would to pick up heat from one place and disperse it outdoors. [AFAIK there is no actual "coil" (heat exchanger) in them].

The refrigerant (Freon/ Puron etc.) can thusly stay within the buildng and/or the chiller unit.

The fan, as shown in the picture above, simply blows air over cascading water to release its heat /cool it (the water). The cascading is usually done via metal, stationary louvers.

A great deal of water is lost to evaporation, which is automatically replaced by a float-valve similar to a toilet tank.

It should be interesting to note, IIRC, that bacterial build-up in these thing is what is blamed for Legionaire's disease and the like.

http://www.medicalnewstoday.com/articles/18413.php

 

[toggleswitch]

They appear to be also called evaporative condensers.

Large buidlngs may have a saline solution (water & salt)or water & anti-freeze (propylene gylcol) to circulate chilled water to heat echangers (fumctioning as "evaporators" that draw warm room air over them and blow out chilled / dried air.

Theses will have a different loop of water and anti-freeze for the condenser cooling-tower side.

The chiller unit unit itself (and the refrigerant) may be relatively self-contained.

Hope this helps!

http://www.baltimoreaircoil.com/

 

[joelippard]

We have one

here at the church where I work. When I first came here we had a 1957 York 8 cylinder, 75hp reciprocating chiller. It pretty much looked and sounded like a V8 running. This was paired with a Marley cooling tower on the outside. If you stood beside the York the motor was so big that it came up to your waist and the Marley could have easily eaten you if you fell thru the grates while it was running. I was scared of that damn chiller and I'm man enough to say it. I used to have to fire that thing up and it dimmed every light on the property when it started and made awful sounds, matter of fact it shook the whole room.

We now have a more modern all outdoor chiller system by Trane. Uses alot less energy and has two screw-type compressors that scream terribly.

 

[whirlcool]

A lot of office buildings in Houston that were built in the 40's-late 60's have cooling towers.

The cooling towers I have seen are huge affairs, sometimes two stories high. They have metal corners and angled wood slats horizontally down the sides of them. Usually with rust stains on them.
When they are running, you always hear the sound of water rushing nearby. They also have huge fans on the top of them to move air through them, which are loud. The usual placement for these things in in the building parking lot or a distance away from the back of the building.

I have found that if you go inside a building cooled by one of these, the air is cool, but much more humid than buildings cooled by conventional methods.

 

[toggleswitch]

Sounds reasoanble as the brine solution going to the indoor coil(s) is prrobably not as cold as a refrigerant-cooled evaporator coil and therefore doesn't dehumidify as well.

Then again, in those days, the systems could simply have been be so oversized that they didn't/don't run LONG enough to dehumidify properly.

 

[alr2903]

Cooling towers make me think of Ms. Erin Brockovich. alr2903