low powered chiller

[uwiik]

I am looking for new ideas to cool down water in my saltwater pond (90000 L). Current water temp is 26-28 celcius. I was thinking about using large capacity air blower being injected into the water with stone diffuser and put the air blower in a temperature sealed small container with cool air (16 celcius) being injected into the small container by means on a small capacity aircon. will this method actually help to cool down my water???

[humbugy]

you might be better off digging down a large vessel and circuilate water threw a heat exchanger and your pool system, you migth have to dig kinda deep though, and bury more than one container, you would have to do the math for how much heat you have, and how much heat you need to remove.
the air blower idead sounds pretty in-efficent.

[billsreef]

The surface area and contact time with the water is not going to make for an efficient system. I think humbugy's idea of a geothermal heat exchanger would be the most efficient.

[uwiik]

sounds like a good idea, any useful links for the construction and application of this geothermal heat exchange??

[BeanAnimal]

That is 23,000 gallons. You need about 3.5 degrees F of cooling.

Lets ignore that there is heat input to the system during the day and possibly a loss during the night.

Lets just assume that you need to bring the pond down 3.5 degrees F.

So 23,000 Gallons is 191,590 pounds of water. So at 1 BTU per pound per degree F, you need about 574,770 BTUs of cooling.

Lets just round off and say that 1 gallon of evaporation gives you 8,500 BTUs of cooling. That means it will take about 68 gallons of evaporation to remove the heat. You should be able to leverage 68 gallons more evaporation by the use of a waterfall and/or a misting system.

Lets assume that the heat of the day is 12 hours. That is about 5.75 gallons an hour of evaporation.

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1 TON of phase change cooling (air conditioning/chilling) is 12,000 BTU per hour. So it would take a 1 TON chiller about 16 hours to pull that volume of water down 3.5 degrees. So in the real world you would need a 5 Ton chiller to do the work.... I would not want to be the electric bill on that piece of equipment!

[uwiik]

Hehehehehe, with my current setup I paid US$1500 for electricity, can't imagine with the additional chiller.... Once I finished my new farm and finished my new website I'll post the link..... The heat is not so bad, I use foil bubble heat insulation on my roof, the water measure 28 max (29 on the hottest day). So are you suggesting that I better of bringing down temp by increasing evaporation ??? lots of fan???

[BeanAnimal]

Yes, evaporation is the most efficient means of cooling that you can provide (That is what a chiller does anyway... evaporation in a closed loop of refrigerant!)