air washer system with chilled water

[smpsmp45]

I am looking for some technical data on this issue. I had some charts from Flakt, but I am not sure if they are relevent now a days. The air temp ofcourse is less compared to normal air washer system

[Samarjit Sen]

Could you please let me know as to what informations you require. Air Conditioning with air washer is very common. We had done a number of such works and have recently completed a project where temperature and humidity were both to be controlled. We had used humidifiers with chilled water.

[smpsmp45]

I am looking for charts which show air conditions after chilled water air washer against normal water ( Ambient) air washer system

[Ravi]

Insignificant, practically.

[Victorman]

Hola !

Please be more specific on the information you
want.

Are you trying to design an air washer to control
temperature and humidity while using a chilled water coil ?

Do you want to know what happens to the air
when passing through the washer and the coil ?

Regards

Victorman

[smpsmp45]

I al looking for a situation wherein when air passes over chiiled waer air washer, at what conditions air comes out

[Dilip sahasrabu]

Hi,
I am also looking forward for the same arrangement that is using chilled water in air washer instead of normal fresh water. Has anybody idea about it? Please reply as it will help me too.

[Victorman]

Hola !

The Trane Company in La Crosse Wisconsin USA , publishes a book titled " Trane Air Conditioning Manual ",

this book explains in detail the action of the air and water when brought in contact with each other ,it
also has a section on " Air Washers ".

You can find the book in Amazon.

l hope this will help you.
best regards

Victorman

[smpsmp45]

Many thanks Victorman

[lana]

Hi smpsmp45,

To know this you have to study "Mass Transfer".

Using chilled water in an air washer is a waste of energy.

Mohamed Khamis can help you a lot on this subject.

Cheers

[smpsmp45]

I think I should send a PMS to Mr. Mohamed Khamis on this then. SOme customers do insist on this.

[Samarjit Sen]

Please let us know as to the result of your discussions.

[smpsmp45]

Surely. I shall post that data here

[Ravi]

The effect is insignificant because of the large difference between the latent heat and sensible heat, incase of water. The latent heat of evaporation of water is about 2441.68kJ/kg (at ambient temperature) and the specific heat is 4.18kJ/kgC. This means, you have to have a temperature difference of 584 C or you have to provide 584 kgs of water, for a temperature difference of 1C if you want to remove as much heat as it is possible if you evaporate 1kg of water.

I am giving here a sample calculation to illustrate the advantage of going with chilled water at 5C when compared to 25C water.

Let us assume that your inlet conditions are 30C DBT and 60% RH. This corresponds to a WBT of 22.5C. Assuming 75% effectiveness of a direct evaporative cooler, you can get a dT of (30-22.5)*0.75 = 5.625C. So, you can reduce the air temperature to 24.4C. The total sensible heat removed from air can be calculated by 1.23W/(L.s.K)xflowrate(L/s)xdT(K). Assuming an air flowrate of 472L/s, the sensible heat removed form air (which is imparted to the evaporating water) equals 1.23x472x5.625 = 3265.65W (or 3.265kW). The enthalpy of water and steam at 25C are 104.83kJ/kg and 2546.5kJ/kg respectively, so the latent heat of evaporation is (2546.6-104.83) = 2441kJ/kg.

To remove 3.265 kW from air, you have to evaporate 3.265/2441 = 0.00133kg/s of water. This is, essentially, the flowrate of water across the evaporative cooler. If you use 5C chilled water instead of using 25C water, you can get a sensible heat benefit from chilled water to the tune of 0.00133kg/s x 4.18kJ/kgC x (25-5)C = 0.11kW.

Going back to the sensible heat equation of air, 0.11kW would reduce the air temperature by 110W/(1.23W/L.s.Kx475L/s) = 0.188C (or K).

Hope this clarifies the issue at hand.

[smpsmp45]

Great explaination with example. Many thanks

[mohamed khamis]

Hi SmpSmp45

Sorry for being late to particpate ur thread. Anyhow there is attachment I wish it could help and reply ur question.

Best wishes

[smpsmp45]

Excellent info & many thanks