Water consumption on cooling tower 1

[MedicineEng]

All:
I´m trying to calculate the estimated make-up water volume in a cooling tower, for the purpose of establishing its water treatment costs, but I´m struggling to come up with a solution to this problem. I thought about trying to obtain the volume of air that passes through the tower, see it´s initial characteristics (of temperature and RH) and then assume that this air comes out saturated and see the water quantity difference in a psychometric chart, but the reality is that I don´t know the air leaving temperature and I am not sure how accurate is this method.

Does anybody has any idea on how to nail this?

Thanks in advance for your help

 

[Compositepro]

The worst case is that all the heat load is handled by evaporation. On high humidity days there will be less evaporation. Blow-down to remove the build-up of dissolved solids will add to your water requirement.

 

[RossABQ]

Do you have an energy model for the building/systems served? If you do it should have annual ton-hours cooling. That will give you the annual gallons evaporated, to which you need to add drift and blowdown losses.

If it's an existing building/system, you will have to develop seasonal data or assume some kind of load profile.

 

[GHartmann]

I am almost certain you could have found this in Perry's Handbook.

But anyway here is a link to a simplified method:


Cooling Tower Make-up

 

[Compositepro]

That link passes through the Twilight Zone.

 

[GHartmann]

Sorry, hopefully here is the correct link:

http://www.checalc.com/solved/ctmakeup.html

 

[RossABQ]

That will give the peak water consumption. For most facilities, the cooling load is highly seasonal, so some kind of load profile over the year is needed to have a meaningful water treatment cost.