Dear all
I am going to simulate humid climate using Ansys Fluent , Since there is no option to enter the exact value of RH% (Relative Humidity) in Fluent set up, I've found it's better to use mass fraction of water in moisture for inlet boundary condition.
My question is whether mass fraction is same as Humidity ratio?
If yes, why entering the calculated mass fraction of water using Psychometric calculator regarding to RH and Dry bulb temperature, gives the incorrect RH in Fluent?
If No, I'd be appreciated for any help.
No, is not the same.
Humidity ratio is computed based on the saturated conditions at specific pressure. AS you said using the psychometric chart for SPECIFIC pressure. The mass ratio depends on other factors,for example, hold up, slip velocity etc.
I recommend you to read papers about cooling tower they address it thoroughly. You will end up writing a subroutine to consider this effect.
Alright Julio
I didn't get it yet. As you said humidity ratio and mass fraction are not same. On the other hand, they both are related to the RH% value. At the specific pressure and dry bulb temperature, considering RH% value, estimates the value of those both and also other parameters.
I care about mass fraction while it's only parameter (except temperature and pressure) has been used in Fluent and related to RH%. (Same for Moll fraction).
I need to know for a specific RH%, what procedure should I follow in Fluent.
Cheers.
I am so sorry Mahdi; I did not read your questions thoroughly. I thought you were referring to volume fraction. You are right both are related through the RH and again I recommend you to read papers related to cooling tower.
I am so sorry for my misunderstanding. !!
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