Equation for evaporation loads in pools

spooki · August 6, 2015, 06:41

Hi,

I would like to insert into Ansys CFX Setup following equation for evaporation loads from the swimming pool:

w = A/Y * (pw - pa) * (0.089 + 0.0782*V)

where:
w = evaporation of water, kg/s
A = area of pool surface, m^2
Y = latent heat required to change water to vapor at surface water temperature, kJ/kg
pw = saturation vapor pressure taken at surface water temperature, kPa
pa = saturation pressure at room air dew point, kPa
V = air velocity over water surface, m/s

How can I take into consideration, eg. saturation pressure, which value depends on temperature value? I guess there is no variable or formula available for it in Ansys, so I have to prepare it by myself? If so, how can I do it? Formula refering to another formula?

Thanks in advance for your answers!

ghorrocks · August 6, 2015, 18:46

Your question is not a CFX question, it is general physics. I will leave it up to you to derive this formula as only you know what is appropriate for what you want to do. But implementing it in CFX as a mass source term should be straight forward once you have it.

August 6, 2015, 06:41	Equation for evaporation loads in pools	#1
spooki New Member Piotr Join Date: Aug 2015 Posts: 1 Rep Power: 0	Hi, I would like to insert into Ansys CFX Setup following equation for evaporation loads from the swimming pool: w = A/Y * (pw - pa) * (0.089 + 0.0782*V) where: w = evaporation of water, kg/s A = area of pool surface, m^2 Y = latent heat required to change water to vapor at surface water temperature, kJ/kg pw = saturation vapor pressure taken at surface water temperature, kPa pa = saturation pressure at room air dew point, kPa V = air velocity over water surface, m/s How can I take into consideration, eg. saturation pressure, which value depends on temperature value? I guess there is no variable or formula available for it in Ansys, so I have to prepare it by myself? If so, how can I do it? Formula refering to another formula? Thanks in advance for your answers!

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August 6, 2015, 18:46		#2
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,703 Rep Power: 143	Your question is not a CFX question, it is general physics. I will leave it up to you to derive this formula as only you know what is appropriate for what you want to do. But implementing it in CFX as a mass source term should be straight forward once you have it.