Hvac - latente load

wiseamine · December 14, 2018, 15:41

Dear Members,
I need advice and guidance to simulation the latent load in CFD.
How to include the latent and how to estimate the humidity to evaluate an HVAC system.
Thank you in advance.
Regards
Wise Amine

ghorrocks · December 14, 2018, 17:44

I don't understand what you mean by latent load. What aspect of latent heat are you interested in modelling?

You can model humidity in CFX with a user variable or as a multicomponent mixture. The user variable is simpler and adequate as long as the change in humidity does not change the gas properties. Multicomponent mixture is required for gas properties being a function of humidity or if you want to model phase change.

wiseamine · December 18, 2018, 02:36

Thank you for your answer,

The main latent load is generated from the human occupancy, (10 people)
each person is generating 80 w latent and 80 sensible as per the colling load,

the aim of the project is to consider the latent load/humidity in addition to the sensible load.
Regards
Amine

ghorrocks · December 18, 2018, 04:21

That is simple. Add a heat source of 80W for each person and an additional variable source or a mass fraction source (depending on how you are modelling humidity) for the humidity generated.

Alternately if the people are modelled as cutouts in your geometry you can add a heat source wall boundary condition and a additional variable/mass fraction wall boundary condition.

December 14, 2018, 15:41	Hvac - latente load	#1
wiseamine New Member Wise Amine Join Date: Dec 2018 Posts: 2 Rep Power: 0	Dear Members, I need advice and guidance to simulation the latent load in CFD. How to include the latent and how to estimate the humidity to evaluate an HVAC system. Thank you in advance. Regards Wise Amine

December 14, 2018, 17:44		#2
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,719 Rep Power: 143	I don't understand what you mean by latent load. What aspect of latent heat are you interested in modelling? You can model humidity in CFX with a user variable or as a multicomponent mixture. The user variable is simpler and adequate as long as the change in humidity does not change the gas properties. Multicomponent mixture is required for gas properties being a function of humidity or if you want to model phase change. __________________ Note: I do not answer CFD questions by PM. CFD questions should be posted on the forum.

December 18, 2018, 04:21		#4
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,719 Rep Power: 143	That is simple. Add a heat source of 80W for each person and an additional variable source or a mass fraction source (depending on how you are modelling humidity) for the humidity generated. Alternately if the people are modelled as cutouts in your geometry you can add a heat source wall boundary condition and a additional variable/mass fraction wall boundary condition. __________________ Note: I do not answer CFD questions by PM. CFD questions should be posted on the forum.

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December 18, 2018, 02:36		#3
wiseamine New Member Wise Amine Join Date: Dec 2018 Posts: 2 Rep Power: 0	Thank you for your answer, The main latent load is generated from the human occupancy, (10 people) each person is generating 80 w latent and 80 sensible as per the colling load, the aim of the project is to consider the latent load/humidity in addition to the sensible load. Regards Amine