humid air calculation 1

[Flippowitsch]

Hi,

humid air enters a heat exchanger with e. g. 20 °C and 80 % relative humidity. On the outside there will be condensed water.
To calculate the air outlet temperature, I divide the air volume flow into three parts:
[ul]
[li]dry air, T_in to T_out[/li]
[li]vapor water, only sensible heat, T_in to T_out[/li]
[li]vapor water, latent heat, T_in to liquid water T_out (assuming that air out and water out are the same temperature)[/li]
[/ul]

My question:
Is the vapor water's inlet state on the saturated vapor line or is it superheated? So, should I calculate the vapor water inlet enthalpy at T=20°C and quality=1.0 or at T=20°C and the saturation pressure that belongs to T_out (assuming that the liquid water is not subcooled). Please find a picture below. Is it the orange or the green line?

Thanks

Philipp

 

[pmover]

Phillipp,

will a psychrometric chart meet your needs?

an online search reveals -

https://www.engineeringtoolbox.com/docs/documents/816/psychrometric_chart_29inHg.pdf

 

[Flippowitsch]

Hi pmover,

please excuse my late response.
I will have a look at the psychrometric chart. Thanks.

Philipp

 

[pierreick]

Hi,
All the formula you need to deal with humidity problems :

http://www.michell.com/calculator/

Hope this is going to help you and others .
Pierre