Select for dehumidification or cooling?

[mech5]

Does anyone know what criteria to use to select an air handler for either cooling or dehumidification? I used two design conditions using ASHRAE Fundamentals handbook.
Thanks

 

[willard3]

Familiarize yourself with sensible and latent cooling components of air system cooling loads.

High sensible loads = lots of air and shallow coils
High latent loads = less air and deeper coils

 

[mech5]

If I use the selection for the hottest day, the sensible load will be satisfied, but the latent load. If I use the most humid day selection, the latent load will be satisfied, but not the sensible.

 

[MintJulep]

How far apart are the two design conditions and how different an equipment selection do they drive?

Remember that the ASHRAE design conditions aren't necessarily "real". They result from a lot of statistical mumbo-jumbo over a large number of years of data.

Use an hourly data set like TMY and see how many hours per year each equipment selection will operate in an unsatisfactory way. Maybe tweak the selection a bit and try again.

It's an engineering judgement thing.

 

[MechEngNCPE]

Why not satisfy both? Grab a psych chart and get your capacity the old fashioned way. Use the design day Dry bulb and design RH, get your enthalpy from that then use Qt=cfm*4.5*deltaH

 

[mech5]

What I did is choose the most humid day selection, since it resulted in a large load by 30 MBH. I kept the hottest day airflow and used it with the higher load. My system has a reheat coil, so I won't sub-cool the space.
Thanks for the help.