Secondary refrigerants (Brines)

Hello;

It´s been a long time since i post for the last time.. i´ll remedy

I´ve been studying secondary refrigerants these last months as somebody told me that industrial refrigeration (at least in Spain) is tending to use secondary refrigerants (like Ethylen/Propylen glycol) in 0/+2 ºC refrigeration rooms.

I´ve read that one advantage is an easier control of relative humidity.

Could anybody explain me why?

On the other hand which devices are used in this control?

Adios, amigos