Relative humidity control in smokehouse and maturing (climatic) chamber?

[bato87]

What service is the green and the grey ducts?

What does R mean?

We have Vemag smokehouse and maturing (climatic) chamber,this is a photo from they catalog(found on net).I do not now what R mean?
I am interested in the principle of work maturing (climatic) chamber.
If system have cold transfer(evaporator) and heating,how is relative humidity maintained?
In chamber is fermented sausages which are the source of moisture.

If someone can explain me in more detail, I'm not completely sure how it is maintained humidity?

Thanks