Cold storage rooms such as meat storage, pharmaceutical storage, food storage, storage of fruits and vegetables etc. need to maintain certain humidity levels. The challenge in such environments is that condensation dehumidifiers freeze up, requiring us to do a manual de-icing of them to make them work. Condensation dehumidifiers work in the principle of condensing the atmospheric moisture content. However this will not work when the temperature of the room and the intake air is lower than approximately 10°C.
It is possible to do de-icing of dehumidifiers so that it can work at low temperatures. However it is laborious to do this de-icing of the dehumidifiers. There are dehumidifiers having auto anti-icing systems that shut the compressor off if ice is detected, and thereby stopping the dehumidification process itself. It turns out to be a higher investment without value of having a dehumidifier in colder climates or extremely cold rooms.
Desiccant dehumidifier for cold rooms
One way to overcome this challenge is to invest in a dehumidifier that works by absorption and not mechanically requiring it to heat the condenser coil. The absorption dehumidifiers which are known as desiccant dehumidifiers are better options in colder climates, but may turn to be a bit expensive than the mechanical ones.
Desiccant dehumidifiers take the intake air and pass through a rotary disc consisting of an adsorbent like silica gel. For this reason it is also known as rotary dehumidifier. The intake air is processed and converted into two streams of air viz. wet air and dry air. The dry air is recirculated within the same area and the wet air is to be thrown out of the room. Thus the moisture is removed out of the room through the wet air. The silica gel works for 2-3 years after which it need to be replaced.
By principle in the condensation types there is only one intake and one outlet air flow. The outlet air flow is dry air since the moisture content has been converted into water. But in desiccant type, there is one intake and two outlet air flow.
Why we can’t use condensation dehumidifiers for cold rooms, freezers & walk in chillers?
By principle, condensation is cooling down the air and during this process, the moisture content of the air is converted into water. However in a cold environment whether it is inside a cold room, chiller or in extreme winter conditions, the air is already cold and it is not possible to further cool down the air to convert the moisture content into water. Hence the economically viable option is to use desiccant dehumidifiers in such areas.
You can read the pdf file of Comparison Sheet of Dessicant Dehumidifiers for the detail comparison of dehumidifiers type.