dehumidifier evaporating temp

[crocens]

Hi all.

First of all, sorry for my english, i'm from Poland :)

My question is only teoretical. Let say we have an air dryer, power from 25kW to 100kW, air flow through evaporator about 16000 m3/h.Air temp. 14deg. C.

What is a good evaporating temperature? must it be above 0 deg. C to avoid evaporating freezing, or can it be for ex. -5 deg. C?

[NoNickName]

Temperature at any point of the coil shall never be below 0°C to avoid frosting.
The best temperature is a compromise between compressor efficiency and dehumidification capacity.
If you are designing a new system, you may need to tabulate compressor power input against dehumidification capacity, and find your best breakeven point.

[Sandro Baptista]

It also depends on what relative humidity you want for a specific air temperature of the medium.

The evaporating temperature could be a little below 0ºC with no problem giving you the possibility to increase the capacity of the cold coil.

[botrous]

The evaporation tempreture should be below the dew point of the air to be treated.
Depending on the design conditions, leave a deltaT of 5 degree between the dew point and the evaporation tempreture as a minimum difference , but make sure you are always positive.