1 reply to this topic

[DuncanN]

Hi there,

I am currently stuck on a problem which involves the drying of wet solids using an air stream. the air stream is being heated before entering the drier.

The temp of air before the heater is known, as is its humidity (which will stay constant over the heater). The outlet temperature from the drier is known but the humidity isn't.

I need to find the drying time of the solids from 50% w/w to 10% w/w. My problem is that I don't know how to find the temperature difference across the heater to be able to find the drying rate (using R=Kc A deltaT) as the inlet temperature is not given.

Any help would be greatly appreciated.

Thank you

[markymaark]

Well. You're saying your air is being heated and the humidity stays the same...then you go on to say you don't know the exiting humidity.
-All you're doing is increasing the T. Relative Humidity (%) will decrease but the total amount of water lb Water/lb BDA (Bone Dry Air) will stay the same (nothing is being added or leaving).

Therfore you know the T and Humidity of the air entering the drier. So you can use your formula since you know the deltaT across the heater.