Heat Balance - Rotary Dryer - Predicted dT < Actual dT

[CraigC782]

Rookie attempting to model an existing rotary dryer. Given the input and output conditions of air and solids, there is a large excess of heat going "somewhere." I can't explain it with losses to the outside of the drum (insulated).

Heat gained by the solids includes sensible heat plus heat of evaporation.

Heat lost by the airflow includes sensible heat.

What am I missing? The only thing I can think of is a miscalculation of airflow. Given that I calculated it based on anemometer readings, avg vel x area = volumetric flow rate. Multiply that by density = mass flow rate.

I also cannot discout air mixing, as the solid feed slot is open to the atmosphere...

 

[Latexman]

Air leakage? Does it run under a vacuum (leakage in) or a pressure (leakage out)?

Good luck,
Latexman

 

[StoneCold]

Are you taking into account humidity of air coming in and air going out in your heat capacities?

 

[omnomnom]

What about evaporation energy of the water?