Assuming the hot air flow is essentially constant for a flash, spray or rotary dryer (a reasonable assumption), and the evaporative load to the dryer is suddenly increased either by a production rate or an increase in MC of the feed to the dryer, the hot air will be cooled further due to the increased evaporative load (EvL) that consumes more sensible heat from the hot air flow; consequently, the delta T parameter increase will be directly proportional to the evaporative load (EvL). Therefore, EvL is directly proportional to (∆T) and may be written as shown by the relationship given below.

EvL = K(∆T)

This allows the EvL to be substituted into the original Delta T model and used to sense and control the evaporative load.

EvL = Ka(∆T)p – (Kb/Sq)

This eliminates use of an expensive weigh belt and a problematic MC sensor on the wet feed to a dryer as a feedforward signal to reduce long dead times when using currently-available inline MC meters that are incapable of being installed inside-the-dryer.