Dryer Design Calculator

The dry solids mass flow — the part of the material that isn't water — stays constant through drying, so the calculator first finds that fixed dry-solids rate from the wet feed and initial moisture, then works forward to find what total product rate (dry solids plus remaining water) corresponds to your target final moisture. A lower final moisture target means less water remains in the product, which is why it directly changes the dry product rate even though the incoming feed hasn't changed.

Sensible heat only needs to raise water's temperature, using its heat capacity of about 4.18 kJ per kg per degree, while latent heat has to fully vaporize that water, which takes roughly 2,260 kJ per kg regardless of temperature. Because vaporization's energy cost per kilogram is so much larger than a typical few dozen degrees of heating, latent heat dominates the total energy required in almost every realistic drying scenario.

The calculator applies a 1.5× time penalty to batch operation to approximate the falling-rate drying period, where a fixed charge of material dries unevenly as its surface moisture depletes faster than moisture can migrate up from its interior. Continuous dryers move material steadily through the airflow and tend to operate closer to a constant drying rate, which is why they're modeled as faster for the same water-removal task.

Yes — this calculator computes exit humidity as removed water divided by dry air mass without checking whether the air stream is actually capable of holding that much moisture at the given drying temperature. If your airflow rate is set very low relative to the water being removed, the reported humidity can exceed what real air could physically carry before condensing, so treat an unusually high result as a signal to increase airflow rather than as a literal design number.