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Heat transfer coefficients, U, are typically in the 40 - 80 kcal/m2*°Ohr or 8 - 16 BTU/ft2*°F*hr range with higher values for the constant rate zone.

Indirect dryer calculations are based on mass and energy balance using heat transfer coefficients obtained experimentally for various drying zones. These calculations are quite straightforward and center around determining evaporation capacity, heat energy and amount of heating medium flow needed, taking into account feed and product moisture and temperature, heat medium type (steam, oil) and temperatures, heat sources and losses, etc.