DESIGN CALCULATION OF MODULAR COMPONENTS IN A TWO-STAGE HEAT PUMP DRYER

Abstract

Heat pump drying is often applied to the dehumidification of food, fruit, and
other heat sensitive materials in which raw materials is dried by low temperature
and low relative humidity air thanks to the features of heat pumps. Thus, energy
consumption of heat pump drying systems are lower than that of other
conventional convective drying methods. This work addresses a detailed model for
the design calculation of a two-stage heat pump drying system. Mathematical
model of a heat pump drying system is composed of sub model: drying chamber,
heat pump, and drying efficiency models. Mass and heat balances of both
refrigerant and drying air are applied to all components of the drying system for the
development of the entire mathematical model of a heat pump dryer. The general
model including all sub models addressed in this work can be used for design
calculation of every single modular component of a heat pump dryer at the stage of
constant drying rate. As an example, detailed calculation steps of a two- stage heat
pump drying using R134a refrigerant is given in this work.