ABSTRACT
Industrial wood drying is an energy-intensive consuming operation. Heat pump-assisted dryers reduce the thermal energy consumption by incorporating one or more heat pump(s), which recover heat by cooling the kiln air below its dew point and recycling the latent heat of condensation. Theoretically, heat pump-assisted batch-type dryers are totally closed systems, which use suitably designed air-to-air heat pumps to condense moisture vaporized from the wood in order to rewarm a part of the recirculated drying air. Single-stage heat pump-assisted dryers are extensively used because of limited temperature differences that can be achieved inside most of wood drying chambers. Dryers and heat pumps are both complex thermodynamic systems. Consequently, systems integrating dryers and heat pumps are much more complex than each of these components separately.
