24 April 2012

Using industrial heat pumps in sawmills for lumber drying


Industrial heat pumps based on the vapour compression cycle and used for wood drying have advantages such as
high annual utilisation factors and energy efficiency, proper control of product moisture content, reduced energy
consumption and relatively short pay-back periods. On the other hand, among their limitations when compared
with basic hot air convective dryers, there are higher capital and maintenance costs, more complex operation and
requirement for competent operators. This article firstly presents the energy performances of a 13 m3 dryer coupled
with a 5.6 kW (compressor) low-temperature heat pump for hardwood (yellow birch, hard maple) drying.
The second industrial application describes a 354 m3 air-forced dryer equipped with two 65 kW (compressor)
high-temperature drying heat pumps and steam heating coils for softwood (white spruce, balsam fir) drying.