Jun. 27, 2007 – Canada Canadian sawmills traditionally deliver 72 million m3 of resinous lumber per year. About 2% are dried using low-temperature heat pumps and the rest through other technologies using bark-, natural gas- or oil-fired boilers as primary energy sources. However, such products are well suited to high-temperature drying. Two hybrid (electricity/fossil) industrial-scale high-temperature heat pump prototypes for resinous lumber drying have been developed and investigated in Canada.
Several improvements have been achieved in terms of working fluid selection, refrigerant fl ow control, system operating stability, dehumidifying capacity control and optimum drying schedules. The thermodynamic operation and specific energy performances of high-temperature drying heat pumps have finally reached all expected targets.