Bamboo scrimber production: optimization of post-impregnation drying process using a heat pump dryer

The efficient and energy-saving drying process during the production of bamboo scrimber with preserved performance remains challenging. Herein, varying post-impregnation drying temperatures and times were applied first to study the drying rate and energy consumption of impregnated bamboo bundle in a heat pump dryer. Then curing activity of phenolic resin (PF), the physical and mechanical properties of bamboo scrimber were investigated. The results showed that the drying rate was remarkably related to the drying temperature, whereas energy consumption was more dependent on drying time. Drying at 60°C using the heat pump dryer enhanced the drying efficiency by 33-67% and obtained 51-63% energy saving compared with the drying processes in enterprises. Besides, the curing activity of PF was well maintained during drying at various temperatures and times, hence satisfactory physical and mechanical properties of bamboo scrimber were achieved. As a result, drying with heat pump technology at 60°C was the optimal post-impregnation drying condition, and is applicable to practical bamboo scrimber production.