ON MOISTURE EXCHANGE PROCESSES DURING CONVECTIVE DRYING OF LARCH LUMBER IN BATCH-TYPE CHAMBERS
Moisture exchange processes in lumber drying in general and larch drying in particular have a significant impact on the intensity of moisture removal. The intensity of moisture removal from the surface of the board largely depends on the circulation rate of the drying agent on the surface of the board. At the same time, standard drying modes are limited by regulating parameters such as temperature and relative humidity, which is clearly not enough to control the rate of moisture removal from the surface of the board. Therefore, one of the problems that needs to be solved is the installation of high-rate modes that allow to synchronize the processes of moisture transfer and moisture exchange. It has been established that moisture transfer and moisture exchange depend not only on temperature and humidity conditions, but also on the rate modes of the drying agent, which reach the maximum value in the inter-row channels of the lower rows of the pile. Consequently, the drying potential reaches its maximum values in the lower rows of the lumber pile. Therefore, with insufficient performance of the fan-driven unit for the movement of air masses, there is a significant drop in the drying potential along the height of the pile. If the entire drying period of larch lumber is conditionally divided into three stages, then the maximum effect of the drying potential occurs during the second stage, when a significant part of the water which is brought to the surface of the board is removed by evaporation. At this stage of drying the maximum value of the asynchrony of the processes of moisture exchange and moisture transfer along the height of the pile is observed. The purpose of this work is to justify the high-rate circulation modes of the drying agent on the surface of larch lumber.