Influence of gradient moisture content on hot pressing heat transfer of bamboo scrimber and it’s mathematical model

Abstract

Abstract Hot pressing process is an important process in the preparation of bamboo scrimber. However, due to the low thermal conductivity of fiberized bamboo veneer and the low heat transfer efficiency in the preparation of bamboo scrimber, the processing time is prolonged. At the same time, due to the influence of moisture content in the hot pressing process, the “boiler effect” of the core layer with a sharp increase in temperature and excessive steam pressure will appear, resulting in the risk of board explosion. In this study, a pavement method with gradient moisture content is explored, which can make the surface water vaporize and produce steam impact on the core layer, thus improving the heat transfer efficiency of the core layer and reducing the hot pressing period. The results show that when paving with gradient moisture content, the heating rate of the core layer is increased to a certain extent due to the promotion of steam impact on the core layer temperature. At the same time, due to the low moisture content of the core layer, the saturated steam cannot be formed from the moisture to the core layer, so the obvious “boiler effect” will not appear in the core layer, which can improve the hot pressing efficiency and reduce the risk of board explosion. In addition, this method does not reduce the mechanical properties of the panel. Meanwhile, this study introduces a straightforward gradient moisture content paving method and has made structural enhancements to the hot press machine, enabling the practical implementation of gradient moisture content paving.

Keywords

• Gradient paving
• Bamboo scrimber
• Heat transfer
• Boiler effect