Numerical analysis of convective drying of gypsum boards

Convective drying of gypsum boards is investigated by numerical modelling, within the context of gypsum board manufacturing where enhancing processing efficiency, reducing energy usage and optimising product quality are essential. The aim of this parametric study is to provide a first step towards modelling of the drying process in an industrial drier by investigating the main factors impacting the drying process, such as the influence of air speed, turbulence intensity, approach flow temperature and heterogeneous drying conditions but also the influence of the paper liner on the drying process. Therefore, this study is performed for a simple configuration and at ambient air temperatures. In terms of air flow modelling, CFD simulations are performed in addition to the use of standard convective transfer coefficients. The sensitivity of the drying process to the air flow conditions is found to be limited for a gypsum board with a paper liner due to the high resistance of the paper liner to vapour transport, compared to the boundary layer resistance. Thus, guidelines for modelling drying of gypsum boards under representative manufacturing conditions conclude that detailed flow modelling is less critical to assess this specific drying problem. Instead, characterisation of the material transport properties at high temperatures is more relevant, particularly for the paper liner.