Modeling of conventional timber drying using alternative methods

Architects are increasingly specifying sustainable solid wood products within buildings. Many specify a high degree of uniform appearance. This contrasts with standard timber outdoor yard-based air-drying processes that can result in non-uniform appearance. Timber discolouration that has resulted from the drying process leads to the discarding of a high-quality natural resource. The lower recovery rates resulting from defects significantly lower economic yields and increase reprocessing costs. The conventional rack based drying process is subject to multiple environmental factors that can cause this degradation. Rack surveys can map and reveal the location and severity of timber defects resulting from the drying process, but in some cases, it is difficult to understand the reason that certain defects happen under different drying conditions. Almost all those defects are the result of heat and moisture flows throughout the timber racks. Historically, computational fluid dynamics software has been used to simulate the drying processes, however, these tools only explore the flow of heat and not the significant changes in moisture that occurs in timber during the drying process. Recognizing this deficiency, this research explores the alternative use of hygrothermal simulation software tools to view the flow of heat and moisture through racks of drying timber located in an outdoor environment. Traditionally, these tools have been used to inform envelope design of buildings. Liaising with software developers from Germany, this research is exploring the capability of two-dimensional hygrothermal simulation tools to mimic moisture affecting discoloration patterns during the timber drying process.