Although the drying process can improve the overall quality and usefulness of forest products, if drying is not carefully controlled, drying loss can be substantial. As most drying defects occur when the lumber moisture content is above fiber saturation point (FSP), measurement of moisture content (MC) above FSP is critically important. In this study, a technique was developed which permits use of an electrical resistance moisture meter RDX-1 (Delmhorst Instrument Company) to measure MCs of red oak and yellow-poplar during drying when MC is above FSP. The Lignomat in-kiln probe electrode was used throughout experiments. Two experiments were conducted. The first dealt with developing a two-point technique to measure MC above FSP. The other evaluated the effect of the moisture gradient on the MC reading from the meter. During the drying, pin electrode also was used when oven-dry MC was about 40% in order to compare the MC readings by the pin electrode and the probe electrode. The experimental results show the correlation between the MC readings and oven-dry MC of the sample is quite high during drying; the correlation of each sample is higher than 0.9. Based on this relationship, two-point technique of measuring MC above FSP was developed. This technique can predict MC above FSP of red oak within 5%, and the MC of yellow-poplar within 10%. From the experiment, it was found, when MC is above FSP, MC readings measured by probe electrodes are significantly different from those measured by pin electrodes. It was also found that the moisture gradient affects the MC readings dramatically. The depths of probes inserted into the boards are an important parameter for measuring MC. Different depths yield different MC readings. / Master of Science

Woody biomass transportation costs and market values/costs are strongly correlated with the woody biomass moisture content. Properly managing moisture content can potentially lead to economic and environmental advantages in biomass energy markets. Good management requires accurate moisture content measurements. Therefore, availability of accurate, precise, reliable, and efficient tools to assess woody biomass moisture content is essential. In this study, six different tools (Fibre-Gen HM200, IML Hammer, Humimeter BLW, Timbermaster, Humimeter HM1 and Wile Bio Meter) were evaluated. The six tools employed three different measurement technologies; acoustic, conductance, and capacitance. Woody biomass samples were collected over one season (summer 2011) at three different locations in western Oregon (Corvallis, Dallas, and Clatskanie) for three softwood species and three hardwood species: Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco), Ponderosa pine (Pinus ponderosa L.), western hemlock (Tsuga heterophylla (Raf.) Sarg.), hybrid poplar (Populus spp.), Madrone (Arbutus spp.), and Garryana Oak (Quercus garryana Dougl. ex Hook). Twenty 3-meter long log (20 to 400mm diameter) specimens were collected per species; 18 specimens were divided into two different treatments (open vs. covered), and the two remaining specimens were chipped. In addition, approximately 100 kilograms per species of hogfuel (limbs and tops) were collected and chipped. Moisture content measurements of logs, chips, and hogfuel were made regularly over a four month period. These data was used to develop multiple linear regression models for assessing the moisture content of the six species using the six tools. The major factors considered in the regression models were species (6), treatment (2), and tools (6). The data were also used to estimate the sample size needed for each tool. The best tool from each technology type was identified. The results generated from this study show that (1) none of the tools are accurate without calibration for different species, (2) the best model/tool combination could only explain about 80% of the variability in measurements, (3) further product development is required in some cases to ensure that the tools are robust for industrial application, and (4) there is a wide range in efficiency of the tools (i.e., 50 minute tool efficiency range). The Fibre-Gen HM200 and Wile Bio Meter were the most accurate, precise and efficient tools tested. The cost of transporting woody biomass from the forest to woody biomass plants is "optimized" when the moisture content drops to approximately 30% (wet basis). Validation of the models developed for three of the tools tested (Fibre-Gen HM200, Humimeter BLW and the Wile Bio Meter) indicates that the tools are accurate below 35% MC (wet basis). This suggests they could be used for making threshold transportation decisions, i.e., determining when to haul. / Graduation date: 2013