Terrance E. Conners

VOC extraction from softwood through low-headspace heating

Summary Volatile organic compounds (VOCs), principally terpenes, released during wood drying face present or potential regulation. Two approaches are reported to control VOC release: heating green wood, or irradiating it with microwave energy, both in a low-headspace environment where evaporation is minimized. Low-headspace heating of green flakes (for OSB manufacture) releases VOCs but proportionately much less water. Hence, it is feasible to extract and collect the VOCs from green wood prior to drying, and to then dry it with lowered emissions. Irradiating flakes with microwave leads to contrasting behavior. Water is released with very little VOC loss if the flakes are microwaved in an open container. Microwaving under low-headspace conditions removes the VOCs, but retains the water in the wood. The water trapped in the wood because of the low-headspace restriction drives the VOCs out of the hydrophobic regions (e.g., resin canals) where they are principally located, into hydrophilic zones. Movement out of the hydrophilic environment and out of the wood is then quite rapid. Hence, either VOC or water release can be targeted by adjusting the headspace during microwaving. Most of the VOCs lost during drying originate from the surface, and low-headspace microwaving releases this surficial material. Hydrogen isotope exchange work shows that microwaving increases water access to the exchangeable protons in dry, or partially dry, wood tissue. The terpenes are carried out with the small amount of steam generated. Similar results are obtained with low-headspace radiofrequency (RF) irradiation of lumber; RF treatment does not induce a significant change in strength.

A Handheld Programmable-Logic-Device-Based Temperature and Relative-Humidity Sensor, Processor, and Display System Platform for Automation and Control of Industry Processes

The development, testing, and validation of a small versatile battery-powered handheld programmable-logic-device (PLD)-based temperature and relative-humidity (RH) sensor, processor, and display system platform is addressed in this paper. An initial and illustrative application of the platform, which is used for its validation-temperature and RH sensing, calculation, and display of equilibrium moisture content of wood, is described. The platform may be utilized for computation and display of a range of temperature- and RH-sensitive metrics/parameters of importance to other process industries. The cost of the platform is important but not the highest priority. As illustrated in the wood-process-industry application of the platform, a higher priority is an ability to efficiently explore, implement, and compare, in a timely manner, different processor microarchitectures and display system formats which may be used in the calculation and display of any process-industry temperature- and/or RH-dependent process metric(s). This could include simultaneous calculation and display of multiple metrics which are a function of temperature and RH. After comparison, a best processor microarchitecture and display system can then be chosen and implemented based on specific industry process application performance/cost and other requirements. A PLD-based sensor, processor, and display system platform offers this opportunity.

A Hand-Held Programmable-Logic-Device Based Temperature and Relative-Humidity Sensor, Processor and Display System Platform for Automation and Control of Industry Processes

The development, testing, and validation of a small versatile battery-powered handheld programmable-logic-device (PLD)-based temperature and relative-humidity (RH) sensor, processor, and display system platform is addressed in this paper. An initial and illustrative application of the platform, which is used for its validation-temperature and RH sensing, calculation, and display of equilibrium moisture content of wood, is described. The platform may be utilized for computation and display of a range of temperature- and RH-sensitive metrics/parameters of importance to other process industries. The cost of the platform is important but not the highest priority. As illustrated in the wood-process-industry application of the platform, a higher priority is an ability to efficiently explore, implement, and compare, in a timely manner, different processor microarchitectures and display system formats which may be used in the calculation and display of any process-industry temperature- and/or RH-dependent process metric(s). This could include simultaneous calculation and display of multiple metrics which are a function of temperature and RH. After comparison, a best processor microarchitecture and display system can then be chosen and implemented based on specific industry process application performance/cost and other requirements. A PLD-based sensor, processor, and display system platform offers this opportunity.

The Differential Thermal Response of Knots and Clear Wood Following Rapid Heating

This study correlated the differential clear wood versus knot wood thermal response to rapid heating for 12 wood species to differences in specific gravity, equilibrium moisture content, extractives content, and microfibril angle. It was found that the relative levels of these variables explain much of the observed difference in clear vs. knot wood temperature following rapid heating. Rapid heating resulted in cooler knot wood temperatures which differ from hotter knot wood temperatures found by previous researchers for longer-term heating.

Development and validation of a programmable logic device (PLD) based sensor and processor microarchitecture system for equilibrium moisture content calculation in wood industries

Equilibrium Moisture Content (EMC) is a metric affecting the performance of wood in many applications. EMC value is a function of the temperature and the relative humidity of the surrounding air of wood. Knowing this value while processing wood is extremely important. This paper addresses the development and experimental validation of a small hand-held special purpose sensor and processor system used to sense, calculate and display the value of EMC of wood depending on surrounding environmental conditions. An appropriate temperature and humidity sensor is chosen for the system. Calculation of EMC requires many arithmetic operations with stringent precision requirements. Various arithmetic algorithms and systems are compared and a suitable choice is made. Two resulting processor organizations, microarchitectures and designs are developed and compared based on accuracy, performance and implementation cost. The designs are captured in a Hardware Description Language (HDL), then synthesized and functionally validated and performance evaluated via HDL virtual prototype simulation. Experimental hardware prototypes of both microarchitectures were implemented to Programmable Logic Device (PLD) technology (specifically Field Programmable Gate Array (FPGA) technology) and used for final experimental hardware prototype functional and performance testing and evaluation. A best processor microarchitecture for the EMC sensor and processor system was selected based on computational accuracy, performance and cost.