Wood and Fiber Science (E-Journal)
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LIFE-CYCLE ASSESSMENT OF A DISTRIBUTED-SCALE THERMOCHEMICAL BIOENERGY CONVERSION SYSTEM
Get PDFAbstractExpanding bioenergy production from woody biomass has the potential to reduce net greenhouse gas (GHG) emissions and improve nation’s energy security. Science-based and internationally accepted life cycle assessment (LCA) is a tool essential for policy makers to decide on expanding renewable energy production from newly developed technologies. A distributed-scale high-temperature thermochemical conversion system, referred to as the Tucker renewable natural gas (RNG) unit was evaluated on producing medium-energy synthesis gas (syngas) and biochar along with its waste from harvested woody biomass. Mass and energy balances, cumulative energy demand (CED), and life cycle inventory (LCI) flows were found based on operational data from a 1-hr continuous run. Emission data summarized from the cradle-to-gate LCI showed biomass and fossil CO2 emissions of 159 g and 534 g, respectively, for each oven-dry kg of wood chips pyrolyzed. LCA, applied in accordance with ISO 14040:2006, was used to determine the potential environmental impacts. Total GHG is 0.595 kg CO2 eq/ OD kg of wood chips processed. Contributions to the total GHG contribution were 20.7% from upstream forest resource extraction and chip processing at sawmill and 77.6% from thermochemical conversion process with propane combustion. The remaining1.62% was from parasitic electricity operating the Tucker RNG unit. Quantifying Global Warming Potential (GWP) showed the carbon benefits (eg low GHG emissions) along with the carbon “hotspots” from burning propane to maintain the endothermic reaction in the Tucker RNG unit. Using low-energy syngas generated from what was originally a waste in the pyrolysis reaction to augment propane combustion would reduce GHG emissions (ie fossil CO2) by about 30.4%.
UNDERSTANDING THE EFFECTS OF DRYING METHODS ON WOOD MECHANICAL PROPERTIES AT ULTRA AND CELLULAR LEVELS
Get PDFConventional kiln and vacuum drying are commonly used in industry to dry wood. In this research, an attempt was made to develop a better understanding of the effects of both drying methods on the mechanical properties of wood at the ultra-structure and cellular structure levels. Dynamic mechanical analysis (DMA) and nanoindentation (NI) were used together with standard static bending tests according to ASTM D143 to assess the respective effects of both drying methods on the performance of yellow birch (Betula alleghaniensis Brit.) wood, an important species in the Canadian wood industry. Measurements of equilibrium moisture content (EMC) at different relative humidity (RH) levels showed that vacuum drying consistently yielded higher EMC values. Vacuum-dried wood also exhibited superior MOE and MOR performance. Tests conducted by DMA demonstrated that the chemical structure of wood had undergone more changes during conventional kiln drying than during vacuum drying. The elastic modulus and hardness measured by the nanoindentation technique revealed that the impact of wood drying can be detected at the cell wall level as well. The results of this study showed that special attention should be paid to the effects of specific drying methods on the chemical structure of wood, as the chemical changes occurring in the kiln impact on the quality of the final products.
EFFECTS OF LOG POSITION IN THE STEM AND CUTTING WIDTH ON SIZE DISTRIBUTION OF BLACK SPRUCE CHIPS PRODUCED BY A CHIPPER-CANTER
Get PDFFifteen stems of black spruce (Picea mariana (Mill.) B.S.P.) coming from the Abitibi-Témiscamingue region, were cross-cut into three sections: bottom, middle, and top logs. Logs were fragmented producing three faces with a chipper-canter using three cutting widths (CW) of 12.7, 19.1, and 25.4 mm. Chip dimensions were assessed by thickness, width, and length (Domtar and Williams classifications). Knot characteristics [total knot number (TKN) and area (TKA)] were assessed in the three cant faces. Growth ring attributes [earlywood density, latewood density (LWD), ring density, earlywood proportion, ring width and rings per mm (R/mm)], mechanical properties (shear, splitting, modulus of elasticity (MOE) and modulus of rupture in bending), and basic density were evaluated on samples obtained within each CW area. The results showed that most of these wood attributes were affected by the log position in the stem and/or CW. The weighted mean chip thickness (WCT) and chip size distributions were significantly affected by the log position and CW. WCT increased as CW increased. WCT variation with height could be principally associated to the number and size of knots within the stem. However, the presence of higher taper in the bottom logs produced thicker chips. Multiple linear regressions showed that CW, TKN, LWD, and TKA were significant predictors of WCT. Moreover, chip thickness distribution was affected primarily by TKA, cutting height and LWD, while the width and length distribution was mainly affected by R/mm, TKN and MOE. Chip size variation is to some point determined by knot characteristics, bending properties, growth ring width, and wood density of the raw material. These results showed the potential benefits of classifying logs in woodyards and better controlling the raw material attributes in sawmills. If the CW is combined with the knowledge of the raw material, chip dimensions can be adjusted using other fragmentation parameters to increase chip size uniformity
COMPARISON OF NONDESTRUCTIVE TESTING METHODS FOR EVALUATING NO. 2 SOUTHERN PINE LUMBER: PART A, MODULUS OF ELASTICITY
Get PDFModulus of elasticity (MOE, or E) is one of the main quality indicators in structural lumber stress grading systems. Due to a relatively high amount of variability in contemporary sawn lumber, it is important that nondestructive evaluation technology be utilized to better discern high-E-value pieces from low-E-value pieces. The research described in this study is from a laboratory test of three nondestructive technologies applied to 343 pieces of visually graded No. 2 southern pine lumber collected across the southeast region of the United States. The evaluated technologies included continuous lumber test in continuous proof bending (Metriguard Model 7200 High Capacity Lumber Tester), transverse vibration (Metriguard E-Computer), and two stress wave tools (Falcon A-Grader and Carter Holt Harvey Director HM200). For each of the nondestructive techniques, results were compared with static E as determined by the four-point static bending tests following ASTM D198-14. In all cases, the nondestructive techniques successfully predicted E for all lumber sizes, with linear regression r2 values ranging from 0.77 to 0.86
Screwdriving Torques in Particleboards
No full textCharacteristics of torques for driving screws into particleboards were investigated in this study. Factors evaluated on screw seating and stripping torques (SET and STT) were pilot-hole diameter, embedded screw orientation, and particleboard (PB) material physical and mechanical properties such as material core density, particle size, and internal bond (IB) strength. Recorded torque–time curves, which illustrate the complete process of driving screws into PB materials, indicated that screw torques behave similarly in sides and faces of PB and that the whole screwdriving process can be described as a two-phase process. PB materials evaluated in this study had mean SET from 0.66 to 1.94 N-m, STT from 2.03 to 6.51 N-m, and STT-to-SET ratios from 2.5 to 5.0. Statistical analyses indicated that the SET and STT of driving screws into PB faces were significantly greater than their corresponding values into PB edges. The SET and STT in PB materials with pilot holes were lower than their corresponding ones without pilot holes. SET and STT values can be estimated using power equations including PB material core density and particle length and IB strength
CONSUMER PREFERENCES AND PURCHASE INTENTIONS FOR RATTAN FURNITURE
Get PDFAlthough research on consumer preference and purchase intentions has received significant attention, little research has been performed with respect to furniture products, particularly in the area of empirical hypothesis testing. This study used regression models to test hypotheses relating to positional goods consumption and environmental and sustainable consumption theories to investigate consumers’ preference for rattan cane furniture and their intentions to purchase the product. A questionnaire was administered to 750 staff and students from universities, polytechnics, and research institutions in Ghana. The results showed that social status, modernity, and environmental safety supported the preference and purchase intentions for rattan cane furniture, whereas mixed results emerged from sustainable consumption. The most important driver of preference for rattan cane furniture was modernity, followed byenvironmental safety, social status, and sustainable consumption. In the case of purchase intentions, social status emerged as the most important factor, followed by modernity, and then environmental consumption. Building a positive social, environmental, and sustainable image of rattan cane furniture will enhance the product’s value, and this will culminate in increasing consumers’ preference for the product and their intentions to purchase the product. The study concluded that through market segmentation, manufacturers, and marketers of rattan cane furniture can target consumers who are proenvironmentalists and those who want to use the product to enhance their social image, thereby attracting a price premium
Mathematical Model to Predict Preheating Time and Temperature Profile in Boxed-Heart Square Timber during Preheating
Get PDFThe objective of this study was to develop a two-dimensional mathematical model that can beused to calculate the heat transfer in larch boxed-heart square timber during the preheating process. The preheating time obtained with the calculations agreed with the experimental results. Both experiments and calculations indicated that it took about 6.5 h for the center of the timbers (120 mm thick 120 mm wide) to reach ambient temperature, suggesting that the model can be used to accurately estimate preheating times. During the preheating process, the simulated core temperature of the wood agreed with the experimental result. However, for the remaining locations, the relative error was rather large, with the value first increasing and then decreasing with time. Therefore, the model can only be used to accurately estimate temperature at the core region of the wood. Furthermore, the results suggested that MC had no significant effect on preheating time
Effects of Carbonization Temperature on Chemical and Microcrystalline Structural Change in Wood–Ceramics Prepared from Liquefied Pine Wood and Wood Powder
Get PDFA new type of wood–ceramics was prepared by carbonizing liquefied wood instead of usingthermosetting resin. In this study, the effects of the unit cell of the wood powder and the aromatic ring in liquefied wood on the chemical and microcrystalline structural changes of wood–ceramics under different carbonization temperatures were discussed. Results from Fourier transform IR spectroscopy showed that carbonization affected the structure change of functional groups; broke C–H, C–O, and C¼C bonds; and facilitated the removal of H+ and O2–. X-ray diffraction analysis indicated that the microcrystalline structure of both wood and liquefied wood was changed to produce graphene sheets as the carbonization temperature increased, and a higher carbonization temperature contributed to a more orderly arrangement of microcrystalline graphite and formed a six-membered carbon ring structure. The number of graphite microcrystals, crystallite size, and the stacking height of the layer plane increased, whereas d002 decreased. The values of d002, La, and Lc were 0.3740, 3.2572, and 0.5754 nm as the temperature reached 1600C, respectively. However, the wood–ceramics remained difficult to completely graphitize