Within-tree variability of internal stress generated during drying of rubberwood lumber

Tomad, Jaipet; Jantawee, Sataporn; Preechatiwong, Wanchart; Matan, Nirundorn

doi:10.1007/s00107-017-1204-9

Cited by 7 publications

(14 citation statements)

References 32 publications

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“…The authors obtained these sets of experiments and their results from Tomad et al. [ 11 ]. Figure 4 shows the construction of the wood dryer.…”

Section: Methodsmentioning

confidence: 99%

“…Traditionally wood drying process consumes more than 60% of total energy usage, mainly in heat and electricity [ 10 ]. As the rubberwood industry is very significant for Southern Thailand and provides the primary export earnings for the local industry, there are extensive research activities carried out by Thai researchers [ 5 , 10 , 11 , 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 ]. Some of these researches focus on novel drying processes [ 14 , 16 , 17 , 19 , 22 , 25 ].…”

Section: Introductionmentioning

confidence: 99%

“…Some of these researches focus on novel drying processes [ 14 , 16 , 17 , 19 , 22 , 25 ]. The others work on the effects of drying conditions on the dried products [ 5 , 11 , 12 , 14 , 15 , 26 , 27 , 28 , 29 ]. A few published articles investigated moisture equilibrium relationship, drying kinetics, drying time reduction, drying process optimization, and energy efficiency in lab-scale and industrial-scale driers [ 10 , 18 , 21 , 24 , 30 , 31 , 32 , 33 , 34 ].…”

Section: Introductionmentioning

confidence: 99%

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Effect of air velocity, temperature, and relative humidity on drying kinetics of rubberwood

Chanpet

Rakmak

Matan

et al. 2020

Heliyon

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Kiln drying of rubberwood lumbers is a complex transport phenomenon for realistic modeling and simulation. To decouple this complexity, researchers usually divide their research into two parts. The first one is single-lumber drying kinetics to describe how wood lumber responds to its surface conditions. Then they combine this drying kinetics with a lumped transport model or dispersion model or computational fluid dynamics. The mathematical models are then solved numerically to predict the industrial kiln drying behaviors. This work focuses on the drying kinetics of stacked rubberwood lumbers using hot air at different air velocity (0.5, 1.5, 2.5, 3.5, 4.0 m/s), relative humidity (6–67% relative humidity (RH)) and temperature (60–100 °C). The drying kinetics followed the conventional drying theory. However, the two drying periods, namely constant and falling rate (CRP and FRP), were not distinct. As the air velocity increased, the transition from CRP to FRP is faster. The middle of the transition period (at critical moisture content, CMC) moves closer to the fiber saturation point (FSP). The overall mass transfer coefficients in the falling rate period for stacked rubberwood drying were lower than those predicted by the Ananias correlation. Hence, a modified formula was proposed, representing the overall moisture transfer coefficients as a function of air velocity, temperature, relative humidity, and lumbers thickness for the range of variables under investigation satisfactorily. In general, the drying rate and the overall moisture transfer coefficient increased with increasing air velocity, drying temperature, and decreasing RH. Relative humidity directly affects the driving force of moisture transfer rate because higher RH is associated with higher equilibrium moisture content. A lumped parameter model for kiln drying was also developed. After being integrated with the estimated mass transfer coefficient, the model can predict the moisture profiles in lab-scale kiln drying satisfactory, although the model needs more validation data. These kinetic parameters and correlation for stacked rubberwood drying can be used in more complex models and process optimization in future research.

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“…The authors obtained these sets of experiments and their results from Tomad et al. [ 11 ]. Figure 4 shows the construction of the wood dryer.…”

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Effect of air velocity, temperature, and relative humidity on drying kinetics of rubberwood

Chanpet

Rakmak

Matan

et al. 2020

Heliyon

Self Cite

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“…The maximum possible value of shrinkage and swelling of wood based on the class of operating conditions, is 3.4 mm and the coefficient of thermal expansion this should be taken into account in the design and operation. It is also necessary to take into account the coefficient of thermal expansion which depends on the moisture content in the wood [4,5,6].…”

Section: Object Of Studymentioning

confidence: 99%

“…The inclination of fibres increases durability of wood at spalling but complicates its mechanical processing and reduces ability to a bend. Timber with tangential fiber slope is characterized by increased longitudinal shrinkage and warping [4].…”

Section: Technological Featuresmentioning

confidence: 99%

Energy efficiency of timber construction joint with wooden screw

et al. 2019

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The topicality of studied subject is based on inappropriate usage of different materials in wooden structures, since using metal joint in wooden construction leads to reduction of construction working life cycle. In this regard, a study of several options for wooden screw carving was conducted in order to determine the most appropriate one (screw). There are several different types of carving, such as: trapezoidal, triangular, rectangular, etc. The most appropriate ones are trapezoidal and triangular-section threads for wooden screws. The effectiveness of a wooden screw thread was determined from the conditions (capacity) of shear fracture and bearing stress. After analyzing the results of calculations of the specific capacity for shear fracture and bearing stress, it can be concluded that the value of specific bearing capacity for shear fracture is less than the value of bearing stress by 1.3%. Therefore, a further comparison of the trapezoidal thread and the triangular cross-section will proceed from the spalling conditions. It has been found that the most effective thread is a triangular cross-section. Based on the results of calculations, a mathematical model has been established that describes the dependence of the carrying capacity on the screw diameter.

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An approach for indirect monitoring of moisture content in rubberwood (Hevea brasiliensis) during hot air drying

2019

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Within-tree variability of internal stress generated during drying of rubberwood lumber

Cited by 7 publications

References 32 publications

Effect of air velocity, temperature, and relative humidity on drying kinetics of rubberwood

Effect of air velocity, temperature, and relative humidity on drying kinetics of rubberwood

Energy efficiency of timber construction joint with wooden screw

An approach for indirect monitoring of moisture content in rubberwood (Hevea brasiliensis) during hot air drying

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