A THEORETICAL AND EXPERIMENTAL INVESTIGATION OF THE CONVECTIVE DRYING OF AUSTRALIAN<i>PINUS RADIATA</i>TIMBER

Sutherland, J.W.; Turner, Ian; Northway, R.L.

doi:10.1080/07373939408962208

Cited by 10 publications

(5 citation statements)

References 12 publications

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“…The fourth test of the RP2 [13] also provided valuable data on the strength properties of red pine (Pinus resinosa). MOE and MOR were determined on specimens kerfed every two and six inches.…”

Section: Warp Measurementsmentioning

confidence: 99%

“…[8,12] However, in spite of fast drying through the end grain, most of the overall drying must occur through the side grain (perpendicular to board length) because of the typically large ratios between length and width or thickness of dimension lumber. [13] Sutherland et al [13] established that, except for the end-drying, practically all of the drying takes place from the upper and lower (wide) faces. Therefore, one-half the thickness of a board effectively dries through each wide face.…”

Section: Introductionmentioning

confidence: 99%

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Green Kerfing Treatment for Improving Softwood Lumber Drying: A Review

2014

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Kerfing is a lumber-drying improvement technique that consists of cuts along both sides of boards, transversal to the longitudinal axis. The rationale behind this procedure is that, by cutting the fibers, the moisture loss through the end-grain is increased. The aim of this paper is to evaluate the effects of kerfing on drying time, warp occurrence, and bending properties, based on different experiments conducted during the last seven years. In most cases, kerfing reduced the drying time by half of that of the control samples. Results were inconclusive regarding reduction of warp. Regarding the bending strength of treated pieces, kerfing caused a minimum loss of moment of inertia in the piece, resulting in a slightly lower bending strength and higher stiffness. INTRODUCTIONWood has a number of properties that make it an excellent choice for a wide range of purposes. However, the mechanical properties and dimensional stability of wood, among other properties, are greatly affected by the amount and distribution of the water present in the wood cells. Because of this, the drying process becomes paramount for wood utilization. [1] The main purpose of lumber drying is to bring wood to a moisture content that facilitates its use, achieving dimensional stability once processed and during use. It has been established [2,3] that the presence of free water and bound water significantly increases the susceptibility of wood to fungal attack, so that wood's resistance to other agents of biodeterioriation and mechanical properties are also greatly improved by drying. [4] However, lumber drying is typically the most energy-consuming process; 70% or more of the energy used in lumber and veneer manufacturing goes into drying. [4,5] As concluded by Erickson, [5] energy consumption could be even higher for hardwood species due to the longer drying times required to achieve the desired final moisture content (MC). Moreover, drying is frequently the most time-consuming process in the wood products'

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Section: Warp Measurementsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Green Kerfing Treatment for Improving Softwood Lumber Drying: A Review

2014

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“…특정지역에서 얻어진 결과를 전국적으로 확대시키기 위하여 초기함수 율, 온도, 상대습도를 활용하여 수종별 회귀식을 제시하는 연구가 수행되었으며 (Denig and Wengert, 1982), 실험을 통해 얻어진 수분확산계수 등을 적용한 수치해석 모델을 개발하고, 각각의 계수를 다른 지역의 기상자료를 통하여 변화시키는 방법이 제시되 었다 (Hart, 1982). 임의의 재료 내 열전달과 물질전달을 분석하기 위하여 유한차분법이 제시되었으며 (Holman, 1989), 유한차분 법을 이용하여 목재내부의 함수율 분포에 대한 1차원 해석 (Sutherland et al, 1992)과 2차원 해석 (Ranta-Maunus, 1994;Perré et al, 1993)이 수행되었다. 국내에서는 소나무 대단면재의 고온건조 중 함수율 변화를 예측 (Kim et al 2017)하고, 곰솔 원목의 열처리 중 온도분포를 예측 (Han et al 2016)하기 위하여 유한차분법이 사용되었다.…”

Section: The Predictionunclassified

“…While these studies have presented finite difference methods to analyze heat and mass transfer in arbitrary materials (Holman, 1989), the method was used to conduct one-dimensional analysis (Sutherland et al, 1992) and two-dimensional analysis (Ranta-Maunus, 1994;Perré et al, 1993). There were studies in Korea to predict the MC change during the high temperature drying of Korean red pine timber (Kim et al, 2017) and to predict the temperature distribution during heat treatment of black pine wood (Han et al, 2016).…”

Section: Introductionmentioning

confidence: 99%

Moisture Content Change of Korean Red Pine Logs During Air Drying: II. Prediction of Moisture Content Change of Korean Red Pine Logs under Different Air Drying Conditions

Han¹,

Chang²,

Eom³

et al. 2019

Journal of the Korean Wood Science and Technology

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Air drying was carried out on 15 Korean red pine logs to provide a prediction model of the moisture content (MC) change in the wood during drying. The final MC was 17.4% after 880 days since the beginning of air drying in the summer for 6 Korean red pine logs with 68.7% initial MC. The final MC was 16.0% after 760 days since the beginning of air drying in the winter for 9 Korean red pine logs with 35.8% initial MC. A regression model with R-squared of 0.925 was obtained as a result of multiple regression analyses with initial MC, top diameter, temperature, relative humidity, and wind speed as independent variable and and MC change during air drying as dependent variable. The initial MC and top diameter, which is the characteristic of Korean red pine, have greater effect on the MC decrease during air drying compared to meteorological factors such as the temperature, relative humidity, and wind speed. Two-dimensional mass transfer analysis was performed to predict the MC distribution of Korean red pine logs during air drying. Two prediction models with different air drying days and different meteorological factors for the determination of the diffusion coefficient and surface emission coefficient were presented. The error between the different two methods ranged from 0.1 to 0.8% and the difference from the measured value ranged from 2.2 to 3.6%. By measuring the internal MC during air drying of Korean pine logs with various initial MC and diameter, and calculating the moisture transfer coefficient in wood for each meteorological condition, the error of the prediction model can be reduced.

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“…Salin [12] used the first empirical model from a Swedish handbook of timber drying. Sutherland et al [13,14] also employed this model for simulation of heat transport in wood. In this formula, heat convection coefficient was assumed to be an exponential function of the air velocity as h h = 8.0 V 0.67 where h h is heat convection coefficient, W m -2 K -1 ; V is the air velocity, m s -1 .…”

Section: Empirical Model For Heat Convection Boundary Conditionmentioning

confidence: 99%

Parameters for Heat Transport in Radiata Pine Board

Liu

Wang

2010

AMR

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A universal transit heat transport equation was represented and all parameters for applying such a formula to drying of Radiata pine were modeled, incorporating reasonable physical conditions. In previous empirical models, the influence of drying temperature on the conviction heat transfer was ignored, though it is parentally not negligible. In this study, a multivariate regression model was developed from previous experimental data, in which both air velocity and drying temperature were taken into consideration. In addition, the models of heat diffusion properties in axial, tangential and radial directions were presented in which drying conditions and wood properties were taken into account. With those models, scenario computer simulation may be conducted to explore the drying phenomena of Radiata pine board.

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A THEORETICAL AND EXPERIMENTAL INVESTIGATION OF THE CONVECTIVE DRYING OF AUSTRALIANPINUS RADIATATIMBER

Cited by 10 publications

References 12 publications

Green Kerfing Treatment for Improving Softwood Lumber Drying: A Review

Green Kerfing Treatment for Improving Softwood Lumber Drying: A Review

Moisture Content Change of Korean Red Pine Logs During Air Drying: II. Prediction of Moisture Content Change of Korean Red Pine Logs under Different Air Drying Conditions

Parameters for Heat Transport in Radiata Pine Board

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