EFEITO DA TEMPERATURA E VELOCIDADE DO AR SOBRE A TAXA DE SECAGEM DA MADEIRA DE <i>Pinus elliottii</i> Engelm

Santini, Elio José; Haselein, Clóvis Roberto

doi:10.5902/198050981684

RESUMO

Para avaliar o efeito da temperatura e velocidade do ar sobre a taxa de secagem, peças de madeira de Pinus elliottii de 25 x 125 x 750 mm foram submetidas à secagem em estufa semi-industrial de convecção forçada. O processo foi conduzido para duas temperaturas e duas velocidades de ar e controlado por meio de um sistema computadorizado. Os resultados mostraram que a taxa de secagem tem uma relação diretamente proporcional com a temperatura, velocidade do ar e umidade da madeira. Por meio da análise de regressão múltipla detectou-se efeito estatisticamente significativo da temperatura e da velocidade do ar sobre a taxa e o tempo de secagem, com um nível de confiança de 99%. Como a importância da velocidade do ar na secagem decresce com a diminuição do teor de umidade, sugere-se, por razões de economia, mais investigações acerca das relações entre as duas variáveis durante o período de taxa de secagem decrescente

Palavras-chave:
taxa de secagem; umidade da madeira; velocidade do ar; temperatura de secagem.

ABSTRACT

To evaluate the effect of temperature and air velocity on drying rate, slash pine wood pieces of 25 x 125 x 750 mm were dried in semi-industrial kiln with forced convection. The process was conduct for two temperatures and two air velocities and controlled by a data acquisition system. The results showed that the drying rate has a direct relationship to temperature, air velocity and wood moisture content. Through multiple regression analysis it was possible to detect statistically significant effect of temperature and air velocity on drying rate and drying time, at 99% confidence level. Since the influence of air velocity on wood drying decreases with moisture content, because of economic reasons, more investigations were suggested about the relationship between the two variables during falling-rate drying period.

Key words:
drying rate; wood moisture content; air velocity; drying temperature

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REFERÊNCIAS BIBLIOGRÁ FICAS

HANN, R.A. Drying yellow-poplar at temperatures above 100^oC. Forest Prod. J., v. 14, n. 5, p. 215-220, 1964.
HERZBERG, B.L.; TAYLOR, F.W.; ROSEN, H.N. Factors that affect the time required to high-temperature dry pine dimension lumber. Forest Prod. J ., v. 35, n. 7/8, p. 34-36, 1985.
KOLLMANN, F.F.P.; SCHNEIDER, A. Der Einfluss der Belüftungsgeschwindigkeit auf die Trocknung von Schnittholz mit Heissluft-Dampf-Gemischen. Holz Roh-Werkstoff, Berlin, v. 13, n. 3, p. 81-94, 1960. For. Abstr., Farnham Royal, v. 21, n. 4, p. 669-670, 1960. Ref. 5085. Resumo.
MACKAY, J.F.G.; OLIVEIRA, L.C. Kiln operator's handbook for Western Canada. Vancouver: Forintek Canada Corp., 1989. 61p. (Special Publication No. SP-31).
MILOTA, M.R.; TSCHERNITZ, J.L. Correlation of loblolly pine drying rates at high temperatures. Wood and Fiber Science, v. 22, n. 3, p. 298-313, 1990.
PRICE, E.W.; KOCH, P. A note on effects of kiln stick thickness and air velocity on drying time of southern pine 2 by 4 and 2 by 6 lumber. Wood and Fiber, v. 13, n. 2, p. 115-119, 1981.
RASMUSSEN, E.F. Dry kiln operator's manual. Agric. Handb., Madison, n. 188, p. 1-197, 1961.
SALAMON, M. High-temperature drying on its effect on wood properties. Forest Prod. J ., Madison, v. 19, n. 3, p. 27-34, 1969.
SALAMON, M.; MCINTYRE, S. Manipulation of air velocity permits drying time savings. Canadian For. Ind., v. 89, n. 9, p. 49-57, 1969.
SANTINI, E.J. Influência da temperatura na taxa de secagem e contração da madeira de Pinus elliottii proveniente de plantios de rápido crescimento. Série Técnica, FUPEF/UFPR, Curitiba, n. 5, p. 1-15, 1980.
SCHAFER, R.F. What you should know about high-temperature drying. Canadian For. Ind ., v. 93, n. 10, p. 70-71, 1973a.
SCHAFER, R.F. Use of time schedules in kiln-drying softwood. Canadian For. Ind., v. 93, n. 11, p. 47-49, 1973b.
SCHNEIDER, A. Zur Konvektionstrocknung von Schnittholz bei extrem hohen Temperaturen. Erste Mitteilung: Trocknungs-verlauf und Brettemperaturen bei Trocknungstemperaturen von 110 bis 180°C. Holz Roh-Werkstoff, Berlin, v. 30, n. 10, p. 382-394, 1972.
SCHNEIDER, A. Untersuchungen über den Einfluβ der Trocknungsbedingungen auf die Gleichmäβigkeit des Verlaufes der Konvektionstrocknung von Schnittholz. Holz als Roh-und Werkstoff, v. 38, n. 3, p. 103-107, 1980.
SIMPSON, W.T. Dry kiln operator's manual. Agric. Handb., Madison, n. 188, p. 1-274, 1991.
SIMPSON, W.T.; ROSEN, H.N. Equilibrium moisture content of wood at high temperatures. Wood Fiber, Lawrence, Kansas, v. 13, n. 3, p. 150-158, 1981.
SIMPSON, W.T.; SAGOE, J.A. Relative drying times of 650 tropical woods: estimation by green moisture content, specific gravity, and green weight density. General Technical Report, Madison, n. 71, p. 1-27, 1991.
STEINHAGEN, H.P. Effect of kiln air velocity, at various moisture content levels, on drying rate of 4/4 yellow-poplar sapwood. Forest Prod. J., v. 24, n. 4, p. 45-47, 1974.
TAYLOR, F.W.; MITCHELL, P.H. Drying pine lumber at very high temperatures and air velocities. Wood Fiber Sci., Madison, v. 19, n. 3, p. 239-245, 1987.
TREMBLAY, C.; CLOUTIER, A.; FORTIN, Y. Experimental determination of the convective heat and mass transfer coefficients for wood drying. Wood Science and Technology, v. 34, n. 3, p. 253-276, 2000. Resumo.
VERMAAS, H.F. Fundamentals of superheated steam and superheated vapour drying. South African Forestry Journal, n. 142, p. 17-23, 1987.

Datas de Publicação

Publicação nesta coleção
Jul-Dec 2002

Histórico

Recebido
23 Nov 2001
Aceito
18 Out 2002

Este é um artigo publicado em acesso aberto sob uma licença Creative Commons

[1] HANN, R.A. Drying yellow-poplar at temperatures above 100^oC. Forest Prod. J., v. 14, n. 5, p. 215-220, 1964.

[2] HERZBERG, B.L.; TAYLOR, F.W.; ROSEN, H.N. Factors that affect the time required to high-temperature dry pine dimension lumber. Forest Prod. J ., v. 35, n. 7/8, p. 34-36, 1985.

[3] KOLLMANN, F.F.P.; SCHNEIDER, A. Der Einfluss der Belüftungsgeschwindigkeit auf die Trocknung von Schnittholz mit Heissluft-Dampf-Gemischen. Holz Roh-Werkstoff, Berlin, v. 13, n. 3, p. 81-94, 1960. For. Abstr., Farnham Royal, v. 21, n. 4, p. 669-670, 1960. Ref. 5085. Resumo.

[4] MACKAY, J.F.G.; OLIVEIRA, L.C. Kiln operator's handbook for Western Canada. Vancouver: Forintek Canada Corp., 1989. 61p. (Special Publication No. SP-31).

[5] MILOTA, M.R.; TSCHERNITZ, J.L. Correlation of loblolly pine drying rates at high temperatures. Wood and Fiber Science, v. 22, n. 3, p. 298-313, 1990.

[6] PRICE, E.W.; KOCH, P. A note on effects of kiln stick thickness and air velocity on drying time of southern pine 2 by 4 and 2 by 6 lumber. Wood and Fiber, v. 13, n. 2, p. 115-119, 1981.

[7] RASMUSSEN, E.F. Dry kiln operator's manual. Agric. Handb., Madison, n. 188, p. 1-197, 1961.

[8] SALAMON, M. High-temperature drying on its effect on wood properties. Forest Prod. J ., Madison, v. 19, n. 3, p. 27-34, 1969.

[9] SALAMON, M.; MCINTYRE, S. Manipulation of air velocity permits drying time savings. Canadian For. Ind., v. 89, n. 9, p. 49-57, 1969.

[10] SANTINI, E.J. Influência da temperatura na taxa de secagem e contração da madeira de Pinus elliottii proveniente de plantios de rápido crescimento. Série Técnica, FUPEF/UFPR, Curitiba, n. 5, p. 1-15, 1980.

[11] SCHAFER, R.F. What you should know about high-temperature drying. Canadian For. Ind ., v. 93, n. 10, p. 70-71, 1973a.

[12] SCHAFER, R.F. Use of time schedules in kiln-drying softwood. Canadian For. Ind., v. 93, n. 11, p. 47-49, 1973b.

[13] SCHNEIDER, A. Zur Konvektionstrocknung von Schnittholz bei extrem hohen Temperaturen. Erste Mitteilung: Trocknungs-verlauf und Brettemperaturen bei Trocknungstemperaturen von 110 bis 180°C. Holz Roh-Werkstoff, Berlin, v. 30, n. 10, p. 382-394, 1972.

[14] SCHNEIDER, A. Untersuchungen über den Einfluβ der Trocknungsbedingungen auf die Gleichmäβigkeit des Verlaufes der Konvektionstrocknung von Schnittholz. Holz als Roh-und Werkstoff, v. 38, n. 3, p. 103-107, 1980.

[15] SIMPSON, W.T. Dry kiln operator's manual. Agric. Handb., Madison, n. 188, p. 1-274, 1991.

[16] SIMPSON, W.T.; ROSEN, H.N. Equilibrium moisture content of wood at high temperatures. Wood Fiber, Lawrence, Kansas, v. 13, n. 3, p. 150-158, 1981.

[17] SIMPSON, W.T.; SAGOE, J.A. Relative drying times of 650 tropical woods: estimation by green moisture content, specific gravity, and green weight density. General Technical Report, Madison, n. 71, p. 1-27, 1991.

[18] STEINHAGEN, H.P. Effect of kiln air velocity, at various moisture content levels, on drying rate of 4/4 yellow-poplar sapwood. Forest Prod. J., v. 24, n. 4, p. 45-47, 1974.

[19] TAYLOR, F.W.; MITCHELL, P.H. Drying pine lumber at very high temperatures and air velocities. Wood Fiber Sci., Madison, v. 19, n. 3, p. 239-245, 1987.

[20] TREMBLAY, C.; CLOUTIER, A.; FORTIN, Y. Experimental determination of the convective heat and mass transfer coefficients for wood drying. Wood Science and Technology, v. 34, n. 3, p. 253-276, 2000. Resumo.

[21] VERMAAS, H.F. Fundamentals of superheated steam and superheated vapour drying. South African Forestry Journal, n. 142, p. 17-23, 1987.

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