EUCALYPTUS LOGS DRYING AT HIGH TEMPERATURES<sup>1</sup>

Oliveira, Aylson Costa; Pereira, Bárbara Luísa Corradi; Carneiro, Angélica de Cássia Oliveira; Fialho, Lucas de Freitas; Figueiró, Clarissa Gusmão; Vital, Benedito Rocha; Magalhães, Mateus Alves de

doi:10.1590/1806-90882017000200007

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Articles • Rev. Árvore 41 (2) • 2017 • https://doi.org/10.1590/1806-90882017000200007 copy

EUCALYPTUS LOGS DRYING AT HIGH TEMPERATURES¹

SECAGEM DA MADEIRA DE EUCALIPTO EM TORAS A ALTAS TEMPERATURAS

Authorship SCIMAGO INSTITUTIONS RANKINGS

ABSTRACT

The objective of this work was to evaluate the drying speed of Eucalyptus urophylla logs in high temperatures and the influence of the presence or absence of bark and also the diameter of the log in the drying rate. Eucalyptus logs 60 cm long were divided into three diameter classes: 8-12 cm; 12,1-16 cm and 16,1-20 cm. The logs were dried in a heater with forced air circulation, in the presence or absence of bark in five temperatures: 50, 75, 100, 125 and 150ºC. The mass and the initial moisture were determined from each log and the water loss was kept up with periodic weightings, closing the drying process when the logs reached 20% moisture. The drying rate of the logs was calculated using the ratio between the total loss of moisture and the time in hours in order to reach the established moisture. It was concluded that the increase in temperature promotes the raise of the drying ratio, as being higher for smaller logs in relation to bigger ones and in addition to this, the bark effect was not significant in the drying of eucalyptus logs above 100ºC. It was also concluded that the best conditions for the operation of artificial dryers for Eucalyptus logs containing bark and separated in diameter classes would be at 125ºC.

Keywords:
Drying rate; Moisture content; Artificial dryers

Table 1 Parameters set of templates to moisture content reduce of the logs over time for Class 1, 2 and 3 at different temperatures and in bark presence and absence.

Diametric Class	Temperature	Bark	a	b	R²
Class 1 (Ø8-12 cm)	50ºC	Present Absent	71,75 65,462	0,07 0,059	0,9955 0,9991
	75ºC	Present Absent	58,253 55,576	0,325 0,355	0,9963 0,9961
	100ºC	Present Absent	55,258 57,502	0,666 0,87	0,9965 0,9929
	125ºC	Present Absent	51,932 50,879	1,931 1,889	0,9675 0,9987
	150ºC^* * Linear model	Present Absent	-55,007 -49,957	44,666 47,071	0,9973 0,9992
Class 2(Ø 12,1 -16 cm)	50ºC	Present Absent	50,127 46,148	0,044 0,068	0,9958 0,9889
	75ºC	Present Absent	55,668 53,464	0,151 0,192	0,9951 0,9949
	100ºC	Present Absent	48,964 50,673	0,474 0,551	0,9940 0,9908
	125ºC	Present Absent	45,005 55,615	0,907 0,908	0,9774 0,9871
	150ºC^* * Linear model	Present Absent	-40,144 -37,963	53,597 48,947	0,9865 0,9942
Class 3(Ø 16,1 -20 cm)	50ºC	Present Absent	54,693 50,128	0,040 0,059	0,9963 0,9959
	75ºC	Present Absent	79,600 78,455	0,086 0,095	0,9978 0,9981
	100ºC	Present Absent	68,930 59,546	0,420 0,420	0,9957 0,9984
	125ºC	Present Absent	67,466 74,060	0,674 0,739	0,9894 0,9903
	150ºC	Present Absent	71,451 69,161	0,618 0,607	0,9823 0,9922

Table 2 Average drying rate values, %/hour, Eucalyptus logs depending on the drying temperature, diameter class, and bark presence or absence.

Diametric Class	Bark	Drying rate (%/hour)
Diametric Class	Bark	50ºC	75ºC	100ºC	125ºC	150ºC
Class 1(Ø 8-12 cm)	Present Absent	0,12 0,09	0,48 0,51	0,93 1,31	2,68 2,59	2,29 2,43
Class 2(Ø 12,1 -16 cm)	Present Absent	0,06 0,09	0,22 0,27	0,64 0,75	1,15 1,30	1,67 1,58
Class 3(Ø 16,1 -20 cm)	Present Absent	0,06 0,08	0,15 0,17	0,70 0,63	1,09 1,25	1,06 1,01

Sociedade de Investigações Florestais Universidade Federal de Viçosa, CEP: 36570-900 - Viçosa - Minas Gerais - Brazil, Tel: (55 31) 3612-3959 - Viçosa - MG - Brazil
E-mail: rarvore@sif.org.br

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EUCALYPTUS LOGS DRYING AT HIGH TEMPERATURES1

SECAGEM DA MADEIRA DE EUCALIPTO EM TORAS A ALTAS TEMPERATURAS

ABSTRACT

EUCALYPTUS LOGS DRYING AT HIGH TEMPERATURES¹