In situ measurement of wood moisture content in high-temperature steam

Ishikawa, Atsuko; Kuroda, Naohiro; Kato, Atsushi

doi:10.1007/s10086-003-0521-2

Cited by 17 publications

(10 citation statements)

References 5 publications

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“…Initially, oven-dry samples (MC i 0 ± 0 %; mean value ± standard deviation) took up moisture, leading to MC f between 10 and 13 % (Table 2), which coincides with Rautkari and Hill (2014) and is in line with wood sorption in high-temperature and high water vapor pressure environments (Engelhardt 1979;Lenth and Kamke 2001;Kubojima et al 2003;Ishikawa et al 2004). However, the fact that MC f increased with the peak duration of the treatments at 145°C may indicate that an equilibrium state was not reached within the time frame of the process.…”

Section: Resultsmentioning

confidence: 93%

Wood moisture content during the thermal modification process affects the improvement in hygroscopicity of Scots pine sapwood

2016

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Elevated wood moisture contents during the thermal modification process have been shown to adversely affect the improvement in dimensional stability and hygroscopicity. This study tested the hypothesis that the effect of elevated wood moisture content is based on the impact of water on chemical reactions which determine the cell wall matrix stiffness. Samples of Scots pine sapwood (Pinus sylvestris L.) were thermally modified in saturated water vapor at different peak temperatures and durations starting either in oven-dry or in water-saturated state. For a given mass loss caused by the modification process, the improvement in maximum swelling and equilibrium moisture content was stronger for oven-dry samples. After removal of water-soluble degradation products, which caused a cell wall bulking effect, the maximum swelling even increased after modification in water-saturated state. Based on dynamic vapor sorption measurements, it was evidenced that the modification in oven-dry state increased the cell wall matrix stiffness which improved dimensional stability and hygroscopicity. Enhanced bond formation in the polymeric network, i.e., via condensation and cross-linking reactions during the treatment of oven-dry wood, is suggested as a cause for this increase in matrix stiffness. In contrast, the modification in water-saturated state enhanced the flexibility of the cell wall matrix, which increased the cell wall swelling and limited the improvement of hygroscopicity to the reduction in OH groups by removal of hemicelluloses. This enhanced matrix flexibility was potentially caused by predominant hydrolytic cleavage of bonds in case of water-

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Section: Resultsmentioning

confidence: 93%

Wood moisture content during the thermal modification process affects the improvement in hygroscopicity of Scots pine sapwood

2016

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“…It has been shown that energy consumption is often lower, smaller equipment may be used, there is a reduced risks for fires and explosions, and harmful emissions may be eliminated. [2][3][4] Acceptance has occurred with lumber and coal drying where superheated steam has proven quality benefits over the use of hot air [5][6][7][8] as well as in the sugarbeet industry where energy efficiencies compared to hot air are very high. [9] The next step in utilization of superheated steam may be in the field of processing, where drying of a product is not the primary objective.…”

Section: Introductionmentioning

confidence: 99%

Effects of Superheated Steam Processing on the Textural and Physical Properties of Asian Noodles

Pronyk¹,

Cenkowski²,

Muir³

et al. 2008

Drying Technology

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Asian noodles were simultaneously cooked and dried in superheated steam at temperatures from 110 to 150 C and steam velocities of 0.5, 1.0, and 1.5 m/s. Textural and key physical properties of color, breaking stress, and starch gelatinization were measured to ascertain the effects of the superheated steam processing. Textural properties of adhesiveness, springiness, cohesiveness, chewiness, resilience, and hardness determined from a TPA were found to be generally unaffected by steam velocity. All properties but springiness increased with an increase in processing time. Increasing temperature decreased adhesiveness, springiness, cohesiveness, and resilience but increased hardness and chewiness to a small degree. Processing time greatly affected noodle color, resulting in browning at greater processing times. Results show that velocity was not a significant factor (p > 0.05) on the breaking strength of noodles. Temperature was only significant (p < 0.05) at 110 and 120 C and breaking stress decreased with increasing temperature. There were small decreases in breaking stress with processing time. Combined gelatinization of both amylopectin and amylose was an average of 80.5% for all superheated steam processed samples.

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“…Figure 4 shows that the drying rates of superheated steam were much higher than hot air, which took 7 to 8 days to reduce the moisture content of the wood to the acceptable value of less than 15% (Pang 1996(Pang , 2000. This was due to the impingement process (Peng et al 2012), which caused rapid heat transfer to the wood surface and stimulated a quick loss of moisture (Li et al 1999;Ishikawa et al 2004). However, hot air drying at a constant rate gave faster results than that of superheated steam, due to lower humidity inside the chamber.…”

Section: Drying Ratesmentioning

confidence: 99%

Investigation of drying characteristics in superheated steam drying of UF-impregnated Chinese fir

Quan

et al. 2017

Eur. J. Wood Prod.

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Urea formaldehyde (UF) resin-impregnated Chinese fir (Cunninghamia lanceolata (Lamb.)Hook.) was dried at different temperatures in an atmospheric pressure superheated steam dryer. Drying characteristics, moisture content, drying rate, temperature profile, drying defects, and color change were investigated. The moisture content was reduced from 66.21 to 11.79% within 30 h without causing severe drying defects; in contrast, the conventional hot air process required 7-8 days.After 25 h of drying, the temperatures at both the center and the surface of wood remained stable. After 34.5 h, the surface temperature gradually approached the steam temperature. The color of the superheated steam dried Chinese fir appeared slightly more intense yellow and red than the control. Investigation of the UF-impregnated Chinese fir wood by scanning electron microscopy (SEM) revealed that the majority of the lumens and voids, including the microvoids in wood structure, was filled with urea formaldehyde resin.

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In situ measurement of wood moisture content in high-temperature steam

Cited by 17 publications

References 5 publications

Wood moisture content during the thermal modification process affects the improvement in hygroscopicity of Scots pine sapwood

Wood moisture content during the thermal modification process affects the improvement in hygroscopicity of Scots pine sapwood

Effects of Superheated Steam Processing on the Textural and Physical Properties of Asian Noodles

Investigation of drying characteristics in superheated steam drying of UF-impregnated Chinese fir

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