جستجوی مقالات مرتبط با کلیدواژه "drying" در نشریات گروه "صنایع چوب و کاغذ"

In this research, the performance of a semi-greenhouse solar kiln was evaluated for dying different wood species in different season in Karaj. This study was carried out in two separate parts. In the first part, the flat-sawn boards of oak and fir with a nominal thickness of 50 mm were dried during summer of the year 2012. In the second part, the flat-sawn boards of beech and poplar with the same thickness were dried in autumn, 2014 and spring, 2015. For both parts, the boards were also air-dried. The temperature measured inside the solar kiln was 35 ºC greater than that outside during daytime and also the kiln temperature ranged from 55 to 75ºC during 10 a.m. to 2 p.m.. In both parts of research, all wood species dried in the solar kiln faster with better quality compared to those air-dried. The severity of casehardening and surface checking in the boards dried in the solar kiln was lower and more homogenous moisture profile was observed. In addition, the final moisture content was lower for the boards dried in the solar kiln.

In this study, the effect of different drying methods on cellulosic nanofibers and resulting composites investigated. Four methods were examined to dry nanofibrillated cellulose suspensions: air drying, oven drying, spray-drying and freeze drying. The particle size and morphology of the CNFs were determined via dynamic light scattering, scanning electron microscopy, and morphological analysis. Freeze drying formed ribbon-like structures of the CNFs with nano-scale thicknesses. Width and length were observed in tens to hundreds of microns. Spray-drying formed particles with a size distribution ranging from nanometer to several microns. Spray-drying is proposed as a technically suitable manufacturing process to dry CNF suspensions not only with dimension in nano range but also improving mechanical properties of poly (lactic acid) based composites.

In this research، the effect of wetwood and blue stain on the drying rate and fluid transport coefficients of poplar (P. nigra) was evaluated. For this purpose، five boards with dimensions of 150 × 35 × 45 mm were cut from wet wood، normal wood and stained -wood areas of freshly cut lumbers in Taleghan region and then dried to the final moisture content of 8 percent inside a laboratory dryer at temperature of 50 °C، relative humidity of 60% and air velocity of 1 m/s. Overall، drying time was 120 h. After drying، the transverse permeability and diffusion coefficients were measured. The results showed that the wetwood had no decreasing effect on the drying rate of poplar wood; however، it reached to the final moisture content slower due to higher initial moisture content. Also، the wetwood had no significant effect on the transverse permeability but reduced the diffusion coefficient. In contrast to the wetwood effects، the drying rate، permeability and diffusion coefficients were increased due to the blue stain.

In this research، the influence of paper drying condition، as one of the most important variable in paper recycling، on the characteristics of fibers was studied. In this respect، bagasse soda pulp was collected from Pars Paper mill in Khozestan province and handsheets were made. The control hand sheet samples were dried at room temperature and the rest of the handsheets were dried using drum dryer set at 60° C for 3 hours، 100° C for 50 minutes and 120° C for 25 minutes to reach the same moisture content as the sheets dried at room temperature. Then، these handsheets were slushed in water and the pulp properties were determined. The results showed that with increasing the drying temperature، cellulose content did not change while hemicelluloses were reduced. Although the assessment of changing the lignin content with micro kappa method showed an increasing trend، but based on previous literature، it was concluded that the result are not justified. Also، the results indicated that changing the degree of polymerization and crystallinity did not show a consistent trend، showing initial reduction following by increased values. These results were attributed to interaction effect of drying temperature and time.

In this study، the effect of drying method on the permeability coefficient of the oak wood (Quercus infectoria Oliv) was studied. Freshly-cut logs of oak were prepared from Oureman، the east area of Kourdistan in Iran. Then، boards with nominal thickness of 6 cm were cut. The boards were dried using two methods. In the first method، the boards were air dried to the moisture content close to FSP for 45 days and then they were kiln dried using T5-D1 schedule. In the second method، the boards were dried from green condition to the final moisture content of 10% using T5-D1 schedule. Then، the permeability coefficient in the transverse and longitudinal directions in both heartwood and sapwood regions was measured، separately. Results showed that the permeability of oak boards dried by kiln drying method both in the transverse and longitudinal directions and also in the heartwood and sapwood regions was greater than that of those dried by the combined method (air drying + kiln drying).

The physical and anatomical properties of old date palm wood (Phoenix dactylifera L.) and its drying behavior were studied. Four old date palm trees grown in Bam city (Kerman provenience) were felled. Then، boards with the dimension of 300 × 50 × 30 mm were cut at DBH of trees from pith to bark. After measuring the green moisture content and specific gravity the boards were dried in a semi-industrial kiln to reach the final moisture content of 8% using a mild wood drying schedule. Cross-sectional anatomical measurements were performed on the nearest boards to the bark and pith. Results showed that the green moisture content and specific gravity of date palm wood ranged between 150-260% and 0. 29–0. 39 and the moisture content was increased and the specific gravity decreased from pith to bark. Anatomical observations and statistical analysis revealed that there was no statistically significant difference between average number of vessel elements and vessel bundles between pith and bark، but the mean vessel area in pith was considerably greater than bark. Results also showed that the drying rate of date palm wood was high reaching to the final moisture content of 8% within 7 days. Drying rate of bark samples was higher than those of the pith and no deformation and surface crack was observed in the dried boards.

In order to establish a kiln drying schedule for Poplar (Populus nigra) lumbers of 5 cm thickness commercially cut from Taleghan region، three schedules، namely T8-F4، T8-F5 and T9-F4 were adopted to dry the lumbers to the final moisture content of 11 ± 2%. Dry bulb temperatures for the schedules were adjusted at 54، 54 and 60 °C، while the final dry-bulb temperatures were adjusted at 82، 82 and 71 °C، respectively. The severity of surface، internal checks and warp in the lumbers were measured before and after the drying process and quality control methods were used to analyze wood defects. Results indicated that drying of Poplar lumber using each of the three schedules was satisfactory; however، the third schedule (T9-F4) resulted in better drying quality than did the others. Also، equalizing of lumbers for 24h is recommended.