SHORT NOTE. THERMAL CHARACTERISTICS OF SENGON WOOD DRYING USING INFRARED AND COMBINED INFRARED-HOT AIR METHODS

This research aimed to determine the thermal characteristics of sengon wood due to drying at temperature of 70, 80, and 90oC with air velocity of 1 and 3 m/s using infrared (IR) and combined infrared-hot air (IR-HA) method. The thermal characteristics analyzed included temperature distribution, reduction in moisture content, and drying rate. The results of drying wood samples using IR method showed that the fastest drying time was obtained at 90oC with air velocity of 1 m/s. However, for combined IR-HA method, the optimal condition was achieved at air velocity of 3 m/s. The largest drying rate attained using combined IR-HA method was 0.27 g/min, while the smallest was recorded at 0.094 g/min with IR method. These results showed that combined IR-HA method produced a more evenly distributed temperature and faster drying time compared to the IR method

The effect of the circular saw blade body structure on the concentric distribution of the temperature along the radius during the wood cutting process

The paper presents the experimental results of a research aimed at the distribution of the temperature on thecircular saw blade body. The temperature was measured at four distances from the centre of the circular saw blade body (60 mm, 70 mm, 80 mm, 90 mm) by means of an infrared thermometer. Three circular saw blades with the diameter of 350 mm and a variable adjustment of the body (without slots and coating, with slots and without the coating, with both slots and coating) were used for the longitudinal sawing of the spruce wood (Picea excelsa) with the thickness of h = 25 mm. Feed speed vf = 12 m•min-1 and cutting revolutions n = 4000 min-1 were constant. The measured temperature was in the range from 22°C to 30°C. The highest measured temperatures were recorded on the circular saw blade with the slots and coating.

Effects of temperature and thickness of wood based boards on formaldehyde emission

This study investigated the effects of board thicknesses and temperature on formaldehyde emission (FE) for different wood based boards, sampled from standard particleboard (PB) and medium density fiberboard (MDF). Test samples with the thicknesses of 8, 12, and 18 mm analyzed for formaldehyde emission at temperatures of 10, 20, 25, and 30°C and 65% relative moisture conent for 60, 120, and 180 minutes after production. The highest value of FE was found at 1.2922 ppm for PB and 0.3800 ppm for MDF of 18 mm, treated at the temperature of 30°C. The lowest emission was found to be 0.0611 ppm in the PB of 8 mm, and 0.0444 ppm for 18 mm MDF, treated at a temperature of 10°C. A significant increase for FE was detected in all board types at the temperatures of 20, 25, and 30°C. However, a significant decrease was also detected at 10°C for all types of boards. Accordingly, an increase from 101% to 1,192% and a decrease from 39% to 9% was observed for PBs. MDF samples yielded better results as an increase from 4% to 280% and a decrease from 55% to 31%. Regarding distance to E1 (0.10 ppm), all values were above the limits of E1 (≤ 0.10 ppm, EN 717-1), except samples treated at 10°C. In conclusion, the temperature and thickness of wood based boards significantly affect their formaldehyde emissions.

Effects of temperature on volatile organic compounds and odor emissions of polyvinyl chloride laminated MDF

The objective of this study was to investigate odor active compounds of polyvinyl chloride (PVC) laminated medium density fiberboard (MDF) and explore the effect of temperature on total volatile organic compound (TVOC) and odor emissions. A micro thermal extractor was used based on the technology of gas chromatography–mass spectroscopy/olfactometry. The results showed that fruity, sweet, fragrant, and aromatic were the dominant odor impressions of PVC laminated MDF and were primarily concentrated in aromatics. Decoration treatment could effectively prevent the release of some odor compounds from MDF, yet these could add new odor substances. In the test period, the total odor intensity of MDF decreased more rapidly than that of PVC because of the characteristic of exposure. The TVOC from PVC increased when the temperature increased, and the effect was more significant early in the test period. Increasing temperature could accelerate the appearance of some odor active substances. The fastest release of odorant compounds occurred at 40°C. At higher temperature (60°C in this experiment), some substances could be enhanced, causing an increase in TVOC and odor. The temperature contrast between 40°C and 60°C contributed greatly to the release of alkanes, alcohols, esters, and ketones.

Moisture at contacts of timber-concrete element

The subject of the article is to monitor the changes of moisture on the contact surface concrete and timber part of the composite timber-concrete beam. The moisture directly affects the properties of timber and causes its volume changes and degradation processes. These effects reduce of durability and load capacity of the structures. The beam was placed at the exterior. The observed contacts of the beam are often critical on real structures, as it is difficult to repair and maintenance in the case of increasing moisture or intrusion of dirt. The experiment was used to monitor and evaluate the dependence of changing moisture in contacts depending on ambient environmental conditions.