جستجوی مقالات مرتبط با کلیدواژه « Moisture Content » در نشریات گروه « صنایع چوب و کاغذ »

The calculation of heating value is one of the most important properties of biomass fuels to calculate the design or simulation of thermal conversion systems for energy production from biomass. Biomass with higher thermal energy value and optimal composition is more desirable for the systems. In present investigation, properties of eight types of non-woody biomass relevant to combustion were evaluated. Important characteristics requiring analysis were moisture and ash content, volatile matter, elemental composition (C, H, N, S, and O), high and low heating values (HHV and LHV) of these residues. The heating value has been evaluated based on experimental (by colorimeter bomb) and computational methods. The content of sulfur is a limiting factor for environmental pollution and was higher than other reports. The high percentage of ash in bagasse Pith requires the use of it as mixing with bagasse in order to increase the efficiency of the energy production system. It is recommended to mix bagasse pith with bagasse due to the high amount of ash in order to increase the efficiency of energy conversion systems. Regarding to the volatile matter, bagasse and reed are superior to the rest of biomass to produce energy by gasification system. The highest heating values were obtained for corn straw and bagasse and the lowest heating values were for bagasse pith and rice straw, respectively. There is good correlation between the methods of heating value determination, so it shows that the proper computational model has been used.

The use of renewable energies, such as biomass, is becoming increasingly important as countries realize that bioenergy present an approach to their international commitments to reduce greenhouse gas emissions. Biomass with higher thermal energy value and optimal composition is more desirable for the thermal conversion systems. In present investigation, properties of ten type's wood biomass relevant to combustion were evaluated. Important characteristics requiring analysis for the biomass were moisture and ash content, volatile matter, elemental composition (C, H, N, S, and O), and high and low heating values (HHV and LHV). The heating value has been determined based on experimental and computational methods by colorimeter bomb and elemental content, respectively. The results showed that eldarica pine biomass had the highest content of biomass sulfur, which is undesirable environmental factor in the bioenergy system. Regarding to the fixed carbon to volatile matter ratio, Citrus sinensis var. thomson has the lowest ratio, so it is the best biomass for the gasification process. The highest and lowest heating values were determined for the poplar pruning residues (group a) and apple (group b and c), respectively. The highest and lowest of HHV and LHV were measured for P. deltoides and Malus spp., respectively.

In this study, the effects of mat moisture content and press temperature on physical and mechanical properties of three layered oriented strand boards were evaluated. Two levels of mat moisture content 7% and 10% and three levels of press temperature 180 ˚c , 200 ˚c and 220 ˚c were applied and 12 mm in nominal thickness laboratory boards were made from mixture of three clones of ten-year-old hybrid poplar ( populous euramericana vernirubensis, p. e. I-214, P. e. 561/41) while the strands on the surface layers are aligned in the long direction of the board and the middle layer strands are cross aligned to the surface layers. In all treatments, board targeted density of 0/7 g/cm3 and press time of 8 min and phenol-formaldehyde resin (PF) content of 7% based on the oven dry weight of the strands were held constant. The mechanical and physical properties of the boards were measured as defined in relevant European standards EN 300 for OSB/1 and OSB/2. Overall results showed that all boards made from above mentioned conditions exceed the EN 300 standards for MOR, MOE, IB and TS24. The bending properties (MOR and MOE) of boards were significantly improved as the mat moisture content increased from 7 to 10%. The highest MOR was achieved at 10% mat moisture content and 220 ˚c press temperature and the highest MOE was achieved at 10% mat moisture content and 180 ˚c press temperature. The Modulus of Rupture (MOR) and Thickness swelling (TS24) were significantly improved as the press temperature increased from 180 ˚c to 220 ˚c. The lowest TS24 was achieved at 7% mat moisture content and 220 ˚c press temperature and the highest IB was achieved at 7% mat moisture content and 200 ˚c press temperature.

In this research the effects of moisture content and cutting speed on the specific shearing energy and shearing stress for four variety of almond tree (Mamayy, Rabi, Sefid and Shahrodi12) was investigated and results the each any the varieties were compared with each other. Shear properties of almond wood varieties in this study, using a universal testing machine manufactured STM20 Sntam was determined. Knife bevel form of one-sided and edge angle is 40 degree.The characteristics at three moisture levels of 18, 25 and 45% (w.b.) wet basis, three cutting speed levels of 20, 30 and 40 mm/min and in three size 6, 9 and 12 mm were determined. The results of analysis of variance (ANOVA) showed specific shearing energy and shearing stress to all test factors were response significant (P

In this investigation، the surface chemical properties of the beech wood layers were characterized and the impact of drying condition on the strength of the bond was examined. Defect free beech logs were harvested and then the layers were prepared. The moisture content of the specimens were adjusted at 30، 40 and 50% (dry basis) and then the specimens were air dried under the environment of 30% relative humidity and 21ºC to reach the equilibrium moisture content of about 10% (dry basis). The pH and buffering capacity of the surface layer and the layer 0. 5 mm underneath the surface were measured. The dried specimens were bonded using urea-formaldehyde resin and the tensile strength and wood failure were measured using relevant ASTM method. The results showed that as the moisture content prior to air drying was increased، the tensile strength was reduced، but the effect of this variable on tensile strength was not statistically significant. However، the effect of moisture content on wood failure was statistically significant at 99% significance level. The effect of the pH of the under layer on both tensile strength and wood failure was statistically significant at 95%. As the moisture content of the wood increased، the pH of the surface layer increased and the strength of the bond with urea-formaldehyde resin was deteriorated. At higher initial moisture of the wood، the alkaline buffering capacity of the surface layer was lower and its effect of the strength was not statistically significant، but it was significant on wood failure at 99% level. The alkaline buffering capacity of under layer was also changed and statistically affected the bond strength and wood failure at 95% level. The higher alkaline buffering capacity of the under layer adversely affected the tensile strength of the bond. The lowest acid buffering capacity was measured from specimens with 40% initial moisture content and as the acid buffering capacity was increased، the tensile strength was reduced and the wood failure was higher. The impact of surface layer acid buffering capacity on tensile strength was on statistically significant، but on wood failure was statistically significant at 99% level.