Research Articles

To improve the particle transport computational fluid dynamics models of impulse-cyclone airflow drying systems, a Eulerian-Lagrangian discrete particle model (commercial code ANSYS Fluent 2019 R1) was extended to describe the temperature field, airflow velocity field, and particle distribution in the impulse and cyclone dryers. The results showed that the velocity of the airflow considerably changed after wood flour was added into the system, with an approximate velocity difference between the particles and airflow of 2 m/s. An increased feed rate led to a backflow area at the bottom of the cyclone dryer, which caused reflux and a long residence time of the wood flour in and near the cyclone dryer. By comparing the calculated temperature, velocity, and time curves with the measured temperature and velocity sensor values, the error between the simulated value and the experimental value was only approximately 15%. The current work verifies that the Eulerian-Lagrangian discrete particle model of the impulse-cyclone airflow drying process established via the computational fluid dynamics simulation method was effective. The conclusion provides a reliable theoretical basis for the technological design of impulse-cyclone airflow drying systems, thus providing a way to optimize the structure of impulse-cyclone airflow drying systems in the future.

Common solid wood panel defects affect the appearance of timber products and reduce their value for use. It is necessary to remove defects from solid wood panels to achieve a panel layout. A whole wooden beam column is cut into solid wood panels of different sizes, according to the requirements. Aiming to overcome problems of weak convergence ability, single-objective optimization, and the poor optimization effect of solid wood panel layout optimization based on a traditional genetic algorithm, an improved multi-objective solid wood panel layout optimization based on NSGA-II (Non-dominated sorted genetic algorithm-II) algorithm was proposed. Reverse learning was used to generate a reverse population to increase the search capability of the algorithm and to solve the problem of insufficient population diversity in the genetic algorithms. A combination of directional variation and uniform variation was used to improve the optimization effect and solve the problem of small individual differences in the evolution of the algorithm. The improved multi-objective optimization algorithm showed better optimization and stability than the NSGA-II algorithm. The number of convergence iterations was reduced and simultaneous optimization of multiple objectives can be realized.

Numerous situations in daily life necessitate a decision. Several of them entail selecting the best option from a number of available options. In many such cases, no single solution is optimal for all of the performance characteristics. This study proposes using grey relational analysis (GRA), a multiple criteria decision making (MCDM) method, to solve this problem. Material selection is vital in designing and developing products, especially for composites materials requiring special attention. The substitution of conventional materials with natural fibres as base material is commonly practised due to high material consumption in mass-producing plastic components that could harm the environment. Therefore, in this work, natural fibres were chosen as composite reinforcement in the design of cyclist helmets. This approach was used to evaluate the right natural fibre and is able to fulfill the needs of consumers and the environment. From the results, the GRA method was utilised and revealed that pineapple was the best top ranking natural fibre with a grade of 0.5687, followed closely by bamboo with a grade of 0.5678, and abaca with a grade of 0.4966. Error analysis was performed to increase the confidence level of the results obtained.

Scotch pine wood flour was modified with butyric anhydride to determine the effect of wood modification on the properties of 3D-printed composites. The 3D printer filaments were obtained by mixing wood flour and polylactic acid (PLA) with a twin-screw extruder. The composites were printed via a 3D printer from the obtained filaments. The mechanical, thermal, and morphological properties of the composites were investigated. According to the mechanical test results, the tensile strength values of the modified wood flour (MWF)-added composites were higher than the unmodified wood flour (UMWF)-added composites. It was also observed that the flexural strength and flexural modulus of MWF-added composites decreased compared to the UMWF-added composites. According to the investigation of the thermal properties of the composites, the thermal degradation temperature value of the 20% MWF-added PLA composite was higher than other composites. Therefore, through the investigation of breaking surfaces of the composites using scanning electron microscopy, it was observed that the interface bonding between PLA polymer matrix and wood flour was improved by modification.

To reduce the fluctuation of the heat source water temperature and ambient temperature caused by variations in solar radiation, a solar absorption refrigeration system with a supplementary biomass combustion device for the office area of a factory was designed. A numerical model of the solar energy absorption refrigeration system based on the Aspen Plus software was developed. In particular, the effects of the heat source water temperature, condenser temperature, evaporation temperature, and dilute solution flow rate on the cooling capacity, coefficient of performance, unit equipment duty, and generator temperature during actual operation were investigated. The heat load of each piece of equipment in the unit were found to increase correspondingly with the increase of the heat source temperature when the evaporating temperature and condensing temperature are constant. The coefficient of performance of the unit decreased as the condensing temperature increased keeping the temperature of the heat source constant. The results demonstrated that the flow rate of the dilute solution has effects on the occurrence temperature, cooling capacity, and the unit performance coefficient.

Effects of continuous press speed (580 and 600 mm/s) and conditioning time (0 and 72 h) on some physical and mechanical properties and formaldehyde content of particleboards were investigated. The 18 mm thick boards were manufactured using urea-formaldehyde, with a 50% pine, 40% oak wood, and 10% poplar biomass mixture of the wood materials. According to the results of the unconditioned samples, the density, modulus of rupture (MOR), moisture content (MC), thickness swelling (TS), and water absorption (WA) were increased 0.8%, 4.4%, 0.4%, 4.4%, and 5.5% when press speed increased from 580 to 600 mm/s, while thickness, modulus of elasticity (MOE), internal bond (IB), surface soundness (SS), and free formaldehyde (FF) were decreased 0.3%, 4.9%, 2.4%, 10.6%, and 21.1%, respectively. On the contrary to the results of unconditioned samples, MOE and SS were increased 1% and 1.4%, respectively, and WA was decreased 3.5% with the increase in press speed when samples were conditioned for 72 h. Free formaldehyde content was the most prominent parameter influenced by the increase in press speed both for the unconditioned and 72 h conditioned samples.

The butanol acetone ratio (B/A ratio) is a critical index to evaluate the process of ABE fermentation. In this article, fern root starch with yeast extract added (FY) was used as substrate for ABE fermentation. The final B/A ratio in a 5 L anaerobic fermentor reached the highest levels of 3.42, which signified an increment of 41% compared with corn. The mechanisms for the high B/A ratio of FY substrate were as follows: 1) the weakened organic acid circuit resulted in decreased acetone synthesis; 2) the NADH level of butanol synthesis was high; 3) coA transferase activity was low and butanol dehydrogenase activity was high. The final butanol concentration and substrate utilization were examined in a 5 L anaerobic fermentor, and the results validated the feasibility of ABE fermentation with FY as substrate.

Maltodextrin is a potential natural adhesive for particleboard because it is reactive and freely soluble in water. However, maltodextrin has a low water resistance and a high melting point that hinder its development as a particleboard adhesive. An addition of ammonium dihydrogen phosphate (ADP) as a catalyst of maltodextrin was expected to overcome its weaknesses. The optimal pressing temperature was expected to be affected due to the addition of catalysts. This research aimed to investigate the effect of maltodextrin/ADP ratios and pressing temperatures on particleboard properties made from Salacca frond. The maltodextrin/ADP ratios used in this research were 100/0, 90/10, and 80/20 wt%, and the pressing temperatures were set at 200 and 220 °C. The combination of an increased ADP ratio in maltodextrin and an increased pressing temperature improved the particleboard properties. The water resistance was also significantly improved by addition of ADP and increased pressing temperature. Thermal analyses showed that the onset temperature of weight reduction of maltodextrin added particles was lowered by addition of ADP. The results suggested that a maltodextrin/ADP mixture could be a promising particleboard binder.

The effectiveness of chemical steeping was examined as a novel pretreatment prior to hydrolysis to influence the extractable yield of glucose and xylose from oil palm trunk (OPT). The chemical steeping parameters were 0.2% sodium metabisulphite (w/v), 0.5% lactic acid (v/v), 26 ± 2 °C, and 1 h, followed by dilute acid hydrolysis (2%, 4%, and 6% of sulphuric acid (v/v); 115 °C, 120 °C, and 130 °C; 15 min, 30 min, and 60 min). For comparison, the glucose and xylose yield extracted from untreated OPT was also examined. Thermal analysis showed that the lactic acid and sodium metabisulphite successfully degraded the lignocellulose of OPT. The total extracted glucose and xylose yield was improved, and was approximately 2.5% to 28.8% higher than the yield extracted from non-pretreated OPT fines. RSM analysis showed that the 130 °C x 50 min x 2% was predicted as the optimum parameters for the extraction of glucose and xylose through chemically treated OPT, and followed the dilute acid hydrolysis process. Analysis of variance showed that the hydrolysis parameters were significant model terms for the glucose and xylose yield. In conclusion, chemical steeping was successful as a pretreatment to increase the extractable glucose and xylose yield from OPT.

Vertical form fill seal machines are commonly used to form pouches. This paper aimed to optimize the sealing parameters and evaluate the runnability of flexible paper-based packaging materials with a polyethylene coating, differentiated by their grammages and thicknesses. This was done in comparison with a commercial plastic film, an oriented polypropylene and polyethylene laminate, using two different sealing jaw patterns in an industrial-scale vertical form fill seal machine. Based on the results obtained, the first observable seal was found at a sealing temperature of 90 °C for the paper-based material and a sealing temperature of 100 °C for thermoplastic film, both at a dwell time of 2 s. It was shown that the paper-based material had a larger sealing window, up to a sealing temperature of 220 °C, before the material started to turn brown, while the thermoplastic film shrank at a sealing temperature of 140 °C. Several peel and compression strength tests were performed to evaluate the flexible paper-based material. Furthermore, several hindering issues were observed in the paper-based material during the production runs. These included wrinkling, web buckling, friction in the forming tubes, pouches airtightness, etc. As such, recommendations for further investigations and future studies are given.