Search Results (156)

The amount of waste generated by society is constantly increasing. Consequently, there is a need to develop new and better methods of treating it. A significant part of municipal waste is biowaste, which can be treated as a source of valuable resources such as nutrients, organic matter, and energy. The present work aims to determine the properties of the tested household biowaste and the possibility of using it as feedstock in slow pyrolysis to obtain biochar. The slow pyrolysis process of the biowaste was carried out in an electrically heated Horizontal Tube Furnace (HTF) at temperatures of 400 °C, 500 °C, and 600 °C in a nitrogen atmosphere. The analysis showed that depending on the type and composition of the biowaste, its properties are different. All the biowaste tested has a high moisture content (between 63.51% and 81.53%), which means that the biowaste needs to be dried before the slow pyrolysis process. The characteristics of kitchen biowaste are similar to those of food waste studied by other researchers in different regions of the world. In addition, the properties of kitchen biowaste are similar to those of the typical biomasses used to produce biochar via slow pyrolysis, such as wood, almond shells, and rice husks. Both kinds of garden biowaste tested may have been contaminated (soil, rocks) during collection, which affected the high ash content of spring (17.75%) and autumn (43.83%) biowaste. This, in turn, affected all the properties of the garden biowaste, which differed significantly from both the literature data of other garden wastes and from the properties of typical biomass feedstocks used to produce biochar in slow pyrolysis. For all biowaste tested, it was shown that as the pyrolysis temperature increases, the yield of biochar decreases. The maximum mass yield of biochar for kitchen, spring garden, and autumn garden biowaste was 36.64%, 66.53%, and 66.99%, respectively. Comparing the characteristics of biowaste before slow pyrolysis, biochar obtained from kitchen biowaste had a high carbon content, fixed carbon, and a higher HHV. In contrast, biochar obtained from garden biowaste had a lower carbon content and a lower HHV. Full article

Thermal modification applies to a technique for the enhancement of biological durability, stability, and appearance of wood. Much is known about its effects on the chemical and physical attributes of wood. However, there is a knowledge gap concerning the effects of heat treatment on surface coating performance of different wood species. The focus of this research is heat treatment regulation of 160 °C, 180 °C, and 200 °C for three commercially important wood species which are Populus (poplar), Quercus (oak), and Pinus (pine). These treatments were evaluated in relation to coating performance indicators adhesion, integrity, and visual stability during and after natural and artificial weathering. It was revealed that specific responses among species differences exist. Populus behaved differently and exhibited a steady loss in mass and volume. Quercus demonstrated gradual degradation alongside enhanced lignin stability. Pinus exhibited maintenance of volume and mass until 180 °C after which accelerated degradation was observed. Coating durability and adhesion exhibited dependence on thermal condition, wood species, porosity, surface chemistry and microstructural variations that occurred. The research results can be used to streamline finishing processes for thermally modified wood while underscoring the critical nature of precise treatment parameter adjustments guided by species-specific responses to ensure long-term stability. Full article

Heat treatment is a widely employed method for modifying solid wood and has also been extended to veneer-type woods. Owing to the thinness and ease of handling of veneers, the regulation of protective media in heat treatment has not been highly regarded by the industry and is scarcely reported in research. In light of this, in this paper, rubber wood (Hevea brasiliensis) veneer is taken as the research subject to investigate the influences of heat treatment with hot air (HTHA) and heat treatment with superheated steam (HTSS) at different temperatures on the chemical properties, longitudinal tensile strength, color values, hygroscopicity, thermal degradation performance and microstructure of the wood. The results show that heat treatment alters the chemical properties of wood. Both heat treatments reduce the content of hemicellulose and other components in the veneer, and the characteristic peak of lignin in HTSS is slightly enhanced. The crystallinity of the veneer slightly increases after heat treatment, and the increase in HTSS is greater than that in HTHA. Through scanning electron microscopy, it is observed that heat treatment can effectively remove starch granules in rubber wood veneer, with HTSS being superior to HTHA, and the removal effect increases with the rise in temperature. The longitudinal tensile strength of the veneer decreased by 0.69%, 3.87%, and 24.98% respectively at 135~155 °C HTHA, and by 3.25%, 7.00%, and 18.47% respectively at 135~155 °C HTSS. Both heat treatments reduced the lightness of the veneer and increased the chroma index. At 155 °C, the color difference value of the veneer treated by HTSS was smaller than that treated by HTHA. The effects of heat treatment on the moisture absorption performance of the veneer were different. The equilibrium moisture content of the veneer treated at 135 °C HTHA and 135~155 °C HTSS was lower than that of the untreated material, indicating an improvement in moisture absorption stability. The maximum moisture sorption hysteresis of untreated material is 3.39%. The maximum moisture sorption hysteresis of 135 °C HTHA is not much different from that of untreated material. The values of 145 °C and 155 °C HTHA increase by 8.85% and 9.14% respectively. The values of 135 °C, 145 °C, and 155 °C HTSS increase by 22.42%, 25.37%, and 19.47% respectively. The moisture absorption hysteresis of the veneer increases after heat treatment, and the effect of HTSS improvement is more significant. From the TG and DTG curves, it can be seen that the residual mass percentage of the veneer after heat treatment is higher than that of the untreated material. The residual mass percentage of HTHA at 135 °C, 145 °C, and 155 °C increased by 3.13%, 3.07%, and 2.06% respectively, and that of HTSS increased by 5.14%, 7.21%, and 6.08% respectively. Full article

In order to rationally utilize wood materials, increase wood quality, and mitigate drawbacks, research on industrial techniques for timber protection and preservation is essential on a European and global scale. When high-quality timber enters the market, it offers structures and objects that have considerable added value. This study examines the performance of thermally treated (6 h at 170 °C and 200 °C) softwood species (fir wood) when exposed outdoors and applied on wooden building structures as cladding timber, among other structures. International standards were applied for the characterization of the untreated and thermally treated wooden boards after the treatments in terms of physical, hygroscopic, and surface properties. In contrast, all the boards (of dimensions 390 × 75 × 20 mm in length, width, thickness respectively) were exposed outdoors to direct sunlight and a combination of biotic and abiotic factors for a six-month period to mainly investigate the thermal properties (heat transfer analysis/insulation properties) using a real-time test in situ, as well as to investigate their potential resistance to natural weathering (color, surface roughness, visual inspection, etc.). Heat transfer in the thermally treated wood specimens was found to be much slower than that in the untreated specimens, which, combined with lower hygroscopicity and higher dimensional stability, reveals the high potential of thermally treated wood utilization in outdoor applications, such as cladding, facades, frames, and other outdoor elements. Full article

To utilize a huge amount of oil palm trunk (Elaeis guineensis) biomass as wall insulation, its dimensional stability and insulation properties need to be improved. Thermal modification (TM) (without compression or densification) is one of the efficient methods widely used for improving insulation properties and dimensional stability of wood material, but such an existing method requires a complex system. In this work, the TM of oil palm wood with an initial density of 219 ± 34 kg/m³ was performed at 200 °C using a hot press machine. The optimum heat-treatment durations (2 h, 4 h, and 6 h) for their potential for insulation wall applications were explored. TM improved dimensional stability, sound-absorption coefficient, and thermal conductivity by approximately 66.7%, 26.7%, and 24.6%, respectively, but increased volatile organic compound (VOCs) emission compared with the control. Heat-treatment duration notably affected mass loss, density, and thermal conductivity. Compared with available natural material-based insulation walls, TM oil palm showed better insulation performance for all treatment durations. Thus, the heat-treatment duration of 2 h is suggested to save the energy consumption in the heat-treatment process while still achieving the same level of sound absorption, dimensional stability, and VOC emission performance as that of the long heat-treatment duration. Full article

The accounting methodology for renewable energy in the European Union’s (EU) renewable heating and cooling targets is often treated as a mere technical detail, yet it has profound implications for the effectiveness of climate policies. This paper highlights a critical misalignment within the Renewable Energy Directive (RED), which inadvertently disincentivises the deployment of more efficient heating technologies. By accounting for the energy harnessed to produce the useful heat, rather than the useful heat itself, the current metrics disproportionately credit the least efficient heating systems with generating the most renewable heat. An electric heat pump with a seasonal performance factor of 3 producing 100 units of renewable heat gets credited with 100 units of heat, despite using only 33 units of input energy, whereas a wood fireplace with an efficiency of 50% gets credited with 200 units of heat. The less efficient the device, the more renewable credits it receives for producing the same amount of useful heat. This misalignment undermines decarbonisation efforts by over-crediting inefficient technologies while failing to fully recognise high-efficiency solutions like heat pumps. This paper proposes revising the RED to account for useful energy output, ensuring a more accurate reflection of technology contributions. We also propose increasing the binding heating and cooling targets of 0.8 pp/year and 1.1 pp/year so that they reflect the needed contribution of the heating and cooling sector to reach the binding headline target of 42.5% by 2030. This shift would incentivise efficiency, better align with EU climate goals, and support the transition to a low-carbon heating and cooling sector in line with the 2030 emissions reduction target. Full article

The properties of wood change after heat treatment, affecting its applications. Glossiness, a key aesthetic property, is of great significance in fields like furniture. Precise prediction can optimize the process and improve product quality. Although the traditional back propagation neural network (BPNN) has been applied in the field of wood properties, it still has issues such as poor prediction accuracy. This study proposes an improved whale optimization algorithm (IWOA) to optimize BPNN, constructing an IWOA-BPNN model for predicting the glossiness of heat-treated wood. IWOA uses chaos theory and tent chaos mapping to accelerate convergence, combines with the sine cosine algorithm to enhance optimization, and adopts an adaptive inertia weight to balance search and exploitation. A dataset containing 216 data entries from four different wood species was collected. Through model comparison, the IWOA-BPNN model showed significant advantages. Compared with the traditional BPNN model, the mean absolute error (MAE) value decreased by 66.02%, the mean absolute percentage error (MAPE) value decreased by 64.21%, the root mean square error (RMSE) value decreased by 69.60%, and the R² value increased by 12.87%. This model provides an efficient method for optimizing wood heat treatment processes and promotes the development of the wood industry. Full article

Many modern technologies rely on materials that harm the environment. Glass manufacturing, for instance, is both expensive and environmentally damaging. In response, scientists have developed a technique to replace glass with transparent wood, an innovative, versatile, and sustainable alternative. Wood naturally retains heat, is durable, and remains cost-effective, making it promising substitute for glass and plastic in window production. This innovation highlights the urgent need for eco-friendly technologies to replace or improve existing materials. This work explores cork as a sustainable alternative for producing transparent materials, potentially replacing transparent wood. Unlike wood, cork can be harvested from the same tree for up to 300 years. The process followed a method like transparent wood production, involving delignification, bleaching, and forced polymer impregnation. The choice of bleaching agent significantly impacted results—samples treated with sodium hypochlorite solution appeared whiter but became extremely fragile, whereas hydrogen peroxide preserved mechanical properties better. The resin-to-hardener ratio was crucial, with higher resin content improving polymer infiltration and transparency. While fully transparent cork was not achieved, the resulting translucent material lays the groundwork for future research in this field. Full article

Wood heat treatment is considered by many to be an eco-friendly wood modification method, given that only heat is applied during the treatment. However, it is essential to recognize that energy consumption can give rise to various environmental challenges. Quantitative evaluation of the environmental performance of a wood modification technology is always a challenge faced by the wood processing industry. To perform a comprehensive assessment, it is imperative to adopt a life-cycle-based approach, which is still very limited for heat-treated wood in China. This study investigated the mass and energy consumption of heat-treated radiata pine lumber in life cycle stages from forest management in New Zealand to wood heat treatment in East China and calculated its environmental impacts using the ReCiPe method. Two heat supply scenarios, i.e., on-site wood-fired boilers and off-site coal-fired power plants, were compared to evaluate the influence of national policy on environmental performance. Transoceanic shipping and lumber drying were found to be the life cycle stages dominating the environmental impacts level, and human-health-related impacts, mainly fine particulate matter, photochemical ozone formation, human toxicity, and global warming, were the major environmental impacts of heat-treated radiata pine lumber. With on-site heat supply, more heat and electricity were consumed due to a lower boiler efficiency and more energy demands. However, the impact assessment showed lower environmental impacts in this scenario. The non-fossil and carbon-neutral nature of wood is the key to the environmental advantages of this heat supply scenario. Full article

This study integrates the Backpropagation (BP) Neural Network with several optimization algorithms, namely Hippopotamus Optimization (HO), Parrot Optimization (PO), Osprey Optimization Algorithm (OOA), and Goose Optimization (GO), to develop four predictive models for the adhesive strength of heat-treated wood: HO-BP, PO-BP, OOA-BP, and GO-BP. These models were used to predict the adhesive strength of the wood that was heat-treated under multiple variables such as treatment temperature, time, feed rate, cutting speed, and abrasive particle size. The efficacy of the BP neural network models was assessed utilizing the coefficient of determination (R²), error rate, and CEC test dataset. The outcomes demonstrate that, relative to the other algorithms, the Hippopotamus Optimization (HO) method shows better search efficacy and convergence velocity. Furthermore, XGBoost was used to statistically evaluate and rank input variables, revealing that cutting speed (m/s) and treatment time (hours) had the most significant impact on model predictions. Taken together, these four predictive models demonstrated effective applicability in assessing adhesive strength under various processing conditions in practical experiments. The MAE, RMSE, MAPE, and R² values of the HO-BP model reached 0.0822, 0.1024, 1.1317, and 0.9358, respectively, demonstrating superior predictive accuracy compared to other models. These findings support industrial process optimization for enhanced wood utilization. Full article

In this study, an Improved Zebra Optimization Algorithm (ZOA) is proposed based on the search mechanism of the Sparrow Optimization Algorithm (SSA), the perturbation mechanism of the Particle Swarm Algorithm (PSO), and the adaptive function. Then, Improved Zebra Optimization Algorithm (IZOA) was used to optimize the Deep Hybrid Kernel Extreme Learning Machine Model (DHKELM), and the IZOA-DHKELM was obtained. The model has been used to predict the color of heat-treated wood for different species, temperatures, times, media, and profile types. In this article, the original DHKELM and the ZOA-DHKELM were compared to verify the validity and accuracy of the model. The results indicated that the IZOA-DHKELM decreased the mean absolute error (MAE), root mean square error (RMSE), and mean absolute percentage error (MAPE) by 56.2%, 67.4%, and 34.2%, respectively, while enhancing the coefficient of determination, $R^2$, to 0.9952 compared to the ZOA-DHKELM. This demonstrated that the model was significantly optimized, with improved generalization ability and prediction accuracy. It can better meet the actual engineering needs. Full article

This study evaluates the chemical, physical, mechanical, and biological properties of untreated and heat-treated Cryptomeria japonica (Thunb ex L.f.) D.Don wood from the Azores, Portugal. Heat treatment was performed at 212 °C for 2 h following the Thermo-D class protocol. Chemical analysis revealed an increase in ethanol soluble extractives and lignin content after heat treatment, attributed to hemicellulose degradation and condensation reactions. Dimensional stability improved significantly, as indicated by reduced swelling coefficients and higher anti-swelling efficiency (ASE), particularly in the tangential direction. Heat-treated wood demonstrated reduced water absorption and swelling, enhancing its suitability for applications requiring dimensional stability. Mechanical tests showed a decrease in bending strength by 19.6% but an increase in the modulus of elasticity (MOE) by 49%, reflecting changes in the wood’s structural integrity. Surface analysis revealed significant color changes, with darkening, reddening, and yellowing, aligning with trends observed in other heat-treated woods. Biological durability tests indicated that both untreated and treated samples were susceptible to subterranean termite attack, although heat-treated wood exhibited a higher termite mortality rate, suggesting potential long-term advantages. This study highlights the impact of heat treatment on Cryptomeria japonica wood, emphasizing its potential for enhanced stability and durability in various applications. Full article

The objective of this study was to investigate some of the properties of ash (Fraxinus excelsior L.) wood treated at a temperature of 185 °C for 3 h. We tested the samples’ physical properties, including their dimensional stability in the form of water absorption and radial/tangential swelling and their surface roughness, as well as their mechanical characteristics such as Brinel hardness and bending strength. Our results show that the water absorption and swelling values of the samples improved, ranging from 27% to 32% and from 21% to 46%, respectively. Also, the Brinell hardness of the thermally treated wood registered a slight decrease from 19.5 N/mm² to 15.2 N/mm² in the radial direction and from 15.7 N/mm² to 12.2 N/mm² in the tangential direction. It appears that the bending resistance of the samples decreased, which is generally thought to be an adverse effect of heat treatment on any wood species. Full article

This study investigates the performance of DC corona discharge electrostatic precipitators (ESPs) for NO conversion to increase DeNO_x technologies’ efficiency for small-scale biomass combustion systems. Experiments were conducted using a 5 kW automatic wood pellet domestic heat source with combustion gas treated in a specially designed ESP operated in both positive and negative corona modes, resulting in a reduction in NO concentrations from 130 mg/m³ to 27/29 mg/m³ for positive/negative polarities (at 0 °C and 101.3 kPa). NO conversion efficiency was evaluated across a range of specific input energies (SIEs) from 0 to 50 J/L. The results demonstrate that DC corona ESPs can achieve up to 78% NO reduction, with positive corona demonstrating a greater energy efficiency, requiring a lower SIE (35 J/L) compared to the negative corona mode (48 J/L). A detailed analysis of reaction pathways revealed distinct conversion mechanisms between the two modes. In positive corona, dispersed active species distribution led to more uniform NO conversion, while negative corona exhibited concentrated reaction zones with about 20% higher ozone production. The reactions involving O and OH radicals were more important in positive corona, whereas ozone-mediated oxidation dominated in negative corona. The research results demonstrate that ESP technology with DC corona offers a promising, energy-efficient solution for NO_x control in small-scale combustion systems. Full article

Wooden structures are prone to fire hazards, and studying their combustion properties is vital for their protection. Samples of fresh pine wood (FP) and pine subjected to artificially accelerated aging (treated at 240 circulation) were collected and prepared for analysis. The heat-release rate, smoke production, and yields of carbon monoxide (CO) and carbon dioxide (CO₂) from both types of pine were assessed using conical calorimetry to determine their combustion characteristics. A historic building in Xi’an was modeled using PyroSim to serve as a representative case. The experimentally obtained combustion characteristics of the two pine wood types were inputted into the model, and the Fire Dynamics Simulator (FDS) software was utilized to simulate the development of fire in both newly constructed and aging historic buildings. The results suggest that aging impairs the wood’s combustion properties and increases the susceptibility of pine to ignition. Consequently, this accelerates the spread of fire in wooden structures, leading to a rapid increase in temperature and swift smoke production during fires, thus amplifying the fire risk to historic wooden buildings. Full article