Study on the surface changes of heat-treated aspen wood due to aging by different techniques

Heat-treated wood undergoes degradation induced by weathering factors such as solar radiation, temperature variations, rain, and snow. The aging of heat-treated wood affects significantly its surface properties. In this study, the artificial aging test of heat-treated wood using a UV chamber was carried to see the effect of aging on the wood surface. The net radiative heat transfer to the wood sample surfaces in this chamber was estimated in order to determine the corresponding natural weathering times. A complete understanding of the surface changes during the weathering process would allow the development of new treatments and finishes that would greatly enhance the durability of heat-treated wood against degradation due to weathering. Study of the heat-treated wood surface before and after weathering by different techniques helps provide an insight into the degradation process. The techniques and tools for studying heat-treated wood surfaces include color measurement, contact angle test for wettability analysis, light microscopy, FTIR, XPS, and SEM. Each technique gives information on different aspects such as chemistry, structure, and appearance. In this article, the utilization of these techniques is discussed. A number of results for different cases are presented. The aging affects the color of the tangential and radial surfaces differently. During aging, lignin decreases and OH increases; and this increases the wettability of wood.Papers presented to the 12th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, Costa de Sol, Spain on 11-13 July 2016

A novel high temperature heat treatment process for wood

Papers presented to the 11th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, South Africa, 20-23 July 2015.Wood is heated to temperatures in the range of 180–240°C in heat-treatment furnaces. At these temperatures, the wood structure undergoes changes leading to better dimensional stability, better resistance to biological attacks, and a darker attractive color. The high-temperature heat treatment of wood is an alternate and ecologically-sound wood preservation process to chemically treated wood. During heat treatment, wood goes through simultaneous heat and mass transfer. The heat is transferred from the hot gases to the wood boards in the furnace. As the temperature of wood increases, water content of wood vaporizes and diffuses out of the boards. At higher temperatures, a number of irreversible structural changes take place in wood cells. The furnace design is important to carry out the heat treatment process uniformly and effectively. A new heat treatment furnace design has been proposed at UQAC and a prototype furnace has been built and tested. Also, a 3D model of the furnace was developed to complement the experimental work and to gain insight into the heat treatment process taking place in the furnace. In this article, the new furnace design and its advantages are discussed. Results of the measurements and predictions of the mathematical model are presented to show the effectiveness of the new furnace design for heat treating standard wood boards as well as pieces of wood with different geometries.The authors would like to thank the administration of the University of Quebec at Chicoutimi (UQAC), the Foundation of the University (FUQAC), The Natural Sciences and Engineering Research Council of Canada (NSERC), Canada Economic Development for Quebec Regions (CED), Ministère de l’Économie, de l’Innovation et des Exportations (MEIE, previously MDEIE) and SOVAR.am201

Study on weathering behavior of jack pine heat-treated under different conditions

Paper presented at the 9th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, Malta, 16-18 July, 2012.It is of considerable importance to investigate the influence of weathering on the degradation processes of heat-treated wood. Kiln-dried (untreated) jack pine (Pinus banksiana) and jack pine heat-treated at three different temperatures (190°C, 200°C, and 210°C) were exposed to artificial weathering for different periods in order to understand the degradation processes due to weathering. Before and after exposure, their color and wettability by water were determined. Structural changes and chemical modifications at exposed surfaces were also investigated using SEM, FTIR spectroscopy, and XPS. The results revealed that the photo-degradation of lignin and the presence of extractives play important roles in color change and wetting behavior of heat-treated wood surfaces during weathering. The structural changes also influence the wettability. The effects of weathering for woods heat-treated under different conditions were similar, but different from those for untreated wood.dc201

Description and applications of a 3D mathematical model for horizontal anode baking furnaces

In aluminum industry, carbon anodes are consumed continuously during alumina reduction in the electrolysis cells. Anodes are made of calcined coke, butt, and recycled anode particles and pitch as the binder. Green anodes are baked in large furnaces where they attain specific properties in terms of density, mechanical strength, and electrical conductivity. Baking is an important and costly step in carbon anode production. The proper operation of the furnace provides the required anode quality. Mathematical modeling allows the prediction of the heating profile of anodes during baking. Taking into account all the relevant phenomena, a 3D transient mathematical model was developed to simulate the different stages of the baking process in the furnace. The predictions give a detailed view of the furnace operation and performance. In this article, the 3D model is described, and the results on the impact of various parameters on furnace behavior are presented

A dynamic process model for predicting the performance of horizontal anode baking furnaces

Anode manufacturing is an important step during the production of primary aluminum, and baking is the costliest stage of the anode manufacturing process. The industrial challenge resides in obtaining a good anode quality while keeping the energy consumption, environmental emissions, and cost to minimum. A dynamic process model has been developed for horizontal anode baking furnaces. It covers all important phenomena such as fuel combustion, generation and combustion of volatiles (tar, methane, and hydrogen), air infiltration, and heat losses to the atmosphere and the foundation. The model was built using two coupled sub-models of the flue and the pit and was validated using the plant data. It simulates the dynamic behavior of the furnace and gives a prediction of its operation and performance. In this article, the modelling approach will be described, and the results of a number of case studies will be presented