Rechnergestützte Partikelmessung an Materialien in der Holzwerkstoffindustrie

The established procedures of particle measuring can be completed by methods of measuring based on computer-controlled image analysis because they are more versatile and can easily be adapted to new problems. The WKI disposes of a free-programmable image analyser and uses it for the measuring of samples of materials typical for the wood based industry. Different problems occur for wood particles, fibre-based material and binder particles during the preparation, measuring and assessment. The obtained results allow more distinguished statements on the materials than conventional measuring methods but when interpreting the results it has to be taken into consideration that the measuring methods are based on different physical principles.     

Development of strategies for reducing air pollutant emissions in the European community

In view of increasing economic and environmental problems, energy supply strategies as well as air pollutant emission reduction strategies are required. These strategies should be designed in accordance with the specific development of a country or region. In the past they were mainly considered with respect to the finiteness of natural resources and the scarcity of economic resources. In recent years the ‘joint-production’ of air pollutant emissions in the energy sector has been increasingly recognized as an additional argument. As a consequence, concepts on future energy pathways, which should be efficient with respect to both economic development and environmental protection, have to be devised. For this purpose energy-environmental models such as EFOM-ENV can be used as analytic tools. The paper discusses optimal future energy supply structures that result from different strategies for air-pollution control in the countries of the European Community. The results have been obtained by applying the energy flow optimization model (EFOM), which has been extended by additional environmental modules to EFOM-ENV. The issues of the paper are based on research activities that the authors are performing for the Commission of the European Communities (CEC), Brussels, and the European Research Center for Air Pollution Control Measures (PEF), Karlsruhe, in close co-operation with research institutes in member countries of the European Community.     

Strategie für eine Konversion der Chlorchemie

Strategy for Conversion of Chlorine Chemistry . After years of discussion about ?cessation of chlorine chemistry”?, the study entitled ?Conversion of Chlorine Chemistry”? [1] commissioned by the Environmental Ministry of the State of Hesse in Germany and undertaken by Prognos AG provides the very first detailed comparative ecological and economical assessment of production process and products of ?chlorine chemistry”? and industrially feasible alternatives and presents a strategy for partial transformation. This accomplished on the basis of a systematic assessment of risks and benefits, as demanded by the Geman parliametary commission ?Protection of Humankind and the Environment”?.     

Simulation automatischer Fehlstellenerkennungsverfahren für Holzoberflächen

Ohne Zusammenfassung     

Experimental and Numerical Characterization of the Influence of a Smoldering Cellulosic Substrate on a Cigarette’s Ignition Propensity Test

An experimental and numerical investigation was conducted to characterize the influence of the cellulosic substrate used to assess the ignition propensity (IP) of cigarettes. Such an IP test is currently prescribed by the ISO 12863 standard and its results typically show poor repeatability. It is believed that such a low reproducibility is mainly due to the variability of the cigarette itself but it is unclear as to what extent the substrate also influences the variability of the test results. Therefore, the objective of this investigation was to analyze the potential influence of the substrate by first characterizing the thermodynamic behavior experimentally and then constructing a numerical model that can quantify the relative influence of the distinct parameters. A suite of experimental methods that included TGA, DSC, infrared measurements and laser triangulation among others was used to measure the thermophysical properties of the substrate. These properties were then used to build a CFD model that simulated the smoldering combustion experienced by the substrate during the IP test. After validating the model against contactless temperature measurements, a parametric study consisting of 363 IP simulations was performed, which served to quantify the relative importance of 13 thermophysical parameters when varying in ranges of about 5%–50%. The results indicated that the heat capacity, pyrolysis activation energy, and air gap thickness are the most influencing aspects of the substrate because they influence the heat absorbed by the substrate about 7%, 26% and 33%, respectively. The latter parameter was found to significantly vary with each test and its influence was comparable to that of some major properties of the cigarette such as the cigarette’s temperature and burning rate. It is therefore postulated that the variability of the substrate itself plays an important role on the poor repeatability of the test and it may comprise its reliability.     

Characterisation of hardwood fibres used for wood fibre insulation boards (WFIB)

European Journal of Wood and Wood Products - Wood fibre insulation boards (WFIB) are typically made from softwood fibres. However, due to the rapid decrease in softwood stands in Germany, the...     

Virtual characterization of MDF fiber network

A virtual design method for medium density fiberboards (MDF) is proposed with the aim to optimize the fiber orientation and lay-up of MDF. The new method estimates the stiffness and strength by using microstructure models of the MDF fiber network. The virtual design is used to improve the manufacturing technology of MDF plates with multilayer oriented fiber structure. Experimental investigations of the mechanical behavior of MDF microstructure for various fiber geometries, glue content and distribution are complicated, time consuming and expensive. On the other side, virtual microstructure design allows to develop a new wood fiber based material with less experimental work. Microstructure models help to better understand the non-linear damage mechanical behavior of a wood fiber network depending on fiber geometrical parameters. Such parameters as crack distribution and fiber deformation on micro-scale level are complicated to experimentally measure, but possible to model using computer simulations. The virtual design tool requires less empirical data. The model takes into account information on average wood fiber orientation, fiber diameter, fiber length and mechanical properties of wood fiber cell wall and glue. The numerical method for strength and stiffness analysis of MDF microstructure was calibrated using standard MDF with non-oriented fibers. It turned out that this method gives precise results for MDF with oriented fibers and even with multilayer structure. The proposed virtual microstructure design tool can significantly improve and speed-up the optimization manufacturing technology of MDF and other wood fiber based composites.