Development of a porous burner for low calorific gaseous fuels offering a wide operating range [in press]

This work presents the development of a burner for the utilization of low calorific value waste gas, as it arises in the production of high purity hydrogen from biogas using an oxidative steam reforming process. Stable combustion of different fuel gases with fluctuating gas composition over a wide operating range is assured by the application of combustion in an inert porous medium (PIM) utilizing a kinematic flame stabilization mechanism. The development of the PIM-burner bases on calculated effective flame speeds within PIM derived from a 1-D numerical model including harsh operating conditions with preheating temperatures above 800 K and carbon dioxide concentration of 70 %-vol in the fuel gas. Experiments are conducted on a tailored test rig in order to validate numerical predictions by comparison of calculated effective flame speeds to eff ective flame speeds derived from temperature measurements in PIM

Combustion Characterization of Solvents used in Coil Coating Processes: Experiments and Kinetic Modelling

A combined experimental and chemical kinetics modelling approach is presented to account for the combustion behaviour of solvents utilized in coil coating processes. Heating values and laminar burning velocities of typical industrial solvent formulations comprising alcohols, ethers, esters and aromatics are experimentally investigated. Due to the complexity of species participating in the solvent formulations surrogate solvents are introduced, one for each considered formulation. An “in-house” chemical kinetics mechanism has been extended in order to take into account the solvents’ combustion and consists of 321 species participating in 1826 reactions. Its overall performance is validated against the laminar burning velocity measurements. A good qualitative and quantitative reproduction of the experimental curves is depicted with maximum discrepancies observed in the range of 10-15%

Numerical investigation of an innovative furnace concept for industrial coil coating lines

In this work, the engineering performance of an innovative furnace concept developed for continuous drying and curing of paint-coated metal sheets (coil coating process) is investigated through advanced modeling and numerical simulation techniques. Unlike the traditional and wide-spread coil coating furnaces – which operate according to the so-called convective air-drying technology –, the present furnace concept relies on infrared radiative heating to drive solvent evaporation and curing reactions. Radiative heat is provided by the operation of radiant porous burners which are fed with evaporated solvents. The current furnace concept consists of two main chambers (the radiant burner section and the curing oven section) with different gas compositions (atmospheres) that are separated by a semi-transparent window. The window allows energy transfer and prevents gas mixing between the two sections. To utilize the solvent-loaded atmosphere available in the curing oven section as fuel – and to prevent the development of explosive conditions therein –, a novel inertization concept shielding the curing oven section from the external environment is considered. The current furnace concept aims at improving process intensification and promoting energy efficiency. For the current furnace concept, numerical simulation results support a suitable and competitive performance for drying the applied coatings in comparison with the traditional approach. Simultaneously, a safe operation is predicted, without (i) solvent leakage from the furnace and (ii) oxygen entrainment from the surrounding ambient into the furnace. These conditions are satisfied demonstrating a safe operation and a complete evaporation of solvents from applied liquid film coatings

Numerical investigation of an innovative furnace concept for industrial coil coating lines

This research was funded by the European Community's Framework Programme for Research and Innovation Horizon 2020 under grant agreement no. 768692 (ECCO). Publisher Copyright: © 2023 The Author(s)In this work, the engineering performance of an innovative furnace concept developed for continuous drying and curing of paint-coated metal sheets (coil coating process) is investigated through advanced modeling and numerical simulation techniques. Unlike the traditional and wide-spread coil coating furnaces – which operate according to the so-called convective air-drying technology –, the present furnace concept relies on infrared radiative heating to drive solvent evaporation and curing reactions. Radiative heat is provided by the operation of radiant porous burners which are fed with evaporated solvents. The current furnace concept consists of two main chambers (the radiant burner section and the curing oven section) with different gas compositions (atmospheres) that are separated by a semi-transparent window. The window allows energy transfer and prevents gas mixing between the two sections. To utilize the solvent-loaded atmosphere available in the curing oven section as fuel – and to prevent the development of explosive conditions therein –, a novel inertization concept shielding the curing oven section from the external environment is considered. The current furnace concept aims at improving process intensification and promoting energy efficiency. For the current furnace concept, numerical simulation results support a suitable and competitive performance for drying the applied coatings in comparison with the traditional approach. Simultaneously, a safe operation is predicted, without (i) solvent leakage from the furnace and (ii) oxygen entrainment from the surrounding ambient into the furnace. These conditions are satisfied demonstrating a safe operation and a complete evaporation of solvents from applied liquid film coatings.publishersversionpublishe

On the continuous Weber and k-median problems

We give the first exact algorithmic study of facility location problems having a continuum of demand points. In particular, we consider versions of the ''continuous k-means (Weber) problem'' where the goal is to select one or more center points that minimize average distance to a set of points in a demand region. In such problems, the average is computed as an integral over the relevant region, versus the usual discrete sum of distances. The resulting facility location problems are inherently geometric, requiring analysis techniques of computational geometry. We provide polynomial-time algorithms for various versions of the L1 1-mean (Weber) problem. We also consider the multiple-center version of the L1 k-means problem, which we prove is NP-hard for large k

Analyse großer Datenmengen und Clusteralgorithmen im Bausparwesen

Kollektivanalysen und darauf aufbauende Prognosen sind seit langem ein wichtiger Beitrag der Bausparmathematik zu Fragen der Liquiditätsplanung, der Produktpflege und der Produktentwicklung. Im Rahmen einer Kooperation zwischen den Landesbausparkassen und dem Zentrum für Paralleles Rechnen wurden daher Bausparmodelle entwickelt, die der Analyse des Verhaltens der Bausparer und der Vorhersage ihres zukünftigen Verhaltens dienen. Eine Weiterentwicklung dieser Modellansätze mit Hilfe der Clusteranalyse soll in diesem Beitrag vorgestellt werden