Enhancing DPCD in Liquid Products by Mechanical Inactivation Effects: Assessment of Feasibility

The enhancement of standard dense phase carbon dioxide (DPCD) pasteurization by additional mechanical effects was assessed in this work. These effects were induced during pasteurization by the sudden depressurization in a narrow minitube. The high flow velocities, moderate pressures (40–80 bar) and low temperatures (25–45 °C) lead to intense degasification and shear stress. The inactivation of the test microorganism Escherichia coli DH5α (E. coli DH5α) was determined before and after depressurization in the minitube, representing entirely chemical DPCD via dissolved CO₂ and total inactivation comprising the effects of dissolved CO₂ and mechanical effects, respectively. Compared to conventional DPCD pasteurization, which is mostly attributed to chemical effects, the additional mechanical effects increased the inactivation efficiency considerably.     

Kinetische Parameteridentifikation und Modelldiskriminierung am Beispiel der nassen Oxidation von Thiosulfat

Coke technology involves polluted wastewater, which must be treated efficiently in order not to pollute the environment and to comply with legal regulations. This requires a thorough understanding of the process. Due to the large number of possible modifications, sulfur compounds occupy a special position and, thus, knowledge of the reaction pathways and kinetics is essential for the design of apparatuses. By means of parameter estimation and model discrimination, kinetics are determined on the basis of experimental data and reaction schemes of the wet oxidation of thiosulfate are evaluated in order to describe the concentration course of all species with sufficient accuracy.     

Mesostructured Nonwovens with Penguin Downy Feather‐Like Morphology—Top‐Down Combined with Bottom‐Up

Polymer fibers play an important role in nature and technical systems. Fiber morphologies with off‐standing branches, as found in nature, e.g. in penguin downy feathers, provide unique properties but are unknown for man‐made polymer fiber systems. We discovered that it is possible to initiate seeded growth from trisamide seeded polystyrene fibers, prepared by core‐shell electrospinning, to form off‐standing supramolecular trisamide branches similar to penguin downy feathers but in polymer nonwovens and in nanoscale. Resulting mesostructured nonwovens show unique properties. For example, air filtration efficiency of 99.8% for the filtration of 0.3 µm aerosol particles, being significantly higher compared to neat electrospun polystyrene nonwovens as bench‐mark, showing only an efficiency of about 52.6%. Most remarkably, the pressure drop observed in filtration tests and thus, the energy consumption during filtration, did not increase up to a certain content of off‐standing supramolecular fibrils. This is a unique behavior, as higher filtration capabilities are typically connected to higher energy consumptions and pressure drops. Hence, branching electrospun fibers with supramolecular fibrils paves the way to new mesostructured nonwovens with unique morphologies, property profiles and applications in filtration, catalysis, and energy storage/harvesting, exploiting nature's concepts.     

Modellierung einer Einscheibentrockenkupplung mithilfe des C&C2-Ansatzes zur Identifikation von kritischen Gestalt-Funktion-Zusammenhängen bezüglich des Schwingungsphänomens zwangserregtes Kupplungsrupfen

Forschung im Ingenieurwesen - In diesem Beitrag wird ein systematisches Vorgehen zur Identifikation von kritischen Gestalt-Funktion-Zusammenhängen mit Einfluss auf zwangserregtes...     

Resistivity-Based Evaluation of the Fatigue Behavior of Cast Irons

Cast irons are used in particular for highly stressed components in the automotive and commercial vehicle industry, e.g., for crankcases and in the wind power industry, e.g., for rotor hubs. The mechanical properties of cast irons are strongly influenced by parameters like phase composition of the matrix, graphite shape, micro-pinholes, and micro-cracks. The measurement of the electrical resistance in the unloaded state and its change during cyclic loading offers the possibility to get detailed information about the actual defect density and the cyclic deformation behavior. In the scope of the present work, stress-controlled load increase tests and constant amplitude tests were carried out at ambient temperature with specimens of the perlitic cast irons EN-GJL-250 (ASTM A48 35B), EN-GJV-400, and EN-GJS-600 (ASTM 80-55-06). Beside electrical measurements, scanning electron microscopy (SEM) was used to characterize the microstructure and to correlate the change of microstructural details with cyclic properties.     

Setup and experimental validation of a 5 kW HT-PEFC stack

This paper presents a performance analysis of a 5 kW_el high temperature polymer electrolyte fuel cell (HT-PEFC) stack. Stack design and sizing is adapted to auxiliary power unit (APU) applications assuming the use of middle distillates. The parameter study comprises the variation of the fuel type (reformate, with pure hydrogen as a reference), the stoichiometry on the anode (1.3–2.7) and cathode (1.25–4.0) sides and the carbon monoxide (CO) concentration (0.9–3.5%) in the reformate. At 0.5 A cm^?2, a coolant inlet temperature of 160 °C, stoichiometric factors of 1.3 on the anode and 2 on the cathode side and reformate operation, two interconnected full stacks produced 5 kW of electric power. The focus of the present work is an examination of the robustness of the full stacks through an analysis of the 70 single cell voltages. By comparison to other published operational parameter studies, this paper makes a significant contribution to the application of the methodology not to single cells or short stacks, but to a stack with technical relevance in the high power class.     

Adhesive bonding of beech wood modified with a phenol formaldehyde compound

Untreated (controls) and phenol–formaldehyde (PF)-modified beech wood (10 and 25?% solid content) were glued with phenol resorcinol formaldehyde (PRF) and polyvinyl acetate (PVAc). Shear strength of PRF-bonded specimens was higher than that of PVAc-bonded ones under dry and wet conditions irrespective of the pre-treatment. Under dry conditions, only PVAc-bonded specimens exhibited reduction in shear strength due to PF-modification with 25?% PF concentration as compared to the controls. PF treated wood provided inferior bonding under wet conditions with the exception of 25?% PF concentration specimens glued with PRF adhesive. Modification with PF resulted in a decrease of adhesive penetration into the porous network of interconnected cells, especially at 25?% PF concentration.     

Sparse Representation and Visualization for Direct Numerical Simulation of Premixed Combustion

Direct Numerical Simulations of premixed combustion produce terabytes of raw data, which are prohibitively large to be stored, and have to be analyzed and visualized. A simultaneous and integrated treatment of data storage, data analysis and data visualization is required. For this, we introduce a sparse representation tailored to DNS data which can directly be used for both analysis and visualization. The method is based on the observation that most information is located in narrow‐band regions where the chemical reactions take place, but these regions are not well defined. An approach for the visual investigation of feature surfaces of the scalar fields involved in the simulation is shown as a possible application. We demonstrate our approach on multiple real datasets.