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- 6 Materialchemie (855)
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Die BAM ist als Benannte Stelle im Rahmen der europäischen
Richtlinien 97/23/EG über Druckgeräte (PED) [1] und
1999/36/EG über ortsbewegliche Druckgeräte (TPED) [2] bei
der Zertifizierung von Ausrüstungsteilen für Druckgefäße (PED
und TPED), Baugruppen (PED) und der Neubewertung von
Baumustern (TPED) tätig. In diesem Beitrag wird die Zertifizierung
einschließlich der dabei gewonnenen Erfahrungen
und in der Praxis auftretenden Problemen auf Seiten der
Hersteller und Benannten Stellen bei der Zertifizierung nach
diesen europäischen Richtlinien vorgestellt. Die wesentlichen
Probleme ergeben sich aus der Zuordnung der Druckgeräte
zu entsprechenden Kategorien innerhalb der Richtlinien und
aus der Überschneidung mit anderen europäischen und
nationalen Richtlinien.
Die neue Europäische Richtlinie über ortsbewegliche Druckgeräte - Was kommt, was geht, was bleibt?
(2010)
Im Vortrag wird auf die rechtlichen Grundlagen der Richtlinie 2010/35/EU eingegangen. Dies umfasst die Definition von ortsbeweglichen Druckgeräten, die an sie gestellten technischen Anforderungen und die Anforderungen an deren Konformitätsbewertung. Des Weiteren wird die Anwendung der Richtlinie auf Feuerlöscher und deren Treibgasflaschen diskutiert
Im Vortrag wird auf die aktuellen Anforderungen aus dem Gefahrgutbeförderungsrecht an Ventilschutz einschließlich Schutzkragen als integraler Bestandteil einiger Gasflaschen und LPG-Sicherheitsventilen eingegangen. Des Weiteren werden die aktuell laufenden Revisionen der Normen EN ISO 11117 für Ventilschutz und EN 13953 für LPG-Sicherheitsventile diskutiert.
Im Vortrag wird auf die rechtlichen Grundlagen der Richtlinie 2010/35/EU eingegangen. Dies umfasst die Definition von ortsbeweglichen Druckgeräten, die an sie gestellten technischen Anforderungen und die Anforderungen an deren Konformitätsbewertung. Des Weiteren wird die Anwendung der Richtlinie auf Feuerlöscher und deren Treibgasflaschen sowie die damit verbundenen Probleme in der Praxis diskutiert.
Im Vortrag wird auf die rechtlichen Grundlagen der Richtlinie 2010/35/EU eingegangen. Dies umfasst die Definition von ortsbeweglichen Druckgeräten, die an sie gestellten technischen Anforderungen und die Anforderungen an deren Konformitätsbewertung. Des Weiteren wird die Anwendung der Richtlinie auf Feuerlöscher und deren Treibgasflaschen sowie die damit verbundenen Probleme in der Praxis diskutiert.
Geothermal brine is considered to be an aggressive
environment as it contains various dissolved salts.
Even though carbon steel is commonly used as a
construction material due to its machinability and
economical reason, it is susceptible to uniform and
localized corrosion in a high temperature and high
pressure system. Therefore, a coating system is
introduced to protect the carbon steel against
corrosion in such environment.
1. Carbon steel is susceptible to uniform corrosion in presence of oxygen, with corrosion rate of immersion at 150 °C of 0.39 mm/a.
2. Exposure test of carbon steel at 150°C and 10 bar (pressurized by Ar) results in pitting corrosion with depth of 19 µm and width 4 µm on average.
3. OCP measurement shows that the stability of measurement is reached after 40 hours of immersion in the solution.
4. EIS measurement is useful to observe the effect of temperature, immersion time, and coating composition on the corrosion processes of coated metals for use in geothermal application.
Fireside Chat - Sharing PhD
(2019)
Geothermal brine is a complex system containing a wide variety of dissolved salts resulting from the condition s in a geothermal well. These fluids lead to corrosion in pipes and other parts of geothermal system construction and necessitate intense research efforts in finding new suitable materials. Carbon steel is susceptible to corrosion in geothermal brine especially when it is exposed to a high temperature and high-pressure medium, which is considered to be an aggressive environment. An artificial geothermal water, bas ed on a brine composition found in Indonesia, was used to investigate the performance of high alloyed materials. The electrolyte has pH 4 and contains 1,500 mg/l Cl-, 20 mg/l SO4 2-, 15 mg/l HCO3 -, 200 mg/l Ca 2+, 250 mg/l K+, and 600 mg/l Na+. In order to protect the bare material in geothermal application, it is necessary to either use high alloyed material s or coatings. In this research, a coating system consisting of polyaniline and silicon dioxide was investigated regarding its behavior to protect carbon steel. In detail, the effect of SiO2 and polyaniline (PANi) addition was evaluated by exposure and electrochemical tests for 7 days, i.e. electrochemical impedance spectroscopy (EIS) and open circuit potential (OCP) at room temperature and 150 °C with 1 MPa pressure.
According to the results of the experiments carried out, the following points can be concluded:
1. Exposure tests showed that specimens with the addition of SiO2 particles and polyaniline particles exhibit better corrosion resistance than specimens with the addition of only polyaniline particles or binder only.
2. Open circuit potential measurements showed that in the beginning of the experiments, both coatings had an open circuit potential 100 mV higher than carbon steel. Within one day of immersion, the potential of carbon steel increased significantly, indicating the formation of oxide layer. After extended exposure the carbon steel potential sat between PS1 (which had higher potential) and PS2 (which had a lower potential) and all three were in the range –600 mV to –500 mV vs Ag/AgCl.
3. Both coatings PS-1 and PS-2 were degraded with increasing exposure time, shown by the decrease of absolute impedance value at low frequency range after 2, 4, and 6 days exposure.
4. Potentiodynamic test was performed after 3 hours and 6 days exposure, and it was shown that the coating in the initial stage exhibited more passive behavior than the specimens exposed for 6 days.
Electrochemical deposition of polyaniline on carbon steel for corrosion study in geothermal solution
(2018)
Polyaniline has been widely developed for many applications, e.g., sensor, supercapacitor component, electrochromic devices, and anticorrosion pigments [1]. Although the addition of polyaniline pigment in organic coatings has been an alternative for corrosion protection in industrial application, the protection mechanism is still not fully understood [2]. Herein in this study, as a part of the development of polyaniline/silicon dioxide coating for geothermal application, polyaniline has been deposited electrochemically on carbon steel surface and tested in geothermal solution to study the contribution of polyaniline in the corrosion protection of a polyaniline-based composite in the geothermal system. The electrochemical deposition was carried out by immersing carbon steel in 0.1 M oxalic acid and 0.05 M aniline, with the polarization potential of -0.6 – 1.5 V vs. Ag/AgCl, and a scan rate of 10 mV/s. To observe the surface/interface reaction between the electrolyte and electrode surface during the electrochemical polymerization, electrochemical impedance spectroscopy (EIS) measurement was applied after each cycle. For corrosion study in the geothermal application, this experiment used an artificial geothermal solution with the composition of 1,500 mg/l Cl-, 20 mg/l SO42-, 15 mg/l HCO3-, 200 mg/l Ca2+, 250 mg/l K+, and 600 mg/l Na+, and pH 4 to simulate a geothermal brine found in Sibayak, Indonesia. Electrochemical measurements were performed by monitoring the open circuit potential over seven days, with the interruption of EIS every 22 hours. The experiments were performed at room temperature and 150 °C (1 MPa) in a free oxygen environment. Polyaniline coated carbon steel is more durable in a room temperature environment compared to 150 °C, which could be caused by the iron oxalate dissolution at elevated temperature. This degradation was further proven by the impedance spectra, which showed a reduction of approximately ten times for specimens measured at 150 °C as compared to the specimens measured at room temperature.
The determination of the blast protection level of civil engineering buildings components
against explosive effects represents a topic of crucial importance, in current practice. However, some key aspects of blast resistant structures design have been only marginally considered in the last decade, and currently still require appropriate regulations. This is especially true in the case of windows and facades, where the intrinsic material brittleness is the major influencing parameter for blast-resistant assemblies. While blast assessment of buildings and systems is usually achieved by means of experimental investigations, as well as numerical simulations, general regulations and guidelines are currently missing.
In this regard, the European Reference Network for Critical Infrastructure Protection (ERNCIP) Thematic Group “Resistance of Structures to Explosion Effects” attempts to develop guidelines and recommendations aimed to harmonise test procedures in experimental testing of glass windows under blast, as well as standardized approaches for their vulnerability assessment via numerical modelling. In this paper, major Thematic Group outcomes and next challenges are briefly summarized.
Mathematical analysis of the bulging effect in high power laser beam welding of thick steel sheets
(2021)
The present work is devoted to the mathematical analysis of the bulging effect in high-power laser beam welding of thick steel sheets. The numerical results are based upon experimental results from previous studies, revealing the relationships between the bulging effect, the hot cracking formation, and the distribution of alloying elements in the weld pool. The widening of the molten pool in its middle area is observed for both complete and partial penetration welding of 8 mm - 15 mm thick structural steel sheets. The weld pool shape is extracted from the simulations to evaluate the extent of the necking and bulging of the solidification isotherm and their influence on the hot cracking formation and the mixing behavior of the weld pool. Relying on an earlier numerical study utilizing a fixed keyhole, simulation models considering a dynamic keyhole are developed thereto. The link between the bulge and the studied phenomena is found to be significant.
Ein neuartiger Modellierungsansatz für die Berechnung des transienten Temperaturfeldes beim Laserstrahlschweißen mit einer äquivalenten Wärmequelle wurde vorgestellt. Das numerische Modell wurde in zwei Studien unterteilt. Im ersten Teil wurde der Laserstrahlschweißprozess in einer stationären Schmelzbadsimulation untersucht. Die lokale Schmelzbadgeometrie und das Temperaturfeld wurden unter Berücksichtigung der Effekte der thermokapillaren und freien Konvektion, der latenten Wärme und der temperaturabhängigen Materialeigenschaften bis hin zur Verdampfungstemperatur ermittelt. Die Ergebnisse wurden benutzt, um eine äquivalente volumetrische Wärmequelle zu definieren. In der folgenden Studie wurde damit das transiente Temperaturfeld im geschweißten Bauteil berechnet. Die numerischen Ergebnisse wurden durch parallel laufende Experimente validiert.
Transient process simulation of heat transfer in laser beam welding with an equivalent heat source
(2017)
A multi-physics modelling framework developed for the prediction of the three-dimensional transient temperature field of the laser welding process is presented. The numerical model consists of two studies. In the first study, a steady-state CFD process simulation of full-penetration keyhole laser beam welding was performed. Considering the effects of latent heat, natural and thermo-capillary convection and temperature-dependent material properties up to evaporation temperature the local weld pool geometry and temperature field were obtained. These results were used in the second subsequent study, as an equivalent volumetric heat source, by the prediction of the transient thermal cycle during and after fusion welding. Here the energy input and the movement of the heat source were realized by a novel technique, making use of pointwise constraints and a moving mesh provided with helper lines and additional remeshing condition. The numerically calculated results were compared to experimentally observed weld pool shapes and time-temperature curves and show a very good agreement.
A simplified model for numerical simulation of laser metal deposition process with beam oscillation
(2018)
A simplified model for the numerical simulation of the laser metal deposition process with beam oscillation is proposed. The model studies circular and lateral oscillations in order to reduce the porosity of the deposited part, to increase the process efficiency and the gap bridging ability as well. The deposition rate is increased by modifying the shape and the width of the molten pool through an optimized laser beam power distribution and oscillation amplitude. The relationship between the process conditions and the shape of the fabricated part are determined. It is found that an increase of the amplitude by a lateral oscillation of the beam reduces the heat flux and hence the shape of the deposited wall. A good correlation between the numerically calculated results and the experimental measurements is obtained.
This work aims to find the thermal cycles during and after fusion welding through simulation by first calculating the resulting local temperature field in the quasi-stationary part of the process. Here complete-penetration keyhole laser beam welding with a laser power of 18 kW on a 15 mm thick slab of a low-alloyed steel at a welding speed of 2 m/min is considered. In order to physically depict the laser material interaction a multi-physics numerical model including the effects of phase transformation, thermo-capillary convection, natural convection and temperature-dependent material properties up to evaporation temperature is developed.
It uses a fixed keyhole geometry with a right truncated circular cone shape to introduce the laser beam energy to the workpiece. In a subsequent study, the resulting local temperature field is then used as an equivalent heat source in order to predict the unsteady thermal cycle during and after fusion welding. The translational movement of the laser beam through the workpiece is represented by a moving mesh approach. For the simulation, stationary heat transfer and fluid dynamics are described by a system of strongly coupled partial
differential equations. These are solved with the commercial finite element software COMSOL Multiphysics 5.0. The results of the numerical simulation are validated by experiments, where the weld bead shapes and the thermal cycles show good correlation.
Der vorgestellte Modellierungsprozess dient zur Abschätzung einer geeigneten äquivalenten Wärmequelle und Berechnung des thermischen Verhaltens beim Laserstrahlschweißen. Die Methode Kombiniert die Vorteile von gägngigen Simulationsverfahren und reduziert die berücksichtigte Anzahl an physikalischen Aspekten und Kalibrierungsparameter. Durch die modellierten physikalischen Phänomene konnten die Informationen über die Strömung im Schmelzbad und dessen Einfluss auf die resultierende lokale Temperaturverteilung und folglich auf das transiente Temperaturfeld gewonnen werden. Dadurch wurde die Simulatioszeit(inkl. Kalibrierungsaufwand) auf weniger als einen Tag Rechenzeit verringert.
A transient simulation including the impact of the laser energy, the melting of the metal and the development of the weld pool was conducted to observe the evolution of the vapor capillary and the solidification of the melt in pulsed laser beam welding of AISI 304 steel. The phase field method was implemented to investigate the evolution and behavior of the liquid-gas interface during welding and to describe the condensed and vapor phases. The effects of phase transition, recoil pressure, thermo-capillary and natural convection, vaporization and temperature dependent material properties were taken into account. A Gaussian-like heat source under consideration of the Fresnel absorption model was used to model the energy input of the laser beam. The heat source model was extended by a newly developed empirical approach of describing multiple beam reflections in the keyhole. To validate this new model, the numerical results were compared to experimental data and good agreement regarding the size and shape of the weld pool was observed.
The present work deals with the recently confirmed widening of the weld pool interface, known as a bulging effect, and its relevance in high power laser beam welding. A combined experimental and numerical approach is utilized to study the influence of the bulge on the hot cracking formation and the transport of alloying elements in the molten pool. A technique using a quartz glass, a direct-diode laser illumination, a high-speed camera, and two thermal imaging cameras is applied to visualize the weld pool geometry in the longitudinal section. The study examines the relevance of the bulging effect on both, partial and complete penetration, as well as for different sheet thicknesses ranging from 8 mm to 25 mm. The numerical analysis shows that the formation of a bulge region is highly dependent on the penetration depth and occurs above 10 mm penetration depth. The location of the bulge correlates strongly with the cracking location. The obtained experimental and numerical results reveal that the bulging effect increases the hot cracking susceptibility and limits the transfer of alloying elements from the top of the weld pool to the weld root.
Numerical study on the formation of a bulging region in partial penetration laser beam welding
(2022)
A transient three-dimensional thermo-fluid dynamics numerical model was developed to study the formation of a bulging region in partial penetration laser beam welding. The model accounts for the coupling between the fluid flow, the heat transfer, and the keyhole dynamics by considering the effects of multiple reflections and Fresnel absorption of the laser beam in the keyhole, the phase transitions during melting and evaporating, the thermo-capillary convection, the natural convection, and the phase-specific and temperature-dependent material properties up to the evaporation temperature. The validity of the model was backed up by experimentally obtained data, including the drilling time, the weld pool length, the local temperature history outside the weld pool, the process efficiency, and a range of metallographic cross-sections. The model was applied for the cases of partial penetration laser beam welding of 8 mm and 12 mm thick unalloyed steel sheets. The obtained experimental and numerical results reveal that the bulging region forms transiently depending on the penetration depth of the weld, showing a tendency to transition from a slight bulging to a fully developed bulging region between penetration depths of 6 mm and 9 mm, respectively.
Recent studies have confirmed the widening of the weld pool interface, known as a bulge effect, during deep penetration high power laser beam welding. The link between such geometric particularities of the weld pool shape and the hot cracking phenomena is significant. The present work seeks to extend the level of understanding by investigating their relationship. A coupled multiphysics, multiscale numerical framework is developed, comprising a series of subsequent analyses. The study examines the influences of the bulge on the three most dominant effects causing hot cracking, namely the thermal cycles, the mechanical loading, and the local microstructure. The bulge in the weld pool shape forms approximately in the middle of the plate, thus correlating with the location of hot cracking. It increases the hot cracking susceptibility by enhancing the three dominant effects. The numerical results are backed up by experimental data.
This article is devoted to the study of the bulging effect in deep penetration laser beam welding. The numerical results of the investigations are based upon experimental results from previous studies to reveal the relationship between the bulging effect and the hot cracking formation, as well as the mixing of alloying elements in the weld pool. The widening of the molten pool in its center area can be observed in full penetration as well as in partial penetration welds on 8 mm and 12 mm thick structural steel plates, respectively. The weld pool shape is extracted from the simulations to evaluate the extent of the necking of the solidification line as well as the bulging phenomena and its influence on the hot cracking phenomena. Relying on an earlier numerical study utilizing a fixed keyhole, simulation models considering a dynamic keyhole are developed thereto. Additionally, the mixing behavior of alloying elements during partial penetration is investigated. The link between the bulge and the studied phenomena is found to be significant.
The shape of the weld pool in laser beam welding plays a major role to understand the dynamics of the melt and its solidification behavior. The aim of the present work was its experimental and numerical investigation. To visualize the geometry of the melt pool in the longitudinal section a butt joint configuration of 15 mm thick structural steel and transparent quartz glass was used. The weld pool shape was recorded by means of a high-speed video camera and two thermal imaging MWIR and VIS cameras. The observations show that the dimensions of the weld pool vary depending on the depth. The regions close to the surface form a teardrop shaped weld pool. A bulge-region and its temporal evolution were observed approximately in the middle of the depth of the weld pool. Additionally, a transient numerical simulation was performed until reaching a steady state to obtain the weld pool shape and to understand the formation mechanism of the observed bulging phenomena. A fixed keyhole with an experimentally obtained shape was used to represent the full-penetration laser beam welding process. The model considers the local temperature field, the effects of phase transition, thermo-capillary convection, natural convection and temperature-dependent material properties up to evaporation temperature. It was found that the Marangoni convection and the movement of the laser heat source are the dominant factors for the formation of the bulging-region. Good correlation between the numerically calculated and the experimentally observed weld bead shapes and the time-temperature curves on the upper and bottom surface were found.
The weld pool dynamics and shape play a fundamental role in keyhole mode welding. The presented work aims the experimental and numerical investigation of the influence of the weld pool characteristics on the formation of hot cracking. The experimental procedure allows recording the molten pool in the longitudinal section of a butt joint configuration of 15 mm thick structural steel and transparent quartz glass by using a high-speed video camera and two thermal imaging cameras. The observations show that the dimensions of the weld pool vary depending on the depth. The regions close to the surface form a teardrop-shaped weld pool. A bulge-region and its temporal evolution are observed approximately in the middle of the depth of the weld pool, where hot cracking appears. A numerical framework including models for the weld pool dynamics, global temperature field, transient stress state, crystal growth, diffusion and macro-segregation and subroutines for their one-way couplings is developed. The numerically obtained and experimentally observed results are in a good agreement. It is shown that the bulge-region leads to a delay in the solidification behavior, increased temporal tensile stresses and accumulation of impurities in the defect region and hence enhance the probability of hot cracking formation.
The weld pool dynamics and shape play a fundamental role in keyhole mode welding. The presented work aims the experimental and numerical investigation of the influence of the weld pool characteristics on the formation of hot cracking. The experimental procedure allows recording the molten pool in the longitudinal section of a butt joint configuration of 15 mm thick structural steel and transparent quartz glass by using a high-speed video camera and two thermal imaging cameras. The observations show that the dimensions of the weld pool vary depending on the depth. The regions close to the surface form a teardrop-shaped weld pool. A bulge-region and its temporal evolution are observed approximately in the middle of the depth of the weld pool, where hot cracking appears. A numerical framework including models for the weld pool dynamics, global temperature field, transient stress state, crystal growth, diffusion and macro-segregation and subroutines for their one-way couplings is developed. The numerically obtained and experimentally observed results are in a good agreement. It is shown that the bulge-region leads to a delay in the solidification behavior, increased temporal tensile stresses and accumulation of impurities in the defect region and hence enhance the probability of hot cracking formation.
The geometrical characteristics of the weld end crater are commonly used for the validation of numerical results in welding simulation. A semi-analytical model calculating the cooling stage of the welding process after the moving energy source is turned off has been developed. A solution for various combinations of heat sources and workpieces has been found. The theoretical limits for the heat transfer of the absorbed energy during cooling in a thin plate and a semi-infinite body were studied. It is shown that after turning off the energy source, an additional melting of the base material in longitudinal direction may occur. The developed technique is applied to complete-penetration keyhole laser beam welding of a 2 mm thick austenitic chromium-nickel 316L steel plate at a welding speed of 20 mm/s and a laser power of 2.3 kW. The results show a theoretical increase of the weld end crater length in comparison to the length of the steady-state weld pool of up to 19 %. A shift of the centre of the end crater, in which the solidification of the liquid metal ends, towards the tail of the end crater relative to the axis of the heat source at the time of its termination, was computed. The speed and the direction of crystallization of the molten material in the weld pool and the end crater were found to be different. A good agreement between the computational results and the welding experiments was achieved.
A numerical framework simulation of the steady-state thermal behaviour in keyhole mode welding has been developed. It is based on the equivalent heat source concept and consists of two parts: computational thermo-fluid dynamics and heat conduction. The solution of the thermo-fluid dynamics problem by the finite element method for a bounded domain results in a weld pool interface geometry being the input data for a subsequent heat conduction problem solved for a workpiece by proposed boundary element method. The main physical phenomena, such as keyhole shape, thermo-capillary and natural convection and temperaturedependent material properties are taken into consideration. The developed technique is applied to complete-penetration keyhole laser beam welding of a 15 mm thick low-alloyed steel plate at a welding speed of 33 mm/s and a laser power of 18 kW. The fluid flow of the molten metal has a strong influence on the weld pool geometry. The thermo-capillary convection is responsible for an increase of the weld pool size near the plate surfaces and a bulge formation near the plate middle plane. The numerical and experimental molten pools, cross-sectional weld dimensions and thermal cycles of the heat affected zone are in close agreement.
Thermoresponsive polymers have shown great potential in applications such as bioseparation, drug delivery and diagnostic. Only few thermoresponsive polymers that present an upper critical solution temperature (UCST) in a relevant temperature range, i.e. phase separate from solution upon cooling, have been reported so far. Moreover, the most studied UCST type polymers namely polybetaines are difficult to use under physiological conditions, which significantly restricts their potential applications. Therefore, UCST polymers with sharp and robust phase transition in physiological conditions (in the presence of salts, ions etc.) are highly needed in order to extend the range of applications of this class of polymers. Herein, a robust UCST-type copolymer of acrylamide (AAm) and acrylonitrile (AN) (poly(AAm-co-AN)) was prepared by reversible addition fragmentation chain transfer (RAFT) polymerization and its thermo-induced aggregation behavior in aqueous media was studied. At temperature below the UCST, the copolymer chains were aggregated together. The aggregate size was found to be larger with increasing AN contents and became smaller upon dilution of the copolymer solutions. While above the UCST, the copolymer chains were expanded and weekly associated in solution. The association between the copolymer chains formed smaller aggregates with increasing the AN contents or the dilution of the solutions. A model is proposed to explain such aggregation-association behavior of the Fig. 1.
Figure 1. Schematic illustration of the proposed thermos-induced aggregation behavior of the poly(AAm-co-AN) in aqueous solution.
Atherosklerotische Läsionen können durch Magnetresonanztomographie (MRT) unter Verwendung von sehr kleinen Eisenoxidnanopartikeln (VSOP) sichtbar gemacht werden. VSOP akkumulieren in atherosklerotischen Plaques und dienen somit als Atherosklerosesonde.
Das Ziel dieses Projektes war die Abbildung der Verteilung von Europium-dotierten VSOP (Eu-VSOP) durch Laserablation ICP-MS in histologischen Dünnschnitten der Aortenwurzelregion des ApoE-Knockout-Mausmodells, das reich an atherosklerotischen Plaques ist. Darüber hinaus wurde untersucht, ob die VSOP-Akkumulation in den Plaques mit anderen Biomarkern der Entzündung wie Makrophagen und verändertem Endothel korreliert. Somit wäre eine Beurteilung, ob es sich hierbei um instabile bzw. vulnerable Plaque-Regionen handelt möglich. Zu diesem Zweck wurden Antikörper mit verschiedenen Lanthaniden markiert und mit der Eu-VSOP-Verteilung unter Verwendung von LA-ICP-MS in einem Multiplex-Messmodus korreliert.
Eine mögliche Korrelation von reaktiven Stickstoffspezies (RNS) mit endogenem Eisen oder Eu-VSOP kann ebenfalls durch LA-ICP-MS nachgewiesen werden. Zu diesem Zweck wurden RNS-spezifische Antikörper auch mit Lanthaniden markiert.
Small, mobile propane gas vessels are widely spread and comprise additional hazards in case of a surrounding, intensive fire. The aim of the presented work is to holistically investigate the potential consequences of failure of these off-the-shelf propane gas vessels in case of an absence or malfunction of safety devices. In order to generate a statistically valid dataset, a total of 15 identical propane gas bottles without pressure relief device, each containing m = 11 kg of liquid propane, were underfired in horizontal position. For each selected fire type (wood fire, petrol pool fire, propane gas fire), five vessels were tested under identical conditions. Next to extensive camera equipment including a high-speed camera, systems to record the internal pressure of the gas cylinder, the resulting shock wave overpressure (three positions) and the flame and vessel temperature (three + three positions) during the underfiring were used. Also the unsteady, highly dynamical thermal radiation caused by the explosion of the expanding gas cloud was logged. The fragments were georeferenced and weighed after each test. The experiments prove the failure of all the gas cylinders at a burst pressure of pb = [71 … 98 bar] with a fragmentation into up to seven parts (average: four objects) and a subsequent explosion of the expanding vapour after mixing with the surrounding air. The overpressure measured in the close-up range (distance to the cylinder d = 5 m) resulting from the shockwave caused by the cylinder burst was up to pmax = 0.27 bar, which can potentially lead to significant injuries to humans and damage to building structures and infrastructure, especially in connection with the explosion and the resultant thermal radiation. The distance covered by the fragments after the failure was up to r = 260 m; 47% of the fragments hit the ground more than r = 50 m away from the position of failure.
In this presentation the current focus areas of the competence centre H2Safety@BAM are shown. The fields of competence include “Material properties and compatibility”, “Process and plant safety”, “Component testing, component safety and approval” as well as “Sensors, analytics and certified reference Materials. Moreover, the cross-cutting activities regarding “Education and training” and the testing possibilities and planed test facilities at the Test Site for Technical Safety (BAM TTS) are presented.
In dem hier vorgestellten Projekt wurde die Wirksamkeit mechanischer Schläge als Zündquelle für wasserstoffhaltige Atmosphären in Abhängigkeit von der inhomogenen Materialpaarung systematisch untersucht. Dabei wurden praxisrelevante Materialien wie Edelstahl, niedrig legierter Stahl, Beton und Nichteisenmetalle betrachtet. Es wurde festgestellt, dass eine Zündung vermieden werden kann, wenn Nichteisenmetalle in Kombination mit verschiedenen metallischen Werkstoffen verwendet werden. In Kombination mit Beton muss die kinetische Schlagenergie auch mit Nichteisenmetallen weiter begrenzt werden, um eine wirksame Entzündung zu vermeiden. Außerdem wurde untersucht, wie sich die Beimischung von Wasserstoff zu Erdgas auf die Wirksamkeit mechanischer Stöße als Zündquelle auswirkt. Bei Beimischungen von bis zu 25 % Wasserstoff und sogar mehr konnte kein Einfluss festgestellt werden. Die Ergebnisse sind vor allem relevant im Zusammenhang mit der Umwidmung des Erdgasnetzes oder der Beimischung von Wasserstoff im Erdgasnetzes.
The effects of hydrogen admixture to natural gas on explosion regions, explosion group classification, explosion severity and on areas with explosive mixtures in case of gas release was studied experimentally. With increasing hydrogen fractions the mixtures become mainly more "critical", but up to 10 mole% hydrogen the influence on the safety characteristics are very low. By using appropriate calculation methods some of the safety characteristics could be calculated with good accuracy.
LEL, UEL LOC, MESG, pmax and (dp/dt)max of hydrogen/natural gas-mixtures were determined systematically according to international standards.
Mixtures of natural gas and hydrogen mainly become more „critical“ with increasing hydrogen fraction.
The effect of up to 10 Vol% H2–admixture to natural gas on safety characteristics is very low, no major adaption of existing measures for explosion protection is necessary.
More substantial adjustment of measures for explosion protection is necessary at hydrogen fractions of more than 25 Vol%.
Some of the safety characteristics can be estimated with good accuracy by calculation methods.
Im Vortrag werden zum einen sicherheitstechnische Aspekte bei der Herstellung von Gasgemischen aus geringen Anteilen an Lachgas und brennbaren Gasen diskutiert. Zum anderen werden allgemein Vorgehensweisen und Berechnungsmethoden zur sicherheitstechnischen Beurteilung der Herstellung von Gasgemischen mit brennbaren und oxidierenden Komponenten vorgestellt.
Im Vortrag wird auf die sicherheitstechnische Beurteilung in Hinblick auf den Explosionsschutz bei der Herstellung und Füllung von Gasgemischen mit brennbaren und mit oxidierenden Komponenten eingegangen. Anhand von Beispielen werden u.a. Vorgehensweisen und Berechnungsmethoden beschrieben, anhand derer beurteilt werden kann, ob Gasgemische überhaupt sicher hergestellt werden können und in welcher Reihenfolge die Komponenten zur sicheren Herstellung der Gemische gefüllt werden sollten.
Sicherheitstechnische Kenngrößen von Erdgas/Wasserstoff-Gemischen bei der Power-to-Gas-Technologie
(2015)
The presentation is divided in two parts. In the first part the significance of mechanical impacts as ignition source for hydrogen containing atmospheres is shown and recent results of a research project evaluating ignition probabilities under different conditions is presented. In the second part future challenges in the field of hydrogen safety are discussed. Finally, the German National Hydrogen Safety Alliance is introduced.
This is a digital lecture on Explosion Protection for Hydrogen Applications. It was designed in context with the project "KICstartH2 Accelerating Sustainable Hydrogen Uptake Through Innovation and Education" and integrated in a teaching module of the University of Birmingham. It is divided in five parts: Introduction, Avoiding Explosive Mixtures, Avoiding Ignition Sources, Mitigation of Consequences and Summary & Comparison.
In this presentation the results of the Project HySpark are shown. Mechanical impacts are among the important possible ignition sources to be considered in explosion protection. Hydrogen is particularly prone to be ignited by mechanical impacts compared to natural gas. The effectivity of mechanical impacts as ignition source is dependent from different parameters. In this work the effectivity of impacts as an ignition source for hydrogen containing atmospheres was studied experimentally depending on the inhomogeneous material pairing of the impact. Moreover it was studied, how the effectivity of mechanical impacts as ignition source changes when hydrogen is added to natural gas.
In this presentation the drivers for the rise of hydrogen technologies are outlined and main challenges for the market ramp-up are shown. Finally, the activities and capabilities of the competence center H2Safety@BAM are characterized and some of the current projects at BAM adressing the main challenges for hydrogen technologies are presented focussing on the hydrogen transport and infrastructure.
In this lecture the safety related properties of hydrogen and hydrogen mixtures and explosion protection measures are shown and compared with other fuel gases. Measures for primary explosion protection (avoiding flammable mixtures), secondary explosion protection (avoiding ignition sources) and constructive explosion protection (mitigating the consequences of explosions) when handling hydrogen and hydrogen mixtures are presented.
The Joint European Summer School JESS 2022 addresses these issues by offering high quality graduate level courses on selected topics of vehicle technology, innovation & business development, safe handling of hydrogen, and modelling. The course content is tailored to the needs of a diverse audience: newcomers to the field, experienced students, and young professionals working at the forefront of fuel cell and hydrogen applications.
In this presentation the capabilities and different research activities at BAM in the field of hydrogen safety are outlined. A deep dive focussing the transport of hydrogen in pipelines adressing issues on material compatibility, gas quality and test methods is presented. Another deep dive is presented focussing on safety aspects of liquid hydrogen adressing issues of rapid phase transition (RPT) and Boiling liquid expanding vapour explosion (BLEVE). Finally a brief overview on other safety related research activities is given.
Hydrogen differs from most other flammable gases regarding the safety related properties. Mainly the minimum ignition energy (MIE) is particularly low and the burning velocity is particularly high. Hydrogen mixtures are formed in different hydrogen applications, for example if hydrogen is added to the existing natural gas grid, if synthetic gas (mixture of CO and H2) is produced or in biogas plants. Safety related properties of hydrogen mixtures were determined experimentally and are presented in this presentation. Moreover the accuracy of estimation methods for safety related properties of hydrogen mixtures is evaluated.”
Wasserstoff unterscheidet sich hinsichtlich der sicherheitstechnischen Eigenschaften von anderen brennbaren Gassen, v.a. durch die sehr niedrige Mindestzündenergie und die sehr hohe Flammengeschwindigkeit. Durch Beimischung von Wasserstoff zum Erdgas ändern sich die sicherheitstechnischen Eigenschaften zum Teil in kritischer Richtung. Bis zu einem Wasserstoffanteil von 10 Mol-% im Erdgas ist aber keine wesentliche Anpassung der Maßnahmen für den Explosionsschutz erforderlich. Synthesgas ist ein weiteres Wasserstoffgemisch das in Zukunft vermutlich zunehmend relevant sein wird. Die beiden Komponenten Wasserstoff und Kohlenmonoxid haben zwar in mancher Hinsicht ähnliche sicherheitstechnische Eigenschaften unterscheiden sich aber auch sehr stark bzgl. der Mindestzündenergie und der Flammengeschwindigkeit.
Im Vortrag werden aktuelle Entwicklungen bei verschiedenen Elektrolysetechnologien kurz vorgestellt. Dann werden für Elektrolyseanlagen spezifische Gefährdungen diskutiert, v.a. die im Zusammenhang mit den Eigenschaften der Gase Wasserstoff und Sauerstoff stehen. Dabei wird auch Bezug auf die Normung- und Regelsetzung genommen und Sicherheitskonzepte werden beispielhaft kurz vorgestellt. Abschließend wird auf Unfallereignisse im Zusammenhang mit der Elektrolyse eingegangen.
Im Projekt HySpark wird die Wirksamkeit mechanischer Schlagvorgänge beim Aufprall von unterschiedlichen Werkstoffen als Zündquelle für wasserstoffhaltige Atmosphären experimentell untersucht. Zum Einen wird die Zündwirksamkeit bei Wasserstoff/Luft-Gemischen in Abhängigkeit der Werkstoffpaarung untersucht. Dabei konnte v.a. festgestellt werden, dass bei Schlagvorgängen von Nicht-Eisen-Metallen mit verschiedenen Stahlsorten die wirksame Zündung vermieden werden kann. Jedoch können bei Schlagvorgängen mit Estrichbeton hohe Zündwahrscheinlichkeiten beobachtet werden. Zum anderen wird der Einfluss von Wasserstoffbeimischungen im Erdgasnetz auf die Zündwirksamkeit von mechanischen Schlägen untersucht. Bei Anteilen bis 25% Wasserstoff konnte bei den Versuchen kein Erhöhung der Zündwahrscheinlichkeit festgestellt werden.
Hinsichtlich ihrer sicherheitstechnischen Kenngrößen (STK) unterscheiden sich Wasserstoff und Erdgas zum Teil stark. Im Vortrag werden verschiedene STK von Erdgas/Wasserstoff-Gemischen im Abhängigkeit des Wasserstoffanteils vorgestellt und die Auswirkung der Beimischung von Wasserstoff zum Erdgas auf die Wirksamkeit von Explosionsschutzmaßnahmen erläutert.
In this lecture the safety related properties og hydrogen compared to other fuel gases and the explosion protection measures of avoiding flammable mixtures, avoiding ignition sources and mitigating the consequences of explosions when handling hydrogen and hydrogen mixtures are presented.
The Joint European Summer School JESS 2021 addresses these issues by offering high quality graduate level courses on selected topics of vehicle technology, innovation & business development, safe handling of hydrogen, and modelling. The course content is tailored to the needs of a diverse audience: newcomers to the field, experienced students, and young professionals working at the forefront of fuel cell and hydrogen applications.
Ergänzend zu früheren Arbeiten. in denen die Explosionsbereiche für Brenngase aus der homologen Reihe der Alkane und Alkene berechnet worden sind, wurden Ergebnisse der Berechnungen für 1-Propanol, Aceton und Difluormethan vorgestellt. Für die Berechnung ist das Modell erweitert worden. so dass auch die Transporteigenschaften der Gasgemische berücksichtigt werden.
Weiterhin ist eine neue Methode zur Berechnung der Spitze des Explosionsbereichs implementiert worden. Die Ergebnisse zeigen. dass die Berechnung der Explosionsbereiche für Alkohole. Ketone und halogenierte Kohlenwasserstoffe mit ähnlicher Genauigkeit wie für Alkane und Alkene möglich ist.
Lachgas kann als Medium in Kälteanwendungen unter -50 °C eingesetzt werden. Da ein explosionsartiger Zerfall von Lachgas bei erhöhtem Druck möglich ist, sind bei entsprechenden Anwendungen Explosionsgefahren zu beachten. Im Vortrag wurden die Voraussetzungen und die Einflussgrößen für den explosionsartigen Zerfall von Lachgas, wie Temperatur, Druck, Geometrie und Zündenergie vorgestellt und diskutiert. Weiterhin wurden Versuchsergebnisse zur Untersuchung des Einflusses geringer Mengen an brennbaren Komponenten (Propan und Öl-Nebel) auf die Explosionseigenschaften vorgestellt und die Stabilisierung der Gemische durch Beimischung von Kohlendioxid diskutiert.
Explosion and decomposition limits of flammable and chemically unstable gases were determined experimentally in a dosed autoclave with varying ignition energy up to 1000 J. The ignition source was a lightning arc caused by an exploding wire igniter as described in EN 1839 B .. In case of methane only the upper explosion limit was influenced significantly by the ignition energy, whereas the lower explosion limit was constant. In case of R32 however. it was the lower explosion limit that was influenced significantly by the ignition energy and not the upper explosion limit. A particularly strong dependency from the ignition energy was found for the decomposition limits of the chemically unstable gases in nitrogen.
Most fluorinated hydrocarbons that shall replace refrigerants with high GWP. like R134a. are flammable. For evaluating inertization measures for explosion protection. flammability of low-GWP refrigerants R1234yf, R32 and R1132a blended with carbon dioxide.
Nitrogen and argon were studied experimentally in a closed autoclave
at atmospheric conditions. Furthermore, a calculation method was
adapted to reduce the experimental costs for flammability studies on
these gas mixtures. For igniting R1234yf in the closed autoclave a
newly developed ignition system was used that allows generating
electric arcs with high ignition energy. Gas mixtures containing the
mildly flammable R1234yf and R32 could be inerted by adding much
less inert gas than mixtures containing R1132a, which is more similar
to unfluorinated hydrocarbons regarding the explosion regions. By
using the adapted model of constant adiabatic flame temperature
profiles estimating the explosion limits of fluorinated hydrocarbons
was possible with similar accuracy as for unf luorinated hydrocarbons.
Climate change and the need to reduce greenhouse gas emissions pose tremendous challenges to policymakers, the economy, and society. In this context, the development of clean, low-emission technologies plays a crucial role in mitigating the negative impact of fossil fuels on the climate. Hydrogen is a promising energy carrier and fuel that, thanks to its versatility, can be used in many applications. However, the adoption of hydrogen technology requires sufficient trust in its safety. To proxy the development of hydrogen safety innovations, we provide an analysis along the three knowledge and technology transfer channels of publications, patents, and standards. Our results show that research on hydrogen safety has increased significantly in the last decades, with hydrogen safety patents experiencing a general upward trend between 1980 and 2020, just recently decreasing. However, an analysis of almost 100 international hydrogen and fuel cell standards shows only a small number of references to scientific publications. This apparently limited transfer of knowledge from publications points to the need to optimize the coordination of the three knowledge and technology transfer channels for the future development of hydrogen technology. Based on the exploration of this gap, we recommend that research on the three channels for hydrogen be intensified and that the impact of hydrogen safety technology research and development on their diffusion be investigated.
Climate change and the need to reduce greenhouse gas emissions pose tremendous challenges to policymakers, the economy, and society. In this context, the development of clean, low-emission technologies plays a crucial role in mitigating the negative impact of fossil fuels on the climate. Hydrogen is a promising energy carrier and fuel that, thanks to its versatility, can be used in many applications. However, the adoption of hydrogen technology requires sufficient trust in its safety. To proxy the development of hydrogen safety innovations, we provide an analysis along the three knowledge and technology transfer channels of publications, patents, and standards. Our results show that research on hydrogen safety has increased significantly in the last decades, with hydrogen safety patents experiencing a general upward trend between 1980 and 2020, just recently decreasing. However, an analysis of almost 100 international hydrogen and fuel cell standards shows only a small number of references to scientific publications. This apparently limited transfer of knowledge from publications points to the need to optimize the coordination of the three knowledge and technology transfer channels for the future development of hydrogen technology. Based on the exploration of this gap, we recommend that research on the three channels for hydrogen be intensified and that the impact of hydrogen safety technology research and development on their diffusion be investigated.
Presentation of the doctoral thesis held at the PhD Colloquium of the Chair of Innovation Management, Freie Universität Berlin. Hydrogen has recently come into political and industrial focus due to its potential to advance the transition to a net-zero economy. Despite this recognized potential, the market ramp-up of hydrogen technologies has not yet been realized at large. Therefore, this thesis attempts to investigate how advances in hydrogen research, innovation, and safety link up to market formation using the Technological Innovation Systems (TIS) and Quality Infrastructure (QI) frameworks. Thereupon, the thesis formulates several recommendations for transitioning to a hydrogen economy.
The Impact of Publications, Patents, and Standards on International Trade - The Case of Hydrogen
(2022)
Hydrogen as a clean energy carrier has received increased attention due to climate change and the need to introduce new, low-emissions technologies to the market. However, the drivers of increased hydrogen use have been barely explored. Therefore, this research paper investigates the impacts of publications, patents, and standards on international hydrogen trade, an established technology diffusion channel. In a fixed-effects (FE) regression model covering 37 countries between 1995 and 2020, we demonstrate that publications, patents, and standards are associated with increased levels of hydrogen exports and imports. Furthermore, we test the technology gap theory and explore the meaning of our empirical results for the hydrogen technological innovation system (TIS). Among others, we show that publications, patents, and standards can contribute to a more developed hydrogen TIS.
This presentation was held at the EURAS 2023 Conference in Aachen.
Against the backdrop of the sustainability transition of economies worldwide, decarbonizing road traffic is high on the agenda. This has focused the interest of policymakers and automobile manufacturers on sustainable, zero-emission powertrain technologies. Among these technologies, hydrogen fuel cell (FC) vehicles have a positive climate impact, given that their hydrogen is produced from renewable energy. However, FC vehicles have not yet gained significant market shares. Therefore, based on the technological innovation systems (TIS) approach, this study analyzes how FC vehicles are influenced by EVs and internal combustion engine (ICE) vehicles as their context structures. To operationalize the technology relations between our focal FC-TIS and its context structures, we use the sum of international publications, patents filed at the European Patent Office, and international ISO and IEC standards as indicators for each technology. Our results show that the FC-TIS is dominated by its context structures, especially regarding commercially relevant patents and international standards. Therefore, we conclude that the FC-TIS is in its formative life-cycle phase and identify the need for intensified patenting and standardization in relation to the competing EVs and ICE vehicles.
This presentation was held at the Eu-SPRI 2023 Conference and provides a comparative analysis of the hydrogen economies in Germany and the Republic of Korea, highlighting similarities and differences. Thereupon, the presentation delves into the requirements for the development of a hydrogen economy, including recommendations for policymaking.
The presentation provides a comparative analysis of the hydrogen economies in Germany and the Republic of Korea, highlighting similarities and differences. Thereupon, the presentation delves into the requirements for the development of a hydrogen economy, including the political and regulatory framework.