Wall-to-particle heat transfer in steam reformer tubes: CFD comparison of catalyst particles

Computational fluid dynamics (CFD) was used to simulate non-reacting heat transfer in a steam reforming packed reactor tube of tube-to-particle diameter ratio (N) equal to 4, with cylindrical multi-hole catalyst particles. These simulations extend those of our previous study [Nijemeisland, M., Dixon, A.G., Stitt, E.H., 2004. Catalyst design by CFD for heat transfer and reaction in steam reforming. Chemical Engineering Science 59, 5185-5191] to provide accurate tube wall temperatures, runs at constant pressure drop in addition to those at constant mass flow rate and simulations of particles with different sizes of holes. At constant pressure drop, particles with higher void fractions allowed higher mass flow rates, resulting in tube wall temperatures and radial temperature profiles in order: solid cylinders>one-hole particles>multi-hole particles. Little difference was seen between three-hole and four-hole particles. The particles with multiple holes gave a substantial reduction in tube wall temperature, with only a small decrease in core tube heat transfer. The effect of hole size was small, for the cases investigated in this study.     

Composition of corrosion products and solid deposits in the flow path of the Verkhnemutnovsk geothermal power station

We present the results from an investigation of the physicochemical characteristics of samples taken from the corrosion products and solid deposits formed in the flow paths of geothermal power stations. The investigation was carried out using different methods, among which were an X-ray phase analysis, electronic microscopy, thermal gravimetry, and infrared and Mössbauer spectroscopy.     

Experimental investigation of thermal performance of a double-flow solar air heater having aluminium cans

This study experimentally investigates a device for inserting an absorbing plate made of aluminium cans into the double-pass channel in a flat-plate solar air heater (SAH). This method substantially improves the collector efficiency by increasing the fluid velocity and enhancing the heat-transfer coefficient between the absorber plate and air. These types of collectors had been designed as a proposal to use aluminium materials to build absorber plates of SAHs at a suitable cost. The collector had been covered with a 4-mm single glass plate, in order to reduce convective loses to the atmosphere. Three different absorber plates had been designed and tested for experimental study. In the first type (Type I), cans had been staggered as zigzag on absorber plate, while in Type II they were arranged in order. Type III is a flat plate (without cans). Experiments had been performed for air mass flow rates of 0.03 kg/s and 0.05 kg/s. The highest efficiency had been obtained for Type I at 0.05 kg/s. Also, comparison between the thermal efficiency of the SAH tested in this study with the ones reported in the literature had been presented, and a good agreement had been found.     

Special features of spatial redistribution of selenium atoms implanted in silicon

The spatial distribution of selenium atoms implanted in silicon was studied by secondary-ion mass spectrometry after annealing in the temperature range of 600–1200°C. For implantation doses exceeding the amorphization dose for silicon, formation of a peak of selenium concentration was detected beyond the mean projected range of selenium ions. The spatial position of the peak correlates well with the spatial position of the plane in which the calculated value of the specific energy losses of selenium ions in elastic collisions (according to the TRIM code) corresponds to the critical value for amorphization of silicon. Accumulation of impurities at the peak occurs at temperatures of 700°C and higher after recrystallization of the amorphized layer. Redistribution of selenium atoms to deeper layers of the sample due to diffusion is controlled by the temperature dependence of the solubility of selenium in silicon.     

Prediction of earthquake damage to urban water distribution systems: a case study for Denizli,Turkey

Prediction of damage to water supply lines during an earthquake is a critical part of seismic planning. This study evaluates the performance of the water supply system in Denizli, Turkey, in the event of an M6, M6.3, M6.5 and M7 earthquake associated with the Pamukkale and Karakova-Akhan Faults. The relative effects of transient ground deformations and permanent ground deformations based on maps of liquefiable soil and zones of predicted lateral ground displacements are compared. The relative effects of the different magnitude earthquakes and pipeline damage relationships on the pipeline performance following a seismic event are assessed.     

Free vibration and buckling stability of FG nanobeams exposed to magnetic and thermal fields

Engineering with Computers - Due to the increasing usage of nanostructures in nanotechnology and nanodevice, the following article aims to investigate the free vibration and buckling behaviours of...     

Upgrading poly(styrene-co-divinylbenzene) beads: Incorporation of organomodified metal-free semiconductor graphitic carbon nitride through suspension photopolymerization to generate photoactive resins

The inclusion of the metal free semiconductor graphitic carbon nitride (g-CN) into polymer systems brings a variety of new options, for instance as a heterogeneous photoredox polymer initiator. In this context, we present here the decoration of the inner surface of poly(styrene-co-divinylbenzene) beads with organomodified g-CN via one pot suspension photopolymerization. The resulting beads are varied by changing reaction parameters, such as, crosslinking ratio, presence of porogens, and mechanical agitation. The photocatalytic activity of so-formed beads was tested by aqueous rhodamine B dye photodegradation experiments. Additionally, dye adsorption/desorption properties were examined in aqueous as well as in organic solvents. Photoinduced surface modification with vinylsulfonic acid and 4-vinyl pyridine is introduced. Overall, metal-free semiconductor g-CN donates photoactivity to polymer networks that can be employed for dye photodegradation and acid–base catalyst transformation through facile photoinduced surface modifications.     

Novel approach with polyfluorene/polydisulfide copolymer binder for high-capacity silicon anode in lithium-ion batteries

In this study, as a novel design with the collaboration of a fluorene and sulfide-based copolymer for Li-ion battery application is presented. Polyfluorene-co-polydisulfide is prepared with desired functional groups to yield a conductivity and good adhesion. These critical and important features are performed by preparing polymers with proper functional groups. The preparation process is accomplished via Suzuki coupling process under Pd catalyst by combining separately synthesized 4,4′-dibromodiphenyl disulfide in combination with 9,9-dioctylfluorene-2,7-bis(trimethylborate). The fully obtained capacity of the silicon particles, that is, at C/10 with the capacity of 1250 mAh g⁻¹ after the 500th cycle, approves the good performance by preserving capacity stability till 600th cycles. The designed and synthesized polymer binder with different functionalities and carbon nanotube additive show better characteristics such as conductivity, high polarity, and binding adhesion. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 48303.     

Entwicklung einer Methode zur nichtinvasiven Messung des Absolutdrucks in teiltransparenten Gebinden mit karbonisierten Getränken

A non-invasive optical measurement technique for food analysis is presented, which allows for a reliable determination of the absolute pressure in beverage bottles with carbonated contents. The method uses a tunable laser diode with an emission wavelength around 2004 nm to record three to four absorption lines of CO₂ and evaluates the pressure broadening of the lines proportional to the absolute pressure. With the developed measuring method, a standard deviation of repeated absolute pressure measurements of up to 5.5 bar of less than 50 mbar could finally be achieved in field measurements on sealed soft drink bottles made of PET.     

Ecological materials and methods in the textile industry: Atmospheric‐plasma treatments of naturally colored cotton

Naturally colored cotton, in accordance with currently increasing interest in ecological textile products and methods, has increased in popularity. Commerce is another of the primary reasons along with interest in environmentally friendly and niche‐concept approaches. However, the color palette is limited; no bleaching or dyeing process is used. Instead, only a pretreatment to make the fibers hydrophilic is necessary. This can be induced with several different methods. In this respect, atmospheric‐plasma treatments have emerged as an alternative. In this study, knitted and naturally colored cotton fabrics were treated with argon and air atmospheric plasma. The hydrophilicity, wickability, surface friction coefficient, air permeability, water vapor permeability, thermal conductivity, thermal resistance, and fastness were investigated. The surfaces of untreated and plasma‐treated fabrics were analyzed with Fourier transform infrared/attenuated total reflectance and scanning electron microscopy to detect and compare the chemical and morphological modifications. The results revealed that atmospheric‐plasma treatments are capable of modifying the surface of naturally colored cotton fabrics without any important loss in the color strength or fastness and thermal properties. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011