Trans FA and solid fat contents of margarines marketed in Turkey

Trans FA (TFA), solid fat contents (SFC), and slip melting points of 12 different tub and stick margarines marketed in Turkey were examined in this study. No trans isomers were found in four margarines, which suggests they were formulated from interesterified or blended fats and oils. The products with no TFA generally had more short-chain saturated FA, which suggests coconut oil-based oil components. TFA content of the other 10 products varied from 7.7 to 37.8%. Compared to the products formulated in North America, Turkish margarines contain more TFA and have higher SFC.     

An experimental study for the effect of different clearances on burr, smooth-sheared and blanking force on aluminium sheet metal

In this study, an experimental study was carried out to examine the effect of different clearances on smooth-sheared depth, burr height and blanking force. Aluminium sheet metals with 0.8, 1, and 1.5 mm thicknesses were used in the experiments. These experiments were carried out in circular blanking dies to 6, 8, 10, and 12 mm diameters. Six different clearances (0.009, 0.064, 0.12, 0.175, 0.231 and 0.287 mm) were used for every material and diameter. The results of the experiment show that burr, smooth-sheared and punch force is strongly related to the clearance value. The results are in agreement with the results of previous theoretical and experimental work in the literature.     

Free radical polymerization of ethyl methacrylate and ethyl α-hydroxy methacrylate: A computational approach to the propagation kinetics

The propagation kinetics of ethyl methacrylate (EMA) and ethyl α-hydroxy methacrylate (EHMA) has been subject to a computational study to understand their free radical polymerization (FRP) behavior in bulk and in solution using Density Functional Theory (DFT). The propagation of EHMA is studied in ethanol and toluene to assess the effect of hydrogen-bonding solvents on FRP of monomers with α-hydroxy functionality. Although EMA and EHMA resemble each other in structure, EHMA propagates faster in bulk due to the presence of intermolecular hydrogen-bonds, which tend to facilitate the approach of the propagating species. This falls in contrast with the experimentally observed lower propagation rates of EHMA in ethanol compared to toluene. Calculations show that the 2.28 rate acceleration in toluene is governed by the ratio of the pre-exponential factors, which reflect the entropies of activation, in both media. The polar protic solvent ethanol has a disruptive effect via hydrogen-bonding on the 6-membered ring shape of EHMA monomers thus decreasing the entropy of activation of the reaction. In the case of toluene, there are no special interactions with the hydrophobic solvent, the entropy of activation is higher than in ethanol.     

Investigations on the variation of corrosion and contact resistance characteristics of metallic bipolar plates manufactured under long-run conditions

Tribological variations, surface conditions (roughness, hardness, coating) and surface interactions between micro-stamping dies and bipolar plate blanks play a critical role in determining the surface quality, channel formation and precision of bipolar plates. This study is aimed to understand the cause, mechanism and consequences of interactions between micro-stamping process conditions and bipolar plate quality. A total of 2000 repeated micro-stamping of 51 μm-thick uncoated and 1 μm-thick ZrN coated SS316L sheet blanks into an array of 750 μm micro-channels were performed using 175-220 kN force levels with constant stamping speed of 1 mm/s. Microscopic examinations were conducted periodically on both die and coated & uncoated plate surfaces to observe topographic variations. In addition, corrosion and contact resistance tests were carried out in the same intervals. Analysis of variance (ANOVA) technique was used to determine the significance of the process parameters on channel height, roughness, corrosion and contact resistance differences. The results revealed similar roughness trends for die and plate surfaces during 2000 micro-stampings. ZrN coating with 1 μm thickness dramatically improved corrosion and contact resistance behavior of plates.     

Catalytic behavior of ruthenium in soybean oil hydrogenation

Soybean oil was hydrogenated with a carbon‐supported ruthenium catalyst (Ru/C) at 165 °C, 2 bar H₂ and 500 rpm stirring speed. Reaction rates, trans isomer formation, selectivity ratios and melting behaviors of the samples were monitored. No catalytic activity was found for the application of 10 ppm of the catalyst, and significant catalytic activity appeared at >50 ppm of active catalyst. The catalyst concentration had an effect on the reaction rate of hydrogenation, but the weight‐normalized reaction rate constant (k_c) was almost independent of the catalyst concentration at lower iodine values. Ru/C generated considerable amounts of trans fatty acids (TFA), including high amounts of trans 18:2, and also stearic acid, due to its very non‐selective nature. The selectivity ratios were found to be low and varied between 1.12 and 4.32 during the reactions. On the other hand, because of the low selectivity, higher slip melting points and solid fat contents at high temperatures were obtained than those for nickel and palladium catalysts. Another different characteristic of this catalyst was the formation (max 1.67%) of conjugated linoleic acid (CLA) during hydrogenation. Besides, CLA formation in the early stages of the reactions did not change very much with the lower iodine values.     

Population balance modelling of protein precipitates exhibiting turbulent flow through a circular pipe

The breakage of liquid-liquid, solid-liquid and solid-gas dispersions occurs in many industrial processes during the transport of particulate materials. In this work, breakage of whey protein precipitates passing through a capillary pipe is examined and an experimentally derived breakage frequency is applied to construct a suitable population balance model to characterize the breakage process. It has been shown that the breakage frequency of precipitate particles is highly dependent on their shear history and on the turbulent energy dissipation rate in the pipe. The population balance equation (PBE) uses a volume density based discrete method which is adapted from mass density based discretization. In addition to comparing the model with experimental data, predicted results at different velocities are presented. It was found that the population balance breakage model provides satisfactory results in terms of predicting particle size distributions for such processes.     

Application of two dimensional (2D) FEA for the tube hydroforming process

Use of FEM in the metal forming process has been a proven analysis tool. Two-dimensional FEA for simplified sections can help to reduce time and cost in part, tooling and process design in tube hydroforming technology as it is a relatively new process, and the existing experience and knowledge base is not as broad as with other forming processes. Some case studies are presented to demonstrate the use of two-dimensional FEA in the hydroforming process. Upon verification through comparison of FEA predictions with experimental results, further planned simulations are conducted to generate simple design rules on geometrical and process parameters.     

Design,synthesis, and characterization of hybrid micro-nano surface coatings for enhanced heat transfer applications

Metal particles coating is extensively used for surface coating a wide range of application including thermal management of electronics, concentrating photovoltaics, sensors and nuclear power plants. Both micro and nano-scale surfaces have been proven to show an enhanced two-phase heat transfer performance by varying surface properties like area, wettability, and roughness. To combine the unique features of both micro and nano-scale surface coatings, this study presents the design, synthesis, and characterization of new hybrid micro-nano scale surface coating by a new two steps approach. Five different types of surfaces; namely, plain nanocoated (PNC), uniform micro-porous (UMP), uniform hybrid micro-nano porous (UHMNP), 2-D modulated microporous (MMP) and modulated hybrid micro-nano (MHMNP) surfaces were fabricated. A new two steps approach of hot-pressing followed by nucleate boiling is used for the fabrication of these surfaces. Successful coating of hybrid micro-nano scale coating was achieved. Considering the critical surface properties of micro and nanoscale coatings, new hybrid micro-nano surfaces have been characterized for SEM, wettability, roughness test. The comparative analysis of these new hybrid coating is also performed with micro coated and uncoated surfaces. With the coating of nanoparticles, the average roughness of PNC surface increased by 4.67 times and that of hybrid micro-nano particle surface by 2.3 times. The deposition of nanoparticles resulted in an increase in contact angle for PNC surface, while the contact angle of hybrid micro-nano surfaces decreases from 126.4° to 82.1°.     

Feasibility of monitoring large wind turbines using photogrammetry

Photogrammetry, which is a proven measurement technique based on determination of the 3D coordinates of the points on an object by using two or more images taken from different positions, is proposed to be a promising and cost efficient alternative for monitoring the dynamic behavior of wind turbines. The pros and cons of utilizing this measurement technique for several applications such as dynamic testing or health monitoring of large wind turbines are discussed by presenting the results of the infield tests performed on a 2.5 MW - 80 m diameter - wind turbine.