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.     

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.     

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°.     

Photofermentative hydrogen production from molasses: Scale-up and outdoor operation at low carbon-to-nitrogen ratio

Photofermentative hydrogen production was carried out under outdoor conditions with a Rhodobacter capsulatus strain on molasses, a renewable and sustainable feedstock. An existing photobioreactor design was scaled-up from 9 L to 20 L. The decreased carbon-to-nitrogen (C/N) ratio of 13.0, compared to our previous work, accelerated growth and resulted in a reduced lag period for hydrogen production as well as higher productivities in the exponential phase. However, the low C/N ratio also promoted a high optical density due to growth, limiting light transmission. Still, the maximum productivity was found as 0.47 mol H₂/(m³·h), significantly higher than our result with the smaller reactor volume. High rates of production could not be maintained presumably due to the combined effects of cloudy periods, the aforementioned C/N ratio and decreasing pH. These results suggest that the scale-up was successful and there is potential for further improvement using optimal C/N ratio and cell concentration values.     

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.     

Increasing the drawing height of conical square cups using anti-lock braking system (ABS)

This paper deals with increasing the drawing height of metal conical square cups with anti-lock braking system (ABS). A novel technique enabling higher drawing height than that achieved in the conventional deep drawing process is introduced, and the principle of the process is explained in this paper. Results of experiments conducted using aluminum alloyed Al-1050 blanks of thickness of 1 mm to draw conical square cups are reported here. Measured drawing load, drawing height and thickness distributions were compared with those obtained from the conventional method. The experimental results showed that higher drawing height of the cup can be achieved by the use of ABS.