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排序方式: 共有376条查询结果,搜索用时 31 毫秒
1.
Stéphane J. C. Weusten Luc C. E. M. Murrer Matheus T. de Groot John van der Schaaf 《American Institute of Chemical Engineers》2021,67(6):e17263
This article investigates the effect of inlet shape, entrance length, and turbulence promoters on mass transfer by using 3D-printed electrolyzers. Our results show that the inlet design can promote turbulence and lead to an earlier transition to turbulent flow. The Reynolds number at which the transition occurs can be predicted by the ratio of the cross-sectional area of the inlet to the cross-sectional area of the electrolyzer channel. A longer entrance length results in more laminar behavior and a later transition to turbulent flow. With an entrance length of 550 mm, the inlet design did no longer affect the mass transfer performance significantly. The addition of gyroid type turbulence promoters resulted in a factor of 2 to 4 increase in mass transfer depending on inlet design, entrance length, and the type of promoter. From one configuration to another, there was a minimal variation in pressure drop (<1600 Pa). 相似文献
2.
研究了Ti-Al-Fe低成本钛合金钨极氩弧焊焊接接头的内部质量、组织和力学性能,并与TC4钛合金进行了比较。结果表明,Ti-Al-Fe低成本钛合金焊缝表面质量良好,焊缝内部融合良好,无焊接缺陷,可焊性好; 2种合金的焊缝区宏观组织均由粗大的柱状晶和少量等轴晶组成,Ti-Al-Fe合金柱状晶组织较细,晶内由针状次生α相和少量的长条状初生α相组成; 2种合金热影响区均为粗大的等轴晶,晶内由大量初生α相和少量针状次生α相及残余β相组成; Ti-Al-Fe低成本钛合金焊缝抗拉强度达到1 204 MPa,比TC4钛合金高111 MPa。 相似文献
3.
Kevin M. P. van Eeten Dennis H. J. Hülsman John van der Schaaf Jaap C. Schouten 《American Institute of Chemical Engineers》2015,61(11):3656-3665
A novel type of rotor‐stator spinning disk device is proposed which allows for the entrapment of solid particles solely by hydrodynamic means. In this new configuration, the solid rotating disk is replaced with two conjoined rotors with a variable gap spacing. Liquid is fed through the top stator and can flow out again through the rotor‐rotor interior and the hollow rotation axis. Moreover, the volume between the two rotors is optionally filled with a highly porous reticulated carbon foam. It was found that particle containment was strongly improved by the presence of this reticulated foam as it hinders the buildup of centripetal boundary layer flow near the disks in the interior of the rotor‐rotor assembly. These centripetal boundary layers drag along particles resulting in a loss of containment. Experiments utilizing glass beads showed that particles with a diameter down to 17.8 µm can be completely entrapped when a carbon foam is placed between the two conjoined disks at rotor speeds up to the maximum investigated value of 178 rad s?1. Additionally, the rotor‐rotor gap did not have an effect on the particle entrapment level when the reticulated carbon foam was omitted and can be ascribed to the build‐up of boundary layers, which is independent of rotor‐rotor distance. © 2015 American Institute of Chemical Engineers AIChE J, 61: 3656–3665, 2015 相似文献
4.
Although many brands develop mobile applications (apps) to build relationships with consumers, most branded apps fail to retain consumers’ loyalty. This study examines the facilitation of consumer loyalty toward branded apps (continuance intention, in-app purchase intention, and word-of-mouth intention) from the dual-route perspective. One route is the affective (relationship) route, where brand benefits (functional benefits, experiential benefits, symbolic benefits, and monetary benefits) drive parasocial interactions between consumers and the brand, which, in turn, influences branded app loyalty. The other route is the utility route, where system characteristics (system quality and information quality) affect perceived usefulness, which, in turn, facilitates branded app loyalty. An online survey was conducted, and the research model was empirically tested using partial least squares structural equation modeling. The findings support the dual-route perspective according to which both affective and utilitarian paths facilitate branded app loyalty. The key theoretical contribution of this study is that it moves beyond the utilitarian path and finds the affective (relationship) path to give a more complete picture of the facilitation of consumer loyalty in the branded app context. A strategy is provided to suggest to practitioners how to design branded apps to facilitate consumer loyalty. 相似文献
5.
J. Schaaf 《Journal of Adhesion Science and Technology》2018,32(19):2111-2127
The strong ice bonding to solid surfaces makes deicing such surfaces a challenging task. In this study, a heat flux will be induced into the interlayer of the ice and in this case aluminum. With a high heat flux it is possible to obtain a small liquid layer between the ice and the aluminum. In metallic materials the heat flux can be induced with an electromagnetic field via induction heating. The thickness of the heated metal layer depends on the frequency applied for the induction heating. High frequencies result in very thin layers of metal heated and hence represent an energy efficient method for de-icing the metal surface. The reduction of the energy consumption for deicing is the main goal. One application is the ice removal in ice slurry generators in this study. Compared to ice removal (scraped surface ice slurry generators) induction heating deicing offers energy and maintenance saving potential. 相似文献
6.
Verena Wiedenmann Kathleen Oehlke Ulrike van der Schaaf Hanna M. Koivula Kirsi S. Mikkonen Heike P. Karbstein 《Journal of food science》2019,84(12):3642-3652
Protein films can be applied to improve food quality and to reduce packaging waste. To overcome their poor water barrier properties, lipids are often incorporated. The function of incorporated lipid depends on the interface between filler and matrix. This study aimed to tailor the properties of a protein–lipid film by designing the oil/water interface to see if the concept of inactive/active filler is valid. Therefore, we varied the emulsifier stabilizing solid lipid nanoparticles (SLN) to promote (via β‐lactoglobulin) or to minimize (via Tween 20) interactions between particle surface and protein. SLN were incorporated into protein films and film properties were determined. Addition of SLN led to significantly decreased water vapor permeability (WVP) of protein films. However, WVP was mainly affected by the emulsifiers and not by the lipid. Protein‐stabilized SLN (BS) replaced a lacking protein in the protein network and therefore did not influence the mechanical properties of the films at ambient temperature. BS‐composite films were temperature sensitive, as lipid and sucrose palmitate melted at temperatures above 40 °C. Tween 20‐stabilized SLN (TS) led to reduced tensile strengths, probably due to perturbative effects of TS and plasticizing effects of Tween 20. Dynamic mechanical analysis showed that TS and Tween 20 increased film mobility. Melting of lipid and emulsifiers, and temperature‐dependent behavior of Tween 20 led to a strong temperature dependence of the film stiffness. By designing the interface, particles can be used to tailor mechanical properties of protein films. Tuned edible films could be used to control mass transfers between foods. 相似文献
7.
Michiel M. de Beer Jos T. F. Keurentjes Jaap C. Schouten John van der Schaaf 《American Institute of Chemical Engineers》2016,62(10):3784-3796
Centrifugal intensification of condensation heat transfer in the rotor–stator cavities of a stator–rotor–stator spinning disc reactor (srs‐SDR) is studied, as a function of rotational velocity ω, volumetric throughflow rate , and average temperature driving force . For the current range of ω, heat transfer from the vapor bubbles to the condensate liquid is limiting, due to a relatively low gas–liquid interfacial area aGL. For rad s?1, a strong increase of aGL, results in increasing the reactor‐average condensation heat transfer coefficient hc from 1600 to 5600 W m?2 K?1, for condensation of pure dichloromethane vapor. Condensation heat transfer in the srs‐SDR is enhanced by rotation, independent of the vapor velocity. The intensified condensation comes at the cost of relatively high energy dissipation rates, indicating condensation in the srs‐SDR is more suited as a means to supply heat (e.g. in an intensified reactor‐heat exchanger), rather than for bulk cooling purposes. © 2016 American Institute of Chemical Engineers AIChE J, 62: 3784–3796, 2016 相似文献
8.
9.
Larry Schaaf 《History of Photography》2013,37(3):181-204
Abstract The rich, productive, and enthusiastic interaction between Henry Talbot and John Herschel is a fascinating microcosm of early photographic research. An isolated experiment, shared by them in 1831, is a typical example of the tantalizing near-misses that pervade the chronicles of the pre-history of photography. Their correspondence in early 1839, before Herschel saw Daguerre's then superior productions, is a window for us today to learn from the initial thoughts of the excited pioneers. We face contemporary reports of discovery and hope, unedited and unrefined by the influence of time and later events. 相似文献
10.
An aluminum nitride (AlN) thick film for ultrasonic transduction was deposited on a silicon wafer by magnetron sputtering. A columnar structure with uniform elemental depth profiles with 40 at.% to 60 at.% (Al-N) concentrations and with a c-axis preferential orientation was observed by X-ray diffraction. The ultrasonic response of the Al/AlN/Si overmoded resonator was characterized from 1.24 MHz to 2 GHz using a vector network analyzer. The time domain transform and the gate features of the vector network analyzer were used to characterize the AlN thick film capabilities in the time and frequency domains. The results show that the obtained resonator operates over a broad frequency range with a central frequency at approximately 930 MHz and a 738 MHz bandwidth at -6 dB. The results were compared with those obtained from a one-dimensional simulation to highlight and predict the AlN response features. A comparison was performed to validate the experimental measurements and to validate the circuit modeling. Overall agreement between the experiment values and the simulation was observed. 相似文献