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553 results on '"Zhao, Donglin"'

32. Repetitive Deformation of Ga-Based Liquid Metal in Acidified CuCl2or FeCl3Solution

Author

Wang, Bingxing, Zhang, Yongcai, Wang, Songlin, Jiang, Xiaoying, Liu, Liheng, and Zhao, Donglin

Abstract

In chemical education, repetitive and large-scale motion of material in a chemical reaction could effectively capture students’ attention and stimulate their interests to further explore the underlying science. Gallium-based liquid metals are more safe and suitable for some classroom demonstrations than mercury to introduce chemical principles. In this article, we describe a visually striking experiment using Ga-based liquid metal. Repetitive and large-scale deformation of liquid metal was observed in an acidified solution of either copper(II) chloride or ferric(III) chloride. To elucidate the mechanism of deformation, the chemical reaction and the interfacial tension are discussed. Deformation can be attributed to a spatial and temporal imbalance of the interfacial tension on the liquid metal induced by the chemical reactions. The simple setups and readily available chemicals enable this experiment to be a suitable and safe classroom demonstration.

Published
2024
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36. Tunnel-type continuous multi-physical field drying equipment: Design, numerical simulation and application.

Author

Zeng, Shiyu, Zhou, Cunshan, Wang, Bo, Lv, Huangzhen, Zhao, Donglin, Wu, Yiran, Lv, Weiqiao, and Xiao, Hongwei

Subjects
DRYING apparatus, COMPUTER simulation, FOOD dehydration, ELECTRIC fields, TEMPERATURE distribution, COWPEA
Abstract

In this study, a tunnel-type continuous multi-physical field drying equipment was developed to combine microwave, hot air, and infrared drying technologies. The microwave source arrangement and hot air equalizing plate were optimized based on numerical simulation to enhance the uniformity of the microwave field and hot air velocity distribution. Mode 4 and opening ratio 37.70% (r = 60 mm) were had the highest electric field distribution and hot air distribution. This equipment was further used to pre-dehydrate cowpeas and the effects of microwave, hot air, and infrared on food drying properties and quality of dried samples were investigated. The results showed that the moisture content was reduced by 20% and the ΔE value greater than 5 after pre-dehydration. Microwave treatment rapidly reduced the moisture content of cowpeas. The infrared treatment significantly improved the uniformity of temperature distribution and the texture profile of the dried sample. The hot air drying increased 10 °C for the overall temperature of the food material and balanced the internal water content of the food material. This study aims to provide future researchers with insights to develop novel microwave-based continuous drying equipment for its commercial applications. [ABSTRACT FROM AUTHOR]

Published
2024
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41. Study on the Microwave Permittivity of Single-Walled Carbon Nanotube

Author

Liu, Xiaolai and Zhao, Donglin

Abstract

In this article, we studied the microwave permittivity of the complex of the single-walled carbon nanotube and paraffin in 2-18GHz. In the range, the dielectric loss of single-walled carbon nanotube is higher, and the real part and the imaginary part of the dielectric constant decrease with the increase of frequency, and the dielectric constant possesses the property of dispersion frequency response. The ?', ?" and tand of the complex of the single-walled carbon nanotube and paraffin increase with the increase of the content of carbon tubes, and it presents good second-order function relationship with the volume fraction of carbon in certain range. The polarization dispersion dielectric response is the main reason that the single-walled nanotube absorbs and wastes microwaves.

Published
2009

50. Liquid macro- and micro-mixing in sparged and boiling stirred tank reactors

Author

Zhao, Donglin

Subjects
660.2832
Abstract

Liquid or gas-liquid stirred tank reactors with vapour generation are ubiquitous in many important industrial processes. The presence of the large volume of vapour may have considerable effects on liquid mixing and mass transfer performance. The aim of the present work has been the investigation of the liquid macro- and micro-mixing characteristics in these reactors. This objective is achieved through the examination of the differences in power draw characteristics, liquid mixing times and undesired byproduct distributions of mixing-sensitive reactions between hot sparged and boiling reactors, and ambient temperature systems. Experimental work was performed in a standard vessel and a tall tank reactor (H = 2T) under ungassed, gassed and boiling conditions. The power draw of up-pumping Lightnin A340 and Chemineer Maxflo (MFu) impellers and the liquid mixing times and micromixing achieved by a Chemineer CD-6 radial flow impeller were investigated in the standard vessel. The power draw characteristics and liquid macromixing rates obtained by three composite impellers (BT6+BT6+CD6, BT6+MFu+MFu and triple A340 impellers) were studied in the tall tank reactor. Experimental results show that the wide blade up-pumping impellers (A340 and MFu) can maintain a relatively high RPD even at high gas loadings and high impeller speeds. When multiple A340 impellers are used as a composite agitator, however, this combination has a greater power decrease upon gas sparging than the radial flow composite agitator (BT6+BT6+CD6) and the mixed flow impeller system (BT6+MFu+MFu) whether under cool gassed or hot sparged conditions. The effect of boiling on RPD is significant only when multiple agitators are operated at the extremes of low and high impeller speeds. Liquid mixing times in boiling and high gas loading systems were investigated through a conductivity technique. In single-impeller (CD-6) systems, gas sparging accelerates the liquid mixing. This can be attributed to the contribution of aeration to the potential energy. With the same shaft power input, boiling systems have the fastest liquid macromixing. This benefits from the work done by the expansion of vapour bubbles. Unlike in single impeller systems, the impeller geometry of composite impeller agitators has a significant effect on liquid mixing rates. Gas sparging has little influence on the liquid mixing times achieved by the radial flow agitator but reduces the rate of liquid mixing in both cool gassed or hot sparged systems agitated by the axial and mixed flow agitators. A compartment model has been used to explain this phenomenon. The effect of boiling on the liquid mixing time depends on the combination of impellers used in the agitator. A new test reaction system, suitable for the investigation of micromixing in boiling and hot sparged systems, is proposed. Experimental results have demonstrated that this reaction pair is easy to use and its product distribution is sensitive to liquid micromixing. Micromixing is apparently improved in boiling reactors. This could in part be attributed to the decrease of liquid viscosity and the contribution of rapid expansion and violent collapse of vapour bubbles, but much work still need to be done before a general conclusion could be drawn. Sparging gases into a hot liquid has little effect on the rate of micromixing, the reasons for which have been discussed. Feed location has a significant effect on the product distribution both in hot ungassed and boiling systems. This is consistent with the results in ambient temperature systems found in the literature.

Published
2002

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