Y. Guan, Baiyun Li, Mengnan Zhu, Sh Cheng, Jiyue Tu, Lu Xing
Owing to the wide applications in a large variety of multi-disciplinary areas, electrowetting-based digital microfluidics (DMF) has received considerable attention in the last decade. However, because of the complexity involved in the droplet generation process, the techniques and configurations for precise and controllable microdrop generation are still unclear. In this paper, a numerical study has been performed to investigate the impact of electrode arrangements on microdrop generation in an electrowetting-based DMF Platform proposed by a previously published experimental work. The governing equations for the microfluidic flow are solved by a finite volume formulation with a two-step projection method on a fixed numerical domain. The free surface of the microdrop is tracked by a coupled level-set and volume-of-fluid (CLSVOF) method, and the surface tension at the free surface is computed by the continuum surface force (CSF) scheme. A simplified viscous force scheme based on the ‘Hele-Shaw cell’ model is adopted to evaluate the viscous force exerted by the parallel plates. The generation process has been simulated with three different electrode arrangements, namely, ‘SL’, ‘SW’, and ‘SQ’. The effect of electrode arrangement on microdrop volume has been investigated. Besides, the influences of the initial microdrop location and volume on the generation process for the ‘SL’ design have been studied. The results can be used to advance microdrop generation techniques for various electrowetting-based DMF applications.
{"title":"A Numerical Study of Electrode Arrangements for Precise Microdrop Generation in an Electrowetting-Based Digital Microfluidic Platform","authors":"Y. Guan, Baiyun Li, Mengnan Zhu, Sh Cheng, Jiyue Tu, Lu Xing","doi":"10.1115/mnhmt2019-4059","DOIUrl":"https://doi.org/10.1115/mnhmt2019-4059","url":null,"abstract":"\u0000 Owing to the wide applications in a large variety of multi-disciplinary areas, electrowetting-based digital microfluidics (DMF) has received considerable attention in the last decade. However, because of the complexity involved in the droplet generation process, the techniques and configurations for precise and controllable microdrop generation are still unclear. In this paper, a numerical study has been performed to investigate the impact of electrode arrangements on microdrop generation in an electrowetting-based DMF Platform proposed by a previously published experimental work. The governing equations for the microfluidic flow are solved by a finite volume formulation with a two-step projection method on a fixed numerical domain. The free surface of the microdrop is tracked by a coupled level-set and volume-of-fluid (CLSVOF) method, and the surface tension at the free surface is computed by the continuum surface force (CSF) scheme. A simplified viscous force scheme based on the ‘Hele-Shaw cell’ model is adopted to evaluate the viscous force exerted by the parallel plates. The generation process has been simulated with three different electrode arrangements, namely, ‘SL’, ‘SW’, and ‘SQ’. The effect of electrode arrangement on microdrop volume has been investigated. Besides, the influences of the initial microdrop location and volume on the generation process for the ‘SL’ design have been studied. The results can be used to advance microdrop generation techniques for various electrowetting-based DMF applications.","PeriodicalId":331854,"journal":{"name":"ASME 2019 6th International Conference on Micro/Nanoscale Heat and Mass Transfer","volume":"153 8 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-12-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125877812","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The graphene oxide-deionized water (GO-DW) and graphene oxide-ethylence glycol (GO-EG) nanofluids were synthesized. The better suspension of nanofluids was achieved. The thermal conductivity of both nanofluids was analyzed. It indicates that GO nanoparticles can strengthen the thermal conductivity of DW base fluids by 22.6%–61.7% and EG base fluids by 15.3%–32.8%. Four copper heat pipes charged with GO-DW and GO-EG nanofluids as well as DW and EG base fluids were experimentally researched, it is discovered that the addition of GO nonoparticles in heat pipe can elevate the condenser wall temperature and reduce the temperature difference. Future analysis finds that, with respect to DW and EG fluids heat pipe, the thermal resistances of GO-DW and GO-EG nanofluids heat pipe are respectively decreased 42.6–52.4% and 31.9%–38.4% for air cooling, and 15.5–16.7% and 11.5%–18.9% for water cooling at condenser section. Besides, the wick structure of GO-DW nanofluids heat pipe was examined by Scanning Electron Microscope, and the effective thermal conductivity of fluid-wick combination was evaluated. The outcomes demonstrate that the evaporator wick surface contains about 0375–1.24μm coating film of GO nanoparticles. Assumed the coating film is 0.75μm, the effective thermal conductivity of fluid-wick combination is respectively enhanced by 66.92 % for GO-DW nonofluids heat pipe and 37.32% for GO-EG nonofluids heat pipe at 70 °C.
{"title":"Experimental Investigation of Graphene Oxide Nanofluids on Thermal Performance of Heat Pipe","authors":"Weilin Zhao, Jun Xu, Jinkai Li","doi":"10.1115/mnhmt2019-4049","DOIUrl":"https://doi.org/10.1115/mnhmt2019-4049","url":null,"abstract":"\u0000 The graphene oxide-deionized water (GO-DW) and graphene oxide-ethylence glycol (GO-EG) nanofluids were synthesized. The better suspension of nanofluids was achieved. The thermal conductivity of both nanofluids was analyzed. It indicates that GO nanoparticles can strengthen the thermal conductivity of DW base fluids by 22.6%–61.7% and EG base fluids by 15.3%–32.8%. Four copper heat pipes charged with GO-DW and GO-EG nanofluids as well as DW and EG base fluids were experimentally researched, it is discovered that the addition of GO nonoparticles in heat pipe can elevate the condenser wall temperature and reduce the temperature difference. Future analysis finds that, with respect to DW and EG fluids heat pipe, the thermal resistances of GO-DW and GO-EG nanofluids heat pipe are respectively decreased 42.6–52.4% and 31.9%–38.4% for air cooling, and 15.5–16.7% and 11.5%–18.9% for water cooling at condenser section. Besides, the wick structure of GO-DW nanofluids heat pipe was examined by Scanning Electron Microscope, and the effective thermal conductivity of fluid-wick combination was evaluated. The outcomes demonstrate that the evaporator wick surface contains about 0375–1.24μm coating film of GO nanoparticles. Assumed the coating film is 0.75μm, the effective thermal conductivity of fluid-wick combination is respectively enhanced by 66.92 % for GO-DW nonofluids heat pipe and 37.32% for GO-EG nonofluids heat pipe at 70 °C.","PeriodicalId":331854,"journal":{"name":"ASME 2019 6th International Conference on Micro/Nanoscale Heat and Mass Transfer","volume":"50 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-12-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123775175","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Successive liquid metal alloy droplet impingements find extensive applications in additive manufacturing technologies and a detailed knowledge about the flow behavior, phase transformation and free surface deformation is required to have a complete understanding and optimization of the process parameters. Experimental research in this field is limited due to extremely small length and time scales involved. Numerical simulation of such process involves challenges like tracking deforming interfaces, modelling the successive droplets, surface tension, flow field and solidification. A non-isothermal enthalpy-based porosity model is used to numerically study the phase change characteristics of successive liquid metal droplet depositing onto a substrate. The flow governing equations are solved using the finite volume scheme. The Coupled Level Set Volume of Fluid (CLSVOF) method is used to track the free surface and the surface tension is modelled using the Continuum Surface Force (CSF) method. The splat morphology, phase change characteristics and effects of various impact conditions on successive columnar droplet depositions are examined.
{"title":"Numerical Study on Successive Liquid Metal Alloy Droplet Depositions","authors":"Vimalan Adaikalanathan, A. Y. Tong","doi":"10.1115/mnhmt2019-4239","DOIUrl":"https://doi.org/10.1115/mnhmt2019-4239","url":null,"abstract":"\u0000 Successive liquid metal alloy droplet impingements find extensive applications in additive manufacturing technologies and a detailed knowledge about the flow behavior, phase transformation and free surface deformation is required to have a complete understanding and optimization of the process parameters. Experimental research in this field is limited due to extremely small length and time scales involved. Numerical simulation of such process involves challenges like tracking deforming interfaces, modelling the successive droplets, surface tension, flow field and solidification. A non-isothermal enthalpy-based porosity model is used to numerically study the phase change characteristics of successive liquid metal droplet depositing onto a substrate. The flow governing equations are solved using the finite volume scheme. The Coupled Level Set Volume of Fluid (CLSVOF) method is used to track the free surface and the surface tension is modelled using the Continuum Surface Force (CSF) method. The splat morphology, phase change characteristics and effects of various impact conditions on successive columnar droplet depositions are examined.","PeriodicalId":331854,"journal":{"name":"ASME 2019 6th International Conference on Micro/Nanoscale Heat and Mass Transfer","volume":"15 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-12-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127914723","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
F. Su, Yiming Fan, He Xu, N. Zhao, Yangbo Deng, Yulong Ji, Hongbin Ma
Thin film evaporation is an efficient phase change heat transfer style, and could achieve ultra-high cooling rate if it was applied for cells vitrification. In this paper, an experimental study for prostate cancer cells vitrification was done. The cells ultra-high speed freezing method was based on thin film evaporation of liquid nitrogen. In order to examine the feasibility of the new method, the comparison experiments, in which the other two generic approaches of cell cryopreservation were used, were done. The methods were respectively the equilibrium freezing method and the open pulled straws vitrification method. At the same time, the influences of the concentration of cryoprotectant on cooling rate and cell survival rate were analyzed. The results showed that the ultra-high speed freezing method based on thin film evaporation can obtain higher cooling rate and better cell survival rate than the other two conventional cryopreservation methods. It preliminarily proved the feasibility of this method applied to the cells vitrification process. In addition, both the cooling rate and the cell survival rate are affected by the concentration of the cryoprotectant in the cell suspension. The cooling rate decreases with the concentration of the cryoprotectant increasing, but cell survival rate increases first and decrease afterwards with the increase of the concentration of the cryoprotectant, in which an optimum value exists. This study will promote the practicality of the new ultra-fast cell freezing method.
{"title":"Ultra-High Speed Vitrification of Prostate Cancer Cells Based on Thin Film Evaporation","authors":"F. Su, Yiming Fan, He Xu, N. Zhao, Yangbo Deng, Yulong Ji, Hongbin Ma","doi":"10.1115/mnhmt2019-3910","DOIUrl":"https://doi.org/10.1115/mnhmt2019-3910","url":null,"abstract":"\u0000 Thin film evaporation is an efficient phase change heat transfer style, and could achieve ultra-high cooling rate if it was applied for cells vitrification. In this paper, an experimental study for prostate cancer cells vitrification was done. The cells ultra-high speed freezing method was based on thin film evaporation of liquid nitrogen. In order to examine the feasibility of the new method, the comparison experiments, in which the other two generic approaches of cell cryopreservation were used, were done. The methods were respectively the equilibrium freezing method and the open pulled straws vitrification method. At the same time, the influences of the concentration of cryoprotectant on cooling rate and cell survival rate were analyzed. The results showed that the ultra-high speed freezing method based on thin film evaporation can obtain higher cooling rate and better cell survival rate than the other two conventional cryopreservation methods. It preliminarily proved the feasibility of this method applied to the cells vitrification process. In addition, both the cooling rate and the cell survival rate are affected by the concentration of the cryoprotectant in the cell suspension. The cooling rate decreases with the concentration of the cryoprotectant increasing, but cell survival rate increases first and decrease afterwards with the increase of the concentration of the cryoprotectant, in which an optimum value exists. This study will promote the practicality of the new ultra-fast cell freezing method.","PeriodicalId":331854,"journal":{"name":"ASME 2019 6th International Conference on Micro/Nanoscale Heat and Mass Transfer","volume":"38 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-12-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131882653","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Piezoelectric vibration energy harvesting technology has attracted significant attention for its applications in integrated circuits, microelectronic devices and wireless sensors due to high power density, easy integration, simple configuration and other outstanding features. Among piezoelectric vibration energy harvesting structures, cantilevered beam is one of the simplest and most commonly used structures. In this work, a vertically staggered rectangle-through-holes (VS-RTH) cantilevered model of mesoscale piezoelectric energy harvester is proposed, which focuses on the multi-directional vibration collection and low resonant frequency. To verify the output performances of the device, this paper employs basic materials and fabrication methods with mathematical modeling. The simulations are conducted through finite element methods to discuss the properties of VS-RTH energy harvester on resonant frequency and output characteristics. Besides, an energy storage circuit with high power collection rate is adopted as collection system. This harvester is beneficial to the further application of devices working with continuous vibrations and low power requirements.
{"title":"Energy Harvesting Performance of Vertically Staggered Rectangle-Through-Holes Cantilevered in Piezoelectric Vibration Energy Harvester","authors":"Shanshi Gao, H. Ao, Hongyuan Jiang","doi":"10.1115/mnhmt2019-4223","DOIUrl":"https://doi.org/10.1115/mnhmt2019-4223","url":null,"abstract":"\u0000 Piezoelectric vibration energy harvesting technology has attracted significant attention for its applications in integrated circuits, microelectronic devices and wireless sensors due to high power density, easy integration, simple configuration and other outstanding features. Among piezoelectric vibration energy harvesting structures, cantilevered beam is one of the simplest and most commonly used structures. In this work, a vertically staggered rectangle-through-holes (VS-RTH) cantilevered model of mesoscale piezoelectric energy harvester is proposed, which focuses on the multi-directional vibration collection and low resonant frequency. To verify the output performances of the device, this paper employs basic materials and fabrication methods with mathematical modeling. The simulations are conducted through finite element methods to discuss the properties of VS-RTH energy harvester on resonant frequency and output characteristics. Besides, an energy storage circuit with high power collection rate is adopted as collection system. This harvester is beneficial to the further application of devices working with continuous vibrations and low power requirements.","PeriodicalId":331854,"journal":{"name":"ASME 2019 6th International Conference on Micro/Nanoscale Heat and Mass Transfer","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-12-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129311847","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Jincai Yu, W. Ye, Baoling Huang, D. Villaroman, Qi Wang
Phonon Monte Carlo method is a popular method for modeling particle dominated phonon transport. Its accuracy critically depends on its inputs such as relaxation time and dispersion, which are difficult to be obtained accurately and efficiently. As a result, empirical models with many fitting parameters are often used. In addition, for large-scale 3D nanostructured systems, the required computational cost is very high. In this article, we present an efficient and highly parallelizable phonon Monte Carlo method using MFP-cumulative thermal conductivity as the only input. The efficiency is enhanced by incorporating the recently proposed variance-reduction method, and the accuracy is ensured because the MFP-based cumulative thermal conductivity can be accurately obtained by experiments or first principles calculation. Moreover, with the MEP-cumulative thermal conductivity as the input, optical phonons can be naturally included in the calculation, which further improves the accuracy.
{"title":"MFP-Based Monte Carlo Method for Nanostructure Phonon Transport","authors":"Jincai Yu, W. Ye, Baoling Huang, D. Villaroman, Qi Wang","doi":"10.1115/mnhmt2019-4136","DOIUrl":"https://doi.org/10.1115/mnhmt2019-4136","url":null,"abstract":"\u0000 Phonon Monte Carlo method is a popular method for modeling particle dominated phonon transport. Its accuracy critically depends on its inputs such as relaxation time and dispersion, which are difficult to be obtained accurately and efficiently. As a result, empirical models with many fitting parameters are often used. In addition, for large-scale 3D nanostructured systems, the required computational cost is very high. In this article, we present an efficient and highly parallelizable phonon Monte Carlo method using MFP-cumulative thermal conductivity as the only input. The efficiency is enhanced by incorporating the recently proposed variance-reduction method, and the accuracy is ensured because the MFP-based cumulative thermal conductivity can be accurately obtained by experiments or first principles calculation. Moreover, with the MEP-cumulative thermal conductivity as the input, optical phonons can be naturally included in the calculation, which further improves the accuracy.","PeriodicalId":331854,"journal":{"name":"ASME 2019 6th International Conference on Micro/Nanoscale Heat and Mass Transfer","volume":"31 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-12-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"117006231","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Meng Zhang, Wu Zhang, Zhengwei Wu, W. Cai, Z. Zheng, Yicheng Chen, C. Lan
In this paper we experimentally studied the instabilities of pre-stretched viscoelastic fluid in cross-slot devices. We first investigate the instability of the flow in a standard cross-slot at different Weissenberg numbers without pre-stretch. It is found the viscoelastic flow is transformed from the steady symmetric state to the instabilities states including the steady asymmetric state and the non-periodically oscillated asymmetric state. This is due to the extension of the polymer in the viscoelastic fluid at the stagnation point stretched by the extensional flow in the cross-slot. We then modified the cross-slot channel in which the viscoelastic fluid is pre-stretched before entering the crossroad region. Due to the pre-stretch, elastic energy is pre-stored in the polymer, and the energy required to fully extend the polymer is also different with those extending from equilibrium state. As a result, the flow remains in the steady asymmetric state in all tested Weissenberg number condition.
{"title":"Instabilities of Pre-Stretched Viscoelastic Flow in Microfluidic Cross-Slot Devices","authors":"Meng Zhang, Wu Zhang, Zhengwei Wu, W. Cai, Z. Zheng, Yicheng Chen, C. Lan","doi":"10.1115/mnhmt2019-4120","DOIUrl":"https://doi.org/10.1115/mnhmt2019-4120","url":null,"abstract":"\u0000 In this paper we experimentally studied the instabilities of pre-stretched viscoelastic fluid in cross-slot devices. We first investigate the instability of the flow in a standard cross-slot at different Weissenberg numbers without pre-stretch. It is found the viscoelastic flow is transformed from the steady symmetric state to the instabilities states including the steady asymmetric state and the non-periodically oscillated asymmetric state. This is due to the extension of the polymer in the viscoelastic fluid at the stagnation point stretched by the extensional flow in the cross-slot. We then modified the cross-slot channel in which the viscoelastic fluid is pre-stretched before entering the crossroad region. Due to the pre-stretch, elastic energy is pre-stored in the polymer, and the energy required to fully extend the polymer is also different with those extending from equilibrium state. As a result, the flow remains in the steady asymmetric state in all tested Weissenberg number condition.","PeriodicalId":331854,"journal":{"name":"ASME 2019 6th International Conference on Micro/Nanoscale Heat and Mass Transfer","volume":"192 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-12-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116648518","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Mass transfer is a ubiquitous transfer phenomenon, efficient means of mass flux regulation are of great significance to various fields. Recently, because of superior physical properties, meta-materials have been widely concerned, and the research on flux regulation using meta-materials has been rapidly developed. However, the relevant research in the field of mass transfer has progressed much more slowly than expected. In this work, the characteristic regulation of gas diffusion in meta-material functional region was investigated. Through coordinate transformation, Fick diffusion equation and gas diffusivity were derived mathematically. Different kinds of homogeneous isotropic materials are alternately compounded based on equivalent medium theory to form meta-material functional region, which realize the characteristic regulation of oxygen, nitrogen and their mixtures. In addition, the simulation results are in agreement with the derived formulas mutually verified and quantitative analysis of geometric factors affecting gas regulation process is carried out.
{"title":"Control Characteristics of Mass Diffusion in a Meta-Material Based on Transformation Coordinate Method","authors":"Hao Zhang, Yiyi Li, Zhuang Ma, Quan Zou","doi":"10.1115/mnhmt2019-4228","DOIUrl":"https://doi.org/10.1115/mnhmt2019-4228","url":null,"abstract":"\u0000 Mass transfer is a ubiquitous transfer phenomenon, efficient means of mass flux regulation are of great significance to various fields. Recently, because of superior physical properties, meta-materials have been widely concerned, and the research on flux regulation using meta-materials has been rapidly developed. However, the relevant research in the field of mass transfer has progressed much more slowly than expected. In this work, the characteristic regulation of gas diffusion in meta-material functional region was investigated. Through coordinate transformation, Fick diffusion equation and gas diffusivity were derived mathematically. Different kinds of homogeneous isotropic materials are alternately compounded based on equivalent medium theory to form meta-material functional region, which realize the characteristic regulation of oxygen, nitrogen and their mixtures. In addition, the simulation results are in agreement with the derived formulas mutually verified and quantitative analysis of geometric factors affecting gas regulation process is carried out.","PeriodicalId":331854,"journal":{"name":"ASME 2019 6th International Conference on Micro/Nanoscale Heat and Mass Transfer","volume":"17 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-12-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"117120855","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
3D amorphous carbon-based membrane materials with continuous carbon skeleton were obtained from the fruit waste pomelo peel. The microstructure shows honeycomb in the transverse direction with pore size ranging from 50∼100 μm, while in the longitudinal direction, the inner surface of the carbon membrane shows unique structure, i.e., rollable ladders with carbon rungs twinkled intimately around the vertical stringers, which is considered to contribute to the mechanical strength of the carbon membrane. The tensile test indicates that prolonged yield stage is observed in the stress-strain curve of the membrane material, the corresponding fracture morphology showing different fracture surfaces, which confirms the alleviation of the applied load by changing the crack direction. In addition, the elastic modulus of the carbon membrane material is 140 MPa. The elongation of the yield period is considered to facilitate the structure stability of the carbon membrane material as anode material in Lithium-ion battery (LIBs).
{"title":"Fabrication and Mechanical Property of Bioinspired Three Dimensional Amorphous Carbon Membrane As Anode in Lithium Ion Battery","authors":"Xueliang Wang, Z. Qu, Yaping Wang","doi":"10.1115/mnhmt2019-3990","DOIUrl":"https://doi.org/10.1115/mnhmt2019-3990","url":null,"abstract":"\u0000 3D amorphous carbon-based membrane materials with continuous carbon skeleton were obtained from the fruit waste pomelo peel. The microstructure shows honeycomb in the transverse direction with pore size ranging from 50∼100 μm, while in the longitudinal direction, the inner surface of the carbon membrane shows unique structure, i.e., rollable ladders with carbon rungs twinkled intimately around the vertical stringers, which is considered to contribute to the mechanical strength of the carbon membrane. The tensile test indicates that prolonged yield stage is observed in the stress-strain curve of the membrane material, the corresponding fracture morphology showing different fracture surfaces, which confirms the alleviation of the applied load by changing the crack direction. In addition, the elastic modulus of the carbon membrane material is 140 MPa. The elongation of the yield period is considered to facilitate the structure stability of the carbon membrane material as anode material in Lithium-ion battery (LIBs).","PeriodicalId":331854,"journal":{"name":"ASME 2019 6th International Conference on Micro/Nanoscale Heat and Mass Transfer","volume":"47 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-12-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125395858","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Zheng Lian, Y. Ren, K. Koh, Jun He, G. Chen, Xiaogang Yang
Needle-based microfluidic system that comprised of needle-based microfluidic devices (NBMD) in parallel connection was employed to generate polydimethylsiloxane (PDMS) microdroplets using oil-in-water (O/W) single emulsion template. The parallel-connection could be simply realized by multiple single NBMD connected via flow diverting devices. The versatile flow diverting devices could not only avoid the additional use of injection pumps for introducing fluids into the microfluidic system, but also enhance the yields of microdroplets. The entire production rate of the system has been raised to 535 drops per minute compared with that using a single NBMD which yields to 133 drops per minute. All the microdroplets were produced under dripping flow regime. If identical flow conditions and channel diameters were applied, the generated microdroplets from the each microchannel could have high monodispersity. Despite of several parameters that could affect the droplet sizes, for example, flow rate exerted on each channel and the channel size which depended on the selection of various needle combinations of the inlet and outlet needles, the inter-needle distance between those two needles may significantly influence the size of droplets. Thus, it shall be controlled carefully to remain the same distance in terms of achieving high monodispersity of the droplet sizes. On the other hand, one can vary the sizes of needles applied in the same batch of production or by adjusting the inter-needle distance in order to realize the production of microdroplets with various sizes. Moreover, diverse types of microdroplets could be produced simultaneously through different channels by NBMD. In this research, sugar and multi-walled carbon nanotubes (CNTs) were utilized as dopants mixing with PDMS precursor as the dispersed phase to produce PDMS-S and PDMS-CNTs microdroplets. The droplets could be collected and thermally solidified off-site for other applications. This platform does not require sophisticated equipment and is very cost-effective compared with conventional microfluidic devices such as PDMS devices or glass capillary devices. Hence, the system has great potential to produce microdroplets at a large scale.
{"title":"High Throughput Fabrication of Microdroplets Using Needle Based Microfluidic System","authors":"Zheng Lian, Y. Ren, K. Koh, Jun He, G. Chen, Xiaogang Yang","doi":"10.1115/mnhmt2019-4263","DOIUrl":"https://doi.org/10.1115/mnhmt2019-4263","url":null,"abstract":"Needle-based microfluidic system that comprised of needle-based microfluidic devices (NBMD) in parallel connection was employed to generate polydimethylsiloxane (PDMS) microdroplets using oil-in-water (O/W) single emulsion template. The parallel-connection could be simply realized by multiple single NBMD connected via flow diverting devices. The versatile flow diverting devices could not only avoid the additional use of injection pumps for introducing fluids into the microfluidic system, but also enhance the yields of microdroplets. The entire production rate of the system has been raised to 535 drops per minute compared with that using a single NBMD which yields to 133 drops per minute. All the microdroplets were produced under dripping flow regime. If identical flow conditions and channel diameters were applied, the generated microdroplets from the each microchannel could have high monodispersity. Despite of several parameters that could affect the droplet sizes, for example, flow rate exerted on each channel and the channel size which depended on the selection of various needle combinations of the inlet and outlet needles, the inter-needle distance between those two needles may significantly influence the size of droplets. Thus, it shall be controlled carefully to remain the same distance in terms of achieving high monodispersity of the droplet sizes. On the other hand, one can vary the sizes of needles applied in the same batch of production or by adjusting the inter-needle distance in order to realize the production of microdroplets with various sizes. Moreover, diverse types of microdroplets could be produced simultaneously through different channels by NBMD. In this research, sugar and multi-walled carbon nanotubes (CNTs) were utilized as dopants mixing with PDMS precursor as the dispersed phase to produce PDMS-S and PDMS-CNTs microdroplets. The droplets could be collected and thermally solidified off-site for other applications. This platform does not require sophisticated equipment and is very cost-effective compared with conventional microfluidic devices such as PDMS devices or glass capillary devices. Hence, the system has great potential to produce microdroplets at a large scale.","PeriodicalId":331854,"journal":{"name":"ASME 2019 6th International Conference on Micro/Nanoscale Heat and Mass Transfer","volume":"95 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-12-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124221419","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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