Mira Schmalenberg, Fabian Sallamon, Christian Haas, N. Kockmann
Solid-liquid suspension flow is often involved in the production of pharmaceuticals and fine chemicals. In these fields, working with continuous small-scale equipment in order to save costs and resources is of increasing interest. Therefore, it is also important to enable process control for small-scale apparatus, which requires the development of new concepts to observe and control crystallization processes in minichannel equipment. The particles and crystals should be detected and measured with as low impact as possible because contact between process medium and the sensors can often lead to the incrustation of the sensor, disturb the particle size and shape, or contaminate the system. For the observation of crystallizing processes in minichannel crystallizers, a non-invasive, temperature-controlled flow-cell is designed in this work. In particular, this flow cell has been designed to examine crystals in a fluorinated ethylene propylene (FEP) tube with an inner diameter of 1.6 mm. Crystals can be investigated using a standard optical camera and microscope. An image processing routine enables the evaluation of crystal size. This is crucial for the assessment of the process and crystal size distribution, which is often a quality criterion in the crystallization process. The contribution will show how the flow-cell for two-phase flow is constructed and the evaluation routine is implemented. Based on experimental data, the applicability of the equipment and the evaluation method are described.
{"title":"Temperature-Controlled Minichannel Flow-Cell for Non-Invasive Particle Measurements in Solid-Liquid Flow","authors":"Mira Schmalenberg, Fabian Sallamon, Christian Haas, N. Kockmann","doi":"10.1115/icnmm2020-1062","DOIUrl":"https://doi.org/10.1115/icnmm2020-1062","url":null,"abstract":"\u0000 Solid-liquid suspension flow is often involved in the production of pharmaceuticals and fine chemicals. In these fields, working with continuous small-scale equipment in order to save costs and resources is of increasing interest. Therefore, it is also important to enable process control for small-scale apparatus, which requires the development of new concepts to observe and control crystallization processes in minichannel equipment. The particles and crystals should be detected and measured with as low impact as possible because contact between process medium and the sensors can often lead to the incrustation of the sensor, disturb the particle size and shape, or contaminate the system.\u0000 For the observation of crystallizing processes in minichannel crystallizers, a non-invasive, temperature-controlled flow-cell is designed in this work. In particular, this flow cell has been designed to examine crystals in a fluorinated ethylene propylene (FEP) tube with an inner diameter of 1.6 mm. Crystals can be investigated using a standard optical camera and microscope. An image processing routine enables the evaluation of crystal size. This is crucial for the assessment of the process and crystal size distribution, which is often a quality criterion in the crystallization process.\u0000 The contribution will show how the flow-cell for two-phase flow is constructed and the evaluation routine is implemented. Based on experimental data, the applicability of the equipment and the evaluation method are described.","PeriodicalId":198176,"journal":{"name":"ASME 2020 18th International Conference on Nanochannels, Microchannels, and Minichannels","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2020-07-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127374550","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}
Multiphase simulations and computational methods with precisely quantified interfaces are important for variety of engineering applications. A few of these applications are: heat transfer utilizing boiling processes, optimizing combustion, and additive printing/deposition processes. In these applications, calculating the length of the interface between two phases (e.g. a vapor and liquid) is particularly critical. Errors in the calculation of the size of the interface propagate over subsequent time steps thereby producing inaccurate rates of phase-change, fluid velocities, and convection heat transfer. This work proposes a method to reduce the reduce error in interface calculations in multiphase simulations. The proposed method uses the interface inclination and the vapor volume-fraction on each computational cell to compute the interface surface area. Moreover, this work provides details on proper declaration and computation of mass transfer with the Volume-of-Fluid sharp interface tracking algorithm. The performance of the proposed approach is compared with the accepted method that estimates interface surface area with gradients of vapor volume fractions. Computer simulations of spherical bubble growth in superheated liquid demonstrate the relevance of the proposed approach. Results indicate that the errors with the accepted method could propagate to 20% (relative to the theoretical estimation) in the prediction of bubble growth rate and fluid velocities. The proposed approach leads to errors of less than 1% in the prediction of bubble growth rate and fluid velocities.
{"title":"A Proposed Approach for Accurate Estimation of Interface Surface Area in Multiphase Simulations","authors":"S. P. Shipkowski, I. Perez-Raya, S. Kandlikar","doi":"10.1115/icnmm2020-1038","DOIUrl":"https://doi.org/10.1115/icnmm2020-1038","url":null,"abstract":"\u0000 Multiphase simulations and computational methods with precisely quantified interfaces are important for variety of engineering applications. A few of these applications are: heat transfer utilizing boiling processes, optimizing combustion, and additive printing/deposition processes. In these applications, calculating the length of the interface between two phases (e.g. a vapor and liquid) is particularly critical. Errors in the calculation of the size of the interface propagate over subsequent time steps thereby producing inaccurate rates of phase-change, fluid velocities, and convection heat transfer. This work proposes a method to reduce the reduce error in interface calculations in multiphase simulations. The proposed method uses the interface inclination and the vapor volume-fraction on each computational cell to compute the interface surface area. Moreover, this work provides details on proper declaration and computation of mass transfer with the Volume-of-Fluid sharp interface tracking algorithm. The performance of the proposed approach is compared with the accepted method that estimates interface surface area with gradients of vapor volume fractions. Computer simulations of spherical bubble growth in superheated liquid demonstrate the relevance of the proposed approach. Results indicate that the errors with the accepted method could propagate to 20% (relative to the theoretical estimation) in the prediction of bubble growth rate and fluid velocities. The proposed approach leads to errors of less than 1% in the prediction of bubble growth rate and fluid velocities.","PeriodicalId":198176,"journal":{"name":"ASME 2020 18th International Conference on Nanochannels, Microchannels, and Minichannels","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2020-07-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131679628","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}
Being an extremely vigorous process involving a continuous intense bubble activity, repetitive pool boiling study is essential for many industrial applications. In this work, we have utilized highly thermally conductive and highly wettable graphene nanoplatelets (GNP) to form GNP-Copper based composite coatings for enhancing the pool boiling heat transfer performance. A multi-step electrodeposition technique was implemented to develop robust coatings on the copper substrates. Repetitive pool boiling studies were conducted on the 2% GNP-Cu coating which achieved the highest CHF of 286 W/cm2 and HTC of 204 kW/m2-°C. After investigating the effect of repetitive boiling on deposited GNP layers and morphology, it was found that GNP were reduced to form r-GNP (reduced GNP) and small increment in pore sizes was observed. Additionally, with repetitive boiling, it was observed that the heat transfer coefficient was continuously increased and compared to pristine copper surface 2% GNP-Cu coating yielded ∼456% increment in HTC at the end of third repetitive test.
{"title":"Fundamental Insight on Morphological Changes of Graphene Nanoplatelets-Copper (GNP-Cu) Coatings: Effects of Repetitive Pool Boiling Tests","authors":"A. Rishi, Anju Gupta","doi":"10.1115/icnmm2020-1027","DOIUrl":"https://doi.org/10.1115/icnmm2020-1027","url":null,"abstract":"\u0000 Being an extremely vigorous process involving a continuous intense bubble activity, repetitive pool boiling study is essential for many industrial applications. In this work, we have utilized highly thermally conductive and highly wettable graphene nanoplatelets (GNP) to form GNP-Copper based composite coatings for enhancing the pool boiling heat transfer performance. A multi-step electrodeposition technique was implemented to develop robust coatings on the copper substrates. Repetitive pool boiling studies were conducted on the 2% GNP-Cu coating which achieved the highest CHF of 286 W/cm2 and HTC of 204 kW/m2-°C. After investigating the effect of repetitive boiling on deposited GNP layers and morphology, it was found that GNP were reduced to form r-GNP (reduced GNP) and small increment in pore sizes was observed. Additionally, with repetitive boiling, it was observed that the heat transfer coefficient was continuously increased and compared to pristine copper surface 2% GNP-Cu coating yielded ∼456% increment in HTC at the end of third repetitive test.","PeriodicalId":198176,"journal":{"name":"ASME 2020 18th International Conference on Nanochannels, Microchannels, and Minichannels","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2020-07-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134467694","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}
A. Owens, M. Godbole, D. Dabydeen, L. Medeiros, P. Phatak, S. Kandlikar
Cancer is one of the most debilitating diseases in the world, affecting over 9.6 million people worldwide every year. Breast cancer remains the second largest cause of death in women. Despite major advances in treatment, over 40,920 women died of breast cancer in 2018 in the United States alone. Early detection of abnormal masses can be crucial for diagnosis and dramatically increase survival. Current screening techniques have varying accuracy and perform poorly when used on heterogeneously and extremely dense breast tissue. Infrared imaging has the potential to detect growing tumors within the breast based on thermal signatures on the breast surface by imaging temperature gradients induced by blood perfusion and tumor metabolic activity. Using clinical patient images, previous methods to estimate tumor properties involve an iterative algorithm to estimate the tumor position and diameter. The details from the MRI are used in estimating the volumetric heat generation rate. This is compared with the published values and the reasons for differences are investigated. The tumor pathology is used in estimating the expected growth rate and compared with the predicted values. The correlation between the tumor characteristics and heat generation rate is fundamental information that is needed in accurately predicting the tumor size and location.
{"title":"A Comparative Analysis of the Tumor Pathology and the Metabolic Heat Generation of Growing Malignant Tumors","authors":"A. Owens, M. Godbole, D. Dabydeen, L. Medeiros, P. Phatak, S. Kandlikar","doi":"10.1115/icnmm2020-1082","DOIUrl":"https://doi.org/10.1115/icnmm2020-1082","url":null,"abstract":"\u0000 Cancer is one of the most debilitating diseases in the world, affecting over 9.6 million people worldwide every year. Breast cancer remains the second largest cause of death in women. Despite major advances in treatment, over 40,920 women died of breast cancer in 2018 in the United States alone. Early detection of abnormal masses can be crucial for diagnosis and dramatically increase survival. Current screening techniques have varying accuracy and perform poorly when used on heterogeneously and extremely dense breast tissue. Infrared imaging has the potential to detect growing tumors within the breast based on thermal signatures on the breast surface by imaging temperature gradients induced by blood perfusion and tumor metabolic activity. Using clinical patient images, previous methods to estimate tumor properties involve an iterative algorithm to estimate the tumor position and diameter. The details from the MRI are used in estimating the volumetric heat generation rate. This is compared with the published values and the reasons for differences are investigated. The tumor pathology is used in estimating the expected growth rate and compared with the predicted values. The correlation between the tumor characteristics and heat generation rate is fundamental information that is needed in accurately predicting the tumor size and location.","PeriodicalId":198176,"journal":{"name":"ASME 2020 18th International Conference on Nanochannels, Microchannels, and Minichannels","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2020-07-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132870884","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}
Microchannel flows are widely used in applications where small diffusion length scales are important. However, their inherent dimensional constrain also translates into high pumping power requirements. Inspired by nature, one possible method to reduce the large viscous pressure losses is to introduce textures in a microchannel. Depending on the interaction between the textured surface and the liquid, the microstructures can either be wetted or nonwetted. Less adhesion between solid and liquid in nonwetted state has made it popular in most of the friction reduction studies. However, in the nonwetted state, preventing liquid from penetrating into the grooves under pressurized conditions and the gas-liquid interface acting like a solid boundary open space to consider the wetted state for friction reduction as well. When dealing with the wetted state we should be aware that penetration of the flow inside the grooves can induce the pressure drag alongside the skin drag. Therefore, the wetted state will lead to a trade-off between skin and pressure drag. The aim of this work is to understand how different microtextures affect the total drag in a laminar microchannel flow. Textured microchannels with width-to-depth aspect ratios of 1, 10 and 50 and different width of the land region have been tested. In order to perform correct comparisons, the textured and baseline microchannels are designed to have the same volume. The results show that increasing the aspect ratio of the trenches introduces an extermum point in the hydraulic resistance of the microchannels. The optimum aspect ratio for the tested microchannels is 10, in which the trenches are not wide enough for streamlines to bend inside the trenches and increase the skin drag and they are not highly dense along the microchannel to reveal the negative effect of the pressure drag. On the whole, the hydraulic resistance of the textured channels is higher than the equivalent baseline for all the tested geometries.
{"title":"Effect of Wetted Microtexturing on Friction in Microchannel Flow","authors":"N. Rabiei, C. Hidrovo","doi":"10.1115/icnmm2020-1083","DOIUrl":"https://doi.org/10.1115/icnmm2020-1083","url":null,"abstract":"\u0000 Microchannel flows are widely used in applications where small diffusion length scales are important. However, their inherent dimensional constrain also translates into high pumping power requirements. Inspired by nature, one possible method to reduce the large viscous pressure losses is to introduce textures in a microchannel. Depending on the interaction between the textured surface and the liquid, the microstructures can either be wetted or nonwetted. Less adhesion between solid and liquid in nonwetted state has made it popular in most of the friction reduction studies. However, in the nonwetted state, preventing liquid from penetrating into the grooves under pressurized conditions and the gas-liquid interface acting like a solid boundary open space to consider the wetted state for friction reduction as well. When dealing with the wetted state we should be aware that penetration of the flow inside the grooves can induce the pressure drag alongside the skin drag. Therefore, the wetted state will lead to a trade-off between skin and pressure drag. The aim of this work is to understand how different microtextures affect the total drag in a laminar microchannel flow. Textured microchannels with width-to-depth aspect ratios of 1, 10 and 50 and different width of the land region have been tested. In order to perform correct comparisons, the textured and baseline microchannels are designed to have the same volume. The results show that increasing the aspect ratio of the trenches introduces an extermum point in the hydraulic resistance of the microchannels. The optimum aspect ratio for the tested microchannels is 10, in which the trenches are not wide enough for streamlines to bend inside the trenches and increase the skin drag and they are not highly dense along the microchannel to reveal the negative effect of the pressure drag. On the whole, the hydraulic resistance of the textured channels is higher than the equivalent baseline for all the tested geometries.","PeriodicalId":198176,"journal":{"name":"ASME 2020 18th International Conference on Nanochannels, Microchannels, and Minichannels","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2020-07-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121250945","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}
An experimental investigation was conducted on falling film evaporation along two porous tubes, which were sintered by stainless-steel powder with a diameter of 0.45 and 1 um, respectively. The test section is a 2 m long sintered tube with an outer diameter of 25 mm and a wall thickness of 2 mm. During the experiment, the pressure inside the tube was maintained at 1 atm, the inlet temperature was 373 K, and mass flux ranged from 0.51 to 1.36 kg/ (m s). Conditions of the steam outside the pipe, which was the heat source, were fixed, while the fouling tests were carried out at a constant mass flow of 0.74 kg/ (m s) using high-concentration brine as work fluid. The overall heat transfer coefficient under different working conditions was tested and compared with the stainless steel smooth tube of the same dimensions. The heat transfer coefficient of the two porous stainless tubes are about 35% and 20% lower than that of the smooth one, showing an inferior effect because the steam in the pores of the pipe wall during the infiltration process will reduce the heat conductivity. The heat transfer coefficient of the smooth tube deteriorated severely due to the deposition of calcium carbonate, which had little effect on the sintered tubes. Besides, the fouling weight of porous tubes is 2.01 g and 0 g compared with 5.52 g of the smooth tube.
{"title":"Heat Transfer and Fouling Performance During Falling Film Evaporation in Vertical Porous Tubes","authors":"Lei Wang, Weiyu Tang, Limin Zhao, Wei Li","doi":"10.1115/icnmm2020-1032","DOIUrl":"https://doi.org/10.1115/icnmm2020-1032","url":null,"abstract":"\u0000 An experimental investigation was conducted on falling film evaporation along two porous tubes, which were sintered by stainless-steel powder with a diameter of 0.45 and 1 um, respectively. The test section is a 2 m long sintered tube with an outer diameter of 25 mm and a wall thickness of 2 mm. During the experiment, the pressure inside the tube was maintained at 1 atm, the inlet temperature was 373 K, and mass flux ranged from 0.51 to 1.36 kg/ (m s). Conditions of the steam outside the pipe, which was the heat source, were fixed, while the fouling tests were carried out at a constant mass flow of 0.74 kg/ (m s) using high-concentration brine as work fluid. The overall heat transfer coefficient under different working conditions was tested and compared with the stainless steel smooth tube of the same dimensions. The heat transfer coefficient of the two porous stainless tubes are about 35% and 20% lower than that of the smooth one, showing an inferior effect because the steam in the pores of the pipe wall during the infiltration process will reduce the heat conductivity. The heat transfer coefficient of the smooth tube deteriorated severely due to the deposition of calcium carbonate, which had little effect on the sintered tubes. Besides, the fouling weight of porous tubes is 2.01 g and 0 g compared with 5.52 g of the smooth tube.","PeriodicalId":198176,"journal":{"name":"ASME 2020 18th International Conference on Nanochannels, Microchannels, and Minichannels","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2020-07-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134049275","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}
A Lagrangian model following the history of every droplet belonging to an evolving droplets population, originally developed to simulate pattern evolution in the framework of in-flight icing phenomenon, is used in order to simulate dropwise condensation over different shaped micro-structured surfaces. Both the mechanical and the thermal energy balances are solved for every droplet, allowing to predict droplet velocity and condensing flow rate. Coalescence phenomenon is also implemented. The model in the present form is an evolution of the code presented at ICNMM 2019, introducing the effect of vapor shear, a physical model of the evolution of the dynamic contact angle during droplet growth and a prediction of condensing flow rate through the solution of thermal energy balance, thus taking into account the influence of the droplet size. Shared memory parallelization is also carried out decomposing the computational domain into different subdomains, allowing the efficient simulation of a larger number of droplets. Here, the model is validated and used to predict the heat transfer performance of hybrid condensation surfaces, both plane and curved, under the action of both gravity and vapor shear. Starting from literature proposals, several patterns, each characterized by a complex composition of patches with different wettabilities, are numerically investigated and the configuration ensuring the best heat transfer performance and liquid drainage is identified. The sensitivity of the solution with respect to the uncertainty on the estimate of some parameters, such as nucleation density, is also discussed.
{"title":"Numerical Prediction of Dropwise Condensation Performances Over Hybrid Surfaces, Under the Action of Gravity and Vapor Shear","authors":"N. Suzzi, G. Croce, P. D’Agaro","doi":"10.1115/icnmm2020-1075","DOIUrl":"https://doi.org/10.1115/icnmm2020-1075","url":null,"abstract":"\u0000 A Lagrangian model following the history of every droplet belonging to an evolving droplets population, originally developed to simulate pattern evolution in the framework of in-flight icing phenomenon, is used in order to simulate dropwise condensation over different shaped micro-structured surfaces. Both the mechanical and the thermal energy balances are solved for every droplet, allowing to predict droplet velocity and condensing flow rate. Coalescence phenomenon is also implemented. The model in the present form is an evolution of the code presented at ICNMM 2019, introducing the effect of vapor shear, a physical model of the evolution of the dynamic contact angle during droplet growth and a prediction of condensing flow rate through the solution of thermal energy balance, thus taking into account the influence of the droplet size. Shared memory parallelization is also carried out decomposing the computational domain into different subdomains, allowing the efficient simulation of a larger number of droplets.\u0000 Here, the model is validated and used to predict the heat transfer performance of hybrid condensation surfaces, both plane and curved, under the action of both gravity and vapor shear. Starting from literature proposals, several patterns, each characterized by a complex composition of patches with different wettabilities, are numerically investigated and the configuration ensuring the best heat transfer performance and liquid drainage is identified. The sensitivity of the solution with respect to the uncertainty on the estimate of some parameters, such as nucleation density, is also discussed.","PeriodicalId":198176,"journal":{"name":"ASME 2020 18th International Conference on Nanochannels, Microchannels, and Minichannels","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2020-07-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130468318","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}
In the present study, the performance of a humidification-dehumidification (HDH) desalination system with the humidifier and the dehumidifier contained in the same enclosure is evaluated. In this design the humidifier system is composed of a vertical copper tube coated with a hydrophilic air-laid paper layer in which saline water is dripped and hot water (from 42.3 to 79.4 °C) flows inside to heat the humidifier system while the dehumidifier consists of an aluminum plate with internal channels for cold water (16 °C) flow. The experimental results show a pure water production rate per unit system volume up to 19.13 L/m3h at a water temperature of 79.4 °C at the evaporator inlet and a hot water mass flow rate of 135 mL/min. This new design has potential for application in desalination systems, especially sin mall systems for use by families living in arid regions.
{"title":"Performance Evaluation of a New Configuration of Direct Contact Humidification Dehumidification (DCHDH) Desalination System","authors":"F. Aguiar, S. Kandlikar","doi":"10.1115/icnmm2020-1014","DOIUrl":"https://doi.org/10.1115/icnmm2020-1014","url":null,"abstract":"\u0000 In the present study, the performance of a humidification-dehumidification (HDH) desalination system with the humidifier and the dehumidifier contained in the same enclosure is evaluated. In this design the humidifier system is composed of a vertical copper tube coated with a hydrophilic air-laid paper layer in which saline water is dripped and hot water (from 42.3 to 79.4 °C) flows inside to heat the humidifier system while the dehumidifier consists of an aluminum plate with internal channels for cold water (16 °C) flow. The experimental results show a pure water production rate per unit system volume up to 19.13 L/m3h at a water temperature of 79.4 °C at the evaporator inlet and a hot water mass flow rate of 135 mL/min. This new design has potential for application in desalination systems, especially sin mall systems for use by families living in arid regions.","PeriodicalId":198176,"journal":{"name":"ASME 2020 18th International Conference on Nanochannels, Microchannels, and Minichannels","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2020-07-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122156769","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}
J. Schuler, L. Neuendorf, Kai Petersen, N. Kockmann
For many applications, such as liquid-liquid or gas-liquid reactions, the generation of monodisperse droplets is of major interest. Therefore, knowledge about the physics of droplet formation is essential and the subject of numerous studies. Droplet formation is usually investigated using optical cameras, which makes optical accessibility necessary. Furthermore, properties defining droplet evolution is obtained from 2D images. In this work, we present a methodology for the 3D investigation of droplet formation in the laminar regime using micro-computed tomography. A special imaging concept and image processing, incorporating the use of a convolutional neural network, is presented. Water droplets are injected into a continuous polydimethylsiloxane stream in a coflowing configuration using a cannula with an inner diameter di = 800 μm and an outer diameter do = 1050 μm that is centered in a thin polymer tube with an inner diameter di = 1600 μm. Volume flow rates of polydimethylsiloxane and water are varied between 0.2 and 0.3 mL min−1. Furthermore, the influence of cannula positioning on droplet formation is investigated. Different quantitative 3D properties are extracted from the CT scans, such as droplet volume and surface of the interface. Thereby, different stages of droplet formation can be identified and the physical understanding of droplet formation is improved.
对于许多应用，如液-液或气-液反应，单分散液滴的产生是主要的兴趣。因此，关于液滴形成的物理知识是必不可少的，也是许多研究的主题。液滴形成通常使用光学相机进行研究，这使得光学可及性成为必要。此外，从二维图像中获得了定义液滴演化的属性。在这项工作中，我们提出了一种使用微计算机断层扫描对层流状态中液滴形成进行三维研究的方法。提出了一种特殊的成像概念和图像处理，结合了卷积神经网络的使用。将内径为di = 800 μm、外径为do = 1050 μm的套管以内径为di = 1600 μm的细聚合物管为中心，以共流形态将水滴注入聚二甲基硅氧烷连续流中。聚二甲基硅氧烷和水的体积流速在0.2和0.3 mL min - 1之间变化。此外，还研究了导管位置对液滴形成的影响。从CT扫描中提取不同定量的三维属性，如液滴体积和界面表面。从而可以识别液滴形成的不同阶段，提高对液滴形成的物理认识。
{"title":"3D Investigation of Droplet Generation in a Miniaturized Coflowing Device Using Micro-Computed Tomography","authors":"J. Schuler, L. Neuendorf, Kai Petersen, N. Kockmann","doi":"10.1115/icnmm2020-1061","DOIUrl":"https://doi.org/10.1115/icnmm2020-1061","url":null,"abstract":"\u0000 For many applications, such as liquid-liquid or gas-liquid reactions, the generation of monodisperse droplets is of major interest. Therefore, knowledge about the physics of droplet formation is essential and the subject of numerous studies. Droplet formation is usually investigated using optical cameras, which makes optical accessibility necessary. Furthermore, properties defining droplet evolution is obtained from 2D images. In this work, we present a methodology for the 3D investigation of droplet formation in the laminar regime using micro-computed tomography. A special imaging concept and image processing, incorporating the use of a convolutional neural network, is presented. Water droplets are injected into a continuous polydimethylsiloxane stream in a coflowing configuration using a cannula with an inner diameter di = 800 μm and an outer diameter do = 1050 μm that is centered in a thin polymer tube with an inner diameter di = 1600 μm. Volume flow rates of polydimethylsiloxane and water are varied between 0.2 and 0.3 mL min−1. Furthermore, the influence of cannula positioning on droplet formation is investigated. Different quantitative 3D properties are extracted from the CT scans, such as droplet volume and surface of the interface. Thereby, different stages of droplet formation can be identified and the physical understanding of droplet formation is improved.","PeriodicalId":198176,"journal":{"name":"ASME 2020 18th International Conference on Nanochannels, Microchannels, and Minichannels","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2020-07-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125707421","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}
Microfluidics has a lot of applications in fields ranging from pharmaceutical to energy, and one of the major applications is micromixers. A challenge faced by most micromixers is the difficulty in mixing within micro-size fluidic channels because of the domination of laminar flow in a small channel. Hence, magnetic field generated by permanent magnets and electromagnets have been widely used to mix ferrofluids with other sample fluids on a micro level. However, permanent magnets are bulky, and electromagnets produce harmful heat to biological samples; both properties are detrimental to a microfluidic chip’s performance. Taking these into consideration, this study proposes rapid mixing of ferrofluid using a two-layer microfluidic device with microfabricated magnet. Two microfluidic chips that consist of microchannels and micromagnets respectively are fabricated using a simple and low-cost soft lithography method. The custom-designed microscale magnet consists of an array of stripes and is bonded below the plane of the microchannel. The combination of the planar location and angle of the array of magnets allow the migration of ferrofluids, hence mixing it with buffer flow. Parametric studies are performed to ensure comprehensive understanding, including the angle of micro-scale magnets with respect to the fluidic channels, total flow rate and density of the array of magnets. The result from this study can be applied in chemical synthesis and pre-processing, sample dilution, or inducing reactions between samples and reagent.
{"title":"Active High-Throughput Micromixer Using Injected Magnetic Mixture Underneath Microfluidic Channel","authors":"A. Surendran, Ran Zhou","doi":"10.1115/icnmm2020-1018","DOIUrl":"https://doi.org/10.1115/icnmm2020-1018","url":null,"abstract":"\u0000 Microfluidics has a lot of applications in fields ranging from pharmaceutical to energy, and one of the major applications is micromixers. A challenge faced by most micromixers is the difficulty in mixing within micro-size fluidic channels because of the domination of laminar flow in a small channel. Hence, magnetic field generated by permanent magnets and electromagnets have been widely used to mix ferrofluids with other sample fluids on a micro level. However, permanent magnets are bulky, and electromagnets produce harmful heat to biological samples; both properties are detrimental to a microfluidic chip’s performance. Taking these into consideration, this study proposes rapid mixing of ferrofluid using a two-layer microfluidic device with microfabricated magnet. Two microfluidic chips that consist of microchannels and micromagnets respectively are fabricated using a simple and low-cost soft lithography method. The custom-designed microscale magnet consists of an array of stripes and is bonded below the plane of the microchannel. The combination of the planar location and angle of the array of magnets allow the migration of ferrofluids, hence mixing it with buffer flow. Parametric studies are performed to ensure comprehensive understanding, including the angle of micro-scale magnets with respect to the fluidic channels, total flow rate and density of the array of magnets. The result from this study can be applied in chemical synthesis and pre-processing, sample dilution, or inducing reactions between samples and reagent.","PeriodicalId":198176,"journal":{"name":"ASME 2020 18th International Conference on Nanochannels, Microchannels, and Minichannels","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2020-07-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130517329","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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