Pub Date : 2011-06-01DOI: 10.1260/1759-3093.2.2-3.151
K. Sarkar, A. K. Santra
Effect of aspect ratio (AR) on heat transfer due to laminar natural convection of Cu-water nanofluid in a two-dimensional differentially heated enclosure has been studied numerically. The transport equations have been discretized using finite volume approach and solved using SIMPLER algorithm. Considering the nanofluid to be incompressible and non-Newtonian, the shear stresses have been calculated using Ostwald-de Waele model. The thermal conductivity of the nanofluid has been calculated from the proposed model by Chon et al. Study has been conducted for AR ??0.125 to 3 while Rayleigh number (Ra) has been varied between 104 and 107 and solid volume fraction (ϕ) of copper particles (diameter = 25 nm) varied from 0.05% to 5%. In general heat transfer decreases with increase in AR and ϕ but increases with increase in Ra. For Ra = 107, maximum heat transfer is obtained between AR = 0.15 - 0.25.
{"title":"Effect of Aspect Ratio on Heat Transfer in a Differentially Heated Square Cavity Using Copper-Water Nanofluid","authors":"K. Sarkar, A. K. Santra","doi":"10.1260/1759-3093.2.2-3.151","DOIUrl":"https://doi.org/10.1260/1759-3093.2.2-3.151","url":null,"abstract":"Effect of aspect ratio (AR) on heat transfer due to laminar natural convection of Cu-water nanofluid in a two-dimensional differentially heated enclosure has been studied numerically. The transport equations have been discretized using finite volume approach and solved using SIMPLER algorithm. Considering the nanofluid to be incompressible and non-Newtonian, the shear stresses have been calculated using Ostwald-de Waele model. The thermal conductivity of the nanofluid has been calculated from the proposed model by Chon et al. Study has been conducted for AR ??0.125 to 3 while Rayleigh number (Ra) has been varied between 104 and 107 and solid volume fraction (ϕ) of copper particles (diameter = 25 nm) varied from 0.05% to 5%. In general heat transfer decreases with increase in AR and ϕ but increases with increase in Ra. For Ra = 107, maximum heat transfer is obtained between AR = 0.15 - 0.25.","PeriodicalId":89942,"journal":{"name":"International journal of micro-nano scale transport","volume":"2 1","pages":"151-166"},"PeriodicalIF":0.0,"publicationDate":"2011-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"66151523","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}
Pub Date : 2011-06-01DOI: 10.1260/1759-3093.2.2-3.167
M. Kumari, R. Gorla
A boundary layer analysis is presented for the mixed convection past a horizontal plate in a porous medium saturated with a nano fluid. The prescribed heat and mass flux boundary conditions are considered. The entire regime of the mixed convection is included, as the mixed convection parameter ξ varies from 0 (pure free convection) to 1 (pure forced convection). The transformed nonlinear system of equations is solved by using an implicit infinite difference method. Numerical results for friction factor, surface heat transfer rate and mass transfer rate have been presented for parametric variations of the buoyancy ratio parameter Nr, Brownian motion parameter Nb, thermophoresis parameter Nt and Lewis number Le. The dependency of the friction factor, surface heat transfer rate (Nusselt number) and mass transfer rate on these parameters has been discussed.
{"title":"Combined Convective Boundary Layer Flow Over a Horizontal Plate Embedded in a Porous Medium Saturated with a Nanofluid","authors":"M. Kumari, R. Gorla","doi":"10.1260/1759-3093.2.2-3.167","DOIUrl":"https://doi.org/10.1260/1759-3093.2.2-3.167","url":null,"abstract":"A boundary layer analysis is presented for the mixed convection past a horizontal plate in a porous medium saturated with a nano fluid. The prescribed heat and mass flux boundary conditions are considered. The entire regime of the mixed convection is included, as the mixed convection parameter ξ varies from 0 (pure free convection) to 1 (pure forced convection). The transformed nonlinear system of equations is solved by using an implicit infinite difference method. Numerical results for friction factor, surface heat transfer rate and mass transfer rate have been presented for parametric variations of the buoyancy ratio parameter Nr, Brownian motion parameter Nb, thermophoresis parameter Nt and Lewis number Le. The dependency of the friction factor, surface heat transfer rate (Nusselt number) and mass transfer rate on these parameters has been discussed.","PeriodicalId":89942,"journal":{"name":"International journal of micro-nano scale transport","volume":"48 1","pages":"167-186"},"PeriodicalIF":0.0,"publicationDate":"2011-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"66151534","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}
Pub Date : 2011-03-01DOI: 10.1260/1759-3093.2.1.85
E. Pankratov, E. Bulaeva
It has been recently shown, that manufacturing of an implanted-junction rectifier in a semiconductor heterostructure for optimal relation between annealing time of radiation defects, materials of the heterostructure and thicknesses of layers of the heterostructure and energy of implanted ions leads to increasing of sharpness of p-n-junction and at the same time to increasing of homogeneity of dopant distribution in doped area. In this paper we consider an approach of annealing of radiation defects to decrease quantity of radiation defects in comparison with standard of annealing. PACS number(s): 72.20. -i; 73.40.Kp; 73.40.Lq; 66.30. -h; 85.40.Ry
{"title":"Decreasing of Quantity of Radiation Defects in an Implanted-Junction Rectifier in a Semiconductor Heterostructure","authors":"E. Pankratov, E. Bulaeva","doi":"10.1260/1759-3093.2.1.85","DOIUrl":"https://doi.org/10.1260/1759-3093.2.1.85","url":null,"abstract":"It has been recently shown, that manufacturing of an implanted-junction rectifier in a semiconductor heterostructure for optimal relation between annealing time of radiation defects, materials of the heterostructure and thicknesses of layers of the heterostructure and energy of implanted ions leads to increasing of sharpness of p-n-junction and at the same time to increasing of homogeneity of dopant distribution in doped area. In this paper we consider an approach of annealing of radiation defects to decrease quantity of radiation defects in comparison with standard of annealing. PACS number(s): 72.20. -i; 73.40.Kp; 73.40.Lq; 66.30. -h; 85.40.Ry","PeriodicalId":89942,"journal":{"name":"International journal of micro-nano scale transport","volume":"1 1","pages":"219-227"},"PeriodicalIF":0.0,"publicationDate":"2011-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"66151729","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}
Pub Date : 2011-03-01DOI: 10.1260/1759-3093.2.1.41
M. A. Cartas-Ayala, R. Karnik
Microfluidics has shown the ability to reproduce many of the techniques used in chemistry and biology, achieving faster and inexpensive results with smaller samples. As part of this effort towards miniaturization, the heating and cooling of samples has become an important step in many devices, especially for nucleic acid analysis. Measuring temperature profiles inside microchannels is required to verify the performance of such devices. Here we introduce a new technique to measure thermal profiles in microchannels: leuco-dye temperature sensitive microbeads, which permits fast, simple and inexpensive measurement of thermal profiles based on color, which enable its use to quickly assess temperature profiles to verify device performance, or as an educational tool for visualizing microscale heat transfer. Using the technique, we present visualization of thermal profiles and measurement of color transition lengths in microfluidic devices and compare the results with theoretical and numerical models with good a...
{"title":"Local Temperature Profile Measurement in Microchannels Using Temperature Sensitive Leuco-Dye Microbeads","authors":"M. A. Cartas-Ayala, R. Karnik","doi":"10.1260/1759-3093.2.1.41","DOIUrl":"https://doi.org/10.1260/1759-3093.2.1.41","url":null,"abstract":"Microfluidics has shown the ability to reproduce many of the techniques used in chemistry and biology, achieving faster and inexpensive results with smaller samples. As part of this effort towards miniaturization, the heating and cooling of samples has become an important step in many devices, especially for nucleic acid analysis. Measuring temperature profiles inside microchannels is required to verify the performance of such devices. Here we introduce a new technique to measure thermal profiles in microchannels: leuco-dye temperature sensitive microbeads, which permits fast, simple and inexpensive measurement of thermal profiles based on color, which enable its use to quickly assess temperature profiles to verify device performance, or as an educational tool for visualizing microscale heat transfer. Using the technique, we present visualization of thermal profiles and measurement of color transition lengths in microfluidic devices and compare the results with theoretical and numerical models with good a...","PeriodicalId":89942,"journal":{"name":"International journal of micro-nano scale transport","volume":"2 1","pages":"41-56"},"PeriodicalIF":0.0,"publicationDate":"2011-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"66151441","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}
Pub Date : 2011-03-01DOI: 10.1260/1759-3093.2.1.57
I. Yang, M. El-Genk
Numerical analysis is performed of the formation of an emulsion of disperse micro-drops in the dripping regime of co-flowing immiscible liquids in co-axial micro-tubes. This parametric analysis investigated the effects of changing the interfacial tension, velocities and viscosities of the two liquids and the diameters of the coaxial micro-tubes on the dynamics, frequency and radius of the forming droplets. The transient, 2-D axisymmetric Navier-Stockes equations of the two liquids and the advection equation for the interface, subject to the momentum jump condition, are solved using a finite element method. Semi-empirical correlations are developed for the dimensionless radius and formation frequency of the droplets, based on numerical results for wide ranges of parameters. The correlations are in good agreement (+10% to -14%) with recently reported experimental measurements for water (mono-disperse) droplets in a continuous flowing salad oil in a co-axial micro-tube.
{"title":"Emulsion Formation in Dripping Regime of Co-Flowing Immiscible Liquids in Co-Axial Micro-Tubes","authors":"I. Yang, M. El-Genk","doi":"10.1260/1759-3093.2.1.57","DOIUrl":"https://doi.org/10.1260/1759-3093.2.1.57","url":null,"abstract":"Numerical analysis is performed of the formation of an emulsion of disperse micro-drops in the dripping regime of co-flowing immiscible liquids in co-axial micro-tubes. This parametric analysis investigated the effects of changing the interfacial tension, velocities and viscosities of the two liquids and the diameters of the coaxial micro-tubes on the dynamics, frequency and radius of the forming droplets. The transient, 2-D axisymmetric Navier-Stockes equations of the two liquids and the advection equation for the interface, subject to the momentum jump condition, are solved using a finite element method. Semi-empirical correlations are developed for the dimensionless radius and formation frequency of the droplets, based on numerical results for wide ranges of parameters. The correlations are in good agreement (+10% to -14%) with recently reported experimental measurements for water (mono-disperse) droplets in a continuous flowing salad oil in a co-axial micro-tube.","PeriodicalId":89942,"journal":{"name":"International journal of micro-nano scale transport","volume":"2 1","pages":"57-84"},"PeriodicalIF":0.0,"publicationDate":"2011-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1260/1759-3093.2.1.57","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"66151447","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 review of gas flow in microchannels of different cross-sections is presented in this article. The phenomenon of slip, slip models and measurement of slip coefficient are first discussed. The planar microchannels are dealt with in great detail; the different analytical, experimental and simulation approaches and solutions available in the literature are reviewed. A review of literature on square, rectangular and circular microchannels have revealed that these microchannels have also been extensively studied. Information on other shapes of microchannels such as triangular, trapezoidal and elliptical is also presented. It is recognized that surface roughness may play an important role; therefore the effect of surface roughness on flow characteristics and overall pressure drop is given due attention. It is further recognized that frequently the microchannels may not be straight; therefore, microchannels with bends or involving sudden expansion/contraction is considered. Empirical correlations and equations ...
{"title":"A Comprehensive Review on Gas Flow in Microchannels","authors":"A. Agrawal","doi":"10.1260/1759-3093.2.1.1","DOIUrl":"https://doi.org/10.1260/1759-3093.2.1.1","url":null,"abstract":"A review of gas flow in microchannels of different cross-sections is presented in this article. The phenomenon of slip, slip models and measurement of slip coefficient are first discussed. The planar microchannels are dealt with in great detail; the different analytical, experimental and simulation approaches and solutions available in the literature are reviewed. A review of literature on square, rectangular and circular microchannels have revealed that these microchannels have also been extensively studied. Information on other shapes of microchannels such as triangular, trapezoidal and elliptical is also presented. It is recognized that surface roughness may play an important role; therefore the effect of surface roughness on flow characteristics and overall pressure drop is given due attention. It is further recognized that frequently the microchannels may not be straight; therefore, microchannels with bends or involving sudden expansion/contraction is considered. Empirical correlations and equations ...","PeriodicalId":89942,"journal":{"name":"International journal of micro-nano scale transport","volume":"2 1","pages":"1-40"},"PeriodicalIF":0.0,"publicationDate":"2011-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1260/1759-3093.2.1.1","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"66151405","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}
Pub Date : 2011-03-01DOI: 10.1260/1759-3093.2.1.99
Ashwin Ramesh, S. Diwakar, Sarit K. Das
The current study numerically investigates the motion of droplets on a surface with a micro cavity using the Volume of Fluid (VOF) technique. The simulation is a precursor to droplet motion on super-hydrophobic surfaces which is the focus of surface engineering research in recent times. The advancing and receding contact angles are tracked as a droplet moves on a single cavity which can be seen as the space between two posts of a typical engineered super-hydrophobic surface. Stick-jump-slip behavior can be seen during the advancing motion of the drop and the reverse is seen during the receding motion. The contact angle evolution is studied for three different post geometries and it is concluded that wider post spacing leads to smaller dynamic contact angles. This study is important from the point of prediction of dynamic contact angles computationally on super-hydrophobic surfaces.
{"title":"Numerical Prediction of Contact Line Dynamics on Super-Hydrophobic Surfaces","authors":"Ashwin Ramesh, S. Diwakar, Sarit K. Das","doi":"10.1260/1759-3093.2.1.99","DOIUrl":"https://doi.org/10.1260/1759-3093.2.1.99","url":null,"abstract":"The current study numerically investigates the motion of droplets on a surface with a micro cavity using the Volume of Fluid (VOF) technique. The simulation is a precursor to droplet motion on super-hydrophobic surfaces which is the focus of surface engineering research in recent times. The advancing and receding contact angles are tracked as a droplet moves on a single cavity which can be seen as the space between two posts of a typical engineered super-hydrophobic surface. Stick-jump-slip behavior can be seen during the advancing motion of the drop and the reverse is seen during the receding motion. The contact angle evolution is studied for three different post geometries and it is concluded that wider post spacing leads to smaller dynamic contact angles. This study is important from the point of prediction of dynamic contact angles computationally on super-hydrophobic surfaces.","PeriodicalId":89942,"journal":{"name":"International journal of micro-nano scale transport","volume":"2 1","pages":"99-108"},"PeriodicalIF":0.0,"publicationDate":"2011-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1260/1759-3093.2.1.99","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"66151738","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}
Pub Date : 2010-12-01DOI: 10.1260/1759-3093.1.4.323
J. Victor, U. Erb
This study is concerned with an analysis of the structural and mechanical design concepts in naturally occurring superhydrophobic structures. It is shown that the non-wetting behaviour of the leaves of two members of the aspen family can be primarily attributed to a dual-scale surface structure consisting of micro-papillae and nano-wax platelets. However, the non-wetting effect is further enhanced by the large leafstalk aspect ratio and associated low moment of inertia, offering little resistance to leaf bending. These leafstalk dimensions result in excessive shaking of the leaves even when there is no noticeable breeze, promoting efficient water droplet roll-off and dry leaf surfaces. It is tentatively concluded that this leaf design may contribute to the aspens' ability to quickly grow in a wide range of environmental conditions. Mimicking the combined effects of micro/nanostructure surface morphology and mechanical motion could be useful in developing a broader design concept range for superhydrophobic...
{"title":"Superhydrophobic Structures on the Basis of Aspen Leaf Design","authors":"J. Victor, U. Erb","doi":"10.1260/1759-3093.1.4.323","DOIUrl":"https://doi.org/10.1260/1759-3093.1.4.323","url":null,"abstract":"This study is concerned with an analysis of the structural and mechanical design concepts in naturally occurring superhydrophobic structures. It is shown that the non-wetting behaviour of the leaves of two members of the aspen family can be primarily attributed to a dual-scale surface structure consisting of micro-papillae and nano-wax platelets. However, the non-wetting effect is further enhanced by the large leafstalk aspect ratio and associated low moment of inertia, offering little resistance to leaf bending. These leafstalk dimensions result in excessive shaking of the leaves even when there is no noticeable breeze, promoting efficient water droplet roll-off and dry leaf surfaces. It is tentatively concluded that this leaf design may contribute to the aspens' ability to quickly grow in a wide range of environmental conditions. Mimicking the combined effects of micro/nanostructure surface morphology and mechanical motion could be useful in developing a broader design concept range for superhydrophobic...","PeriodicalId":89942,"journal":{"name":"International journal of micro-nano scale transport","volume":"1 1","pages":"323-334"},"PeriodicalIF":0.0,"publicationDate":"2010-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"66151352","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}
Pub Date : 2010-12-01DOI: 10.1260/1759-3093.1.4.269
Ji-Hwan Lee, Seunghyun Lee, C. Choi, S. Jang, Stephen U. S. Choi
Numerous studies have shown that nanofluids have superb physical properties, among which thermal conductivity has been studied most extensively but remains controversial. In this review article, we first present important milestones in experimental studies that show new features of the thermal conductivity of nanofluids, together with those that show no such special features. After a brief review of the physical mechanisms proposed to explain the thermal conductivity of nanofluids we present a critical review of the classical and new models used to predict the thermal conductivity behavior of nanofluids. We discuss some controversial issues such as data inconsistencies, the sufficiency and suitability of classical and new mechanisms, and the discrepancies between experimental data and model predictions. At the end of our review, we give some directions for future research in nanofluids and to aid researchers in resolving the controversial issues we are still facing in developing nanofluids with superior t...
{"title":"A Review of Thermal Conductivity Data, Mechanisms and Models for Nanofluids","authors":"Ji-Hwan Lee, Seunghyun Lee, C. Choi, S. Jang, Stephen U. S. Choi","doi":"10.1260/1759-3093.1.4.269","DOIUrl":"https://doi.org/10.1260/1759-3093.1.4.269","url":null,"abstract":"Numerous studies have shown that nanofluids have superb physical properties, among which thermal conductivity has been studied most extensively but remains controversial. In this review article, we first present important milestones in experimental studies that show new features of the thermal conductivity of nanofluids, together with those that show no such special features. After a brief review of the physical mechanisms proposed to explain the thermal conductivity of nanofluids we present a critical review of the classical and new models used to predict the thermal conductivity behavior of nanofluids. We discuss some controversial issues such as data inconsistencies, the sufficiency and suitability of classical and new mechanisms, and the discrepancies between experimental data and model predictions. At the end of our review, we give some directions for future research in nanofluids and to aid researchers in resolving the controversial issues we are still facing in developing nanofluids with superior t...","PeriodicalId":89942,"journal":{"name":"International journal of micro-nano scale transport","volume":"1 1","pages":"269-322"},"PeriodicalIF":0.0,"publicationDate":"2010-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1260/1759-3093.1.4.269","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"66151343","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}
Pub Date : 2010-12-01DOI: 10.1260/1759-3093.1.4.335
A. Bhunia, Ya-Chi Chen, Chung-Lung Chen
This article reports the role of micro-structured surfaces on phase change heat transfer due to impingement of a liquid micro-jet array. Experiments are conducted with an array of sixteen free surface DI water jets, each 125 μm diameter, at two different jet Reynolds number conditions of 1012 and 1747. A systematic, parametric study is carried out with eight different micro-structure patterns, all square cross-section micro-studs, by varying stud size, height, spacing, and stud arrangement (in-line and staggered array of studs). The structures are fabricated over a base area of 0.0001 m2 (1 cm2). In general, compared to the plain base surface, all the micro-structures improve impingement boiling heat transfer. The performance enhancement occurs in all regimes of boiling: at the onset, fully developed nucleate boiling and the critical heat flux (CHF). The optimal microstructure shows up to 78% increase in CHF compared to the plain surface. Heat flux in excess of 1000 Watts/cm2 is demonstrated. The results ...
{"title":"Liquid Micro-jet Array Impingement Boiling on a Micro-structured Surface","authors":"A. Bhunia, Ya-Chi Chen, Chung-Lung Chen","doi":"10.1260/1759-3093.1.4.335","DOIUrl":"https://doi.org/10.1260/1759-3093.1.4.335","url":null,"abstract":"This article reports the role of micro-structured surfaces on phase change heat transfer due to impingement of a liquid micro-jet array. Experiments are conducted with an array of sixteen free surface DI water jets, each 125 μm diameter, at two different jet Reynolds number conditions of 1012 and 1747. A systematic, parametric study is carried out with eight different micro-structure patterns, all square cross-section micro-studs, by varying stud size, height, spacing, and stud arrangement (in-line and staggered array of studs). The structures are fabricated over a base area of 0.0001 m2 (1 cm2). In general, compared to the plain base surface, all the micro-structures improve impingement boiling heat transfer. The performance enhancement occurs in all regimes of boiling: at the onset, fully developed nucleate boiling and the critical heat flux (CHF). The optimal microstructure shows up to 78% increase in CHF compared to the plain surface. Heat flux in excess of 1000 Watts/cm2 is demonstrated. The results ...","PeriodicalId":89942,"journal":{"name":"International journal of micro-nano scale transport","volume":"1 1","pages":"335-350"},"PeriodicalIF":0.0,"publicationDate":"2010-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"66151360","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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