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Fabrication of square microchannel for experimental investigation of two phase flow using conventional machining process
+Model PISC-205; No. of Pages 3
ARTICLE IN PRESS
Perspectives in Science (2016) xxx, xxx—xxx
Available online at www.sciencedirect.com
ScienceDirect journal homepage: www.elsevier.com/pisc
Fabrication of square microchannel for experimental investigation of two phase flow using conventional machining process夽 Ashish Mogra a,∗, Satish Kumar Verma b, Tiju Thomas a a b
NMIMS, MPSTME, Shirpur, Dhule, India SRICT Ankleswar, Bharuch, Gujarat, India
Received 30 January 2016; accepted 8 April 2016 Available online xxx
KEYWORDS Microchannel; Square; Scanning electron microscope; Hydraulic diameter
Summary An attempt has been made to develop the microchannel of hydraulic diameter less than or equal to 0.5 mm. These channels are fabricated using conventional milling machining process. In order to study the inlet configuration effect, two types of junctions such as T and Y are developed. These microchannels are developed on acrylic substrates of 300 mm long and 30 mm wide. The cross section of the channel is selected as non-circular (square). The aim behind to develop small diameter minichannel is for development of experimental set up on two phase flow through microsized channels. The cross section of fabricated microchannel is checked with Scanning Electron Microscope (SEM-S-3400N) and found nearest to desired dimension. The objective of this research is to find out an alternate technique for the fabrication of microchannel instead of complicated and costly techniques. © 2016 Published by Elsevier GmbH. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).
Introduction Two-phase flow in the microchannels plays an important role in many chemical and process industries. The application of
夽 This article belongs to the special issue on Engineering and Material Sciences. ∗ Corresponding author. Tel.: +91 9604066126; fax: +91 2563 286552. E-mail address: [email protected] (A. Mogra).
http://dx.doi.org/10.1016/j.pisc.2016.04.036 2213-0209/© 2016 Published by Elsevier GmbH. (http://creativecommons.org/licenses/by-nc-nd/4.0/).
This
is
microchannel as a microheat pumps, micro heat exchanger and microfluidics devices make attention due to dimension of its cross section. Furthermore the gravitational and viscous forces become less dominant in the microchannels as compared to the inertia and surface tension forces. As a consequence, two-phase flow in microchannels behaves differently from that in macroscopic channels. For two phase flow through microchannel, it is observed that due to the wall wetting effect stratified flow regime does not exist. The available knowledge in the area of design and analysis of micro fluidic devices is directly applicable for two-phase
an
open
access
article
under
the
CC
BY-NC-ND
license
Please cite this article in press as: Mogra, A., et al., Fabrication of square microchannel for experimental investigation of two phase flow using conventional machining process. Perspectives in Science (2016), http://dx.doi.org/10.1016/j.pisc.2016.04.036
+Model PISC-205; No. of Pages 3
ARTICLE IN PRESS
2
A. Mogra et al.
flow. The application of two-phase flows in micro tubes is increasing frequently in many industrial fields like cooling of electronic devices, Biomedical, Microelectromechanical system (MEMS), micro refrigeration systems, and in micro-heat pumps (Santos and Kawaji, 2010). Compact heat exchanger used channels of diameter in the range of 1 mm or less than 1 mm. A micro-channel heat exchanger is essentially an indirect method of cooling, used to maintain the temperature of chip or integrated circuit within operational limits. These heat exchangers are generally used in spacecraft, lab on chip, in air separation plants, chemical process industries, and nuclear reactors. McDonald and Whitesides (2002) developed a new technique to fabricate microchannel on polytetrafluoroethylene (PTFE) and fluoroethylenepropylene (FEP), in the form of outer and inner layer respectively. They used heating, melting and shrinking method for fabrication of microchannel. They used a tungsten wire to make circular cross section. Minimum diameter of the channel that can be produced, dependent upon the tungsten wire diameter. They fabricated three sets of microchannels having the diameter of 13, 25 and 50 m with the length of up to 50 mm. Akbari et al. (Akbari, 2010) developed the first use of cold plasma deposition of polymerizable monomers for the fast, cost effective and easy fabrication of microchannels. A new method named ‘‘plasma polymerisation on sacrificial layer’’ (PPSL) was presented. Channels were formed with one lithographic mask and without any etching or bonding process. The use of polymerized TMDS allowed a rapid creation of capillaritydriven flow systems with channels width ranging from 4 to 700 m. Jian and Wu (2010) fabricated two sets of siliconbased micro pulsating heat pipes (SMPHPs) with trapezoidal cross section having hydraulic diameters of 352 m and 394 m respectively using Microelectro mechanical system (MEMS) technology. Li et al. (Li, 2011) formed the trapezoidal microchannel heat sink by wet etching of the silicon wafers in a solution of Potassium hydroxide (KOH). The silicon trapezoidal microchannel heat sink was 20 mm in length, 10 mm in width, and 500 m in thickness. An experimental investigation has been carried out to study the fluid flow and heat transfer characteristics in a silicon heat sink with 10 parallel trapezoidal microchannels. Abbas et al. (2009) fabricated microchannel using of cold plasma deposition of polymerizable monomers. A new method named ‘‘plasma polymerisation on sacrificial layer’’ (PPSL) is observed. It consists in the direct polymerisation of tetramethyldisiloxan (TMDS) on a photopatterned sacrificial layer. Darvishi et al. (2012) examine ultrafast laser machining of tapered microchannel trenches in both hard (soda—lime and borosilicate glasses) and soft (PDMS elastomer) transparent solids. They developed a simple model for channel width and depth as a function of processing parameters and threshold fluence. Approximated channel sizes from the model are in good agreement with experimental results.
Fabrication procedure of microchannel Small diameter or microchannels are fabricated using number of different methods available in the literature. The fabrication method depends upon the substrate, geometric
features required and application of microchannel. It is observed that creating very fine surface of microchannel another technique known as the silicon micro fabrication is used. The advantage of these technique is to fabricate channel of hydraulic diameter in the range of microns. There are numerous methods for fabrication of microchannel, micromachining is one of the process which can be used to fabricate channels. These methods are the generally used for metal substrates. In addition micro deformation technology (MDT) is becoming more popular technique for fabrication of microchannel. This new technology used to fabricate the microstructures within very high accuracy and high aspect ratio. Many studies have been carried out on fabrication techniques for simple T or Y type branches microchannel with cross section circular or non-circular (i.e., rectangular, triangular, trapezoidal). The objective of this work is to develop microchannels within the range of hydraulic diameter less than or equal to 0.5 mm. These channels were fabricated using conventional or traditional machining process. In order to study the inlet configuration effect, two types of junctions such as T and Y are developed. These microchannels are developed on acrylic substrates of 300 mm long and 30 mm wide. The cross section of the channel is selected as noncircular (rectangular). The dimensions of fabricated channels are measured using Scanning electron microscope. Images at inlet and outlet section are captured using vision measuring system. The microchannels in present study are fabricated using conventional milling machine. The fabrication process starts with the laser cutting of acrylic material of required dimension with high accuracy. The fabrication of microchannel is mainly composed of two portions. In first part machining is done on the bottom parts of the acrylic substrate. In that a slot of rectangular cross section is cut using milling machine. In the second part the bottom plate is covered with the no machined top layer of the same material and same dimension. Then make a screw joint to couple both acrylic plates to get required cross section. Fabrication of microchannel includes other machining process like lath machine for making surface smooth.
Measurement of fabricated microchannel using Scanning Electron Microscope (SEM) The Scanning Electron Microscope (SEM) is a microscope that uses electrons rather than light to form an image. There are many advantages to using the SEM instead of a light microscope. All the pictures were captured by using the SEM kept at the SIC Laboratory, SVNIT, Surat. Measurement is very critical part of any fabricated element. Measurement shows the accuracy of the fabrication process. After fabricating microchannel it is essential to measure the dimension and check the required cross section of microchannel. For that purpose Scanning Electron Microscope (SEM) is used. Fig. 1 shows the captured images of microchannel using SEM. It shows the different view of fabricated microchannel. Different inlet geometries such as Y and T-junctions are fabricated. Table 1 shows geometrical parameters of fabricated microchannels. It is observed that the fabricated
Please cite this article in press as: Mogra, A., et al., Fabrication of square microchannel for experimental investigation of two phase flow using conventional machining process. Perspectives in Science (2016), http://dx.doi.org/10.1016/j.pisc.2016.04.036
+Model PISC-205; No. of Pages 3
ARTICLE IN PRESS
Fabrication of square microchannel for experimental investigation Table 1
3
Geometric parameters.
Sr. No.
Microchannel mixing junction (rectangular)
Width (mm)
Height (mm)
Length (mm)
Required hydraulic diameter (mm)
Actual hydraulic diameter (mm)
1
Y-type
0.5
0.5
300
0.5
0.522
2
T-type
0.4
0.4
300
0.4
0.44
3
Y-type
0.4
0.4
300
0.4
0.407
Angle (◦ )
120 120 120 90 180 90 120 120 120
microchannel is done by conventional milling machine and lathe machine instead for high cost fabrication process. Scanning Electron Microscope (SEM S-3400) is used for measurement of accurate dimension of fabricated microchannel. It is found that the fabricated microchannel have hydraulic diameter nearest to the required dimension.
References
Figure 1 A close view of 400 m hydraulic diameter microchannel measured using SEM.
dimensions are found in good agreement with desired dimension.
Conclusion In present study an attempt is made to develop new cost effective and easy method for fabrication of microchannel used in analysis of two phase flow. Fabrication of
Abbas, A., Supiot, P., Guillochon, D., Bocquet, B., 2009. Capillary microchannel fabrication using plasma polymerized TMDS for fluidic MEMS technology. J. Micromech. Microeng. 19 (045022), 8 pp. Akbari, M., 2010. Flow in rectangular microchannel: an experimental investigation. Darvishi, S., Cubaud, T., Longtin, J.P., 2012. Ultrafast laser machining of tapered microchannels in glass and PDMS. Opt. Lasers Eng. 50, 210—214. Jian, Q., Wu, H.Y., 2010. Flow visualization of silicon-based micro pulsating heat pipes. Sci. China Technol. Sci. 53 (4), 984—990. Li, C., 2011. Numerical Study of Isothermal Gas-liquid Two-phase Bubbly Flow. School of Aerospace, Mechanical and Manufacturing Engineering, Royal Melbourne Institute of Technology (RMIT) University. McDonald, J., Whitesides, G., 2002. Poly (dimethylsiloxane) as a material for fabricating microfluidic devices. Acc. Chem. Res. 35, 491—499. Santos, R.M., Kawaji, M., 2010. Numerical modeling and experimental investigation of gas—liquid slug formation in a microchannel T-junction. Int. J. Multiph. Flow 36.
Please cite this article in press as: Mogra, A., et al., Fabrication of square microchannel for experimental investigation of two phase flow using conventional machining process. Perspectives in Science (2016), http://dx.doi.org/10.1016/j.pisc.2016.04.036
ARTICLE IN PRESS
Perspectives in Science (2016) xxx, xxx—xxx
Available online at www.sciencedirect.com
ScienceDirect journal homepage: www.elsevier.com/pisc
Fabrication of square microchannel for experimental investigation of two phase flow using conventional machining process夽 Ashish Mogra a,∗, Satish Kumar Verma b, Tiju Thomas a a b
NMIMS, MPSTME, Shirpur, Dhule, India SRICT Ankleswar, Bharuch, Gujarat, India
Received 30 January 2016; accepted 8 April 2016 Available online xxx
KEYWORDS Microchannel; Square; Scanning electron microscope; Hydraulic diameter
Summary An attempt has been made to develop the microchannel of hydraulic diameter less than or equal to 0.5 mm. These channels are fabricated using conventional milling machining process. In order to study the inlet configuration effect, two types of junctions such as T and Y are developed. These microchannels are developed on acrylic substrates of 300 mm long and 30 mm wide. The cross section of the channel is selected as non-circular (square). The aim behind to develop small diameter minichannel is for development of experimental set up on two phase flow through microsized channels. The cross section of fabricated microchannel is checked with Scanning Electron Microscope (SEM-S-3400N) and found nearest to desired dimension. The objective of this research is to find out an alternate technique for the fabrication of microchannel instead of complicated and costly techniques. © 2016 Published by Elsevier GmbH. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).
Introduction Two-phase flow in the microchannels plays an important role in many chemical and process industries. The application of
夽 This article belongs to the special issue on Engineering and Material Sciences. ∗ Corresponding author. Tel.: +91 9604066126; fax: +91 2563 286552. E-mail address: [email protected] (A. Mogra).
http://dx.doi.org/10.1016/j.pisc.2016.04.036 2213-0209/© 2016 Published by Elsevier GmbH. (http://creativecommons.org/licenses/by-nc-nd/4.0/).
This
is
microchannel as a microheat pumps, micro heat exchanger and microfluidics devices make attention due to dimension of its cross section. Furthermore the gravitational and viscous forces become less dominant in the microchannels as compared to the inertia and surface tension forces. As a consequence, two-phase flow in microchannels behaves differently from that in macroscopic channels. For two phase flow through microchannel, it is observed that due to the wall wetting effect stratified flow regime does not exist. The available knowledge in the area of design and analysis of micro fluidic devices is directly applicable for two-phase
an
open
access
article
under
the
CC
BY-NC-ND
license
Please cite this article in press as: Mogra, A., et al., Fabrication of square microchannel for experimental investigation of two phase flow using conventional machining process. Perspectives in Science (2016), http://dx.doi.org/10.1016/j.pisc.2016.04.036
+Model PISC-205; No. of Pages 3
ARTICLE IN PRESS
2
A. Mogra et al.
flow. The application of two-phase flows in micro tubes is increasing frequently in many industrial fields like cooling of electronic devices, Biomedical, Microelectromechanical system (MEMS), micro refrigeration systems, and in micro-heat pumps (Santos and Kawaji, 2010). Compact heat exchanger used channels of diameter in the range of 1 mm or less than 1 mm. A micro-channel heat exchanger is essentially an indirect method of cooling, used to maintain the temperature of chip or integrated circuit within operational limits. These heat exchangers are generally used in spacecraft, lab on chip, in air separation plants, chemical process industries, and nuclear reactors. McDonald and Whitesides (2002) developed a new technique to fabricate microchannel on polytetrafluoroethylene (PTFE) and fluoroethylenepropylene (FEP), in the form of outer and inner layer respectively. They used heating, melting and shrinking method for fabrication of microchannel. They used a tungsten wire to make circular cross section. Minimum diameter of the channel that can be produced, dependent upon the tungsten wire diameter. They fabricated three sets of microchannels having the diameter of 13, 25 and 50 m with the length of up to 50 mm. Akbari et al. (Akbari, 2010) developed the first use of cold plasma deposition of polymerizable monomers for the fast, cost effective and easy fabrication of microchannels. A new method named ‘‘plasma polymerisation on sacrificial layer’’ (PPSL) was presented. Channels were formed with one lithographic mask and without any etching or bonding process. The use of polymerized TMDS allowed a rapid creation of capillaritydriven flow systems with channels width ranging from 4 to 700 m. Jian and Wu (2010) fabricated two sets of siliconbased micro pulsating heat pipes (SMPHPs) with trapezoidal cross section having hydraulic diameters of 352 m and 394 m respectively using Microelectro mechanical system (MEMS) technology. Li et al. (Li, 2011) formed the trapezoidal microchannel heat sink by wet etching of the silicon wafers in a solution of Potassium hydroxide (KOH). The silicon trapezoidal microchannel heat sink was 20 mm in length, 10 mm in width, and 500 m in thickness. An experimental investigation has been carried out to study the fluid flow and heat transfer characteristics in a silicon heat sink with 10 parallel trapezoidal microchannels. Abbas et al. (2009) fabricated microchannel using of cold plasma deposition of polymerizable monomers. A new method named ‘‘plasma polymerisation on sacrificial layer’’ (PPSL) is observed. It consists in the direct polymerisation of tetramethyldisiloxan (TMDS) on a photopatterned sacrificial layer. Darvishi et al. (2012) examine ultrafast laser machining of tapered microchannel trenches in both hard (soda—lime and borosilicate glasses) and soft (PDMS elastomer) transparent solids. They developed a simple model for channel width and depth as a function of processing parameters and threshold fluence. Approximated channel sizes from the model are in good agreement with experimental results.
Fabrication procedure of microchannel Small diameter or microchannels are fabricated using number of different methods available in the literature. The fabrication method depends upon the substrate, geometric
features required and application of microchannel. It is observed that creating very fine surface of microchannel another technique known as the silicon micro fabrication is used. The advantage of these technique is to fabricate channel of hydraulic diameter in the range of microns. There are numerous methods for fabrication of microchannel, micromachining is one of the process which can be used to fabricate channels. These methods are the generally used for metal substrates. In addition micro deformation technology (MDT) is becoming more popular technique for fabrication of microchannel. This new technology used to fabricate the microstructures within very high accuracy and high aspect ratio. Many studies have been carried out on fabrication techniques for simple T or Y type branches microchannel with cross section circular or non-circular (i.e., rectangular, triangular, trapezoidal). The objective of this work is to develop microchannels within the range of hydraulic diameter less than or equal to 0.5 mm. These channels were fabricated using conventional or traditional machining process. In order to study the inlet configuration effect, two types of junctions such as T and Y are developed. These microchannels are developed on acrylic substrates of 300 mm long and 30 mm wide. The cross section of the channel is selected as noncircular (rectangular). The dimensions of fabricated channels are measured using Scanning electron microscope. Images at inlet and outlet section are captured using vision measuring system. The microchannels in present study are fabricated using conventional milling machine. The fabrication process starts with the laser cutting of acrylic material of required dimension with high accuracy. The fabrication of microchannel is mainly composed of two portions. In first part machining is done on the bottom parts of the acrylic substrate. In that a slot of rectangular cross section is cut using milling machine. In the second part the bottom plate is covered with the no machined top layer of the same material and same dimension. Then make a screw joint to couple both acrylic plates to get required cross section. Fabrication of microchannel includes other machining process like lath machine for making surface smooth.
Measurement of fabricated microchannel using Scanning Electron Microscope (SEM) The Scanning Electron Microscope (SEM) is a microscope that uses electrons rather than light to form an image. There are many advantages to using the SEM instead of a light microscope. All the pictures were captured by using the SEM kept at the SIC Laboratory, SVNIT, Surat. Measurement is very critical part of any fabricated element. Measurement shows the accuracy of the fabrication process. After fabricating microchannel it is essential to measure the dimension and check the required cross section of microchannel. For that purpose Scanning Electron Microscope (SEM) is used. Fig. 1 shows the captured images of microchannel using SEM. It shows the different view of fabricated microchannel. Different inlet geometries such as Y and T-junctions are fabricated. Table 1 shows geometrical parameters of fabricated microchannels. It is observed that the fabricated
Please cite this article in press as: Mogra, A., et al., Fabrication of square microchannel for experimental investigation of two phase flow using conventional machining process. Perspectives in Science (2016), http://dx.doi.org/10.1016/j.pisc.2016.04.036
+Model PISC-205; No. of Pages 3
ARTICLE IN PRESS
Fabrication of square microchannel for experimental investigation Table 1
3
Geometric parameters.
Sr. No.
Microchannel mixing junction (rectangular)
Width (mm)
Height (mm)
Length (mm)
Required hydraulic diameter (mm)
Actual hydraulic diameter (mm)
1
Y-type
0.5
0.5
300
0.5
0.522
2
T-type
0.4
0.4
300
0.4
0.44
3
Y-type
0.4
0.4
300
0.4
0.407
Angle (◦ )
120 120 120 90 180 90 120 120 120
microchannel is done by conventional milling machine and lathe machine instead for high cost fabrication process. Scanning Electron Microscope (SEM S-3400) is used for measurement of accurate dimension of fabricated microchannel. It is found that the fabricated microchannel have hydraulic diameter nearest to the required dimension.
References
Figure 1 A close view of 400 m hydraulic diameter microchannel measured using SEM.
dimensions are found in good agreement with desired dimension.
Conclusion In present study an attempt is made to develop new cost effective and easy method for fabrication of microchannel used in analysis of two phase flow. Fabrication of
Abbas, A., Supiot, P., Guillochon, D., Bocquet, B., 2009. Capillary microchannel fabrication using plasma polymerized TMDS for fluidic MEMS technology. J. Micromech. Microeng. 19 (045022), 8 pp. Akbari, M., 2010. Flow in rectangular microchannel: an experimental investigation. Darvishi, S., Cubaud, T., Longtin, J.P., 2012. Ultrafast laser machining of tapered microchannels in glass and PDMS. Opt. Lasers Eng. 50, 210—214. Jian, Q., Wu, H.Y., 2010. Flow visualization of silicon-based micro pulsating heat pipes. Sci. China Technol. Sci. 53 (4), 984—990. Li, C., 2011. Numerical Study of Isothermal Gas-liquid Two-phase Bubbly Flow. School of Aerospace, Mechanical and Manufacturing Engineering, Royal Melbourne Institute of Technology (RMIT) University. McDonald, J., Whitesides, G., 2002. Poly (dimethylsiloxane) as a material for fabricating microfluidic devices. Acc. Chem. Res. 35, 491—499. Santos, R.M., Kawaji, M., 2010. Numerical modeling and experimental investigation of gas—liquid slug formation in a microchannel T-junction. Int. J. Multiph. Flow 36.
Please cite this article in press as: Mogra, A., et al., Fabrication of square microchannel for experimental investigation of two phase flow using conventional machining process. Perspectives in Science (2016), http://dx.doi.org/10.1016/j.pisc.2016.04.036