Heat Transfer and Electrokinetic Flow Analysis in Poly(Dimethylsiloxane) Microfluidic Systems

2003 ◽  
Author(s):  
David Erickson ◽  
David Sinton ◽  
Vesna Nikolic ◽  
Dongqing Li
Keyword(s):  
Heat Transfer ◽  
Joule Heating ◽  
Volume Flow Rate ◽  
Flow Analysis ◽  
Numerical Approach ◽  
Temperature Sensitive ◽  
Microfluidic Systems ◽  
Buffer Solution ◽  
Channel Network ◽  
Electrokinetic Flow

Electrokinetic pumping is commonly used as a mechanism for species transport in microfluidic systems. Joule heating, caused by current flow through the buffer solution during electroosmotic flow, can lead to significant increases in the system temperature which can be detrimental to electrophoretic separations and temperature sensitive chemical reactions. In this paper, a combined experimental and numerical approach was used to examine Joule heating and heat transfer at a T intersection for PDMS/PDMS and PDMS/Glass hybrid microfluidic systems. In general it was found the PDMS/Glass chips maintained a more uniform and lower buffer temperature than the PDMS/PDMS systems, since the internally generated heat could be transferred more efficiently (due to the higher thermal conductivity of the glass component) from the channel network to the room temperature reservoir. This increase in temperature was shown to significantly increase the current load and the volume flow rate through the PDMS/PDMS system.

JOULE HEATING INDUCED HEAT TRANSFER IN ELECTROKINETIC FLOW THROUGH MICROFLUIDIC CHANNELS

Equipment ◽  
2006 ◽  
Author(s):  
C. Yang ◽  
G. Y. Tang ◽  
D. G. Yan ◽  
H. Q. Gong ◽  
John C. Chai ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Joule Heating ◽  
Microfluidic Channels ◽  
Electrokinetic Flow ◽  
Flow Through

Microfluidic concentration enhancement of bio-analyte by temperature gradient focusing via Joule heating by DC plus AC field: A numerical approach

2021 ◽  
pp. 1-17
Author(s):  
Amitava Dutta ◽  
Apurba Kumar Santra ◽  
Ranjan Ganguly
Keyword(s):  
Temperature Gradient ◽  
Joule Heating ◽  
Phosphate Buffer ◽  
Phosphate Buffer Solution ◽  
Numerical Approach ◽  
High Concentration ◽  
Buffer Solution ◽  
Temperature Gradient Focusing ◽  
Ac Field ◽  
Target Analyte

Abstract We present a detailed numerical analysis of electrophoresis induced concentration of a bio-analyte facilitated by temperature gradient focusing in a phosphate buffer solution via Joule heating inside a converging-diverging microchannel. The purpose is to study the effects of frequency of AC field and channel width variation on the concentration of target analyte. We tune the buffer viscosity, conductivity and electrophoretic mobility of the analyte such that the electrophoretic velocity of the analyte locally balances the electroosmotic flow of the buffer, resulting in a local build-up of the analyte concentration in a target region. An AC field is superimposed on the applied DC field within the microchannel in such a way that the back pressure effect is minimized, resulting in minimum dispersion and high concentration of the target analyte. Axial transport of fluorescein-Na in the phosphate buffer solution is controlled by inducing temperature gradient through Joule heating. The technique leverages the fact that the buffer's ionic strength and viscosity depends on temperature, which in turn guides the analyte transport. A numerical model is proposed and a finite element-based solution of the coupled electric field, mass, momentum, energy and species equations are carried out. Simulation predict peak of 670-fold concentration of fluorescein-Na is achieved. The peak concentration is found to increase sharply as the channel throat width, while the axial spread of concentrated analyte increases at lower frequency of AC field. The results of the work may improve the design of micro concentrator.

scholarly journals Joule heating and heat transfer in poly(dimethylsiloxane) microfluidic systems

Lab on a Chip ◽  
2003 ◽  
Vol 3 (3) ◽  
pp. 141 ◽  
Author(s):  
David Erickson ◽  
David Sinton ◽  
Dongqing Li
Keyword(s):  
Heat Transfer ◽  
Joule Heating ◽  
Microfluidic Systems

Joule Heating Induced Heat Transfer and Its Effects on Electrokinetic Mixing in T-Shape Microfluidic Channels

2007 ◽  
Author(s):  
Gongyue Tang ◽  
Chun Yang ◽  
Yee Cheong Lam
Keyword(s):  
Heat Transfer ◽  
Electric Field ◽  
Numerical Simulations ◽  
Joule Heating ◽  
Solution Temperature ◽  
Microfluidic Channels ◽  
Governing Equations ◽  
Electrokinetic Flow ◽  
Layer Potential ◽  
Temperature Distributions

In this paper, we report numerical and experimental studies of the Joule heating-induced heat transfer in fabricated T-shape microfluidic channels. We have developed comprehensive 3D mathematical models describing the temperature development due to Joule heating and its effects on electrokinetic flow. The models consist of a set of governing equations including the Poisson-Boltzmann equation for the electric double layer potential profiles, the Laplace equation for the applied electric field, the modified Navier-Stokes equations for the electrokinetic flow field, and the energy equations for the Joule heating induced conjugated temperature distributions in both the liquid and the channel walls. Specifically, the Joule number is introduced to characterize Joule heating, to account for the effects of the electric field strength, electrolyte concentration, channel dimension, and heat transfer coefficient outside channel surface. As the thermophysical and electrical properties including the liquid dielectric constant, viscosity and electric conductivity are temperature-dependent, these governing equations are strongly coupled. We therefore have used the finite volume based CFD method to numerically solve the coupled governing equations. The numerical simulations show that the Joule heating effect is more significant for the microfluidic system with a larger Joule number and/or a lower thermal conductivity of substrates. It is found that the presence of Joule heating makes the electroosmotic flow deviate from its normal “plug-like” profiles, and cause different mixing characteristics. The T-shape microfluidic channels were fabricated using rapid prototyping techniques, including the Photolithography technique for the master fabrication and the Soft Lithography technique for the channel replication. A rhodamine B based thermometry technique, was used for direct “in-channel” measurements of liquid solution temperature distributions in microfluidic channels, fabricated by the PDMS/PDMS and Glass/PDMS substrates. The experimental results were compared with the numerical simulations, and reasonable agreement was found.

Slip and Joule Heating Effects on Peristaltic Transport in an Inclined Channel

2018 ◽  
Vol 10 (3) ◽  
Author(s):  
Tasawar Hayat ◽  
Sadia Ayub ◽  
Anum Tanveer ◽  
Ahmed Alsaedi
Keyword(s):  
Heat Transfer ◽  
Thermal Radiation ◽  
Joule Heating ◽  
Temperature Drop ◽  
Numerical Approach ◽  
Peristaltic Transport ◽  
Partial Slip ◽  
Similar Response ◽  
Soret And Dufour Effects ◽  
Inclined Channel

This study investigates peristaltic transport of Sutterby fluid in an inclined channel. Applied magnetic field is also inclined. Thermal radiation, Joule heating, and Soret and Dufour effects are present. The channel boundaries satisfy wall compliant and partial slip conditions. The problem description is simplified by employing long wavelength and low Reynolds number assumptions. Graphical solutions for axial velocity, temperature, concentration, and heat transfer coefficient are obtained via built-in numerical approach NDSolve. Similar response of velocity and concentration profiles has been recorded for larger inclination. The results reveal temperature drop with larger thermal radiation. Here, radiation and thermal slip increase heat transfer rate.

Heat Transfer and Thermal Mechanical Stress Distributions in Gas Turbine Blades

2009 ◽  
Author(s):  
Fernando Z. Sierra ◽  
Diganta Narzary ◽  
Candelario Bolaina ◽  
Je Chin Han ◽  
Janusz Kubiak ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Mechanical Stress ◽  
Finite Volume ◽  
Turbine Blades ◽  
Numerical Approach ◽  
Conjugate Problem ◽  
Operating Conditions ◽  
Temperature Sensitive ◽  
Blade Surface ◽  
Cooling Effectiveness

In this paper the distributions of heat transfer and thermal mechanical stress in the metal blade surface are investigated. The stream that surrounds the blade was considered at the time that the cooling airflow runs through the blade interior. Cooling channel flow and gases were simulated using a finite volume program, Fluent. The conjugate problem was addressed using coupled domains solid-fluid. Beside the numerical approach, measurements of metal blade surface temperature distributions based on the temperature sensitive paint technique, TSP, were conducted. The cooling effectiveness was compared showing good agreement between computational/experimental results. Additionally to laboratory conditions, finite volume results were obtained for real engine operating conditions. These results were used to establish temperature boundary conditions into a second computational model programmed in ANSYS, based on finite elements. This second model allowed calculating the distribution of thermo-mechanical stress in the blade material. The results show the temperature distribution in the blade surface. Based on this, the heat transfer rate was calculated finding it as a strong function of position. The cooling effectiveness was also calculated, which in turn performs with less variation over the sections of the blade under investigation. Following, the thermal effects in the metal blade surface lead to calculate the stress distribution. Differences in stresses magnitude were also found, suggesting a strong correlation between heat transfer and stress in the metal blade surface.

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