Thermodynamic Efficiency of Porous Glass Electroosmotic Pumps

2003 ◽  
Author(s):  
Shuhuai Yao ◽  
Shulin Zeng ◽  
Juan G. Santiago
Keyword(s):  
Zeta Potential ◽  
Flow Rate ◽  
Maximum Flow ◽  
Pump Current ◽  
Thermodynamic Efficiency ◽  
Two Phase ◽  
Poisson Boltzmann ◽  
Electroosmotic Pumps ◽  
Poisson Boltzmann Equation ◽  
Pump Pressure

This paper presents an analytical and experimental study of electroosmotic (EO) pumps designed to be integrated with two-phase microchannel heat exchangers with load capacities of order 100 W and greater. We have fabricated sintered glass EO pumps that provide maximum flow rates and pressure capacities 33 ml/min and 1.3 atm, respectively, at 100 V applied potentials. We have developed an analytical model to solve for electroosmotic flow rate, total pump current, and thermodynamic efficiency as a function of pump pressure load for these porous-structure EO pumps. The model uses a symmetric electrolyte approximation valid for the high zeta potential regime and numerically solves the Poisson-Boltzmann equation for charge distribution in the idealized pore geometry. The model also incorporates an approximate ionic-strength-dependent zeta potential formulation. The effects of pressure and flow rate on thermodynamic efficiency are also analyzed theoretically and compared to our measurements.

scholarly journals Maximum Flow Rate of a Single Component, Two-Phase Mixture

1965 ◽  
Vol 87 (1) ◽  
pp. 134-141 ◽  
Author(s):  
F. J. Moody
Keyword(s):  
Flow Rate ◽  
Static Pressure ◽  
Maximum Flow ◽  
Single Component ◽  
Maximum Flow Rate ◽  
Vapor Flow ◽  
Two Phase ◽  
Slip Ratio ◽  
Phase Mixture ◽  
Local Slip

A theoretical model is developed for predicting the maximum flow rate of a single component, two-phase mixture. It is based upon annular flow, uniform linear velocities of each phase, and equilibrium between liquid and vapor. Flow rate is maximized with respect to local slip ratio and static pressure for known stagnation conditions. Graphs are presented giving maximum steam/water flow rates for: local static pressures between 25 and 3,000 psia, with local qualities from 0.01 to 1.00; local stagnation pressures and enthalpies which cover the range of saturation states.

Temporal Response of Porous Glass Electroosmotic Pumps

2002 ◽  
Author(s):  
Shuhuai Yao ◽  
Shulin Zeng ◽  
Juan G. Santiago
Keyword(s):  
Flow Rate ◽  
Maximum Flow ◽  
Ion Concentration ◽  
Temporal Response ◽  
Short Term ◽  
Cooling Systems ◽  
Sintered Glass ◽  
Rate Capacity ◽  
Bioanalytical Applications ◽  
Electroosmotic Pumps

Sintered glass electroosmotic pumps have been fabricated that provide maximum flow rates and pressure capacities exceeding 14 ml/min and 1.4 atm, respectively, at 150 V, with an active pumping volume of less than 2 cm3. These compact devices with no moving parts have the potential to impact a variety of applications including microelectronics cooling systems and bioanalytical applications. We present here a preliminary a study of the response of the pumps to changes in fluidic load, including their short-term transient performance. A 0.5 mM borate buffer (pH = 9.2) is used to stabilize pump performance, with nearly optimal flow rate capacity. The experiments are conducted for working electrolytes of varying ion concentration. These performance characteristics are critical to applications that aim to use feedback control of flow rate and pressure over varying conditions.

scholarly journals A Focus on Two Electrokinetics Issues

Micromachines ◽  
2020 ◽  
Vol 11 (12) ◽  
pp. 1028
Author(s):  
Cheng Dai ◽  
Ping Sheng
Keyword(s):  
Boltzmann Equation ◽  
Zeta Potential ◽  
Flow Field ◽  
Drag Coefficient ◽  
Surface Charge ◽  
Physical Picture ◽  
Debye Layer ◽  
Poisson Boltzmann ◽  
Poisson Boltzmann Equation ◽  
Mobile Ions

This review article intends to communicate the new understanding and viewpoints on two fundamental electrokinetics topics that have only become available recently. The first is on the holistic approach to the Poisson–Boltzmann equation that can account for the effects arising from the interaction between the mobile ions in the Debye layer and the surface charge. The second is on the physical picture of the inner electro-hydrodynamic flow field of an electrophoretic particle and its drag coefficient. For the first issue, the traditional Poisson–Boltzmann equation focuses only on the mobile ions in the Debye layer; effects such as charge regulation and the isoelectronic point arising from the interaction between the mobile ions in the Debye layer and the surface charge are left to supplemental measures. However, a holistic treatment is entirely possible in which the whole electrical double layer—the Debye layer and the surface charge—is treated consistently from the beginning. While the derived form of the Poisson–Boltzmann equation remains unchanged, the zeta potential boundary condition becomes a calculated quantity that can reflect the various effects due to the interaction between the surface charges and the mobile ions in the liquid. The second issue, regarding the drag coefficient of a spherical electrophoretic particle, has existed ever since the breakthrough by Smoluchowski a century ago that linked the zeta potential of the particle to its mobility. Due to the highly nonlinear mathematics involved in the electro-hydrodynamics inside the Debye layer, there has been a lack of an exact solution for the electrophoretic flow field. Recent numerical simulation results show that the flow field comprises an inner region and an outer region, separated by a rather sharp interface. As the inner flow field is carried along by the particle, the measured drag is that at the inner/outer interface rather than at the solid/liquid interface. This identification and its associated physical picture of the inner flow field resolves a long-standing puzzle regarding the electrophoretic drag coefficient.

Unsteady Rotating Electroosmotic Flow Through a Slit Microchannel

2016 ◽  
Vol 32 (5) ◽  
pp. 603-611 ◽  
Author(s):  
D.-Q. Si ◽  
Y.-J. Jian ◽  
L. Chang ◽  
Q.-S. Liu
Keyword(s):  
Flow Rate ◽  
Electroosmotic Flow ◽  
Volume Flow Rate ◽  
Electrical Potential ◽  
Velocity Fields ◽  
Volume Flow ◽  
Half Height ◽  
Poisson Boltzmann ◽  
Flow Through ◽  
Poisson Boltzmann Equation

AbstractUsing the method of Laplace transform, an analytical solution of unsteady rotating electroosmotic flow (EOF) through a parallel plate microchannel is presented. The analysis is based upon the linearized Poisson-Boltzmann equation describing electrical potential distribution and the Navies Stokes equation representing flow field in the rotating coordinate system. The discrepancy of present problem from classical EOF is that the velocity fields are two-dimensional. The rotating EOF velocity profile and flow rate greatly depend on time t, rotating parameter ω and the electrokinetic width K (ratio of half height of microchannel to thickness of electric double layer). The influence of the above dimensionless parameters on transient EOF velocity, volume flow rate and EO spiral is investigated.

Optimization of High Flow Rate Nanoporous Electroosmotic Pump

2008 ◽  
Vol 130 (8) ◽  
Author(s):  
Y. Berrouche ◽  
Y. Avenas ◽  
C. Schaeffer ◽  
P. Wang ◽  
H.-C. Chang
Keyword(s):  
Flow Rate ◽  
Pore Radius ◽  
Debye Length ◽  
Maximum Flow ◽  
High Flow ◽  
Nanoporous Silica ◽  
Thermodynamic Efficiency ◽  
Hydraulic Circuit ◽  
Electroosmotic Pump ◽  
Disk Substrate

We present a theory for optimizing the thermodynamic efficiency of an electroosmotic (EO) pump with a large surface area highly charged nanoporous silica disk substrate. It was found that the optimum thermodynamic efficiency depends on the temperature, the silica zeta potential, the viscosity, the permittivity, the ion valency, the tortuosity of the nanoporous silica but mainly the effective normalized pore radius of the substrate scaled with respect to the Debye length. Using de-ionized water as the pumping liquid, the optimized EO pump generates a maximum flow rate of 13.6ml∕min at a pressure of 2kPa under an applied voltage of 150V. The power consumed by the pump is less than 0. 4W. The EO pump was designed to eliminate any bubble in the hydraulic circuit such that the pump can be operated continuously without significant degradation in the performance.

scholarly journals Peristaltically Induced Electroosmotic Flow of Jeffrey Fluid with Zeta Potential and Navier-Slip at the Wall

2019 ◽  
Vol 8 (10) ◽  
pp. 1324-1329
Keyword(s):  
Zeta Potential ◽  
Electrical Potential ◽  
Slip Boundary Condition ◽  
Jeffrey Fluid ◽  
Long Wavelength ◽  
Navier Slip ◽  
Slip Boundary ◽  
Fluid Parameter ◽  
Poisson Boltzmann ◽  
Poisson Boltzmann Equation

This paper concern with the electro-osmotically modulated peristaltic of Jeffrey fluid with zeta potential and Navier-slip boundary condition at the channel wall. The Poisson-Boltzmann equation for electrical potential distribution is assumed to accommodate the electrical double layer. Poisson-Boltzmann equations are simplified by using Debye-Huckel linearization approximation. The closed form analytical solutions are calculated by using low Reynolds number and long wavelength assumptions. Influence of various parameters like electro-osmotic, Jeffrey fluid parameter, Slip parameter and Zeta potential on the flow are discussed through the nature of graphs

Improved Flow Rate in Electro-Osmotic Micropumps for Combinations of Substrates and Different Liquids With and Without Nanoparticles

2015 ◽  
Vol 137 (2) ◽  
Author(s):  
Marwan F. Al-Rjoub ◽  
Ajit K. Roy ◽  
Sabyasachi Ganguli ◽  
Rupak K. Banerjee
Keyword(s):  
Heat Transfer ◽  
Zeta Potential ◽  
Thermal Management ◽  
Flow Rate ◽  
Maximum Flow ◽  
Enhanced Heat Transfer ◽  
Flow Rates ◽  
Current Leakage ◽  
Different Types ◽  
Electro Osmotic Flow

A new design for an electro-osmotic flow (EOF) driven micropump was fabricated. Considering thermal management applications, three different types of micropumps were tested using multiple liquids. The micropumps were fabricated from a combination of materials, which included: silicon-polydimethylsiloxane (Si-PDMS), Glass-PDMS, or PDMS-PDMS. The flow rates of the micropumps were experimentally and numerically assessed. Different combinations of materials and liquids resulted in variable values of zeta-potential. The ranges of zeta-potential for Si-PDMS, Glass-PDMS, and PDMS-PDMS were −42.5–−50.7 mV, −76.0–−88.2 mV, and −76.0–−103.0 mV, respectively. The flow rates of the micropumps were proportional to their zeta-potential values. In particular, flow rate values were found to be linearly proportional to the applied voltages below 500 V. A maximum flow rate of 75.9 μL/min was achieved for the Glass-PDMS micropump at 1 kV. At higher voltages nonlinearity and reduction in flow rate occurred due to Joule heating and the axial electro-osmotic current leakage through the silicon substrate. The fabricated micropumps could deliver flow rates, which were orders of magnitude higher compared to the previously reported values for similar size micropumps. It is expected that such an increase in flow rate, particularly in the case of the Si-PDMS micropump, would lead to enhanced heat transfer for microchip cooling applications as well as for applications involving micrototal analysis systems (μTAS).

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