scholarly journals Development and Application of One-Sided Piezoelectric Actuating Micropump

2013 ◽  
Vol 2013 ◽  
pp. 1-16
Author(s):  
H. K. Ma ◽  
Y. T. Li ◽  
H. C. Su ◽  
W. F. Luo ◽  
T. J. Pan ◽  
...  
Keyword(s):  
Fuel Cell ◽  
Flow Rate ◽  
Maximum Flow ◽  
Cell System ◽  
Valveless Micropump ◽  
The Third ◽  
Air Inlet ◽  
Frequency Modulator ◽  
Microfuel Cell ◽  
Secondary Chamber

Three types of one-sided actuating piezoelectric micropumps are studied in this paper. In the first type, one-sided actuating micropump with two check valves can enhance the flow rate and prevent the back flow in suction mode to keep the flow in one direction. Furthermore, the frequency modulator is applied in the micropump to adjust and promote the maximum flow rate higher than 5.0 mL/s. In the second type, valveless micropump with secondary chamber shows that the secondary chamber plays a key role in the application of the valveless micropump. It not only keeps the flow in one direction but also makes the flow rate of the pump reach 0.989 mL/s. In addition, when a nozzle/diffuser element is used in valveless micropump, the flow rate can be further improved to 1.183 mL/s at a frequency of 150 Hz. In the third type, piezoelectric actuating pump is regarded as an air pump in the application of a microfuel cell system, which can increase more air inlet to improve the fuel/air reaction and further increase the performance of fuel cell.

Critical flow rate of anode fuel exhaust in a PEM fuel cell system

2006 ◽  
Vol 156 (2) ◽  
pp. 512-519 ◽  
Author(s):  
Wenhua H. Zhu ◽  
Robert U. Payne ◽  
Bruce J. Tatarchuk
Keyword(s):  
Fuel Cell ◽  
Flow Rate ◽  
Pem Fuel Cell ◽  
Cell System ◽  
Critical Flow ◽  
Fuel Cell System ◽  
Critical Flow Rate

scholarly journals Design and Characterization of a Magnetically Driven Valveless Micropump for Drug Delivery

2009 ◽  
Vol 3 (2) ◽  
Author(s):  
Y. Zhou ◽  
F. Amirouche ◽  
L. Chen
Keyword(s):  
Magnetic Field ◽  
Drug Delivery ◽  
Resonant Frequency ◽  
Flow Rate ◽  
Excitation Frequency ◽  
Maximum Flow ◽  
Dual Chamber ◽  
Pumping Rate ◽  
Valveless Micropump ◽  
Magnetic Forces

Micropump, an actuation source to transfer the fluid from reservoir to the target place with accuracy and reliability, plays an important role in microfluidic devices. A broad range of micropump applications in biomedical fields are found in the fluid fine regulation and precise control systems for implantable drug delivery, chemical and biological detection, as well as blood transport in cardiology system. A polydimethylsiloxane (PDMS) magnetic composite membrane based on microfabrication with dimensions of 6 mm and 65 μm in diameter and thickness respectively, is employed to actuate a proposed micropump. In micro pumping operation, the fluid flow effects on the actuation and dynamic response of an oscillating membrane are curial to the design of the micropump. Therefore, the resonant frequency of this micro device is estimated considering the added mass and fluid damping to understand the behaviors of the valveless micropump. In this study, the membrane actuation is implemented by a miniaturized electromagnet, which provides an external time-varying magnetic field. The magnetic force on the membrane is proportional to the gradient of the magnetic field and the magnetization of the micro particles embedded in the membrane. The alternating attractive and repulsive magnetic forces on this composite membrane are computed by Finite Element Analysis (FEA). The basic design issues of the electromagnetic actuator involving air gaps, input current signals, and distribution of magnetic flux in the magnetic circuit are presented. Moreover, the magnetic-structure coupling analysis is conducted to determine the maximum deformation and stresses on the membrane, which result from the action of these magnetic forces. Finally, frequency-dependent flow rate of a dual-chamber configuration micropump has been studied. The pumping rate increases almost linearly with the excitation frequency at low ranges and there exists resonant frequencies at which the flow rate will reach a maximum value. After the flow rate peaks, the pumping rate decreases sharply along with the actuating frequencies. The maximum flow rate for the dual-chamber remains at 27.73μl/min under 0.4 A input current with an excitation frequency of 3 Hz. For comparison, a single-chamber micropump reaches a maximum flow rate of 19.61μl/min with a resonant frequency of 4.36 Hz under the same condition.

Piezo-Actuated Valveless Micropumps for Micro-Total Analysis Systems

2010 ◽  
Author(s):  
Arvind Chandrasekaran ◽  
Muthukumaran Packirisamy
Keyword(s):  
Flow Rate ◽  
Glass Substrate ◽  
Flow Characteristics ◽  
Low Frequency ◽  
Lab On A Chip ◽  
Maximum Flow ◽  
Valveless Micropump ◽  
Chip Flow ◽  
Micro Total Analysis Systems ◽  
Total Analysis

In this work, a Piezo actuated Valveless micropump is proposed for applications in Micro-Total Analysis Systems (μTAS) and Lab-on-a-Chip. Flow rectification in the micropump has been brought about with the use of a diffuser element. The device is fabricated on PDMS-Glass substrate with the glass acting as the diaphragm. A PZT disc is integrated with the setup for actuation. The micropump has been characterized for its dynamic behavior, flow characteristics, and pressure. It was found that the maximum flow rate for the micropump was obtained at low frequency which makes it usable for practical μTAS applications.

Estimating Air Flow Rates in a Fuel Cell System Using Electrochemical Impedance

2008 ◽  
Author(s):  
Judith O’Rourke ◽  
Murat Arcak ◽  
Manikandan Ramani
Keyword(s):  
Fuel Cell ◽  
Flow Rate ◽  
Electrochemical Impedance ◽  
Air Flow ◽  
Ac Impedance ◽  
Cell System ◽  
Fuel Cell System ◽  
Impedance Measurements ◽  
Flow Rates ◽  
Current Densities

This paper proposes the use of electrochemical impedance spectroscopy (EIS) to estimate the cathode flow rate in a fuel cell system. Through experimental testing of an eight-cell, hydrogen-fueled polymer electrolyte stack, it shows that the ac impedance measurements are highly sensitive to the air flow rates at varying current densities. The ac impedance magnitude at 0.1Hz allows the distinction of air flow rates (stoichiometry of 1.5–3.0) at current densities as low as 0.1A/cm2. Using experimental data and regression analysis, a simple algebraic equation that estimates the air flow rate using impedance measurements at a frequency of 0.1Hz is developed. The derivation of this equation is based on the operating cell voltage equation that accounts for all the irreversibilities.

Valveless Micropump with Saw-Tooth Microchannel

2014 ◽  
Vol 613 ◽  
pp. 228-235 ◽  
Author(s):  
Ying Hua Xu ◽  
Wei Ping Yan ◽  
Li Guo
Keyword(s):  
Flow Rate ◽  
Maximum Flow ◽  
Width Ratio ◽  
Driving Voltage ◽  
Tooth Structure ◽  
Valveless Micropump ◽  
Micro Pump ◽  
Pump Flow Rate ◽  
Mems Technology ◽  
Micro Total Analysis Systems

The micropump is the executive component in a microfluidic chip which impels the sample to flow. Its performance directly affects the precision and reliability of Micro Total Analysis Systems (μTAS), and it also plays a key role in the targeting transport of trace substances. The single and double chamber valveless micropumps with saw-tooth microchannel were designed. The saw-tooth diffuser/nozzle pipe was fabricated on chrome glass substrate using MEMS technology and the pump diaphragm was manufactured by PMMA material. The piezoelectric bimorph with cantilever beam was adopted as driving pump actuator and PDMS material as pump diaphragm. The valveless micropumps for both single and double chambers were formed with different saw-tooth structure parameters. The flow rate increased about 25% when the sidewall of microchannel changed from smooth to saw-tooth, and with the driving voltage increasing, the positive and negative flow difference of saw-tooth diffuser/nozzle pipe increased significantly, so does the micro pump flow rate. The best diffused angle θ was determined by the microchannel length L of saw-tooth diffuser/nozzle pipe, and the micro pump operated with its maximum flow rate only when the length-width ratio A reached the best value. The flow rate of a saw-tooth diffuser/nozzle valveless micropump with parallel double chambers increased approximately 30% than that of a single chamber.

Comparative Study of Membrane Humidifier and Enthalpy Wheel Humidifier for Large Power Fuel Cell System

2008 ◽  
Vol 6 (1) ◽  
Author(s):  
Lao Xingsheng ◽  
Ma Shihu ◽  
Zhao Juntao ◽  
Zeng Hong ◽  
Zhuge Weilin ◽  
...  
Keyword(s):  
Fuel Cell ◽  
Diffusion Equation ◽  
Flow Rate ◽  
Proton Exchange Membrane ◽  
Cell System ◽  
Proton Exchange ◽  
Low Flow ◽  
Large Power ◽  
Vapor Transfer ◽  
Lower Effect

The performance of membrane humidifier (MH) and enthalpy wheel humidifier (EWH) for a large power proton exchange membrane fuel cell (PEMFC) system is compared using simulations and experiments. The MH model is based on one dimensional diffusion equation and the EWH model is based on the porous media surface diffusion equation. Simulation results agree well with experimental data. According to the results, the effect of intake air temperature has a lower effect on the MH performance than it does on the EWH performance while the air mass flow has a much higher effect on the MH performance than it does on the EWH performance. MH performs better than EWH at a low flow rate but worse at a high flow rate. Vapor transfer mechanism in the humidifiers is also studied.

Measurement of Solid Oxide Fuel Cell System Flow Rate by Tracer Gas Method

2006 ◽  
Vol 4 (3) ◽  
pp. 369-372
Author(s):  
Masatsugu Amano ◽  
Tohru Kato ◽  
Akira Negishi ◽  
Ken Kato ◽  
Ken Nozaki ◽  
...  
Keyword(s):  
Fuel Cell ◽  
Flow Rate ◽  
Calibration Method ◽  
Cell System ◽  
Fuel Cell System ◽  
Mixed Gas ◽  
Tracer Gas ◽  
Sampling System ◽  
Fuel Gas ◽  
Sonic Nozzle

A high-precision method to measure efficiency of fuel cells with a 0.1% margin of error is proposed. This method is principally divided into two procedures: determining the composition of fuel gas to be fed into a fuel cell system and measuring the flow rate of the fuel gas. The composition of the fuel gas is determined by an FTIR (Fourier transform infrared spectrometer) and/or a QMS (quadrapole mass spectrometer) with a built-in sonic nozzle sampling system. The flow rate was measured by the tracer gas method; that is, a given amount of tracer gas, such as one of the noble gases, was introduced into the line of the fuel gas, then, the mixed gas was sampled at the point where the tracer gas had been well mixed, and the concentration of the tracer gas was determined by the QMS. In this paper, a gravimetric calibration method using a highly sensitive balance is also proposed for flow control of the tracer gas. Also proposed are calibration of the FTIR and the QMS to establish the required low uncertainty or high accuracy of the measurement of the efficiency.

Performance Evaluation of a SOFC-GT Hybrid System With Ejectors for the Anode and Cathode Recirculations

2017 ◽  
Author(s):  
Jinwei Chen ◽  
Kuanying Gao ◽  
Maozong Liang ◽  
Huisheng Zhang
Keyword(s):  
Fuel Cell ◽  
Hybrid System ◽  
Flow Rate ◽  
Low Cost ◽  
Cell System ◽  
Operating Conditions ◽  
Momentum Balance ◽  
Fuel Flow ◽  
Inlet Conditions ◽  
Safety Range

The recirculation of the anode and cathode exhaust has huge benefits on the fuel cell system, for instance, keeping proper operating conditions of the reformer and preheating the inlet air which reduces the recuperator size. Furthermore, the ejectors used for the fuel cell recirculation are more reliable and low-cost in maintenance than high temperature blowers. In this paper, an anode and cathode recirculation scheme, both equipped with ejectors, was designed in a Solid Oxide Fuel Cell-Gas Turbine (SOFC-GT) hybrid system. Additionally, a blower was added between the compressor and the heat exchanger to overcome the significant pressure loss caused by the cathode ejector. This configuration separates the compressor from the fuel cell and turbine components, introducing more flexibility in system modification. The investigations were conducted to analyze the performance of the hybrid system with anode and cathode ejectors in this paper. Firstly, the ejector model was established based on the energy, mass and momentum balance equations. Furthermore, it was validated that the ejector model was consistent with the reference data. Secondly, the stand-alone performance of the anode and cathode ejectors was analyzed. The geometry parameters of the ejectors were determined based on the design conditions. Then the off-design performance was analyzed based on the designed ejectors geometry. The results show that the performance of the ejectors is greatly influenced by the inlet conditions of the primary and secondary fluid mass flow rate. Finally, the anode and cathode ejectors were integrated into the SOFC-GT hybrid system. Meanwhile, the off-design and dynamic behaviors of the whole SOFC-GT hybrid system with anode and cathode ejectors for recirculation loops were analyzed. In the end, the results show that the designed ejectors can effectively satisfy the demands of the SOFC-GT system with anode and cathode recirculation loops. And the safety range of relative fuel flow rate is from 0.42 to 1.22 when the rotator speed is constant.

SIMULINK-FEMLAB Integrated Dynamic Simulation Model for a PEM Fuel Cell System

2006 ◽  
Vol 3 (4) ◽  
pp. 452-458 ◽  
Author(s):  
R. Radu ◽  
R. Taccani
Keyword(s):  
Fuel Cell ◽  
Dynamic Simulation ◽  
Flow Rate ◽  
Proton Exchange Membrane ◽  
Simulation Models ◽  
Cell System ◽  
Proton Exchange ◽  
Predictive Tool ◽  
Development Activity ◽  
Exchange Membrane

The necessity for reliable simulation models, able to support the fuel cell systems development activity, has increased continuously during the last years. The present work proposes a model which integrates the finite element method in a dynamic simulation, in order to achieve higher accuracy and the possibility to investigate the influence of various parameters on the fuel cell dynamics. The model is implemented using MATLAB/SIMULINK and consists of two interacting main subsystems that calculates the fuel cell power response and the stack thermal behavior. The first simulates the mass transport and electrochemical phenomena using a model implemented in FEMLAB, and considers as input parameters the stack geometry, reactants pressure, flow rate and composition, and the stack average temperature. The last parameter is also evaluated by the second model, implemented also in FEMLAB, which considers the stack geometry, cooling air flow rate and ambient temperature. Both models were validated using the experimental data acquired on a Ballard Nexa 1.5kWe proton exchange membrane (PEM) system. The results prove that integrated model simulates with accuracy the dynamics of the proton exchange membrane fuel cell type (PEMFC) system and the interaction between the stack and the auxiliaries. The proposed model was used as a predictive tool for two situations. In the first simulation, with a relative fast dynamic, the model demonstrates that the cooling fan control strategy is essential for transient conditions characterized by a significant load decreasing. In the second, the model estimates the variation of the PEMFC main parameters on a 24h cycle, confirming its reliability.

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