Valveless Pump Research Articles

Analysis of the flow rate characteristics of valveless piezoelectric pump with fractal-like Y-shape branching tubes

Microchannel heat sink with high heat transfer coefficients has been extensively investigated due to its wide application prospective in electronic cooling. However, this cooling system requires a separate pump to drive the fluid transfer, which is uneasy to minimize and reduces their reliability and applicability of the whole system. In order to avoid these problems, valveless piezoelectric pump with fractal-like Y-shape branching tubes is proposed. Fractal-like Y-shape branching tube used in microchannel heat sinks is exploited as no-moving-part valve of the valveless piezoelectric pump. In order to obtain flow characteristics of the pump, the relationship between tube structure and flow rate of the pump is studied. Specifically, the flow resistances of fractal-like Y-shape branching tubes and flow rate of the pump are analyzed by using fractal theory. Then, finite element software is employed to simulate the flow field of the tube, and the relationships between pressure drop and flow rate along merging and dividing flows are obtained. Finally, valveless piezoelectric pumps with fractal-like Y-shape branching tubes with different fractal dimensions of diameter distribution are fabricated, and flow rate experiment is conducted. The experimental results show that the flow rate of the pump increases with the rise of fractal dimension of the tube diameter. When fractal dimension is 3, the maximum flow rate of the valveless pump is 29.16 mL/min under 100 V peak to peak (13 Hz) power supply, which reveals the relationship between flow rate and fractal dimensions of tube diameter distribution. This paper investigates the flow characteristics of valveless piezoelectric pump with fractal-like Y-shape branching tubes, which provides certain references for valveless piezoelectric pump with fractal-like Y-shape branching tubes in application on electronic chip cooling.

Theoretical analysis and experimental verification on valve-less piezoelectric pump with hemisphere-segment bluff-body

Existing researches on no-moving part valves in valve-less piezoelectric pumps mainly concentrate on pipeline valves and chamber bottom valves, which leads to the complex structure and manufacturing process of pump channel and chamber bottom. Furthermore, position fixed valves with respect to the inlet and outlet also makes the adjustability and controllability of flow rate worse. In order to overcome these shortcomings, this paper puts forward a novel implantable structure of valve-less piezoelectric pump with hemisphere-segments in the pump chamber. Based on the theory of flow around bluff-body, the flow resistance on the spherical and round surface of hemisphere-segment is different when fluid flows through, and the macroscopic flow resistance differences thus formed are also different. A novel valve-less piezoelectric pump with hemisphere-segment bluff-body (HSBB) is presented and designed. HSBB is the no-moving part valve. By the method of volume and momentum comparison, the stress on the bluff-body in the pump chamber is analyzed. The essential reason of unidirectional fluid pumping is expounded, and the flow rate formula is obtained. To verify the theory, a prototype is produced. By using the prototype, experimental research on the relationship between flow rate, pressure difference, voltage, and frequency has been carried out, which proves the correctness of the above theory. This prototype has six hemisphere-segments in the chamber filled with water, and the effective diameter of the piezoelectric bimorph is 30mm. The experiment result shows that the flow rate can reach 0.50 mL/s at the frequency of 6 Hz and the voltage of 110 V. Besides, the pressure difference can reach 26.2 mm H2O at the frequency of 6 Hz and the voltage of 160 V. This research proposes a valve-less piezoelectric pump with hemisphere-segment bluff-body, and its validity and feasibility is verified through theoretical analysis and experiment.

A spiral-tube-type valveless piezoelectric pump with gyroscopic effect

The valveless piezoelectric pump integrates driving and transmitting into one operating element, and characterizes easy micro-miniaturization. But, there is the original sin of low pressure and low flow. Thus, it must avoid weakness to choose applications field. This paper analyzes the flow characteristics in the rotary spiral-tube, which will cause the Coriolis force, and subsequently influence the fluid moving. The principle of the pump is deduced, and the spiral-tube-type valveless piezoelectric pump is invented. The angular velocity variation can be obtained when the pump attitude changes, which theoretically verifies the gyroscopic effect of the pump. A pump is fabricated for experimental testing. Experiments has shown that when Archimedes spiral $$ \theta = 4\uppi $$ is selected for the tube design, and the rotation speed of the plate is 70 r/min, the pressure differential is 9 mm H2O, which is 1.5 times that of 0 r/min rotation speed. If introduced the low-cost and miniaturized gyroscope, then this may promise potential application in these areas such as smart cars, robots, and home health care.

Analysis of the Flow Resistance Characteristics of Valveless Piezoelectric Pump with Fractal-like Y-shape Branching Tubes

Analysis of the Flow Resistance Characteristics of Valveless Piezoelectric Pump with Fractal-like Y-shape Branching Tubes

半球缺阻流体无阀压电泵的实验验证

半球缺阻流体无阀压电泵的实验验证

Impedance Induce Valve Pump in Closed Loop System

This paper summarises a study which aims to develop and analyze the performance of the valveless impedance pump. Mechanism of valveless impedance pump is to apply acoustic impedance mismatch in order to drive the flow and also consists of a flexible connection at the ends to the more rigid sections. Characteristics of liquid velocity and pressure at the pump base valveless impedance at various supply voltage and different frequencies have been discovered through experimentation. Secondly, this research also aims to discuss the effect volume flow rate (millitres / min) in the elastic tube impedance based on different parameters of the pump pinch. The variation of pinch location and pinch width are also available through the results of this study. This study begins with the design set up to use the software and followed by installing all equipment used for the experiments. Then, this study continues to get results and make an analysis of the impedance pump by experimentation. Results found that all the parameters used in this experiment affect the flow rate in the impedance pump. Additional experiments on the effect of the thickness of the flexible tube on the flow rate gave lower values when the flexible tube is relatively thicker.

Investigation of the Flow in Valveless Pumps

An investigation of flow in valveless micropumps is presented. Numerical simulations are done using ANSYS. It is found that both laminar flow and turbulence phenomena would occurs in the diffuser/nozzle element. And SST (shear stress transport) turbulence model is chosen to be the most appropriate turbulence model,The simulations show when the opening angel gets bigger, the flow in the micropump, especially in the diffuser/nozzle becomes unsteady. When separation flow of fluid appears, pressure loss coefficient decreases rapidly.

In-vitro investigation of a potential wave pumping effect in human aorta

An impedance pump – also known as Liebau pump – is a simple valveless pump that operates based on the principles of wave propagation and reflection. It has been shown in embryonic zebrafish that a similar mechanism is responsible for the pumping action in the embryonic heart during the early stages before valve formation. Recent studies suggest that the cardiovascular system is designed to take advantage of wave propagation and reflection phenomena in the arterial network. In this study we report the results of an in-vitro study that examines the hypothesis that the adult human aorta acts as a passive pump based on Liebau effect. A hydraulic model with different compliant models of an artificial aorta was used for a series of in-vitro experiments. Our result indicates that wave propagation and reflection can result in a pumping mechanism in a compliant aorta.

Theory and experimental verification on valveless piezoelectric pump with multistage Y-shape treelike bifurcate tubes

Among most traditional piezo water cooling systems, piezoelectric valve pumps are adopted as their driving sources. The valves in these pumps induce problems of shock and vibration and also make their structure complicated, which is uneasy to minimize and reduce their reliability and applicability of the whole system. In order to avoid these problems caused by valve structure, a novel valveless piezoelectric pump is developed, which integrates both functions of transforming and cooling. The pump’s Y-shape tree-like construction not only increases the efficiency of cooling but also the system reliability and applicability. Firstly, a multistage Y-shape treelike bifurcate tube is proposed, then a valveless piezoelectric pump with multistage Y-shape treelike bifurcate tubes is designed and its working principle is analyzed. Then, the theoretical analysis of flow resistance characteristics and the flow rate of the valveless piezoelectric pump are performed. Meanwhile, commercial software CFX is employed to perform the numerical simulation for the pump. Finally, this valveless piezoelectric pump is fabricated, the relationship between the flow rates and driving frequency, as well as the relationship between the back pressure and the driving frequency are experimentally investigated. The experimental results show that the maximum flow rate is 35.6 mL/min under 100 V peak-to-peak voltage (10.3 Hz) power supply, and the maximum back pressure is 55 mm H2O under 100 V (9 Hz) power supply, which validates the feasibility of the valveless piezoelectric pump with multistage Y-shape treelike bifurcate tubes. The proposed research provides certain references for the design of valveless piezoelectric pump and improves the reliability of piezo water cooling systems.

Application of a Valveless Impedance Pump in a Liquid Cooling System

In this paper, a novel valveless impedance pump is used, for the first time, in the thermal management of high-performance electronic systems. This small pump comprises an amber latex rubber tube, connected at both ends to rigid copper tubes of different acoustic impedance, and a simple, economic, quiet, and energy-efficient actuation mechanism, which combines a small dc motor and a cam. The motor-activated cam periodically compresses the elastic tube at a position asymmetric from the tube ends. Traveling waves emitted from the compression combine with reflected waves at the impedance-mismatched positions (rubber tube/copper tube interfaces). The resulting wave interference creates a pressure gradient, with the potential to generate a net flow. Several experimental setups for performance tests, using a single impedance pump, an open system with isothermal flow, and a closed liquid cooling system are designed and implemented. The performance of the impedance pump is affected significantly by the actuation frequency (input voltage) and position. The pump flow rate varies nonlinearly with the actuation frequency. The measured maximum flow rate of the current design is 480 ml/min at zero total pump head for operating frequencies in the range 48–63 Hz. The water-cooling system in a closed loop maintains the core temperature of the 60-W dummy heater at 57.8 $^{\circ}{\rm C}$ . Experimental results demonstrate the feasibility of the commercial application of valveless impedance pumps for thermal management in high-performance electronic systems.

Theory and experimental verification of spiral flow tube-type valveless piezoelectric pump with gyroscopic effect

Valveless piezoelectric pump has low-cost and easy miniaturization characteristics, and its important development trend is multi-function integration. The current paper reports a new phenomenon that the flow in a spiral tube element is sensitive to the element attitude caused by the Coriolis force, and that a valveless piezoelectric pump is designed by applying this phenomenon. The valveless piezoelectric pump has both the actuator function of fluid transfer and the sensor function, which can obtain the angular velocity variation when its attitude changes. First, the present paper analyzes the principle of the pump and the flow characteristics in the tube. The calculation formula for the pump flow is also obtained. Second, the relationship between pump attitude and flow is identified, which theoretically verifies the gyroscopic effect of the pump. Finally, a pump is fabricated for experimental testing of the relationship between pump attitude and flow. Experimental results show that when Archimedes spiral θ=4π is selected for the tube design, the pump is most efficient, and the pressure differential between pump inlet and outlet is 29mm H2O, which achieves a one-way mean flow. On the other hand, when the rotation speed of the plate is 70r/min, the pressure differential is 9mm H2O, which is 1.5 times that of 0rpm rotation speed. The spiral tube valveless piezoelectric pump can turn the element attitude into a form of pressure output, which is important for the multi-function integration of the valveless piezoelectric pump and for the development of civil gyroscope in the future.

탄성 튜브가 연결된 펌핑 챔버를 이용한 무밸브 펌프의 수치해석

탄성튜브가 연결된 펌핑 챔버를 이용한 무밸브 펌프를 가상경계방법을 이용하여 수치적으로 연구하였다. 탄성 튜브와 펌핑 챔버 사이의 상호작용으로 인하여 무밸브 펌프 내의 유동이 생성되었으며, 탄성튜브의 스트레칭 계수, 벤딩 계수, 종횡비가 무밸브 펌프의 전체 유량에 미치는 영향을 살펴보았다. 펌프의 메커니즘을 이해하고자, 시간에 따른 탄성 튜브의 움직임과 그에 따른 유동 속도의 변화를 자세히 살펴보았으며, 탄성 튜브의 직경 크기와 펌프의 평균 유량 사이의 관계를 분석하였다.

A Valveless MEMS Pump Utilizing a Thin Film Permanent Magnet

A valveless MEMS pump utilizing a multi-layer thin film NdFeB/Ta permanent magnet (TFPM) has been presented. The MEMS pump consists of a diaphragm actuator utilizing 6μm in thickness and 3 mm in diameter TFPM which is bonded on a membrane made of polydimethylsiloxane (PDMS) of about 80μm thickness, a pump chamber and a pair of diffuser elements. TFPM is sputtered on a 50μm thick Nb sheet. The diffuser elements are used to generate a one-way fluid flow. The chamber is made of acryl plates. UV negative film resist is used to bond different layers. Applying amplitude of ±7.5V square wave voltage, the pump flow rate reaches to 130μL/min at frequency of 15Hz.

Simulation of a valveless pump with an elastic tube

A valveless pump consisting of a pumping chamber with an elastic tube was simulated using an immersed boundary (IB) method. The interaction between the motion of the elastic tube and the pumping chamber generated a net flow toward the outlet throughout a full cycle of the pump. The net flow rate of the valveless pump was examined by varying the stretching coefficient (ϕ), bending coefficient (γ), the aspect ratio (l/d) of the elastic tube, and the frequency (f) of the pumping chamber. As the stretching and bending coefficients of the elastic tube increased, the net flow through the valveless pump decreased. Elastic tubes with aspect ratios in the range of 2⩽l/d⩽3 generated a higher flow rate than that generated for tubes with aspect rations of l/d=1 or 4. As the frequency of the pumping chamber increased, the net flow rate of the pump for l/d=2 increased. However, the net flow rate for l/d=3 was nonlinearly related to the pumping frequency due to the complexity of the wave motions. Snapshots of the fluid velocity vectors and the wave motions of the elastic tube were examined over one cycle of the pump to gain a better understanding of the mechanism underlying the valveless pump. The relationship between the average gap in the elastic tube and the average flow rate of the pump was analyzed. A smaller gap in the elastic tube during the expansion mode and a wider gap in the elastic tube during the contraction mode played a dominant role in generating a high average flow rate in the pump, regardless of the stretching coefficient (ϕ), the aspect ratio (l/d) of the elastic tube, or the pumping frequency of the pumping chamber (f).

VALVELESS PUMPING IN OPEN TANK SYSTEM USING ENERGY CONSERVING COMPARTMENT MODEL

A compartment model of the flow driven by pumping without valves (valveless pumping) in an open tank system is proposed. By the open tank system, we mean that two rigid cylindrical tanks are connected with an elastic tube. An incompressible fluid fills this system up to a certain level in tanks under the gravity. The compartment model for analyzing such open system is derived from the energy principle which will be called the energy conserving compartment model or shortly the ECCM. Based on this ECCM of valveless pumping, we explore the occurrence of directional net flow or directional net power by a specific excitation at an asymmetric part of the elastic tube. The interaction between deformable elastic tube and the fluid inside is considered in the ECCM. The reliability of the ECCM is investigated through some physical examples. The ECCM shows the existence of directional net power of the valveless pump system with open tanks and confirms that the direction and magnitude of the net power depend on the pumping frequency as well. Furthermore, the phase synchronization in time between the fluid pressure difference and the external pinching force over the pumping region is highly related to the direction of energy storing or net power.

Electromagnetic Actuator Utilizing Magnetic Film of Electroplated Alloy and Its Application to Valveless Pumps

Electromagnetic Actuator Utilizing Magnetic Film of Electroplated Alloy and Its Application to Valveless Pumps

Analysis on flow field of the valveless piezoelectric pump with two inlets and one outlet and a rotating unsymmetrical slopes element

Typically, liquid pump and liquids mixer are two separate devices. The invention of piezoelectric pump makes it possible to integrate the two devices. Hower, the existing piezoelectric mixing-pumps are larger because the need the space outside the chamber, and another shortcome of them is that they cannot adjust the mixing ratio of two liquids. In this paper, a new piezoelectric pump being capable of integrating mixer and pump is presented, based on the theory of the piezoelectric pump with the unsymmetrical slopes element (USE). Besides the features of two inlets and one outlet, the piezoelectric pump has a rotatable unsymmetrical slopes element(RUSE). When the pump works, two fluids flow into the inlet channels respectively. Then the RUSE controls the ratio of the two flows by adjusting the flow resistances of the two inlet channels. The fluids form a net flow due to the USE principle, while they are mixed into a homogeneous solution due to strong turbulence flow field and complex vortices generated by RUSE in the chamber. And then the solution flows through the outlet. Firstly, the theoretical analysis on this pump is performed. Meanwhile, the flow field in the chamber is calculated and simulated. And then, the relationship between the flows of the two channels and the rotating angle of the RUSE is set up and analyzed. Finally, experiment with the proposed pump is carried out to verify the numerical results. A RUSE with 20° slope angle is used in the experiment. Four sets of data are tested with the RUSE at the rotating angles of 0°, 6°, 11°, and 16°, respectively, corresponding to the numerical models. The experimental results show that the empirical data and the theoretical data share the same trend. The maximum error between the theoretical flow and the experimental flow is 11.14%, and the maximum error between the theoretical flow ratio of the two inlets and the experimental one is 2.5%. The experiment verified the theoretical analysis. The proposed research provides a new idea for integration of micro liquids mixer and micro liquids pump.

Principle and experimental verification of caudal-fin-type piezoelectric-stack pump with variable-cross-section oscillating vibrator

In the traditional flow-resistance-differential (FRD) type valve-less piezoelectric pump, the generated outflow and pressure are discontinuous because of the inherent periodicity and fluctuation of the pump. To overcome these drawbacks, utilizing the bending vibration of piezoelectric bimorph to drive fluid was conducted. However, our investigation on the current status of this piezoelectric bimorph pump shows that larger driving force and vibration amplitude are required for fluid pumping; the pumping can be realized through the centrifugal force; and the mechanism of fluid pumping is no longer further studied. Based on these cases, the paper designed a piezoelectric-stack pump with variable-cross-section oscillating (VCSO) vibrator by imitating the swing of the caudal-fin of tuna, and the pump is neither the rotating type nor the volumetric type according to the taxonomy. The interaction between the oscillating vibrator and the fluid parcel is firstly analyzed from the viewpoint of momentum conservation, and the analytical expression of pump flow rate is obtained. Then the modal and harmonic response analyses on the vibrator immerged in water are carried out. From the analyses the first two orders resonance frequencies are 832 Hz and 1 939 Hz, respectively, and the peak value of the tip amplitude is 0.6 mm. Laser Doppler vibrometer is used to measure both the frequency and vibration amplitude, and the determined first two orders resonance frequencies are 617 Hz and 1 356 Hz, respectively. The measured tip amplitude reaches to the peak value of 0.3 mm. At last, experimental measurement for the flow rates with different driving frequencies is conducted. The results show that the flow rate can reach 560 mL/min at 1 370 Hz when the pump runs under the backpressure of 30 mm water column. And the flow rate is as much as 560% of that of experiment results carried out by researchers from Brazil. The proposed pump innovates in both theory and taxonomy; in addition, the pump overcomes the drawbacks such as large flow fluctuation and low flow rate in the traditional FRD type pumps, which will help to broaden the application of the valve-less piezoelectric pump.

CFD Analysis of Electromagnetic Based Valveless Pump

This study is a CFD analysis of electromagnetic based valveless pump in biomedical devices and biological MEMS (bioMEMS) application. The focus of the studies are designing a well performed pump where the required displacement of diaphragm can still be achieved even when the force applied is reduced and also a mechanism that requires low input current. Various parameters such as radius of the microcoil and diaphragm; and thickness of the magnet are compared to help choosing a proper pump. By using DesignModeler, Magnetostatic Analysis and Static Structural Analysis of ANSYS, Inc. Version 13.0, the geometry was modeled at micro scale and the results of force and displacement on the diaphragm were simulated. The main findings are the pump only required to be applied with 1.94 mN of force to reach at least 0.11mm of diaphragm displacement with the input current of 0.5 A. The dimensions of the actuator mechanism design are 1.4mm of magnet thickness and 2.05mm of diaphragm radius. Electromagnetic actuation was selected because it can contribute several main benefits which are faster reaction time, longer operational range and low actuating voltage. Thus, it is important to analyze the electromagnetic mechanism to further understand it. Furthermore, the numerical results proved that an actuator mechanism comprises of permanent magnet, PDMS diaphragm and microcoil can provides enough actuating force for a large diaphragm displacement to take place under a safe and consistent pumping process. Hence, the electromagnetic pump design by this study can be used as the best application for microfluidic systems where a high pumping amount is desired.

Computational and experimental characterization of a low-cost piezoelectric valveless diaphragm pump

Flow pumps act as important devices in areas such as Bioengineering, Medicine, and Pharmacy, among other areas of Engineering, mainly for delivering liquids or gases at small-scale and precision flow rate quantities. Principles for pumping fluids based on piezoelectric actuators have been widely studied, since they allow the construction of pump systems for displacement of small fluid volumes with low power consumption. This work studies valveless piezoelectric diaphragm pumps for flow generation, which uses a piezoelectric ceramic (PZT) as actuator to move a membrane (diaphragm) up and down as a piston. The direction of the flow is guaranteed by valveless configuration based on a nozzle–diffuser system that privileges the flow in just one pumping direction. Most research efforts on development of valveless flow pump deal either with computational simulations based on simplified models or with simplified physical approaches based on analytical models. The main objective of this work is the study of a methodology to develop a low-cost valveless piezoelectric diaphragm flow pump using computational simulations, parametric study, prototype manufacturing, and experimental characterization. The parametric study has shown that the eccentricity of PZT layer and metal layer plays a key role in the performance of the pump.