Diaphragm Pump Research Articles

Multistage Micropump System towards Vacuum Pressure

Fraunhofer EMFT’s research and manufacturing portfolio includes piezoelectrically actuated silicon micro diaphragm pumps with passive flap valves. Research and development in the field of microfluidics have been dedicated for many years to the use of micropumps for generating positive and negative pressures, as well as delivering various media. However, for some applications, only small amounts of fluid need to be pumped, compressed, or evacuated, and until now, only macroscopic pumps with high power consumption have been able to achieve the necessary flow rate and pressure, especially for compressible media such as air. To address these requirements, one potential approach is to use a multistage of high-performing micropumps optimized to negative pressure. In this paper, we present several possible ways to cascade piezoelectric silicon micropumps with passive flap valves to achieve these stringent requirements. Initially, simulations are conducted to generate negative pressures with different cascading methods. The first multistage option assumes pressure equalization over the piezo-actuator by the upstream pump, while for the second case, the actuator diaphragm operates against atmospheric pressure. Subsequently, measurement results for the generation of negative gas pressures down to −82.1 kPa relative to atmospheric pressure (19.2 kPa absolute) with a multistage of three micropumps are presented. This research enables further miniaturization of many applications with high-performance requirements for micropumps, achievable with these multistage systems.

Fast Electrochemical Micropump for Portable Drug Delivery Module

Microfluidic devices are capable of precise drug delivery to the human body. For this purpose, they must be equipped with a compact pump that provides a high flow rate and precise dosing. In this paper, we present a micropump based on a fast electrochemical actuator that meets these requirements. It contains three actuators operating in the peristaltic mode. The device is fabricated from glass and silicon wafers using the standard microfabrication processes. The working part of the pump has a size of about 3 mm3, which is an order of magnitude smaller than other types of diaphragm pumps. The small size of the actuators ensures ultrahigh liquid dosing accuracy of 0.14 nL. At the same time, the high frequency of operation of the actuators makes it possible to develop a specific pumping velocity comparable to other types of pumps.

Multiwavelength tissue-mimicking phantoms with tunable vessel pulsation

For the development and routine characterization of optical devices used in medicine, tissue-equivalent phantoms mimicking a broad spectrum of human skin properties are indispensable. Our work aims to develop a tissue-equivalent phantom suitable for photoplethysmography applications. The phantom includes the optical and mechanical properties of the three uppermost human skin layers (dermis, epidermis, and hypodermis, each containing different types of blood vessels) plus the ability to mimic pulsation. While the mechanical properties of the polydimethylsiloxane base material are adjusted by different mixing ratios of a base and curing agent, the optical properties are tuned by adding titanium dioxide particles, India ink, and synthetic melanin in different concentrations. The layered structure of the phantom is realized using a doctor blade technique, and blood vessels are fabricated using molding wires of different diameters. The tissue-mimicking phantom is then integrated into an artificial circulatory system employing piezo-actuated double diaphragm pumps for testing. The optical and mechanical properties of human skin were successfully replicated. The diameter of the artificial blood vessels is linearly dependent on pump actuation, and the time-dependent expansion profile of real pulse forms were mimicked. A tissue equivalent phantom suitable for the ex-vivo testing of opto-medical devices was demonstrated.

Focus on software, data acquisition, and instrumentation

Focus on software, data acquisition, and instrumentation

The Use of Disk-Shaped Diaphragm of Vehicles in Double-Circuit Diaphragm Pumps

Introduction. The article concentrates on improving the efficiency of double-circuit diaphragm pumps, which can be successfully used in heat and water supply systems of industrial and agricultural facilities where there is excess head. It is advisable to equip double-circuit diaphragm pumps with disc-shaped diaphragms interconnected by a rod, for example, from motor vehicles, and to drive them from the available head of the hydraulic network. In order to increase the efficiency of their work and further use, it is necessary to predict the hydraulic characteristics according to the geometric parameters of the membranes and the cycle of their operation in dynamics. Aim of the Article. The article aims at obtaining adequate calculated dependencies of pumped liquid flow rate on speed of double-circuit diaphragm pumps. Materials and Methods. There were used the idealization method from differential geometry, physical experiment, and mathematical statistics to solve the tasks for identifying the relationship between the rod motion and the liquid flow rate for a poppet diaphragm with different geometric surfaces in dynamics. There have been obtained the dependences of pumped liquid volume on the movement of the point of attachment by the poppet diaphragm and the volume flow rate on the movement speed of the point of attachment by the poppet diaphragm with specific geometric parameters for the parabolic and chain line. An experimental testing of the dependence of displaced pumped liquid flow rate on the movement of the attachment point to the stem for the diaphragm type 30 was carried out. Results. Based on the obtained dependences of the volume flow rate on the speed of movement of the point of attachment by a poppet diaphragm with specific geometric parameters for a parabolic and chain line, there were constructed the graphs of dependences of the volume flow rate on the frequency of the working cycle. For practical implementation, there are proposed the dependencies for constructing the hydraulic characteristics of a two-circuit membrane (the dependence of the volume flow rate on the frequency of the working cycle) obtained on the basis of a parabolic interpretation. Discussion and Conclusion. The hydraulic characteristics of a two-circuit membrane pump are close to the equation of a straight line and are consistent with experimental dependencies within 4%.

A Commitment to Action

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An improved cavitation model with thermodynamic effect and multiple cavitation regimes

Mechanical feed pumps in organic Rankine cycle (ORC) power plants can suffer from cavitation to lose their normal feeding performance or even damage. Cavitation models for organic fluids in ORC systems are lacking presently. Hence, a new cavitation model with thermodynamic effect was proposed. Surface tension-controlled, inertia-controlled, intermediate and heat transfer-controlled cavitation regimes, and two key elements: vapour bubble growth rate and vapour bubble number density are included in the model. A known air or non-condensable gas concentration in the liquid was employed to determine cavitation nuclei number density. The model was coded in ANSYS CFX as user defined model and validated with cavitating flows of organic fluid R114 in a venturi, liquid nitrogen and liquid hydrogen on a tapered hydrofoil and warm water around a hydrofoil NACA 0015 in cavitation tunnels based on visualised cavity length. Two model constants, temperature depression, and minimal cavitation number were correlated to bulk liquid temperature, Reynolds number, and Jakob number. The temperature and pressure profiles of liquid nitrogen and hydrogen on hydrofoil surface were examined against the experimental data. The model was applied to simulate unsteady cavitating flows of organic fluid R245fa in a diaphragm pump. It was shown that the temperature depression and minimal cavitation number cannot be correlated to bulk liquid temperature, Reynolds number and Jakob number. Two model constants can be correlated fairly to Reynolds number. The model underestimates the thermodynamic effect by 43% for R114, 18.6% for liquid nitrogen and 32.6% for liquid hydrogen based on temperature depression. The predicted temperature and pressure profiles on hydrofoil surface agree with the experimental data for liquid nitrogen. The model can produce an expected curve of mean pump flow rate against net positive suction head available.

Research on Structurally Constrained KELM Fault-Diagnosis Model Based on Frequency-Domain Fuzzy Entropy

As the core equipment of the high-pressure diaphragm pump, the working conditions of the check valve are complicated, and the vibration signal generated during operation displays non-stationary and nonlinear characteristics. In order to accurately describe the non-linear dynamics of the check valve, the smoothing prior analysis (SPA) method is used to decompose the vibration signal of the check valve, obtain the tendency term and fluctuation term components, and calculate the frequency-domain fuzzy entropy (FFE) of the component signals. Using FFE to characterize the operating state of the check valve, the paper proposes a kernel extreme-learning machine (KELM) function norm regularization method, which is used to construct a structurally constrained kernel extreme-learning machine (SC-KELM) fault-diagnosis model. Experiments demonstrate that the frequency-domain fuzzy entropy can accurately characterize the operation state of check valve, and the improvement of the generalization of the SC-KELM check valve fault model improves the recognition accuracy of the check-valve fault-diagnosis model, with an accuracy rate of 96.67%.

Synthesis of methyl esters from Hippophae rhamnoides via pilot scale hydrodynamic cavitation intensification reactor

The current research demonstrates the capability of hydrodynamic cavitation (HC) for the manufacture of ester sourcing Hippophae rhamnoides (HiRO) seed oil, which is non-edible in nature. According to the authors' best knowledge, the HC pilot developed assembly has not been put to use in any research pertaining to the manufacturing of biodiesel from HiRO triglycerides. The vast majority of the research indicates that optimising the system for the production of biodiesel based on a particular criterion, such as yield, can lead to only one portion of the research. In order to achieve maximum efficiency in the transesterification reaction, it is necessary to optimise not only the amount of output but also the cavitational parameters. The process of transesterification was initiated to overcome mass transfer resistance. In a pilot HC reactor, four novel geometries (orifices disk) cavities were explored. These cavities were helped along by a double diaphragm pump. It was shown that the mass transfer barrier between immiscible reactants can be decreased by increasing the interfacial area, and this effect was observed during the transesterification reaction, which is characterised by significant turbulence induced by cavitating bubbles. This was accomplished by increasing the surface area of the interface between the reactants. When compared to mechanical stirring, using an orifice plate with 21 holes that were 1 mm in diameter resulted in an eightfold increase in yield efficiency and a sixfold reduction in response reaction time at 2 bar inlet pressure. Utilising the hydrodynamic cavitation contributes to the procedure's reduced impact on the natural environment. In conclusion, the Hippophae rhamnoides oil methyl ester (HiROM) that was produced through the process of hydrodynamic cavitation was demonstrated to be both time and energy efficient. The characteristics of the methyl ester that was synthesised were in accordance with the requirements of both EN14214 and ASTM D6751.

Bio-inspired magnetic-driven folded diaphragm for biomimetic robot

Functional soft materials, exhibiting multiple types of deformation, have shown their potential/abilities to achieve complicated biomimetic behaviors (soft robots). Inspired by the locomotion of earthworm, which is conducted through the contraction and stretching between body segments, this study proposes a type of one-piece-mold folded diaphragm, consisting of the structure of body segments with radial magnetization property, to achieve large 3D and bi-directional deformation with inside-volume change capability subjected to the low homogeneous magnetically driving field (40 mT). Moreover, the appearance based on the proposed magnetic-driven folded diaphragm is able to be easily customized to desired ones and then implanted into different untethered soft robotic systems as soft drivers. To verify the above points, we design the diaphragm pump providing unique properties of lightweight, powerful output and rapid response, and the soft robot including the bio-earthworm crawling robot and swimming robot inspired by squid to exhibit the flexible and rapid locomotion excited by single homogeneous magnetic fields.

Effects of E-Cigarette Liquid Ratios on the Gravimetric Filter Correction Factors and Real-Time Measurements.

Electronic cigarettes (ECIGs) generate high concentrations of particulate matter (PM), impacting the air quality inhaled by humans through secondhand exposure. ECIG liquids are available commercially and some users create their own "do-it-yourself" liquids, and these liquids often vary in the amounts of their chemical ingredients, including propylene glycol (PG) and vegetable glycerin (VG). Previous studies have quantified PM concentrations in ECIG aerosol generated from liquids containing different PG/VG ratios. However, the effects of these ratios on aerosol instrument filter correction factors needed to measure PM concentrations accurately have not been assessed. Thus, ECIG aerosol filter correction factors for multiple aerosol instruments (SMPS + APS, MiniWRAS, pDR, and SidePak) were determined for five different PG/VG ratios 1) 0PG/100VG, 2) 15PG/85VG, 3) 50PG/50VG, 4) 72PG/28VG, and 5) 90PG/10VG and two different PM sizes, PM1 (1 μm and smaller) and PM2.5 (2.5 μm and smaller). ECIG aerosols were generated inside a controlled exposure chamber using a diaphragm pump and a refillable ECIG device for all the ratios. In addition, the aerosol size distribution and mass median diameter were measured for all five ECIG ratios. PM2.5 correction factors (5-7.6) for ratios 1, 2, 3, and 4 were similar for the SMPS + APS combined data, and ratios 1, 2, 3 were similar for the MiniWRAS (~2), pDR (~0.5), and SidePak (~0.24). These data suggest different correction factors may need to be developed for aerosol generated from ECIGs with high PG content. The higher correction factor values for the 90PG/10VG ratio may have resulted from greater PG volatility relative to VG and sensor losses. The correction factors (ratios 1-4) for PM2.5 were SMPS + APS data (4.96-7.62), MiniWRAS (2.02-3.64), pDR (0.50-1.07), and SidePak (0.22-0.40). These data can help improve ECIG aerosol measurement accuracy for different ECIG mixture ratios.

PICK AND PLACE ROBOT USING VACCUM GRIPPERS FOR UNEVEN SOLID OBJECTS

- To doing repeated works have become immense in today’s situation, like picking and placing objects from one place to another, have been a tiresome work, our work focuses on taking this job away from humans and handing it to a device which is capable of doing this job in an efficient way on its own. In this paper of two axis robotic arm with vacuum gripper focuses on doing the repeated tasks of picking and placing, so that it could easy the work of humans. We have used hydraulic plunger for robot arm and diaphragm pump for vacuum gripper.

Matching the Optimal Operating Mode of Polydimethylsiloxane Check Valves by Tuning the Resonant Frequency of the Resonator in a Piezoelectric Pump for Improved Output Performance.

This paper proposes to improve the output performance of a piezoelectric pump by matching the resonant frequency of the resonator to the optimal operating mode of bridge-type polydimethylsiloxane (PDMS) check valves. Simulation analyses reveal that the side-curling mode of the PDMS valve is conducive to liquid flow and exhibits a faster frequency response compared with the first bending mode. The first bending resonant frequency of a beam-type piezoelectric resonator was tuned close to the side-curling mode of the PDMS valve by adjusting the weight of two mass blocks installed on both ends of the resonator, so that both the resonator and the valve could work at their best conditions. Experiments were conducted on a detachable prototype piezoelectric pump using PDMS valves with three different lengths. The results confirm that the peak flowrate at the resonant point of the pump reaches its maximum when the resonant frequencies between the resonator and the valve are matched. Maximum peak flowrates of 88 mL/min, 72 mL/min and 70 mL/min were achieved at 722 Hz, 761 Hz and 789 Hz, respectively, for diaphragm pumps using five-, four- and three-inlet-hole PDMS valves, under a driving voltage of 300 Vpp.

Analysis of wave propagation and pulsation in an elastic tube using a diaphragm pump

In this research, the flow wave propagation, speed, and pulsation suppression in an elastic tube were studied using a diaphragm pump. The flow fluctuations with shocking pressure fluctuations occur in the elastic tube because the check ball was blocked, thereby preventing reverse flow. Consequently, the check ball is one of the causes of pulsating flows in diaphragm pumps. However, only a few studies have analyzed the relationship among the check ball movement, pressure, and flow fluctuations. In this study, we constructed several elastic tube experiments: (i) single-tube model; (ii) two-tube model. To predict the flow wave propagation and pulsation in an elastic tube, we developed an axisymmetric theoretical model and compared into the experimental results. Based on our study, the main results were as follows: the relationship among the check ball movement, pressure, and flow fluctuations showed that the pressure and flow rate pulsation were caused by the asymmetry of the check ball movement. Additionally, we observed that the theoretical flow wave propagation trend had a good agreement with the experimental results, although the flow wave speed in the urethane-tube experiment differed considerably from the theoretical prediction. Furthermore, the amplitude of the pulsation increased considerably owing to the reflected wave at the tube exit, although it did not increase when the resistance was added at the exit. Finally, we observed that the pulsation reduced more in the silicon tubes compared to the urethane tubes because the deformation of the silicon tubes was larger than that of the urethane tubes.

Portable Battery-Driven Microfluidic Cell Separation Instrument with Multiple Operational Modes.

Current microfluidic cell separation instruments are commonly bulky, expensive, and inconvenient for use in resource-limited environments. Herein, we developed a low-cost, portable, battery-driven microfluidic cell separation instrument by integrating a microfluidic separator, a low-cost gas-driven flow system, and a flow resistance module. The plug-and-play cell separator enabled by inertial microfluidics was used to realize the label-free solid/solid or solid/liquid separation by switching the operational modes of cell separation and enrichment. To increase the instrument portability, an all-in-one flow resistance module integrated with three different polymer film flow resistance chips was designed to stabilize the gas flow generated by the miniaturized diaphragm pump for low-cost fluid injection under different operational modes. After successfully constructing our instrument, the performance under the separation mode was tested using the blood samples spiked with three different tumor cells. Then, the enrichment mode was performed to concentrate the target cells after separation and thus reduce the sample volume. Excellent separation and enrichment performances were achieved at a high throughput. Our portable microfluidic cell separation instrument offers the advantages of simple operation, small footprint, lightweight, and untethered battery drivenness and thus holds the potential for one-stop cell preparation in resource-limited environments.

New technical concept for alternating tangential flow filtration in biotechnological cell separation processes.

Robust cell retention devices are key to successful cell culture perfusion. Currently, tangential flow filtration (TFF) and alternating tangential flow filtration (ATF) are most commonly used for this purpose. TFF, however, suffers from poor fouling mitigation, which leads to high filtration resistance and product retention, and ATF suffers from long residence times and cell accumulation. In this work, we propose a filtration system for alternating tangential flow filtration, which takes full advantage of the fouling mitigation effects of alternating flow and reduces cell accumulation. We have tested this novel setup in direct comparison with the XCell ATF® as well as TFF with a model feed comprising yeast cells and bovine serum albumin as protein at harsh permeate to feed flow conditions. We found that by avoiding the dead-end design of a diaphragm pump, the proposed filtration system exhibited a reduced filtration resistance by approximately 20% to 30% (depending on feed rate and permeate flow rate). A further improvement of the novel setup was reached by optimization of phase durations and flow control, which resulted in a fourfold extension of process duration until hollow fiber flow channel blockage occurred. Thus, the proposed concept appears to be superior to current cell retention devices in perfusion technology.

Design and operation of the PandaX-4T high speed ultra-high purity xenon recuperation system

In order to recuperate the ultra-high purity xenon from PandaX-4T dark matter detector to high-pressure gas cylinders in emergency or at the end-of-run situation, a high speed ultra-high purity xenon recuperation system is designed and developed. This system includes a diaphragm pump, the heat management system, the main recuperation pipeline, the reflux pipeline, the auxiliary recuperation pipeline and the automatic control system. The liquid xenon in the detector is vaporized by the heat management system, and the gaseous xenon is compressed to 6 MPa at the flow rate of 200 standard litres per minute (SLPM) using the diaphragm compressor. The high-pressure xenon is filled into 128 gas cylinders via the main recuperation pipeline. During the recuperation, the low pressure and temperature conditions of 2 ∼ 3 atmospheres and 178 ∼ 186.5 K in PandaX-4T dark matter detector are kept by the cooperation of the main recuperation pipeline, reflux pipeline and the auxiliary recuperation pipeline to guarantee the safety, and the purity of the recuperated xenon gas is measured to ensure no contamination happened. The development of the high speed ultra-high purity xenon recuperation system is important for the operation of large-scale dark matter detectors with the requirements of strict temperature and pressure environment and low background.

Fault Diagnosis of Check Valve Based on KPLS Optimal Feature Selection and Kernel Extreme Learning Machine

The check valve is the core part of high-pressure diaphragm pumps. It has complex operation conditions and has difficulty characterizing fault states completely with its single feature. Therefore, a fault signal diagnosis model based on the kernel extreme learning machine (KELM) was constructed to diagnose the check valve. The model adopts a multi-feature extraction method and reduces dimensionality through kernel partial least squares (KPLS). Firstly, we divided the check valve vibration signal into several non-overlapping samples. Then, we extracted 16 time-domain features, 13 frequency-domain features, 16 wavelet packet energy features, and energy entropy features from each sample to construct a multi-feature set characterizing the operation state of the check valve. Next, we used the KPLS method to optimize the 45 dimension multi-feature data and employed the processed feature set to establish a KELM fault diagnosis model. Experiments showed that the method based on KPLS optimal feature selection could fully characterize the operating state of the equipment with an accuracy rate of 96.88%. This result indicates the high accuracy and effectiveness of the multi-feature set constructed with the KELM fault diagnosis model.

Research on Twin Extreme Learning Fault Diagnosis Method Based on Multi-Scale Weighted Permutation Entropy.

Due to the complicated engineering operation of the check valve in a high−pressure diaphragm pump, its vibration signal tends to show non−stationary and non−linear characteristics. These leads to difficulty extracting fault features and, hence, a low accuracy for fault diagnosis. It is difficult to extract fault features accurately and reliably using the traditional MPE method, and the ELM model has a low accuracy rate in fault classification. Multi−scale weighted permutation entropy (MWPE) is based on extracting multi−scale fault features and arrangement pattern features, and due to the combination of extracting a sequence of amplitude features, fault features are significantly enhanced, which overcomes the deficiency of the single−scale permutation entropy characterizing the complexity of vibration signals. It establishes the check valve fault diagnosis model from the twin extreme learning machine (TELM). The TELM fault diagnosis model established, based on MWPE, aims to find a pair of non−parallel classification hyperplanes in the equipment state space to improve the model’s applicability. Experiments show that the proposed method effectively extracts the characteristics of the vibration signal, and the fault diagnosis model effectively identifies the fault state of the check valve with an accuracy rate of 97.222%.

Analysis of the thermo-pneumatic properties of copper oxide-based nanofluids for pressure generation during membrane filtration

• The method used in the synthesis of nanoparticles, influences their shapes. • The stability of nanoparticles in nanofluids greatly affects their thermal conductivity enhancement. • The enthalpy of vaporization of volatile liquids is lowered when nanoparticles are dispersed in the fluid. • Nanofluids generally have improved thermal properties than their pure base fluids. The development of nanofluids and their application in heat transfer systems has been improved in recent years. These nanofluids enable heat engines to work at lower temperatures and utilize low-grade energy sources more efficiently especially in membrane filtration systems. In this study, CuO and Cu 2 O nanoparticles were synthesized, characterized, and used in preparing nanofluids. These nanofluids were then tested for vapour pressure generation enhancement in a diaphragm pump. Optimization of the thermo-pneumatic properties of the nanofluids was done through altering the nature, shape, size, and weight concentrations of the copper oxide nanoparticles in different base fluids. The equilibrium vapour pressure generated by a 0.1 wt% CuO nanofluid at 30 °C was found to be 100% higher than that of the pure working liquid. The 0.1 wt% CuO nanofluid also attained equilibrium pressures at a rate that was 37% faster on average than for the pure working liquid in the temperature range of 35 °C to 60 °C. he latent heat of vaporization of the pure volatile liquid was decreased by 15,7% and its thermal conductivity was enhanced by 26,2% by the 0.1 wt% CuO working liquid which showed the best stability at a pH of 6.