Wear dependent virtual flow rate sensor for progressing cavity pumps with deformable stator

This contribution presents a novel wear dependent virtual flow rate sensor for single stage single lobe progressing cavity pumps. We study the wear-induced material loss of the pump components and the impact of this material loss on the volumetric efficiency. The results are combined with an established backflow model to implement a backflow calculation procedure that is adaptive to wear. We use a laboratory test setup with a highly abrasive fluid and operate a pump from new to worn condition to validate our approach. The obtained measurement data show that the presented virtual sensor is capable of calculating the flow rate of a pump being subject to wear during its regular operation.

Optimal Design of High-Speed Partial Flow Pumps using Orthogonal Tests and Numerical Simulations

To investigate the influence of structural parameters on the performances and internal flow characteristics of partial flow pumps at a low specific speed of 10000 rpm,special attention was paid to the first and second stage impeller guide vanes.Moreover,the impeller blade outlet width,impeller inlet diameter,blade inclination angle,and number of blades were considered for orthogonal tests.Accordingly,nine groups of design solutions were formed,and then used as a basis for the execution of numerical simulations(CFD)aimed at obtaining the efficiency values and heads for each design solution group.The influence of impeller geometric parameters on the efficiency and head was explored,and the“weight”of each factor was obtained via a range analysis.Optimal structural parameters were finally chosen on the basis of the numerical simulation results,and the performances of the optimized model were verified accordingly(yet by means of CFD).Evidence is provided that the increase in the efficiency and head of the optimized model was 12.11%and 23.5 m,respectively,compared with those of the original model.

Developing Operational Model for Heat Pumps as Space Heating and Domestic Hot Water Provider

In the United Kingdom, means of meeting domestic heating is being electrified to decarbonise in effort to reduce the greenhouse gases emissions from the burning of natural gas. Therefore, the uptake of heat pumps is on the increase. The operation and working principle of heat pumps must be well understood in the investigations of their impacts on the grid and the grid assets, especially distribution transformers which could be overloaded due to higher peak load demand. This work develops an operational model of heat pumps as combined space heating and domestic hot water provider implemented in MATLAB. The developed operational model of heat pumps is adaptable and repeatable for different input parameters. The developed model is used to generate daily average demand profiles of heat pumps for a typical winter weekday and a typical summer weekday. The generated demand profiles of heat pumps by the developed model compared well with the demand profiles of heat pumps generated from actual field projects which are usually expensive and time-tasking.

Proton pump inhibitors and all-cause mortality risk among cancer patients

BACKGROUND Proton pump inhibitors(PPIs)are widely used,including among cancer patients,to manage gastroesophageal reflux and other gastric acid-related disorders.Recent evidence suggests associations between long-term PPI use and higher risks for various adverse health outcomes,including greater mortality.AIM To investigate the association between PPI use and all-cause mortality among cancer patients by a comprehensive analysis after adjustment for various confounders and a robust methodological approach to minimize bias.METHODS This retrospective cohort study used data from the TriNetX research network,with electronic health records from multiple healthcare organizations.The study employed a new-user,active comparator design,which compared newly treated PPI users with non-users and newly treated histamine2 receptor antagonists(H2RA)users among adult cancer patients.Newly prescribed PPIs(esomeprazole,lansoprazole,omeprazole,pantoprazole,or rabeprazole)users were compared to non-users or newly prescribed H2RAs(cimetidine,famotidine,nizatidine,or ranitidine)users.The primary outcome was all-cause mortality.Each patient in the main group was matched to a patient in the control group using 1:1 propensity score matching to reduce confounding effects.Multivariable Cox regression models were used to estimate hazard ratios(HRs)and 95% confidence interval(CI).RESULTS During the follow-up period(median 5.4±1.8 years for PPI users and 6.5±1.0 years for non-users),PPI users demonstrated a higher all-cause mortality rate than non-users after 1 year,2 years,and at the end of follow up(HRs:2.34-2.72).Compared with H2RA users,PPI users demonstrated a higher rate of all-cause mortality HR:1.51(95%CI:1.41-1.69).Similar results were observed across sensitivity analyses by excluding deaths from the first 9 months and 1-year post-exposure,confirming the robustness of these findings.In a sensitivity analysis,we analyzed all-cause mortality outcomes between former PPI users and individuals who have never used PPIs,providing insights into the long-term effects of past PPI use.In addition,at 1-year follow-up,the analysis revealed a significant difference in mortality rates between former PPI users and non-users(HR:1.84;95%CI:1.82-1.96).CONCLUSION PPI use among cancer patients was associated with a higher risk of all-cause mortality compared to non-users or H2RA users.These findings emphasize the need for cautious use of PPIs in cancer patients and suggest that alternative treatments should be considered when clinically feasible.However,further studies are needed to corroborate our findings,given the significant adverse outcomes in cancer patients.

New aspects in the pathomechanism and diagnosis of the laryngopharyngeal reflux-clinical impact of laryngeal proton pumps and pharyngeal p H metry in extraesophageal gastroesophageal reflux disease

AIM:To determine the laryngeal H+K+-ATPase and pharyngeal p H in patients with laryngopharyngeal reflux(LPR)-symptoms as well as to assess the symptom scores during PPI therapy.METHODS:Endoscopy was performed to exclude neoplasia and to collect biopsies from the posterior cricoid area(immunohistochemistry and PCR analysis).Immunohistochemical staining was performed with monoclonal mouse antibodies against human H+K+-ATPase.Quantitative real-time RT-PCR for each of the H+K+-ATPase subunits was performed.The p H values were assessed in the aerosolized environment of the oropharynx(Dxp H Catheter) and compared to a subsequently applied combined p H/MII measurement.RESULTS:Twenty patients with LPR symptoms were included.In only one patient,the laryngeal H+K+-ATPase was verified by immunohistochemical staining.In another patient,real-time RT-PCR for each H+K+-ATPase subunit was positive.Fourteen out of twenty patients had pathological results in Dxp H,and 6/20 patients had pathological results in p H/MII.Four patients had pathological results in both functional tests.Nine out of twenty patients responded to PPIs.CONCLUSION:The laryngeal H+K+-ATPase can only be sporadically detected in patients with LPR symptoms and is unlikely to cause the LPR symptoms.Alternative hypotheses for the pathomechanism are needed.The role of pharyngeal p H-metry remains unclearand its use can only be recommended for patients in a research study setting.

Unsteady Turbulent Simulation and Pressure Fluctuation Analysis for Centrifugal Pumps

The pressure fluctuation in the flow passage of both impeller and casing is addressed on design condition. The initial conditions for the unsteady turbulent simulation are resulted from the steady calculations, and the three dimensional unsteady turbulent simulation concerning the rotor-stator interaction is executed by a Navier-Stoke solver embedded with k -ε turbulence model and with appropriate moving interface boundary conditions. Detecting points are distributed in the flow passage in different radial and circumferential positions to capture the static pressure fluctuation character for one cycle of the impeller. The time-domain spectrums show that the static pressure curves are periodic and have five peaks and five valleys. With the radius increasing, the pressure fluctuation peak-to-peak values in the impeller are increasing, and reach the maximum value on the interface. In the casing flow passage, those values are about 7% of local static pressure except some ones near the tongue. The values become decreasingly in the diffuser pipe. The frequency spectrums transformed by fast Fourier transform （FFT） show that the dominant frequency is approximate with the blade passing frequency, and the pressure fluctuations in impeller passage have high frequency content while those in casing ones have no such information.

Effects of Blade Number on Characteristics of Centrifugal Pumps

The blade number of impeller is an important design parameter of pumps, which affects the characteristics of pump heavily. At present, the investigation focuses mostly on the performance characteristics of axis flow pumps, the influence of blade number on inner flow filed and characteristics of centrifugal pump has not been understood completely. Therefore, the methods of numerical simulation and experimental verification are used to investigate the effects of blade number on flow field and characteristics of a centrifugal pump. The model pump has a design specific speed of 92.7 and an impeller with 5 blades. The blade number is varied to 4, 6, 7 with the casing and other geometric parameters keep constant. The inner flow fields and characteristics of the centrifugal pumps with different blade number are simulated and predicted in non-cavitation and cavitation conditions by using commercial code FLUENT. The impellers with different blade number are made by using rapid prototyping, and their characteristics are tested in an open loop. The comparison between prediction values and experimental results indicates that the prediction results are satisfied. The maximum discrepancy of prediction results for head, efficiency and required net positive suction head are 4.83%, 3.9% and 0.36 m, respectively. The flow analysis displays that blade number change has an important effect on the area of low pressure region behind the blade inlet and jet-wake structure in impellers. With the increase of blade number, the head of the model pumps increases too, the variable regulation of efficiency and cavitation characteristics are complicated, but there are optimum values of blade number for each one. The research results are helpful for hydraulic design of centrifugal pump.

Numerical Research on Performance Prediction for Centrifugal Pumps

Performance prediction for centrifugal pumps is now mainly based on numerical calculation and most of the studies merely focus on one model. Therefore, the research results are not representative. To make an improvement of numerical calculation method and performance prediction for centrifugal pumps, performance of six centrifugal pump models at design flow rate and off design flow rates, whose specific speed are different, were simulated by using commercial code FLUENT. The standard k-t turbulence model and SIMPLEC algorithm were chosen in FLUENT. The simulation was steady and moving reference frame was used to consider the impeller-volute interaction. Also, how to dispose the gap between impeller and volute was presented and the effect of grid number was considered. The characteristic prediction model for centrifugal pumps is established according to the simulation results. The head and efficiency of the six models at different flow rates are predicted and the prediction results are compared with the experiment results in detail. The comparison indicates that the precision of head and efficiency prediction are all less than 5%. The flow analysis indicates that flow change has an important effect on the location and area of low pressure region behind the blade inlet and the direction of velocity at impeller inlet. The study shows that using FLUENT simulation results to predict performance of centrifugal pumps is feasible and accurate. The method can be applied in engineering practice.

DISCOVERY AND ANALYSIS ON CAVI TATION IN PIEZOELECTRIC PUMPS

The contributing factors for the cavitation in piezoelectric pumps areanalyzed, theoretically, and the device fitting for observing and recording is set up. With it theexperiments are carried out to observe the emergence and the flowing of the cavitations in thepiezoelectric pumps. According to the statistic and the analysis to the data of the experiments, thepeculiar features are discovered. These features are composed of balls-amassing, center-more, andflow-out.

EXPERIMENTAL STUDY ON HIGH-SPEED CENTRIFUGAL PUMPS WITH DIFFERENT IMPELLERS

The experimental study is carried out on high-speed centrifugal pumps withthree different impellers. The experimental results and analysis show that high-speed centrifugalpumps with a closed complex impeller can achieve the highest efficiency and the lowest headcoefficient followed by those with half-open impeller and open-impeller, and can obtain much easilystable head-capacity characrastic curve, while those with a half-open complex impeller can't. Thecharacteristic curve with a open impeller is almost constant horizontal line before droppingsharply. The results also show that the axial clearance between pump casing and impeller caninfluence greatly on the performance of centrifugal pumps.

Experimental Investigation on the Flow-induced Noise under Variable Conditions for Centrifugal Pumps

With extensively using of centrifugal pumps,noise generation in these pumps is increasingly receiving research attention in recent years.The noise sources in centrifugal pumps are mainly composed of mechanical noise and flow-induced noise.And the study of flow-induced noise has become a hotspot and important domain in the field.The flow-induced noise closely related to the inner pressure pulses and vibration of volute in pumps,therefore,it is necessary to research the interaction and mechanism among them.To investigate the relationships,a test system is designed which includes a test loop and a measurement system.The hydrophones and pressure sensors are installed on the outlet of the pump and vibration acceleration sensors are disposed on the pump body.Via these instruments,the signals of noise,pressure pulses and vibration are collected and analyzed.The results show that the level of flow-induced noise becomes smaller as the flow increment during low flow rate operations,and it is steadily close to the design point,then it increases with the growing of flow rate in high flow rate conditions.Furthermore,there are some similar peak points in the power spectrum charts of noise,pressure pulses and vibration.The broadband noise at low flow rate is mostly focused on the region of 0-40 times shaft frequency,which is mostly made by rotating stall and vortex;while the noise at high flow rate conditions is focused on the region of 60-100 times shaft frequency,which may be mostly made by cavitations.The proposed research is of practical and academic significance to the study of noise reduction for centrifugal pumps.

Numerical and Experimental Study on Flow-induced Noise at Blade-passing Frequency in Centrifugal Pumps

With the increasing noise pollution, low noise optimization of centrifugal pimps has become a hot topic. However, experimental study on this problem is unacceptable for industrial applications due to unsustainable cost. A hybrid method that couples computational fluid dynamics （CFD） with computational aeroacoustic software is used to predict the flow-induced noise of pumps in order to minimize the noise of centrifugal pumps in actual projects. Under Langthjem＇s assumption that the blade surface pressure is the main flow-induced acoustic source in centrifugal pumps, the blade surface pressure pulsation is considered in terms of the acoustical sources and simulated using CFX software. The pressure pulsation and noise distribution in the near-cutoff region are examined for the blade-passing frequency （BPF） noise, and the sound pressure level （SPL） reached peaks near the cutoff that corresponded with the pressure pulsation in this region. An experiment is performed to validate this prediction. Four hydrophones are fixed to the inlet and outlet ports of the test pump to measure the flow-induced noise from the four-port model. The simulation results for the noise are analyzed and compared with the experimental results. The variation in the calculated noise with changes in the flow agreed well with the experimental results. When the flow rate was increased, the SPL first decreased and reached the minimum near the best efficient point （BEP）; it then increased when the flow rate was further increased. The numerical and experimental results confirmed that the BPF noise generated by a blade-rotating dipole roughly reflects the acoustic features of centrifugal pumps. The noise simulation method in current study has a good feasibility and suitability, which could be adopted in engineering design to predict and optimize the hydroacoustic behavior of centrifugal pumps.

PRINCIPLE TO CLOSED LOOP CONTROL DIFFERENTIAL CYLINDER WITH DOUBLE SPEED VARIABLE PUMPS AND SINGLE LOOP CONTROL SIGNAL

To control the position of differential cylinder closed loop without usingany throttle elements, a flew idea that two speed variable pumps are used to compensate thenon-symmetric flow of differential cylinder is carried out. According to the leaking property of thesystem, a speed offset principle is also proposed to eliminate the cavitation and tension caused bythe leakage and condensation of oil, which makes the system be in the same state as a valvecontrolled circuit. This principle is explained theoretically and experimentally. Further therelationship that the pressures in cylinder chambers change with load and leakage, and therelationship between biasing speed and pre-load pressures in cylinder chambers are established. Theresearch has proved that the new system has similar technique features as those of controlled withservo valves, but due to the elimination of all the throttle lose the efficiency of system can beimproved greatly.

Performance Study Based on Inner Flow Field Numerical Simulation of Magnetic Drive Pumps with Different Rotate Speeds

Magnetic drive pump has gotten great achievement and has been widely used in some special fields. Currently, the researches on magnetic drive pump have focused on hydraulic design, bearing, axial force in China, and a new magnetic drive pump with low flow and high head have been developed overseas. However, low efficiency and large size are the common disadvantages for the magnetic drive pump. In order to study the performance of high-speed magnetic drive pump, FLUENT was used to simulate the inner flow field of magnetic drive pumps with different rotate speeds, and get velocity and pressure distributions of inner flow field. According to analysis the changes of velocity and pressure to ensure the stable operation of pump and avoid cavitation. Based on the analysis of velocity and pressure, this paper presents the pump efficiency of magnetic drive pumps with different rotated speeds by calculating the power loss in impeller and volute, hydraulic loss, volumetric loss, mechanical loss and discussing the different reasons of power loss between the magnetic drive pumps with different rotated speeds. In addition, the magnetic drive pumps were tested in a closed testing system. Pressure sensors were set in inlet and outlet of magnetic drive pumps to get the pressure and the head, while the pump efficiency could be got by calculating the power loss between the input power and the outlet power. The results of simulation and test were similar, which shows that the method of simulation is feasible. The proposed research provides the instruction to design high-speed magnetic drive pump.

Investigation of the hydrodynamics of slug flow in airlift pumps

A slug flow model considering the dispersed bubbles entrained from the tail of Taylor bubble(TB) and recoalesced with the successive TB was proposed. Experiment was conducted to test the validity of this model by using a high-speed camcorder and particle image velocimetry(PIV). It was found that the model was valid for predicting the characteristics of slug flow in airlift pump within average error of 14%. Moreover, large pipe diameter was found to accelerate the rise velocity of TB and decreases void fraction in liquid slug by a small margin.

Effects of Driving Mode on the Performance of Multiple-Chamber Piezoelectric Pumps with Multiple Actuators

Due to the limited output capability of piezoelectric diaphragm pumps, the driving voltage is frequently increased to obtain the desired output. However, the excessive voltage application may lead to a large deformation in the piezoelectric ceramics, which could cause it to breakdown or become damaged. Therefore, increasing the number of chambers to obtain the desired output is proposed. Using a check-valve quintuple-chamber pump with quintuple piezoelectric actuators, the characteristics of the pump under different driving modes are investigated through experiments. By changing the number and connection mode of working actuators, pump performances in terms of flow rate and backpressure are tested at a voltage of 150 V with a frequency range of 60 Hz -400 Hz. Experiment results indicate that the properties of the multiple-chamber pump change significantly with distinct working chambers even though the number of pumping chambers is the same. Pump performance declines as the distance between the working actuators increases. Moreover, pump performance declines dramatically when the working piezoelectric actuator closest to the outlet is involved. The maximum backpressures of the pump with triple, quadruple, and quintuple actuators are increased by 39%, 83%, and 128%, respectively, compared with the pump with double working actuators; the corresponding maximum flow rates of the pumps are simply increased by 25.9%, 49.2%, and 67.8%, respectively. The proposed research offers practical guidance for the effective utilization of the multiple-chamber pumps under different driving modes.

Acid suppressive therapy improved symptoms due to circumferential cervical inlet patch with proton pumps(H^+/K^+-ATPase)

Cervical inlet patch(CIP), also referred to as esophageal heterotopic gastric mucosa, is regarded as the residue of columnar epithelium of the embryonic esophagus. Narrow band imaging increases the detection rate of CIP. Herein, we present a 55-year-old man with symptomatic circumferential inlet patch. He exhibited globus and dysphagia, and esophagogastroduodenoscopy found cir-cumferential CIP, where im-munohistochemistry revealed the existence of pro-ton pumps(H^+, K^+ -ATPase). His throat symptoms were relieved by acid suppressive therapy with pump inhibitors. This case indicated that CIP should be considered as a differential diagnosis for the cause of globus symptoms in rare cases.

Multi-Field Analysis and Experimental Verification on Piezoelectric Valve-Less Pumps Actuated by Centrifugal Force

A piezoelectric centrifugal pump was developed previously to overcome the low frequency responses of piezoelectric pumps with check valves and liquid reflux of conventional valveless piezoelectric pumps. However, the electro-mechanical-fluidic analysis on this pump has not been done. Therefore, multi-field analysis and experimen- tal verification on piezoelectrically actuated centrifugal valveless pumps are conducted for liquid transport appli- cations. The valveless pump consists of two piezoelectric sheets and a metal tube with piezoelectric elements pushing the metal tube to swing at the first bending resonant fre- quency. The centrifugal force generated by the swinging motion will force the liquid out of the metal tube. The governing equations for the solid and fluid domains are established, and the coupling relations of the mechanical, electrical and fluid fields are described. The bending res- onant frequency and bending mode in solid domain are discussed, and the liquid flow rate, velocity profile, and gauge pressure are investigated in fluid domain. The working frequency and flow rate concerning different components sizes are analyzed and verified through experiments to guide the pump design. A fabricated pro- totype with an outer diameter of 2.2 mm and a length of 80 mm produced the largest flow rate of 13.8 mL/min at backpressure of 0.8 kPa with driving voltage of 80 Vpp. Bysolving the electro-mechanical-fluidic coupling problem, the model developed can provide theoretical guidance on the optimization of centrifugal valveless pump characters.

Improving Suction Performance of Centrifugal Pumps by Using Jetting Device

Improving the suction performance of centrifugal pumps by using jetting device is presented. The theoretical analysis, experimental study and engineering implementation show that suction performance of centrifugal pump can be improved with jetting device and be used for delivering the liquid media requiring high suction performance, whereas the efficiency and head of the pump will decrease a little. The effect of feed-back jetting on suction performance is the most obvious at design point. The suitable rate of feed-back flow is 2%-5%.

Experimental Research on the Dynamic Lubricating Performance of Slipper/Swash Plate Interface in Axial Piston Pumps

The interface between the slipper/swash plate is one of the most important frication pairs in axial piston pumps.The test of this interface in a real pump is very challenging.In this paper,a novel pump prototype is designed and a test rig is set up to study the dynamic lubricating performance of the slipper/swash-plate interface in axial piston machines.Such an experimental setup can simulate the operating condition of a real axial piston pump without changing the relative motion relationship of the interfaces.Considering the lubricant oil film thickness as the main measurement parameter,the attitude of the slipper under the conditions of different load pressure,rotation speed and charge pressure are studied experimentally.After the test,the wear state of the swash plate is observed.According to the friction trace on the surface of the swash plate,the prediction for the attitude of the slipper and the zone easy to wear are verified.