Pump Rotation Research Articles

Experimental Investigation of Organic Rankine Cycle (ORC) for Low Temperature Geothermal Fluid: Effect of Pump Rotation and R-134 Working Fluid in Scroll-Expander

Organic Rankine Cycle (ORC) is one of the solutions to utilize a low temperature geothermal fluid for power generation. The ORC system can be placed at the exit of the separator to extract energy from brine. Furthermore, one of the main components of the system and very important is the pump. Therefore, in this research, the pump rotation is examined to investigate the effect on power output and energy efficiency for low temperature geothermal fluid. The rotation is determined by using an inverter with the following frequencies: 7.5, 10, 12.5, 15 and 17.5 Hz, respectively. R-134 working fluid is employed with 373.15 K evaporator temperature in relation to the low temperature of the geothermal fluid. Furthermore, the condenser temperature and fluid pressure were set up to 293.15 K and 5 × 105 Pa, respectively. This research uses a DC generator with a maximum power of 750 Watt and the piping system is made from copper alloy C12200 ASTM B280 with size 1.905 × 10−2 m and a thickness of 8 × 10−4 m. The results showed that there is an increase in mass flow rate, enthalpy and generator power output along with increasing pump rotation. In addition, it showed that the maximum generator output power was 377.31 Watt at the highest pump rotation with a frequency of 17.5 Hz.

Моделирование охлаждения масла погружного электродвигателя с помощью теплообменника

Submersible motors are part of submersible oil production pumps that convert electrical energy, which is supplied through a cable from VSD, into mechanical energy of pump rotation. Currently, in about 30% of cases, the failure of an electrical submersible pump is due to a failure of the submersible motor. One of the main causes of failures is overheating of the stator winding insulation. Overheating of submersible oil-filled electric motors occurs because more heat is generated inside the motor than is removed through its outer surface. To intensify the heat removal, it is proposed to connect a heat exchanger in series with the motor and to organize the circulation of the oil in a closed loop. Both in the submersible motor and in the heat exchanger, oil flows along the annular gap along the inner surface of the housing, the oil channel is closed through a hole inside the shaft. The aim of the work is to select such a configuration of the annular channel, in which its length would be minimal. Intensification of heat removal by increasing the speed of the coolant is not advisable, because requires the motor to be equipped with a powerful pump for pumping oil, which will become an additional source of heat. Therefore, it was decided to increase the surface area of the annular channel through which heat, through the body of the installation, is removed to the well fluid. A series of calculations was performed for heat exchangers with smooth walls, with fins (perpendicular to the flow direction), and with spiral grooves (which additionally increase the length of the trajectory of oil particles and the time of their thermal contact with the stacks of the heat exchanger body). Computational fluid dynamics calculations showed that heat exchangers made according to the first two design options removed less than half of the heat. According to the third option, the oil was cooled practically to the temperature of the well fluid with a heat exchanger length of about 10% of the submersible motor length.

Wear issues of pumping units

The article presents the possibility of increasing the service life of pumping units. Particular attention is paid to the regulation of the speed of rotation of the pumping unit. There are some assumptions in the mathematical model that do not affect the final result. The factors influencing the operating mode are given. It is indicated that the speed of rotation of the pump shaft significantly affects the wear resistance of the pump blades. Thus, the regulation of the pump rotation speed will rationally increase its service life.

Experimental Study on Deteriorated Performance, Vibration, and Geometry Changes of an Electrical Submersible Pump Under Sand Water Flow Condition

AbstractIn the oil and gas industry, the proppant backflow from fracturing wells severely reduces the lifespan of widely used downhole electrical submersible pumps (ESPs). In field applications, a minimal sand concentration may cause severe damage to ESPs in a short time. In order to resist the three-body abrasive sand wear, flanged tungsten carbide sleeves are used in ESPs. However, the wear-resistant performance of different pump geometry is not well analyzed and understood. Therefore, a 64 h pump erosion and abrasion test was conducted with water at the pump's best efficient flowrate with a sand concentration of 1 wt% to imitate the damage caused by short-term proppant backflow. The test was divided into several periods, after which the pump performance, paint-removal wear pattern, eroded pump geometries, and stage vibration were measured and recorded. The wear-rate on pump stage geometries gradually decreased at the beginning of 8–16 h. Then, the carbide sleeves started to help sustain the pump rotation. As a result, the wear-rate and pump vibration became relatively stable. Therefore, the wear mechanism in the secondary flow region (seal rings and sleeves) is believed to change from abrasive wear to the combined erosive-abrasive wear. The pump overall performance decreased by approximately 10% after the 64 h test. The performance, pump geometry, and vibration data are previous for understanding wear mechanism, predicting failures, improving pump design, and saving the well service cost.

Analysis of the impact of left ventricular assist devices on the systemic circulation

AbstractIn this work we analyze the impact of left ventricular assist devices on the systemic circulation in subjects with heart failure associated with left ventricular dilated cardiomyopathy. We use an integrated model of the left heart and blood flow in the systemic arteries with a left ventricular assist device. We study the impact of the rotation speed of the pump on haemodynamic characteristics of distal arteries. We identify the rotation speed for simultaneous recovery of the healthy average values in all systemic arteries, the heart and the aorta. Our numerical experiments show that blood distribution over the graph of systemic vessels does not depend on flow regimes in ascending aorta. We also observe that the optimal pump rotation speed changes in the atherosclerotic vascular network and depends on stenoses localization.

Thrombotic Risk of Rotor Speed Modulation Regimes of Contemporary Centrifugal Continuous-flow Left Ventricular Assist Devices

Contemporary centrifugal continuous-flow left ventricular assist devices (LVADs) incorporate dynamic speed modulation algorithms. Hemocompatibility of these periodic unsteady pump operating conditions has been only partially explored. We evaluated whether speed modulation induces flow alterations associated with detrimental prothrombotic effects. For this aim, we evaluated the thrombogenic profile of the HeartWare ventricular assist device (HVAD) Lavare Cycle (LC) and HeartMate3 (HM3) artificial pulse (AP) via comprehensive numerical evaluation of (i) pump washout, (ii) stagnation zones, (iii) shear stress regimens, and (iv) modeling of platelet activation status via the platelet activity state (PAS) model. Data were compared between different simulated operating scenarios, including: (i) constant rotational speed and pump pressure head, used as reference; (ii) unsteady pump pressure head as induced by cardiac pulsatility; and (iii) unsteady rotor speed modulation of the LC (HVAD) and AP (HM3). Our results show that pump washout did not improve across the different simulated scenarios in neither the HVAD nor the HM3. The LC reduced but did not eliminate flow stagnation (-57%) and did not impact metrics of HVAD platelet activation (median PAS: +0.4%). The AP reduced HM3 flow stagnation by up to 91% but increased prothrombotic shear stress and simulated platelet activation (median PAS: +124%). Our study advances understanding of the pathogenesis of LVAD thrombosis, suggesting mechanistic implications of rotor speed modulation. Our data provide rationale criteria for the future design optimization of next generation LVADs to further reduce hemocompatibility-related adverse events.

Karakteristik Unjuk Kerja 2 Pompa Sentrifugal Dengan Susunan Seri Sebagai Turbin Pat

The pump is a device used to move fluid from one place to another through a media pipe or channel. The energy in the fluid is produced from the impeller which converts the kinetic energy (velocity) of the liquid into potential (dynamic) energy. Besides being used to move fluid (fluid) at this time the pump can also be used as a turbine by changing the working principle of the pump by giving a drop of water at an altitude to rotate the impeller on the pump so that the pump can operate upside down or called a pump as turbine), in this study the impeller on the pump as a turbine is driven by a water flow or water pressure that is large enough, the water flow is sourced from two centrifugal pumps with a series arrangement that functions as a driving force or fluid distributor which is assumed to be a high water fall or head. The use of centrifugal pumps with a series arrangement is so as to produce a large head to get a high water fall or a maximum head for turning a pump as a turbine. This study uses an experimental method that is using two centrifugal pumps as a fluid distributor and one pump that is used as a turbine and uses a variation of 5 watt and 10 watt light bulb. From the calculation of the suction pump and pump as a turbine without using a light bulb pump speed namely 920.5 rpm and the specific speed of the turbine produced is 76.61 rpm. by using a 5 watt light bulb load the pump rotation speed is 553 rpm and the specific turbine speed produced is 44.24 rpm, using a 10 watt light bulb load the pump rotation speed is 335 rpm and the specific turbine speed produced is 26.8 rpm. The greater the value of the pump head, the resulting water discharge will be smaller and vice versa, the size and size of the pump head obtained is also influenced by the presence of load on theturbine.

Concerns About the Timing and Settings of Initiating Extracorporeal Membrane Oxygenation in Patients With Severe Coronavirus Disease 2019 Pneumonia

To the Editor: We read with great interest the clinical investigation reported by Yang et al (1) published in a recent issue of Critical Care Medicine. The authors describe the characteristics of patients with acute respiratory distress syndrome (ARDS) induced by the novel coronavirus disease 2019 (COVID-19) requiring extracorporeal membrane oxygenation (ECMO). They reported the mortality rate of COVID-19-induced ARDS requiring ECMO as 57.1%, which is similar to the 58.3% reported for outcomes (death or coma) in another case series (2). They also described the timing of initiation and the initial settings of ECMO in patients with severe ARDS induced by COVID-19. We would like to discuss whether the strategy they reported can be considered as standard for ECMO treatment for severe COVID-19 pneumonia. First, regarding the timing of initiating ECMO, the authors state that earlier initiation after mechanical ventilation may be associated with improved outcomes. Although early initiation is reported to be associated with good prognosis in adult ARDS patients (3), COVID-19 pneumonia is reported to present with features different from typical ARDS (4). Would different phenotypes of respiratory failure require different ECMO treatment strategies? We are still doubtful whether early initiation of ECMO can be considered similarly for typical ARDS and COVID-19 pneumonia. Addressing this will require comparisons between early initiation and late initiation groups. Second, the initial setting of ECMO in the study by Yang et al (1) seems to be unique. The authors report that many patients developed bradycardia while the centrifugal pump was on. This raises the question of whether this phenomenon is unique to COVID-19 pneumonia. Looking at the many COVID-19 case series reported to date, we find no descriptions of bradycardia elsewhere. To avoid bradycardia, the authors suggest increasing ECMO pump rotation slowly from 1,500 revolutions per minute (rpm) to the target rotation at increments of 500 rpm every 10 minutes. We speculate venovenous ECMO does not, in fact, have a significant effect on hemodynamics when initiating ECMO as long as a sufficient intravascular volume is maintained. Another report of patients with COVID-19 pneumonia requiring ECMO also described gradually increasing the rotation speed of the centrifugal pump when starting ECMO (5), but at a seemingly faster rate than Yang et al (1) reported. We question then whether it is actually possible to prevent bradycardia using the authors’ method. Finally, have the laboratory test values presented for survivors and nonsurvivors in Table 2 in (1) mistakenly been switched, given that the authors state that “survivors had a significant lower creatinine than nonsurvivors prior to ECMO”; the numbers in Table 2 in (1) are reversed. We are still in the pandemic phase of COVID-19, and thus, appropriate indications and methods for initiating ECMO support in critically ill patients with COVID-19 pneumonia are important to establish.

Measuring the rotational temperature and pump intensity in molecular alignment experiments via high harmonic generation.

We demonstrate a method to simultaneously measure the rotational temperature and pump intensity in laser-induced molecular alignment by the time-resolved high harmonic spectroscopy (HHS). It relies on the sensitive dependence of the arising times of the local minima and maxima of the harmonic yields at the rotational revivals on the pump intensity and rotational temperature. By measuring the arising times of these local extrema from the time-resolved harmonic signals, the rotational temperature and pump intensity can be accurately measured. We have demonstrated our method using N2 molecules. The validity and robustness of our method are tested with different harmonic orders and by changing the gas pressures as well as the distance between the gas exit and the optical axis. Moreover, we have also demonstrated the versatility of our method by applying it to CO2 molecules.

Influence of Pump Rotation Speed on Hydrodynamic Performance and Stator Blade Surface Pressure Pulsation in Torque Converter

Abstract An experimental investigation was performed to characterize the influence of pump rotation speed on the hydrodynamic performance and the associated unsteady pressure on the stator blade pressure-surface in a torque converter. High-resolution miniature transducers were used to obtain the signature of the pressure pulsation at specific surface locations. Results show that the increase of the pump rotation speed can enhance the torque capacity of the stator, leading to a higher torque ratio in the low speed ratio range and an improvement of the highest transmission efficiency. The efficiency increase rate starts to reduce at approximately SR = 0.4, corresponding to where the stator capacity reaches the maximum and exhibits a uniform distribution of the pressure pulsation intensity. The spectral decomposition of the pulsating pressure reveals the existence of two dominating frequencies, which corresponds to the upstream pump turbine interaction and the downstream pump blade passing. Higher pump speeds enhance the pump turbine interaction and results in a more regular pressure pulsation, improving the hydrodynamic performance of the torque converter.

The analysis of bending of the rotational pump’s screws taking into account the variable moments of inertia along the screw

The analysis results of longitudinal and cross bends of screws of rotational pumps is carried out. Check of the offered model of cross-bending of the screw both taking into account, and without thread is executed. The interrelation of bend of the screw and decrease in the moment of inertia of its cross-section is revealed and the model of calculation of the screw on stability in pitch considering these parameters is received.

In vitro evaluation of multi-objective physiological control of the centrifugal blood pump.

Left ventricular assist devices (LVADs) have been used as a bridge to transplantation or as destination therapy to treat patients with heart failure (HF). The inability of control strategy to respond automatically to changes in hemodynamic conditions can impact the patients' quality of life. The developed control system/algorithm consists of a control system that harmoniously adjusts pump speed without additional sensors, considering the patient's clinical condition and his physical activity. The control system consists of three layers: (a) Actuator speed control; (b) LVAD flow control (FwC); and (c) Fuzzy control system (FzC), with the input variables: heart rate (HR), mean arterial pressure (MAP), minimum pump flow, level of physical activity (data from patient), and clinical condition (data from physician, INTERMACS profile). FzC output is the set point for the second LVAD control schemer (FwC) which in turn adjusts the speed. Pump flow, MAP, and HR are estimated from actuator drive parameters (speed and power). Evaluation of control was performed using a centrifugal blood pump in a hybrid cardiovascular simulator, where the left heart function is the mechanical model and right heart function is the computational model. The control system was able to maintain MAP and cardiac output in the physiological level, even under variation of EF. Apart from this, also the rotational pump speed is adjusted following the simulated clinical condition. No backflow from the aorta in the ventricle occurred through LVAD during tests. The control algorithm results were considered satisfactory for simulations, but it still should be confirmed during in vivo tests.

Usefulness of Imaging for Intrathecal Drug Delivery Systems: An update

Intrathecal Drug Delivery Systems are invasive pain treatment techniques that require bypassing the blood-brain barrier in order to implant a catheter inside the CSF. Imaging is a key element before and during implantation as well as in the diagnosis of complications. The understanding of delivery mechanisms has been greatly improved using MRI. Drug diffusion can now be modeled according to infusion level and flow rate for each individual patient. MRI and CT are useful in diagnosing the patient, targeting spinal level, and accurately evaluating implantation concerns or contraindications. Imaging is a key tool during the implantation of the device. Catheter positioning is essential as the treatment diffusion is limited, and the tip of the catheter must be set behind the spinal cord. Currently, fluoroscopy is the gold standard for catheter placement. Biplane Interventional Imaging and surgical CT scan will soon be able to help with more accurate positioning. An ultrasound-guided technique is helpful to localize a recessed septum in challenging pump refill procedures where pumps are deeply situated. Imaging is also essential for device malfunction diagnosis. Plain radiology is currently limited as new catheters have a poor opacity, but it remains useful for confirming motor stall of the peristaltic pump and is appropriate for the diagnosis of pump rotation. High-resolution three-dimensional Computer Tomography reconstruction allows accurate control of catheter positioning and the diagnosis of dislodgment, kinking, and breaking. MRI is the most accurate imagery to diagnose spinal cord injuries following implantation or as an adverse effect of IT treatment such as granuloma. Diffusion control requires dynamic imaging which can be performed by TC99 scintigraphy. This allows for the visualization of drug diffusion and velocity. In the near future, novel techniques such as PET- CT scan could be useful for testing the distribution of intrathecal drugs

EFFECTS OF HIGH FLUID VISCOSITY ON PRESSURE LOSSES OF THE SINGLE-PHASE FLOW INSIDE AN ESP STAGE

The Electrical Submersible Pump (ESP) system is among the most widely used artificial lift methods in the world. This work studies the effects of high fluid viscosity on pressure losses of the flow in an ESP stage. A theoretical model was applied to four different flow cases. First, curves for head and pressure losses at the pump stage were generated and, based on literature formulations available in the model, as well as on adjusted empirical coefficients (for highly viscous fluids), implemented in the model. Subsequently, the heads were estimated and evaluated using experimental data and statistical analyses based on mean square error. The results showed that high fluid viscosity impacted considerably pressure losses and pump performance. In 50% of the cases studied, statistical analyses alone could estimate the head in the pump stage with good accuracy. However, in the remaining cases, it was also necessary to consider the physical behavior of the highly viscous fluids studied. The variability of the selected formulations from the literature (for pump head and pressure losses) with pump rotation, and especially with high fluid viscosity, was considerably larger than the ones found in previous studies for less viscous fluids.

Characterization of Gaseous Plasma Sustained in Mixtures of HMDSO and O2 in an Industrial-Scale Reactor

Optical emission spectroscopy and mass spectrometry was used to characterize gaseous plasma in an industrial reactor of volume 5 m3 during deposition of protective coatings. Plasma was created in mixtures of hexamethyldisiloxane (HMDSO) and oxygen at the powers between 1 and 8 kW. The plasma density was somehow below 1014 m−3. The flows of both gases were varied up to 200 sccm while the effective pumping speed was adjusted by changing the roots pump rotation speed between 250 and 4000 rpm. At such conditions the HMDSO was only partially dissociated to fragments. The behaviour of optical emission lines and mass ion currents was well correlated indicating that even one single technique was sufficient to monitor the behaviour of plasma at various discharge conditions. The optical emission spectroscopy as a simple and economic method is therefore suitable for controlling key processing parameters in such a plasma reactor.

Series and parallel relationship pump performance in FT. Unitas’s practicum tools

Basically, the variation of the pump arrangement in the piping installation is done to get the performance / flow characteristics needed in a particular usage according to the needs, namely the need for a head height that is higher than the flow rate (capacity) or vice versa. Flow regulation method with variations of valve openings (Senen 2004), which is applied in this study with consideration of energy use efficiency, it can be stated that the pump efficiency range of the parallel circuit is high to get a larger flow rate than the series circuit pump. To get the head maximum, the pump efficiency series is smaller than the pump efficiency of the parallel circuit, so that it does not provide an illustration that the optimum pump work has been achieved, so that further research needs to be carried out research with variations in pump rotation (Mastur and Warso 2015) below or above the standard round. But based on the purpose of this study in terms of pump performance, to meet the needs of a high head, the pump installation is arranged in series and vice versa if what is needed in the pump installation system is a high flow rate, the pump is arranged in parallel, so the results of this study have been can meet the needs of practicum for students of Mechanical Engineering Study Program FT. Unitas in terms of how to get the performance of a centrifugal pump installation.

Evaluation of Almitrine Infusion During Veno-Venous Extracorporeal Membrane Oxygenation for Severe Acute Respiratory Distress Syndrome in Adults.

This single-center case series investigated the effect of almitrine infusion on PaO2/fraction of inspired oxygen (FIO2) in 25 patients on veno-venous extracorporeal membrane oxygenation for severe acute respiratory distress syndrome. A positive trial was defined as an increase of PaO2/FIO2 ratio ≥20%. Thirty-two trials were performed. Twenty (62.5%, 95% confidence interval, 37.5%-75%) trials in 18 patients were positive, with a median PaO2/FIO2 ratio increase of 35% (25%-43%). A focal acute respiratory distress syndrome and inhaled nitric oxide therapy were more frequent in patients with a positive response to almitrine. We observed no complications of almitrine use.

Experimental investigation of oil drops behavior in dispersed oil-water two-phase flow within a centrifugal pump impeller

In oil production, one important artificial lift method involves the commonly used centrifugal pump. The use of this pump in the petroleum industry, however, is hindered by some unfavorable operational conditions. Operating centrifugal pumps with gas and viscous fluids, such as dispersions, may lead to a degradation of their performance. The objective of this paper is to analyze oil-water dispersions in a pump impeller, in order to investigate the behavior of oil drops, which may influence the pump working. Thus, experiments were carried out at different pump rotation speeds and water flow rates. Researchers used a facility with a pump prototype that enabled them to visualize the flow in all the impeller channels. Images, captured through a high-speed camera, revealed a unique flow pattern of oil drops dispersed in water. Processed with computer codes, the images indicated that the oil drops were, in general, spherical or elliptical, and only a few broke up in the impeller. The interaction with water caused the oil drops to rotate, deform, and deviate, thus moving in random paths. Size distributions suggested that the drops became smaller as the impeller rotation speed and water flow rate increased. This behavior was due to the turbulence-induced shear stress and kinetic energy. The oil drops’ equivalent diameters ranged from 0.1 to 6.0 mm; velocities took values measurable by units of m/s; accelerations reached hundreds of m/s2; and forces had magnitudes of thousandths of N. Researchers observed a clear dependence between flow conditions and drop dynamics. Carried by the water flow, the oil drops on the suction blade moved faster than those on the pressure blade of a channel. The drop dynamics were significantly influenced by the presence of adverse pressure gradients and water velocity fields.

Constant-Speed Oscillation of a Pump Turbine Observed on a Pumped-Storage Model System

The hydraulic characteristics of pump turbines in off-design conditions, especially the S-shaped characteristics, are crucial for the safety and stability of the unit. To explore the S-characteristics of pump turbines through a transient method, an experimental investigation was conducted based on a pumped-storage model system at Wuhan University. By shutting down the circulating pump, a special transient process was triggered, forcing the pump turbine to operate in turbine mode, turbine brake mode, and reverse rotational pump mode. As the rotational speed of the pump turbine was maintained almost constant in the oscillation process with a maximum deviation of 0.6%, this transient operation was named as constant-speed oscillation (CSO). The parameters for global performance and pressure pulsations in the vaneless gap were measured and analyzed. In addition, the one-dimensional rigid column theory was used to establish a mathematical model for simulation. The results from simulation were quantitatively compared with the experimental results. Finally, the reason for the CSO was theoretically explained based on stability analysis through the established mathematical model. It was observed that the positive slope of ned–Qed characteristic curves at no-flow resulted in this oscillation. In contrast, the simulation was performed under the same conditions with a modified ned–Qed characteristic curve, which had a negative slope at no-flow. However, the results showed that, with the modified characteristic curve, the pump turbine would stabilize at no-flow.

Modelling and reducing fuel flow pulsation of a fuel-metering system during pump mode switching in a turbofan engine

In this research, the transient characteristics of a new type fuel metering system for aircraft turbofan engines using two types of pumps, a gear pump and a centrifugal pump, were studied by modelling and simulation. This new fuel metering system is capable of hydraulically unloading the operating state of each pump by the pump mode switching mechanism within the permissible range of the pump rotation speed and the fuel flow rate and it is possible to reduce the fuel temperature rise due to the pressure loss in the circuit in the operation region of the entire fuel system. In addition to this, by using a small centrifugal pump that can realize high discharge flow rate, it is possible to reduce weight compared to the conventional fuel system. However, when the pump mode is switched, unexpected fluctuation in the fuel flow rate can occur when a large change in the inlet pressure of the system occurs, the pressure control unit cannot follow the change, and the transient phenomenon cannot be suppressed. At this time, the pressure waveform generated at the time of changing the pump mode includes a high frequency component such that the pressure control unit, which plays a role of keeping the metering valve differential pressure constant, cannot follow up. Therefore, in this paper, we focused on the frequency of the pressure change waveform when the pump mode was changed and studied the model of the fuel system inlet pressure in the gear pump mode. Based on that model, we propose a method to reduce the frequency characteristics of the pressure change occurring at the time of pump mode change.