Best Efficiency Point Research Articles

A Comparative Study between Theoretical and Measured Performance of Standard Centrifugal Pumps Running as Turbines

High cost of custom-made conventional turbines and the lack of local manufacturing facilities have created significant obstacles to the development of Pico/micro hydroelectric schemes in the country. In this context it has been identified pump as turbine (PAT) electric schemes can have distinct advantages over conventional turbines because pumps are manufactured locally at mass scale and available in various sizes. But not all pumps are suitable for use as PAT because they have different design details and manufacturing qualities. The performance of a pump used as a turbine is assessed based on two primary parameters: turbine mode head and flow at the Best Efficiency Point (BEP). There are various methods available in the literature for predicting PAT theoretical head and flow at BEP. These methods aim to estimate how the pump will perform when used as a turbine. Despite these prediction methods, there is a consistent deviation of approximately ±20% between the theoretical estimates and the actual measured performance. This indicates that real-world conditions and factors not accounted for in theoretical models can significantly affect the performance of PAT systems. The primary objective of the present study was to measure the deviation between the actual performance and the predicted performance of two PAT systems in terms of head and flow at BEP. This deviation was then compared to the commonly mentioned figure of ±20% in the literature. The study focused on using what it considered to be the most accurate prediction method among those presented in the literature to estimate PAT head and flow at BEP and involved running reverse, 1.1 kW, and 1.6 kW direct-drive standard centrifugal type water pumps in a test rig to measure the actual performance of the two PATs. The results of the study showed a deviation of +27% and -22% between the actual measured head and flow at BEP, and the values predicted by the theoretical method. This deviation is slightly outside the commonly mentioned range of ±20% found in the literature, but this is not expected to have a detrimental effect on the generation of electric power. This implies that, even with the observed slight deviation, the prediction method used in this study can be satisfactorily employed to estimate PAT head and flow at BEP.

Particle image velocimetry in the impeller of a centrifugal pump: Relationship between turbulent flow and energy loss

Turbulent flows play a dominant role in the operation of centrifugal pumps, which find widespread use in industrial settings and various aspects of human life. The dissipation rate of turbulent kinetic energy emerges as a key parameter within these devices, with its local values exerting a significant influence on centrifugal pump performance. Recent advances in particle image velocimetry (PIV) techniques have expanded the ability to analyze complex turbulent flows across a broad spectrum of scales. In this context, this paper aims to deepen our understanding of the turbulent flow field and its correlation with energy loss in centrifugal pump impellers. To achieve this, experiments were conducted using PIV on a transparent pump operating under different conditions. Statistics of the turbulent flow were then obtained from phase-ensemble averages of velocities, vorticity, turbulence production, and local dissipation of turbulent kinetic energy. To overcome the limited spatial resolution constraint of PIV, the large-eddy PIV (LES-PIV) method was employed to estimate the local dissipation rate. In this method, it is assumed that the motion of larger scales is measured by the PIV technique, while the smaller scales (unresolved scales) are modeled by a sub-grid scale model, calculated from the strain rate tensors obtained from the measured fields. Energy losses in the impeller were studied using two methodologies: (i) a conventional method based on power measurements, and (ii) an alternative approach based on the budget of turbulent kinetic energy. Our results reveal that turbulent loss caused by turbulence production is the main source of energy loss in the pump impeller, and it is particularly pronounced in low-flow operating conditions characterized by large-scale structures. On the other hand, in situations where flow rates exceed the best efficiency point (BEP) condition, the predominant flow structures are marked by small-scale features, mainly attributed to local dissipation of turbulence. Our findings clarify the characteristics of energy losses in centrifugal pump impellers and their relationship with the turbulent flow field, and, in addition, providing a methodology for calculating the local turbulent dissipation rate and its limitations when derived from PIV measurements.

Extending the operational range of Francis turbines: A case study of a 200 MW prototype

Francis turbines are now widely used to support the integration of renewable and intermittent energy sources such as solar and wind power. Consequently, these turbines often operate away from their best efficiency point (BEP). Such operations cause detrimental pressure fluctuations in the runner and draft tube, leading to early fatigue failures. To address these harmful flow conditions and extend the operating range of Francis turbines, a mitigation system was developed and tested on a large-scale, high-head 200 MW Francis turbine. The system consists of four circular rods placed in the draft tube with variable radial protrusion lengths, adjustable using linear actuators. Pressure, accelerometer, and vibration sensors installed on the turbine allowed quantification of the rod system performance. The results demonstrate the system’s capability to reduce pressure pulsations by up to 80 % in terms of maximum pressure amplitude and 100 % in terms of fatigue cycle in both low and high-frequency ranges, up to ten times the runner frequency, based on pressure analysis. The optimal rod protrusion ranges from 5 to 20 % of the runner outlet diameter function of the operating load. The impact of the rods’ protrusion on the turbine structure appears negligible from the accelerometer measurements performed on the draft tube and spiral casing. The hydraulic efficiency is reduced by up to 1 %. These findings are significant across a wide range of part-load operations, from 40 % to 60 % load, indicating the potential to extend the operational range of existing Francis turbines. The research presented here is a novel attempt to enhance the existing Francis turbines with a new degree of freedom using protruding rods.

Multiobjective hydraulic optimization of the diffuser vane in an axial flow pump

Separation flows tend to induce a chaotic flow field that eventually leads to energy losses and reduced efficiency. The present study performed a multiobjective optimization to improve the hydraulic performance of an axial flow pump at the best efficiency point (BEP) and critical stall point based on the diffuser vane (DV) geometry. Computational fluid dynamics were applied to predict the hydraulic performance of a series of DV models with design points generated through design of experiment. Six different surrogate models were evaluated based on the R-squared criteria. The nondominated sorting genetic algorithm II was also employed to search for optimum solutions for design variables. Hydraulic performance balance between low and high flow rate conditions was analyzed based on the velocity triangle. After optimization, the efficiency and total head at the BEP of the optimum model were increased by 2.341% and 2.779%, respectively, compared to the reference model. Despite the minimal changes to the hydraulic performance at the critical stall point, the optimal operating range was notably expanded in the high flow rate region. Thorough evaluation of losses attributed to horseshoe, corner, and trailing-edge vortices was conducted in meridional planes, multiple spans, and various cross sections in the DV domain. Additionally, the formation and development of turbulent flow were analyzed in detail by transient simulation. Vibration and noise caused by instabilities in the flow characteristics of the reference model were substantially reduced by 36.76% and 67.342% at the first higher-harmonic frequencies at the BEP and the critical stall point, respectively.

Improvement of energy performance of a two-way pumping station based on controllable diffusion technology

Energy performance is a crucial parameter for evaluating a two-way pumping station. However, the sharp decrease in efficiency within overload flow rates presents a challenge. To address this issue, the controllable diffusion technology (CDT) is developed based on asymmetric inflow theory. Transient numerical simulation is carried out under five different distortion angles. The energy performance and entropy production dissipation before and after the application of CDT are comprehensively studied. (a) First, CDT successfully improves the operation efficiency within the overload flow rate range. The reverse distortion has a better improvement effect than the syntropic distortion. (b) Second, under asymmetric inflow conditions, the reduction in the axial velocity causes the best-efficiency point to deviate toward the overload flow rate. This leads to an increase in the total entropy production (TEP) within 0.7Qdes–0.95Qdes, followed by a decrease within 1.05Qdes–1.3Qdes. (c) Third, the CDT-induced horizontal velocity causes a mismatch between the impeller inflow angle and blade placement angle, which leads to uneven spatial distribution of the total entropy production rate inside the pumping station.

A generalized prediction model for complete performance investigation of pump operated as turbine in microhydro applications using novel approach for improving sustainability

Centrifugal pumps operated in reverse mode (popularly called pump as turbines (PATs)) are well-established as green energy converters, mainly used in microhydro applications due to their lower capital cost. However, the appropriate selection of the pump for reverse-mode application is a critical issue due to the unavailability of its characteristic curve in turbine mode. Therefore, various researchers have proposed models to predict PAT parameters from pump characteristics based on diverse approaches. Still, researchers are striving to develop a prediction model, which can predict the head and flow rates for the PAT with less than ±20 % deviation for both. This work proposed a novel approach to predict the characteristics of PAT with the integration of ensemble regression modelling for Best Efficiency Point (BEP) and from it, by polynomial equations complete characteristics curve. The data from in-house experiments and open literature are used to develop the proposed model excluding the data of four pumps, which are typically used for validation of it. The predicted parameters of PAT from pump characteristics show good agreement for four selected PATs with <10 % maximum deviation. Compared to the literature prediction models, it shows a lower deviation for the same four PATs. A case study based on the field data is carried out to justify the applicability of the proposed model. By using this model selected pump when operated in PAT will produce higher power and generate more revenue compared to literature models, resulting in the economical utilization of resources and improving sustainability. Though the savings are lower, it will be significant for a large number of PAT applications.

Numerical Investigation of Impeller Parameters on the Performance and Internal Flow Characteristics in Regenerative Flow Pumps

Abstract As a particular vane pump, regenerative flow pump (RFP) is not only featured by relatively high head under low flow rate, but also is characterized by compact volume and simple structure. However, the efficiency of RFP is quite low. For the purpose of improving RFP’s hydraulic performance and internal flow, this paper investigates the influence of the matching relation between impeller diameter and height on RFP’s performance. Two cases through changing impeller’s diameter and height are designed and compared. The results show that, as impeller’s diameter increases while keeping the blade’s radial length constant, RFP’s head and efficiency are improved, and the best efficiency point (BEP) shifts gradually from lower flow rate to larger flow rate. Additionally, the ratio of the flow rates at BEP is approximately equal to the ratio of the blade’s middle diameters. On the other hand, as impeller’s height increases, the BEPs among different pump models stay in same flow rate, and there is always an optimal impeller’s height for this RFP model to achieve optimal performance. Finally, the pressure distribution, velocity distribution and mass exchange of different models are analysed to reveal the differences.

Energy loss analysis of a double-suction centrifugal pump using in pump mode and turbine mode

As an economical energy recovery device, pump as turbine (PAT) is widely used in micro-hydropower stations and the chemical industry. The inlet and outlet pipelines connected to the double-suction pump are on the same horizontal line. As the pipeline layout is very convenient, in some chemical industries, the way of residual pressure energy utilization is increasing using the double-suction pump as a turbine. Based on numerical simulation, experimental verification, and entropy generation theory, the energy loss rule of each flow component in the pump mode and turbine mode under different flow rates is compared and analyzed. The results show that when the double-suction pump is used as a turbine, the flow rate at the best efficiency point (BEP) in the turbine mode shifts to a large flow rate by 30.89% and the BEP efficiency decreases by 1.30%. In the pump mode and turbine mode, the main energy loss component is the impeller, and the turbulent entropy generation power and the wall entropy generation power are the main sources of energy loss. The energy loss in the suction chamber and impeller increases sharply, and the energy loss is primarily enhanced in the blade trailing edge and the tongue near due to the unsteady flow in the turbine mode. Due to the complex structure, the spiral suction chamber is not suitable for the flow direction of the fluid flow out of the impeller, and the flow state inside the impeller is negatively affected by the suction chamber in the turbine mode. This paper provides a theoretical basis for the design and application of double-suction centrifugal PAT.

Off-Design Operation and Cavitation Detection in Centrifugal Pumps Using Vibration and Motor Stator Current Analyses.

Centrifugal pumps are essential in many industrial processes. An accurate operation diagnosis of centrifugal pumps is crucial to ensure their reliable operation and extend their useful life. In real industry applications, many centrifugal pumps lack flowmeters and accurate pressure sensors, and therefore, it is not possible to determine whether the pump is operating near its best efficiency point (BEP). This paper investigates the detection of off-design operation and cavitation for centrifugal pumps with accelerometers and current sensors. To this end, a centrifugal pump was tested under off-design conditions and various levels of cavitation. A three-axis accelerometer and three Hall-effect current sensors were used to collect vibration and stator current signals simultaneously under each state. Both kinds of signals were evaluated for their effectiveness in operation diagnosis. Signal processing methods, including wavelet threshold function, variational mode decomposition (VMD), Park vector modulus transformation, and a marginal spectrum were introduced for feature extraction. Seven families of machine learning-based classification algorithms were evaluated for their performance when used for off-design and cavitation identification. The obtained results, using both types of signals, prove the effectiveness of both approaches and the advantages of combining them in achieving the most reliable operation diagnosis results for centrifugal pumps.

Experimental Investigation of Part Load Vortex Rope Mitigation With Rod Protrusion in an Axial Turbine

Abstract The present paper investigates the rotating vortex rope (RVR) mitigation on an axial turbine model by the radial protrusion of four cylindrical rods into the draft tube. RVR mitigation is of particular interest due to the unfavorable pressure pulsations it induces in the hydraulic circuit that can affect turbine life and performance. The protrusion lengths, which were the same among the four rods, were varied according to a predefined sequence. The experiments were performed under four part-load regimes ranging from upper part load to deep part load. Time-resolved pressure measurements were conducted at two sections on the draft tube wall along with high-speed videography and efficiency measurement to investigate the effect of the mitigation technique on the RVR characteristics and turbine performance. The recorded pressure data were decomposed and studied through spectral analyses, phase-averaging, and statistical analyses of the RVR frequency and peak-to-peak pressure amplitude distributions. The results showed different levels of pressure amplitude mitigation ranging from approximately 10% to 85% depending on the operating condition, protrusion length, and the method of analysis. The hydraulic efficiency of the turbine decreased by a maximum of 3.5% that of the best efficiency point (BEP) with the implementation of the mitigation technique. The variations in the obtained mitigation levels and efficiencies depending on protrusion length and operating condition indicate the need for the implementation of a feedback-loop controller. Thus, the protrusion length can be actively optimized based on the desired mitigation target.

Investigation of role of fins in a Francis turbine model's cavitation-induced instabilities under design and off-design conditions

Harnessing hydraulic energy for power generation using Francis turbines presents formidable downstream swirl instabilities, which can lead to pressure surges at part load (PL) conditions. Cavitation-induced issues affect not just the PL operations but also the power generation at the best efficiency point (BEP). To combat these challenges, fins strategically placed on the draft tube (DT) periphery aid in low-pressure recovery, which suppresses the hurdles for stable energy extraction. This ongoing study delves deep into the internal flow dynamics of the turbine, considering various Thoma numbers, and evaluating the impact of fins. The investigation employs numerical simulations utilizing structured and unstructured grids, incorporating the Shear Stress Transport (SST) model and the Rayleigh-Plesset model to model turbulent flow in a two-phase mixture. Preliminary findings reveal that at PL, the presence of fins substantially reduces low-pressure zone formation, minimizing vortex ropes and associated instabilities. The fins positively influence axial velocity, reducing swirl intensity and mitigating pressure pulsations by 60 % at PL. Conversely, at the BEP, the impact of fins appears less pronounced, with zero detrimental effect. In conclusion, with no negative effect at BEP, the incorporation of fins enhances the turbine's operational range and ensures smoother and more stable energy production at PL.

Improvement in energy performance from the construction of inlet guide vane and diffuser vane geometries in an axial-flow pump

Advanced inlet guide vane (IGV) and diffuser vane (DV) geometries were constructed in an effort to increase the energy performance of an axial-flow pump at the best efficiency point (BEP). DV setting angles were also investigated to increase energy performance at the off-design points. By integrating the advantages of an adjustable IGV, combinations of adjustable IGV and DV geometries were constructed and thoroughly analyzed by way of energy loss. The asymmetrical geometry of the IGV, upgraded through the use of a hydrofoil profile, resulted in higher hydraulic performance compared to that of the reference model. The efficiency and total head at the BEP increased significantly with the implementation of the new DV, by 1.456% and 5.756% over those of the reference model, respectively. Using the new DV reduced the unsteady turbulent flow behind the trailing edge of the DV under all flow rate conditions, resulting in a reduction in vibration and noise. The positive setting angles of the DV increased the energy performance in the high-flow-rate region, whereas the negative DV setting angles produced a good performance in the low-flow-rate region. Combining an adjustable IGV with an adjustable DV model resulted in a significant increase in the total head, with more optimal energy performance provided by the positive IGV setting angles. At the BEP and under high-flow-rate conditions, the low-velocity zone is closely related to high entropy generation. Furthermore, these high-entropy generation regions follow the trajectory of the low-velocity zones. However, the low-velocity zone is not strongly associated with the high-entropy generation region when operating under low-flow-rate conditions.

Influence of Positive Guide Vane Geometric Parameters on the Head-Flow Curve of the Multistage Pump as Turbine

In order to reduce the impact of production changes on the performances of pumps as turbines (PATs) in the process industry, it is imperative to lessen head variations at different mass flow rates. This study established a relationship equation between theoretical head and geometric parameters for multistage PATs. The influence of these parameters on the flatness of the head-flow (H-Q) curve was determined through derivation methods. The original PAT was a two-stage pump, and 12 PAT models were designed by modifying the geometric parameters of the positive guide vanes. Fluent software was employed for numerical simulations. The study found that numerical calculations aligned well with theoretical derivations for the flat H-Q curve. Considering the geometric variations in the positive guide vane, increasing the outlet placement angle, blade number, and throat area or decreasing the base circle diameter was able to flatten the H-Q curve effectively; at the best efficiency point, the throat area had the most significant impact on a slope, followed by the outlet placement angle, blade number, and base circle diameter, respectively. The individual contributions to reducing the slope were 0.53, 0.24, 0.1, and 0.09. In terms of the best efficiency point (BEP) of PATs, increasing the throat area appropriately was able to improve the BEP of the PAT by around 1.65% and shifted its BEP towards higher flow rates. However, in other cases, the BEPs all decreased. Increasing the outlet placement angle of the positive guide vane by 3° led to the BEP being reduced by 0.79%. When the number of positive guide vane blades was increased from 8 to 10, the BEP decreased by 1.24%. When the diameter of the base circle of the positive guide vane was decreased, the BEP of the turbine decreased by 0.06%. This study provides theoretical support and can serve as a reference for the design of multistage hydraulic turbines with flatter H-Q curves.

Particle image velocimetry in the impeller of a centrifugal pump: A POD-based analysis

The flow field within the channels of a centrifugal pump impeller is usually complex, containing turbulent structures in a wide range of time and length scales. Identifying the different structures and their dynamics in this rotating frame is, therefore, a difficult task. However, modal decomposition can be a useful tool for detecting coherent structures. In this paper, we make use of proper orthogonal decomposition (POD) of time-resolved flow fields in order to investigate the flow in a centrifugal pump. For that, we carried out experiments using time-resolved particle image velocimetry (TR-PIV) in a pump of transparent material operating at different conditions and obtained the statistical characteristics of the turbulent flow from phase-ensemble averages of velocities and turbulent kinetic energy. The results reveal that at the pump’s best efficiency point (BEP) the flow is well-organized, with no significant flow separation. For flow rates below the BEP, flow separation and vortex structures appear in the impeller channels, making the flow unstable. At flow rates above the BEP, intense jets appear close to the suction blades, while small instabilities occur on the pressure side. The POD analysis shows that at low flow rates, the flow is dominated by large-scale structures with intense energy levels, while at the BEP and higher flow rates, the flow is dominated by small-scale structures. Our results shed light on the turbulence characteristics inside the impeller, providing relevant information for reduced-order models capable of computing the flow in turbomachinery at much lower costs when compared to traditional methods.

Mitigation of the Pressure Pulsations in an Axial Turbine at Speed-No-Load With Independent Guide Vanes Opening

Abstract Hydraulic turbines are operated more frequently at no-load conditions, also known as speed-no-load (SNL), to provide a spinning reserve that can rapidly connect to the electrical grid. As intermittent energy sources gain popularity, turbines will be required to provide spinning reserves more frequently. Previous studies show vortical flow structures in the vaneless space and the draft tube and rotating stall between the runner blades of certain axial turbines operating at SNL conditions. These flow phenomena are associated with pressure pulsations and torque fluctuations which put high stress on the turbine. The origin of the instabilities is not fully understood and not extensively studied. Moreover, mitigation techniques for SNL must be designed and explored to ensure the safe operation of the turbines at off-design conditions. This study presents a mitigation technique with independent control of each guide vane. The idea is to open some of the guide vanes to the best efficiency point (BEP) angle while keeping the remaining ones closed, aiming to reduce the swirl and thus avoid the instability to develop. The restriction is to have zero net torque on the shaft. Results show that the flow structures in the vaneless space can be broken down, which decreases pressure and velocity fluctuations. Furthermore, the rotating stall between the runner blades is reduced. The time-averaged flow upstream of the runner is changed while the flow below the runner remains mainly unchanged.

Performance Evaluation and MPPT Control of a Variable-Speed Pump-as-Turbine System

The pump-as-turbine (PaT) system is a cost-effective alternative to harness hydropower from microscale water resources although its best efficiency point (BEP) is difficult to be estimated without experimental results and its efficiency dramatically drops at partial load. The variable-speed operation of PaT-generator system is proposed in this article to run it at BEP despite changing hydrological conditions. The studies are carried out based on an experimental setup comprising a centrifugal pump, running in turbine mode, coupled with a 3-kW induction generator. The speed control method is based on the rotor field-oriented control and is implemented on an experimental ac/dc converter. Various performance characteristics of the system, including constant-head and constant-speed curves, are extracted and investigated. Then, a modified perturb and observe algorithm is proposed to accurately track the maximum power point of the system. The obtained results clearly demonstrated that the raised issues are resolved well by using the proposed solution.

Optimal hydraulic energy harvesting strategy for PaT installation in Water Distribution Networks

Water Distribution Networks (WDNs) represent a noteworthy field for possible implementation of Small Hydropower (SHP), by replacing Pressure Reduction Valves (PRV) with turbomachines, in particular Pump as Turbines (PaTs), to control and regulate the pressure, while harvesting energy otherwise wasted. Different models were developed to predict the performance and select the positioning of the PaTs for the maximum energy recovery but most of them neglect practical aspect such as: power grid limitations and optimal harvesting strategy. In this framework, we intend to propose a new method to select a PaT, defining its optimal working point, by introducing an energy exploitation coefficient. The proposed methodology is based on the experimental results of a real PaT tested in the high capacity hydraulic laboratory at Polytechnic University of Bari. Firstly, the selected commercial centrifugal pump was tested in both pump and turbine modes. Then, three different approaches, for the Best Efficiency Point (BEP) selection, are described and compared in terms of energy exploitation and capacity factor for a WDN. The first consists of selecting the BEP at the average flow rate, the second one considers the probability distribution of the flow rate and the corresponding available hydraulic energy, whereas the latter is based on the highest energy harvesting. By applying energy production, economic and environmental analyses, the new proposed methodology, based on the third approach, shows a remarkable advantage in terms of exploited energy. Indeed a remarkable 60% energy recovery is achieved with 334 ton CO2/year avoided. Furthermore, the impact of the electrical motor on the maximum power generation (cut-off) is considered. Eventually, useful insights for the future PaT selection and installation are discussed.

Response to Hemostatic Complications During Neonatal Extracorporeal Membrane Oxygenation: Roller Pump and Centrifugal Pump Driven Circuits.

To the Editor: Vermeer et al.1 recently published a case series and in vitro analysis of acute oxygenator failure manifested as a rise in preoxygenator pressure without evidence of gas transfer failure. As practitioners in the field who have fielded similar questions from colleagues describing similar issues, we applaud them for describing this problem that has been informally discussed in meetings and discussion boards for several years. The debate in neonatal extracorporeal life support (ECLS) between roller and centrifugal pumps has a long history.2 While the focus has primarily been on sources of increased hemolysis, the acute failure of the ECLS circuit by oxygenator clogging has received less attention. Vermeer et al.1 began using the RotaFlow in neonatal ECLS because of supply shortages and the availability and experience with adult ECLS. After a disturbing trend of complications, they embarked on a formal assessment of three systems (roller pump, RotaFlow, and PedIVAS) and associated failure rates in the neonatal population. The authors described anticoagulation, heat generation, and overall blood velocity as plausible mechanisms generating the cellular debris that led to the clogging phenomenon. In discussing the velocity, they came very close to what we would consider to be the fundamental problem inherent in the design of any centrifugal pump, which is their best efficiency point (BEP). The BEP is the point at which energy imparted to spinning the impeller generates the most forward bulk flow from the pump. The RotaFlow and PedivAS were designed to operate at 5 and 1.5 L/min, respectively. Schöps et al.3 used computational fluid dynamics to describe zones of recirculation, which do not contribute to the bulk flow of the blood, within adult devices operated at 1 L/min or less. Consequently, blood remains in the pump shear field for an extended time, significantly increasing the risk for hemolysis, which was demonstrated in vitro. Vermeer et al.1 have now provided in vivo evidence for the in silico and in vitro data provided by Schöps et al.3 However, we believe there is still more to the story. Several other factors are likely at play in neonatal ECLS, including cellular fragility4 and hemoglobin greater than 12–13 g/dl, which has been shown to be an independent factor leading to blood damage for neonatal ECLS regardless of pump type.5 A shrinking pool of devices and trained healthcare providers has led to the utilization of devices for the greatest number of patients (adults) in the most vulnerable population (neonates), and these are conditions for which these devices were never designed. Even the PediVAS, which is a pediatric device, is designed to operate at flow nearly three times that required for neonatal ECLS. We believe the study described by Vermeer et al.,1 Schöps et al.,3 Jenks et al.,5 and others in this space are important starting points for the ultimate discussion that a true neonatal ECLS centrifugal blood pump needs to be developed. We hope that such study continues and drives manufacturers to consider the needs of this population, ultimately allowing clinicians to more safely provide the life-saving support that this population needs.

Energy efficiency characterization and optimization of mechanical stirring multiphase dispersion processes: Applied to Kanbara reactors for hot metal desulfurization

In order to achieve the Best Efficiency Point (BEP) of an existing or new design of mechanically stirred multiphase reactors, such as the Kanbara Reactor (KR) desulfurization process, i.e., to realize maximum refining efficiency with minimum energy consumption, thus saving costs and offering high performance, it is essential to establish a quantitative correlation between the stirring power and the utilization rate of the lighter reagent that covering on the heavier phase. Herein, a validated droplet-resolved model based on a Large-scale Dispersed Phase-Resolved Volume of Fluid (LDPR-VoF) approach coupled with a subgrid-scale Large Eddy Simulation (LES) was applied to explore the characteristics of entrainment and dispersion of the lighter liquid reagent, the relevant energy utilization, such as the kinetic energy, turbulent kinetic energy, and its dissipation rate characteristics, with respect to different design and operating conditions during the mechanical stirring process. Furthermore, a crucial measure ηd for the quantitative evaluation of the energy efficiency and the determination of BEP, which represents the ability of an impeller to convert its power input into the dispersion of the upper lighter phase in a layered multiphase vessel, was proposed and used to evaluate the effect of the impeller and reactor inner profiles on the energy efficiency. Eventually, a correlation formula is obtained to assess the utilization rate of the stirring power on the refining performance, which can be used to optimize the design/operation parameters towards the BEP for a mechanically stirred multiphase dispersion reactor.

Experimentally Based Methodology to Evaluate Fuel Saving and CO &lt;sub&gt;2&lt;/sub&gt; Reduction of Electrical Engine Cooling Pump during Real Driving

&lt;div&gt;Engine thermal management (ETM) is a promising technology that allows the reduction of harmful emissions and fuel consumption when the internal combustion engine (ICE) is started from a cold state. The key technology for ETM is the decoupling of the cooling pump from the crankshaft and the actuation of the pump independently. In this article, an electric engine cooling pump has been designed through a novel experimentally based procedure and operated on a vehicle equipped with an advanced turbocharged gasoline engine, particularly interesting for its hybridization potential. In the first phase, a dedicated experimental campaign was conducted off board on an engine identical to the one equipped in the vehicle to assess the characteristics of the cooling circuit and the reference pump performances. The experimental data have been used to design an electric pump with a best efficiency point (BEP) located in a region more representative of the real operating conditions faced by the vehicle during real driving. Once prototyped, the electric pump has been compared to the reference mechanical one on a real driving mission profile whose parameters have been experimentally evaluated. The comparison was made in the same operating conditions of flow rate and the pressure head acting on the revolution speed of the prototype to focus the attention on the effect of the different design choices made possible by the electric actuation. The procedure can evaluate the pump-related fuel consumption, whatever the real vehicle speed profile and the actuation of the pump. The results show that in a driving cycle with urban, extra-urban, and highway phases, the electric pump absorbs 66% less power compared to the mechanical one, which translates into a 0.55 gCO&lt;sub&gt;2&lt;/sub&gt;/km specific emission reduction. This demonstrates the validity of the novel design procedure together with the benefits of the electric actuation.&lt;/div&gt;