Search

In pursuit of enhancing the conveying performance of the spiral axial flow gasliquid multiphase pump, a comprehensive exploration is conducted to unravel the underlying influence mechanism of impeller structural parameters on gas-liquid separation. This study employs the Box-Behnken design, constructing a sample space that encompasses crucial factors such as impeller hub parameters and blade inclination angle, utilizing Computational Fluid Dynamics software to perform numerical simulations of various models within the sample space. Researching the influence of impeller hub diameter ratio and blade inclination angle on the internal flow of a multiphase pump, aiming to determine high-performance parameters under high gas content conditions with the coupled effects of impeller hub diameter ratio and blade inclination angle. The results indicate that the performance improvement becomes more pronounced when the blade inclination angle (γ) is greater than 2°. For hub structure parameters, the relative size of hub inlet coefficient (kd1) and hub middle section coefficient (kd2) is measured using the diameter ratio (kr), where kr ranges from 0.94 to 1.02. After optimization, the impeller hub parameters are kd1 = 0.77, kd2 = 0.76, kr = 1.013, γ = 6.95. In comparison with the original model, when the Inlet Gas Volume Fraction is 60%, the gas phase aggregation (λ) at 0.1Span is reduced by 4.5%, the energy dissipation (σ) is decreased by 5.3%, and the efficiency and head coefficient are increased by 2.331% and 0.05, respectively. Therefore, this study has vital theoretical and technical significance for improving the reliability, stability and efficiency of deepwater oil and gas transportation. [ABSTRACT FROM AUTHOR]

The flow field structure within the clearances of turbomachinery is complex and diverse, exhibiting high-dimensional nonlinearity. How to accurately extract the main structures that affect the internal flow within the turbine from the complex clearance flow has always been a key issue. To explore the impact of the dynamic structure of the clearance flow on the mainstream region in a centrifugal pump, this study combines the dynamic mode decomposition (DMD) method to conduct a thorough analysis of the velocity and pressure pulsation frequencies in the multi-physics fields within the clearance. The study has identified the main characteristic structures under different physical conditions in the clearance and has established the relationship between the characteristic structure frequencies in different physical fields and the impeller frequency. The research indicates that the internal flow within the clearance affects the occurrence of vortices in the volute. Under design conditions, the velocity field within the clearance is primarily influenced by high-order harmonic frequencies of the impeller, and the pressure field is mainly affected by low-order harmonic frequencies of the impeller. This reflects the crucial influence of impeller frequency and inlet flow on the coherent structures within the clearance flow. The research results offer new insights and methods for analyzing complex internal flows in large turbomachinery. [ABSTRACT FROM AUTHOR]

This study comprehensively investigates the flow features and energy loss mechanisms under stall conditions based on computational fluid dynamics (CFD) and hydraulic loss visualization techniques. The three-dimensional unsteady Reynolds-averaged Navier-Stokes (URANS) equations were solved using the shear stress transport (SST) k-ω turbulence model. Furthermore, the entire flow domain of the vertical volute pump was considered to capture the boundary flow behavior accurately. The results illustrate that the critical stall condition occurs at 0.7Qd, where the H-Q curve exhibits a positive slope, and the deep stall condition occurs at 0.65Qd. The growth rate of energy loss from critical stall to deep stall is 182.2%. In the stall condition, a secondary vortex appears at the impeller inlet. A high energy loss occurs at the suction side and trailing edge in the impeller caused by the reduction in the effective inflow area. The energy loss in the blade suction side guide vane is primarily due to the friction loss under the critical stall condition. By contrast, under the deep stall condition, the energy loss in the outlet of the guide vane is mainly the impact loss from the volute of the rear gunner. The impact effect can result in high energy losses near the volute tongue. The entropy production analysis demonstrates that the hydraulic losses in the diffuser are literately greater than that in the impeller and inlet pipe. Hence, optimization of such components can be taken into consideration in future works for performance improvement. [ABSTRACT FROM AUTHOR]

Objective: Regulatory legislation in both the United States and Canada requires water users with medium to high intake volumes to monitor entrainment losses to determine effects and to assess potential mitigation strategies to reduce harm to fish. Recent studies have recommended the use of both increased sampling frequency and sampling volume to characterize fish entrainment for large power plants on the Great Lakes. There is little doubt that increasing the flow rate and volume of water collected for sampling reduces the uncertainty in estimates of annual entrainment. Depending on the type of pump and the pumping flow rate used for entrainment sampling, considerable damage to fish larvae can occur. A screw‐type centrifugal pump has many qualities that make it ideal for entrainment sampling, but it has not yet been used as a sampling device for fish entrainment applications at power plants or other large industrial water users. The objective of this study was to determine mortality of entrainable fish eggs and larvae due to passage through a screw‐type centrifugal pump. Methods: In a laboratory setting, Lake Trout Salvelinus namaycush eggs and larvae, Lake Whitefish Coregonus clupeaformis eggs, and Rainbow Trout Oncorhynchus mykiss juveniles were passed through a screw‐type centrifugal pump at three treatment flow rates: 39.5, 47.3, and 59.1 m3/h. Fish and eggs were monitored for mortality posttreatment and again at 24 and 48 h. Result: Across treatments, very few mortalities were observed. Species specific moralities were four larval Lake Trout, one Lake Whitefish egg, and one juvenile Rainbow Trout. No mortality was observed for Lake Trout eggs. Conclusion: The present study identified high egg and larval survival (≥99%) after passage through a screw‐type centrifugal pump. High survival reduces error associated with identification and counting of entrained organisms, which provides more accurate estimates of annual entrainment losses. Impact statementA screw‐type centrifugal impeller pump results in high survival of entrainable fish (eggs and larvae), which reduces error associated with estimating fish mortality due to entrainment. Reduced error improves entrainment mortality estimates that may be used to develop compensation strategies to mitigate loss of fish from aquatic systems. [ABSTRACT FROM AUTHOR]

This study is based on the design of a portable automatic water level control switch that is capable of switching on the pump when the water level in the overhead tank goes low and switches it off as soon as the water level reaches a pre-determined level to prevent dry-run of the pump in case the level in the underground tank goes below the suction level. The water in the tank is measured by the conductive probes and displaced via the LED indicators. At maximum-set capacity the pump is de-energized to automatically switch off, thereby stopping the inflow of water into the tank. The design approach involves three major stages which are: the power supply unit, the sensing unit, and the motoring and relay unit. The uniqueness of this work is the use of discrete components such as transistors to achieve water level control. This approach is more economical, simpler and easier to implement than the sophisticated programmable logic controllers and computerized microprocessors. [ABSTRACT FROM AUTHOR]

The present study aims to reveal wear characteristics of an impeller pump transporting the mixture of liquid and solid particles. An experimental work is conducted to detect patterns of wear of the pump components. The computational fluid dynamics (CFD) technique and the discrete element method (DEM) are jointly used to simulate the two-phase flow and wear of the pump components. After a 30-hour wear experiment, the inlet edge of the long blades exhibits wavy profiles, and the outlet part of the long blades is worn through. Regarding the volute, only the volute tongue is severely worn. At a particle diameter of 2.0 mm and a solid mass fraction of 10 %, the ratio of the average wear depth of the long blades to that of the volute reaches 64.5. Wear of the blade inlet edge depends on the normal cumulative contact energy, while the tangential cumulative contact energy contributes significantly to wear of the outlet part of the long blades. As the particle diameter increases from 1.0 mm to 3.0 mm, the average depth of wear of the long blades decreases monotonically by nearly 45 %, but the maximum depth of wear increases by about 34 %. The solid mass fraction serves as a key factor influencing wear of the pump components, especially when particles of large size are transported. [ABSTRACT FROM AUTHOR]

Introduction: End stage heart failure is associated with high mortality. However, recent developments such as the ventricular assist device (VAD) have improved patient outcomes, with left ventricular assist devices (LVAD) most commonly implanted.Objective: This narrative review evaluates LVAD epidemiology, indications, normal function and components, and the assessment and management of complications in the emergency department (ED).Discussion: The LVAD is a life-saving device in patients with severe heart failure. While first generation devices provided pulsatile flow, current LVAD devices produce continuous flow. Normal components include the pump, inflow and outflow cannulas, driveline, and external controller. Complications related to the LVAD can be divided into those that are LVAD-specific and LVAD-associated, and many of these complications can result in severe patient morbidity and mortality. LVAD-specific complications include device malfunction/failure, pump thrombosis, and suction event, while LVAD-associated complications include bleeding, cerebrovascular event, infection, right ventricular failure, dysrhythmia, and aortic regurgitation. Assessment of LVAD function, patient perfusion, and mean arterial pressure is needed upon presentation. Electrocardiogram and bedside ultrasound are key evaluations in the ED. LVAD evaluation and management require a team-based approach, and consultation with the LVAD specialist is recommended.Conclusion: Emergency clinician knowledge of LVAD function, components, and complications is integral in optimizing care of these patients. [ABSTRACT FROM AUTHOR]

Abstract A numerical study on cavitation in the centrifugal pump during the transportation of pure water and diesel is carried out. An improved cavitation model based on the Zwart–Gerber–Belamri Model is employed in the simulation. A Cash–Karp fourth–fifth order Runge–Kutta method was used to solve the original Rayleigh-Plesset equation to get the numerical solution. The effects from viscosity and surface tension on bubbles' expansion and compression are taken into account in the improved model instead of the traditional simplification in which the bubble radius is just a function of pressure and density. The coefficients got by fitting the numerical solution are added to the constant pre-multiplier of the Zwart-Gerber-Belrami cavitation model and finally enhance the model. The vapor volume fraction was predicted to be larger in diesel compared to water. The distribution of pressure in diesel is more homogenous than that in pure water. [ABSTRACT FROM AUTHOR]

Abstract Heat supply bottlenecks are common in district heating (DH) networks and makes the DH network work in a non-optimal way, why it is beneficial to address them. The purpose of this paper is thus to investigate risks, opportunities, added values and issues coupled to various bottleneck measures. This is made by in depth interviews with DH companies and through DH network simulations. The results showed numerous risks and opportunities coupled to each bottleneck measure investigated, and are meant to highlight more effective measures, to help increase the competitiveness of and improve the environmental performance of DH. [ABSTRACT FROM AUTHOR]

Prolonged support times in bridge to transplant patients, as well as the growing number of destination patients lead to increased rates of LVAD pump exchanges for pump thrombosis, pump infections, and other device problems. We describe our surgical approach for pump exchanges in patients supported with the Heartware HVAD ventricular assist device. Pump exchanges are performed via a limited thoracotomy in the fourth, fifth, or sixth left intercostal space with cardiopulmonary bypass support. The apical sewing ring as well as the outflow graft are reused in order to limit the complexity of the procedure and minimize the need for extensive dissections. Given the significant reduction in surgical complexity and invasiveness, the described technique should be considered the standard approach for Heartware HVAD patients with device complications necessitating isolated pump exchanges. [ABSTRACT FROM AUTHOR]

Several research studies have been published on CO 2 pipeline transportation. Most of them focus on developing hydraulic models of entire CO 2 pipeline networks. From these studies, a lot of original knowledge has been produced to understand the behaviour of CO 2 pipeline networks under dense phase or supercritical conditions. The globalized modelling approach used in these studies are generally sufficient for carrying out an overall design and operation of an entire CO 2 pipeline network. However, such models are too insufficiently detailed for use in optimizing the performance of a compressor in a CO 2 transport pipeline. This is because in hydraulic models, compression is simulated with adiabatic or polytropic equations which do not account for the geometry and internal fluid flow processes within the compressor. Moreover, in energy requirement calculations involving these equations, compressor efficiency is assumed to be fixed, where as in reality, it varies with change in the purity of the CO 2 stream being compressed. Given that compressors consume most of the energy needed to operate an entire CO 2 pipeline network, it is vital that a detailed analysis of the effect of impurities on machine performance is done as a prerequisite for developing an optimal procedure for compressor sizing and selection. To this end, a quasi-dimensional model based on the laws of conservation was developed and validated for a detailed investigation of the effect of various impurities on the performance of a centrifugal machine handling supercritical carbon dioxide. Results of the study confirm that the power requirement of a compressor is affected by the impurities and provides an insight into the relationship between compressor size, work input and the pressure required to maintain the CO 2 stream flowing in a transport pipeline network in supercritical state. [ABSTRACT FROM AUTHOR]

This paper proposes a fault tolerant control method for condenser fouling in water-cooled chillers. Condenser fouling is one of the common faults in water-cooled chillers that degrade its energy efficiency. Studies were conducted to develop fault detection and diagnostics (FDD) algorithms to address this issue. However, the current FDD techniques are too expensive for some faults that are not very significant such as condenser fouling, and a cheaper alternative may be needed to remove the fault impact. This study addresses this issue by proposing a control method without FDD algorithms to reduce the impact of condenser fouling in water-cooled chillers. It controls the opening of the balancing valve in the condensing water loop to adapt the chiller plant for the effectively smaller condenser. Verification of the control method is conducted by a model of a real chiller plant and comparison with the ordinary operation case is made under two different months and two fouling levels. The results show that the method can help the chiller plant to reduce the impact of condenser fouling by reducing its electricity consumption by 2.0% under normal situation and reducing the impact of fouling by 0.2 to 0.4%. However, the result is not very significant, and more studies with other control inputs are needed for more effective control methods. [ABSTRACT FROM AUTHOR]

Cavitation is a major problem in pump design and operation because this phenomenon may lead to various types of instabilities, including hydraulic performance loss and catastrophic damage to the pump material caused by bubble collapse. Therefore, it is critical to predict the cavitation performance of the pump in the design phase itself. The motivation of this study is to develop a systematic methodology to calculate the cavitation performance of radial flow pumps. In the first step of the present work, a cavitating nozzle flow case for which the bubble dynamic behavior is accurately resolved in literature is studied numerically. Subsequently, the capabilities of three cavitation models, implemented in the commercial code Fluent, are evaluated for three radial flow pumps designed at specific speeds ns=10.4, 22.4 and 34.4. The numerical results are validated with global quantities based on net positive suction head (NPSH) measurements. The results led to the determination of reasonably accurate NPSH values for the defined range of specific speeds. [ABSTRACT FROM AUTHOR]

Background Ankle fractures account for 9% of all fractures seen in the United Kingdom. 15,000 of these fractures undergo operative fixation each year. Soft tissue swelling impacts on timing of fixation due to fears of infection and wound dehiscence. The use of arterio-venous foot pumps (AVFP) is increasing in this population although the evidence for their efficacy is unclear. In order to address this, we present an overview of the evidence for AVFP device use following ankle fracture. Methods In September 2015 an electronic literature search was undertaken of studies comparing two or more methods of swelling reduction in patients with ankle fractures. Of 326 screened, 5 papers ultimately were included. Results Two studies reported a statistically significant reduction in swelling ( p = 0.03) and ( p = 0.03 at 24 hours, p = 0.05 at 48 hours) after using AVFP devices compared to the controls (leg elevation +/ ice therapy). Stockle et al. reported a greater reduction in the preoperative ankle, midfoot and forefoot circumference at 24 hours in their AVFP group (53% versus 32% and 10% in their continuous cryotherapy and cool pack cryotherapy groups respectively). Whereas, Rohner-Spengler et al. observed improved preoperative swelling reduction in patients treated with a multilayer compression bandage when compared to their AVFP group. Keehan et al. reported that time to surgery was considerably reduced in patients treated with an AVFP device, (2.3 days) compared to those treated with leg elevation (4.6 days) ( p = 0.02). Length of stay (LOS) was not influenced by any of the tested interventions. Conclusions AVFP devices have been shown to reduce time to surgery and degree of swelling before operative intervention better than other methods but the strength of evidence to support this remains poor. [ABSTRACT FROM AUTHOR]

Pumping stations are important flood mitigation infrastructure used in coastal cities to remove accumulating floodwater from low-lying areas, where drainage is naturally poor due to very low slope gradient. In coastal mega-cities situated in developing nations, these pumping stations are often vulnerable to trash blockage as a result of frequent dumping of solid waste in water bodies. Given that blocked pumps are common causes of drainage infrastructure failure, the inability to identify the most vulnerable pumping stations can lead to inefficient allocation of limited resources for preventative maintenance of the drainage system. This study proposes an approach for measuring and ranking the vulnerability of pumping stations to trash blockage. In this approach, a trash blockage vulnerability index (TBVI) is developed based on the concepts of exposure, sensitivity and resilience. Using a graph-based network analysis technique, the proposed TBVI is applied to assess and rank the vulnerability of pumping stations in one of the most representative coastal mega-cities − Jakarta, Indonesia. The results show that TBVI can point to the pumping stations that are most vulnerable to trash blockage. Such information are vital to decision makers when planning and prioritising infrastructure to be serviced or upgraded as part of flood preparedness in coastal cities. [ABSTRACT FROM AUTHOR]

Neonatal extracorporeal life support (ECLS) has enjoyed a long history of successful patient support for both cardiac and respiratory failure. The small size of this patient population has provided many technical challenges from cannulation to pumps and oxygenators. This is further complicated by the relatively meager commercial options for equipment owing to the relatively low utilization of neonatal ECLS compared to adults, which has exploded following the H1N1 epidemic and the availability of the polymethylpentene oxygenator. This paper focuses on the impact of equipment choices on thrombosis and hemolysis in neonatal ECLS and the underlying mechanisms behind them. Based upon the available evidence, it is clear neonatal ECLS requires careful attention to the selection and operation of all parts of the ECLS system. Practitioners should also be aware of the factors that increase blood cell fragility, which can impact decisions around equipment and subsequent operation. [ABSTRACT FROM AUTHOR]

Two methods for marine microlitter sampling were compared in the Gulf of Finland, northern Baltic Sea: manta trawl (333 μm) and a submersible pump (300 or 100 μm). Concentrations of microlitter (microplastics, combustion particles, non-synthetic fibres) in the samples collected with both methods and filter sizes remained < 10 particles m − 3 . The pump with 100 μm filter gave higher microlitter concentrations compared to manta trawl or pump with 300 μm filter. Manta sampling covers larger areas, but is potentially subjected to contamination during sample processing and does not give precise volumetric values. Using a submerged pump allows method controls, use of different filter sizes and gives exact volumetric measures. Both devices need relatively calm weather for operation. The choice of the method in general depends on the aim of the study. For monitoring environmentally relevant size fractions of microlitter the use of 100 μm or smaller mesh size is recommended for the Baltic Sea. [ABSTRACT FROM AUTHOR]

Over the past two decades, flood risks have presented a significant challenge for urban areas owing to the increased peak flows resulting from urbanization and climate change. In metropolitan areas, large-scale networks of sewer pipes and pump stations are the main facilities used to mitigate flood damage. During flooding periods, when drainage gates are closed, pumping operations play a major role in efficiently reducing flood damage. To obtain an optimal policy for these operations, a novel robust approach is presented here. In this approach, a long-term operating rule is designed by coupling a mathematical model and a new hybrid harmony search algorithm, while considering the stochastic nature of rainfall events. Application of the proposed method to a real urban drainage system showed a high efficiency in terms of flood mitigation and performance of pumps compared to the current operating rule for the pump station. Compared to the traditional approach, optimal operation decreased peak water levels by an average of 40%, without increasing the number of pump switches. Based on these results, optimizing pumping operations appear to be a practical and highly effective way to reduce flood water levels and urban inundation without making changes to the actual infrastructure of the system. [ABSTRACT FROM AUTHOR]

Routine prophylaxis against venous thromboembolism is indicated following total joint arthroplasty. Prophylactic strategies differ in efficacy and safety, and variable risk exists among patients. Many strategies have been successfully used for chemoprophylaxis as well as mechanical prophylaxis with the use of pneumatic compression. Advances in battery technology and pump miniaturization have expanded the use of pneumatic compression in the post-discharge setting with mobile devices. Pneumatic compression is contraindicated in certain patients, and not all patients tolerate the devices. Mobile pneumatic compression is a valuable adjunct to venous thromboembolic risk mitigation strategies, but does not eliminate the need for pharmacologic agents. [ABSTRACT FROM AUTHOR]

In this work, an automated statistical analysis of vibration characteristics for the condition monitoring of hydraulic systems is proposed. Features from FFT vibration data of a micromechanical accelerometer measured at the gear pump are extracted, selected by their correlation coefficient to the target fault value, and subsequently reduced to discriminant functions which allow the classification of component conditions using multivariate statistics. The approach was successfully evaluated with an experimental hydraulic test bench simulating typical fault scenarios like valve switching degradation or gas leakage of the accumulator. It was shown that the studied fault scenarios can be selectively detected (internal pump leakage) and even quantified concerning the grade of severity in case of valve switching degradation, accumulator gas leakage, and oil aeration. Furthermore, the long-term stability of the statistical model was evaluated over several weeks. [ABSTRACT FROM AUTHOR]

This article dwells upon the principles of constructing the control system for a group of electric drives with parallel regulation channels (for example, water supply pump stations, air ventilation and fire extinction systems, etc.) on the basis of multizone integrating regulator with frequency-pulse-width modulation. It contains functional charts of discrete control systems and combined smoothly discrete regulation. It also considers a system able to self-diagnose catastrophic malfunctions of the circuit components and an automatic switch of reserve control channels. Herein is presented the case of a discrete control system for enterprise-level pumps used to supply recycling water. This system contains four electric drives with water pumps and is able to switch on the reserve control channels automatically. The article may be of interest to specialists in the field of power electronics and information electronics, electric drives and process automation. [ABSTRACT FROM AUTHOR]

In this work, an automated statistical analysis of vibration characteristics for the condition monitoring of hydraulic systems is proposed. Features from FFT vibration data of a micromechanical accelerometer measured at the gear pump are extracted, selected by their correlation coefficient to the target fault value, and subsequently reduced to discriminant functions which allow the classification of component conditions using multivariate statistics. The approach was successfully evaluated with an experimental hydraulic test bench simulating typical fault scenarios like valve switching degradation or gas leakage of the accumulator. It was shown that the studied fault scenarios can be selectively detected (internal pump leakage) and even quantified concerning the grade of severity in case of valve switching degradation, accumulator gas leakage, and oil aeration. Furthermore, the long-term stability of the statistical model was evaluated over several weeks. [ABSTRACT FROM AUTHOR]

Pump station is the biggest energy consumer in a water distribution system (WDS). A large amount of money is expended to provide energy for pumps. The environmental footprint associated with these excess energy demands is a source of concern. By implementing an optimum pump schedule that needs a minimum amount of energy to provide enough pressure and flow for water system, operational cost will be reduced and water system will be more environmentally friendly. Researchers are trying to find practical tools and methods to optimize pump operation. In this research, Pollutant Emission Pump Station Optimization (PEPSO), Darwin Scheduler (DS) and another approach that uses Markov Decision Processes (MDP) have been used as three different tools for optimizing pump operation of WDS of Monroe, MI, USA. In all three methods pumping optimizations have been done based on reducing energy usage, at the end results of running these three tools have been compared. The comparison results show that pump operation that has been taken from MDP algorithm has the best result in terms of energy usage and the number of pump switches, while pump operation taken from DS can be more effective at volume stored in tanks. The simulations showed PEPSO to be considerably faster than the other two evaluated methods in arriving at the optimum solution. [ABSTRACT FROM AUTHOR]

A considerable portion of costs associated with delivering municipal drinking water is related to energy usage. This energy consumption also has environmental implications resulting from the pollutants emitted at power generation plants. Optimizing the cost and environmental emission of energy consumption by strategically scheduling pumping cycles is a multi-objective nonlinear problem that contains considerable number of constraints. The solution space of this type of problem even for a small water network can be very large and finding the boundaries associated with the solution space is quite difficult. Evolutionary optimization methods, such as genetic algorithm, are well suited for solving this kind of problem. In this paper, two methods for describing the pump optimization problem within a genetic algorithm solution framework are considered. Each leads to different methods for conducting crossover and mutation steps of the genetic algorithm. Results are presented when these methods are used with a novel pump optimization software, Pollutant Emission and Pump Station Optimization (PEPSO) using a hydraulic model of a moderately sized municipal drinking water system located in Monroe, MI, USA. Advantages and disadvantages of each method are discussed. Results highlight the need for genetic algorithm coding methods which circumvent infeasible solutions. [ABSTRACT FROM AUTHOR]

Pumps being components of wastewater treatment systems, water supply systems and irrigation systems are exploited under a wide range of operating parameters. User requirements make these equipments to work with functioning parameters close to the limit values recommended by the manufacturers, on low energy efficiency regime. In this manner vibrations occur during operation, which could be under specific rotation, different pump characteristics, dynamic or static load. The present paper would like to emphasize by measurements the vibrations arising from pumps operated at low speeds, to establish dependency relations. Diagnosis of the phenomena is mandatory because it generates malfunction, damage and even pump or system failure. Results obtained and their interpretation are the scientific base for improvement method technical recommendations, for process automation and service programs creation in order to ensure reliable operation and to help repair cost decreasing. [ABSTRACT FROM AUTHOR]

The unsteady flow inside a large centrifugal pump with stay vanes was analyzed in this study. The static performance and pressure fluctuations in the pump were numerically predicted and were compared with experimental data. Considering the relative positions of the impeller to the volute tongue and stay vanes, the static performance which was obtained using a full unsteady calculation was compared with traditional steady calculation results. A comparison of the results with the experimental data showed that the operation condition farther from the design condition resulted in larger differences between the steady simulation and experimental results, with errors beyond reasonable limits, while the performance curves obtained by the unsteady calculations were closer to the experimental data. A comparison of the pressure fluctuations at four monitoring points with the experimental data showed that the amplitudes at HVSI and HVS2 are much larger than at HD1 and HD2. The main frequency for these four monitoring points, which agreed well with the experimental data, was the blade passing frequency. The relative obvious errors in pressure fluctuations for HD1 and HD2 were due to the inlet flow rate variation of the simulation. Thus, unsteady numerical simulations can be used to predict the pressure fluctuations when designing a pump. [ABSTRACT FROM AUTHOR]

Abstract: An inducer is an axial flow impeller with blades that wrap in a helix around a central hub. An inducer serves as a small booster pump for the main impellers. Usually inducers have between 2 and 4 vanes, although they may be more, the inducer imparts sufficient head to the liquid so that the NPSH requirement of the adjacent main impeller is satisfied. Although the inducer usually has a lower NPSH requirement than the main impeller, it can, and often does, cavitate during normal operation, the key is that there is so little horse power involved with an inducer that there is virtually no noise, vibration, or resulting mechanical problems. An inducer invariably has higher suction specific speed (S) than an adjacent impeller (S) is a dimensionless term that describes the inlet characteristics of a pump. [Copyright &y& Elsevier]

This work presents the results of the researches with application in production to achieve innovative low-noise gear pumps using the embedded engineering. It presents the research findings on the pump operating parameters in order to reduce by 70% the pressure pulsations resulting low frequency noise of gear pumps. Innovative design feature is given by the use of gears with inclined teeth at 15°-20° with small play of gears and integration of innovative clearing pieces. The embedded engineering of the low-noise pumps leads to a progressive - continuous pumping system resulting a minimum pulsation of the discharge pressure. The research results lead to increased market competitiveness of the pumps made, which have a noise level of 55 dB at pressures up to 250 bar and 1000.....4000 rev/min, depending on the geometric volume, in the same time accompanying with a very low pulsation of the pressure. [ABSTRACT FROM AUTHOR]

Abstract: El-Salam Pump Stations (1) and (2) are located at 22.1km and 54.3km respectively at El-Salam Canal. When El-Salam Pump Station (1) is in operation, and switching off El-Salam Pump Station (2), water level rises upstream El-Salam Pump Station (2). Water level overtops El-Salam Pump Station (2) and banks upstream it. Flooding then takes place as Wadi El Noqra Canal, Egypt. This necessitates discharging the excess water to protect the pump station and the canal from water flooding when the electricity is shut down. The hydrodynamic simulation of El-Salam Canal determinates the critical time for storage capacity according to location and type of emergency spillways through the numerical model to prevent water overtopping upstream pump stations. Determination of the critical time of storage capacity is considered as a new parameter in case of the hydraulic design of the canal controlled by cross pump stations. [Copyright &y& Elsevier]

Abstract: The present study investigated the working process and characteristics of irrotational centrifugal pumps with the help of mathematical models of three-dimensional flows incompressible fluid on the basis of equations of the Reynolds and <> turbulence model. The results of optimization geometrical parameters are presented. The ratio of geometrical parameters are established, which one meet to two different working processes of pumping over. [Copyright &y& Elsevier]

Abstract: Operating experience of impulse seals under various extreme conditions has confirmed their main positive properties: an effective heat-removal, the ability to condense fluids, gases, gas-liquid mixtures, reversibility with respect to the direction of rotation and the pressure drop to be sealed, the ability to serve as parking seals, significantly lower dimensions as compared with conventional mechanical face seals. The use of such seals can save energy and resources, as well as increase the environmental safety of the pump and compressor equipment. [Copyright &y& Elsevier]

Abstract: This article describes the benefit of monitoring the intravasation rate in addition to the conventional measurement of fluid deficit in hysteroscopic surgical procedures. The intravasation rate is the rate, in milliliters per minute, at which fluid enters the systemic circulation, whereas fluid deficit is the amount of irrigation fluid, in milliliters, already absorbed by the patient. To determine the intravasation rate, a manually operated intravasation monitoring pump was constructed, with which one of us (Dr. Atul Kumar) performed 966 hysteroscopic procedures from May 1993 to February 2010. Because the intravasation rate had to be manually calculated by an assistant, it was decided to replace the assistant with a controller to monitor intravasation rate. The surgical experience gathered from the manually operated pump was used to develop algorithms for the controller. The controller-operated intravasation monitoring pump was constructed, with which 41 hysteroscopic procedures were performed from March 2010 to August 2011. In hysteroscopic procedures, this pump simultaneously displays the real-time intravasation rate and the fluid deficit on an LCD screen. [Copyright &y& Elsevier]

A method based on the medial axis transform (MAT) theory is presented to explore the laws of meridional profiles versus specific speeds for centrifugal pumps. Through extracting each pump's MAT and transforming to two newly introduced variables, striking features emerge. Based on these features, statistics are carried out on the two variables versus specific speeds. A series of pumps is used to verify this method. According to the laws gained from the statistical results, the meridional profile at any specific speed within this series of pumps can be directly drawn through calculations. [ABSTRACT FROM AUTHOR]

The clearance of wear-rings in the impeller of centrifugal pumps has an important influence on the pump's performance. Unfortunately, this effect has not been quite well documented, especially for the centrifugal pumps handling viscous oils. An industrial centrifugal pump with low specific .weed was employed as a model to investigate the effect of the clearance on the performance of the pump. In this experimental study, the clearances of the wear-rings on the impeller shroud and hub were enlarged; the performances of the pump were measured when it pumped water and the viscous oils. The performance curves, the hydraulic parameters, and their relative variation ratios at best efficiency points were examined carefully for different clearances at various viscosities. The results showed that the flow rate is varied relatively in a range of -6%- +5%, the head -10%- +6%, the shaft-power +2%-+8% and the efficiency -19%- +2%, respectively, when the clearance was enlarged from 0.25 mm to 0.85 mm at best efficiency points. The clearance of wear-rings on shroud has a more significant influence on the performance than on the hub. However, such an effect is weakened with increasing viscosity. [ABSTRACT FROM AUTHOR]

Abstract: Pump is main equipment in air conditioning systems and used widely, but its energy consumption is great. In order to improve energy efficiency, using pump controlled by frequency-conversion technology is an effective method. In this paper, the working principle and control method of variable frequency pump is described in detail, and gives a comparison between variable frequency control and traditional control about energy saving effect. Because traditional PID controller can be hard to get good control performance in pump control, this paper presents a control method using fuzzy logic controller to achieve frequency conversion and constant pressure water supply. The controlled variable is obtained by fuzzy control table. The system has energy-saving, security, and stable water pressure, etc. Simulation results show that the proposed controller not only have good robustness, but also have good dynamic and static performance. [Copyright &y& Elsevier]

Abstract: Local delivery of compounds directly into the brain may become an attractive treatment option for several neurological diseases. Higher therapeutic drug levels may be reached at the targeted brain region and in this way systemic side effects avoided. This paper provides an overview of the currently investigated experimental and clinical local delivery strategies in the brain ranging from delivery via pump mechanisms to more advanced techniques with cell and gene therapy. The second part focuses on local brain delivery strategies for epilepsy with special attention to adenosine. Adenosine is a good candidate for local delivery techniques for epilepsy because of its proven anticonvulsive effect and it cannot be given systemically because of systemic side effects. An overview of the current published studies with local delivery of adenosine is given. [Copyright &y& Elsevier]

A 5 kW heat pump water-water function on R22 was built in the Renewable Energy Source Laboratory within the Petroleum - Gas University of Ploiesti. The pump was equipped with 4 types of heat extraction systems from the soil: a groundwater well, a 40 m vertical well with a recirculation loop, a system of spiral loops buried at 2 m depth and a 60 m simple loop. This paper deals with the description of the performance obtained with the heat pump operating on a simple polyethylene loop. The experiment confirms that for this type of exchanger there occurs a decline of the thermal power extracted from soil and that the best mathematical description of this phenomenon is obtained with the function generated by the hyperbolic decline. [ABSTRACT FROM AUTHOR]

Target-based chemotherapies have rapidly become a conventional approach to cancer treatment. However, cell membranes can be impermeable to some treatment candidates that require cellular internalization. Our previous in vitro study described several critical findings on the utility of l -methionine in cancer chemotherapy. First, over a range of 1–5 mg/L, l -methionine inhibited cancer cell growth and proliferation. Second, p53 upregulation and its post-translational modification occurred via ubiquitylation. Third, l -methionine suppressed cell cycle progression in HPAC pancreatic, LNCaP prostate, and MCF-7 breast cancer cells but not in their corresponding benign cells. Finally, l -methionine induced standard changes to the molecular signatures of cancer cells. Previous studies of methionine analogs have implicated their therapeutic potential for multiple malignancies. However, the sulfur and methyl underlying countercurrent exchange mechanisms and electrical–chemical gradients have not been defined clearly. Based on the results obtained in our previous work with cancer cells, we hypothesize the existence of a novel disulfide/methyl-ATP pump in the membrane of cancer cells involved in mediating l -methionine uptake. The cellular entry of methionine is mediated via a sulfur atom and methyl donors from l -methionine replacing the oxygen, similar to the sulfur exchange mechanisms of cellular invasion by alcohol or diphtheria toxin. Methionine analogs can compete for or inhibit the cancer cell membrane disulfide/methyl-ATP pump, possibly inhibiting these cell's import mechanisms. ATP pumps systematically help re-establish sulfur and methyl levels in the cell via a countercurrent exchange mechanism and trigger an orchestrated activation of p53 protein, culminating in cell cycle control and reduced cell proliferation. Targeting this potentially novel disulfide/methyl-ATP pump could be an effective chemotherapeutic treatment for various cancer types. Thus, further mechanistic studies are warranted. [ABSTRACT FROM AUTHOR]

This paper concerns the optimization of single-blade impellers as used in the waste-water industry. When considering wastewater pump hydraulics, both the ability to handle solids and hydraulic efficiency become essential criteria for optimization. An innovative approach was taken to this optimization problem through the combination of two separate tools: design of experiments (DOE) and computational fluid dynamics (CFD). Through the use of DOE, it was possible to investigate the effect on hydraulic performance of five key parameters identified as being critical to solids handling. The designed experiment required 32 runs only, as compared with 243 runs (35), which would have been necessary using the traditional ‘trial-and-error’ approach. For each DOE run, unique impeller geometry was created. A transient numerical methodology was adopted for the performance evaluation of each impeller. The methodology was validated and verified on several single-blade impellers covering a range of design specific speed (Ns=32 to 77). In all benchmark models, excellent agreement with experimental data was observed. The models, resulting from the designed experiment, have advanced the state of the art in terms of single-blade impeller design, quantified relationships between solids handling parameters and led to the development of new higher efficiency single-blade impellers with improved solids handling ability over conventional designs. [ABSTRACT FROM AUTHOR]

A new system concept has been developed for microfluidic devices in which thermal actuation is used to achieve most or all fluid and reaction control functions (e.g., valves, pumps, mixers, separators, heaters, and coolers). Thermal actuation makes it possible to incorporate the fluid-containing components in a module that can be physically separated from the actuation elements, making the fluid-bearing module disposable. The actuation elements are embedded in a reusable module, reducing the complexity and cost of the disposable unit. The thermally-actuated valve is central to the system design, and has been well characterized. Thermal-actuation concepts for other fluid-handling functions have been developed and, in most cases, demonstrated. The approach is scalable from microchip to microtiter-plate formats. It can also be integrated into existing microchip technologies to expand functionality. Prototypes have been built and tested in combination with a DNA array for diagnostics of infectious diseases. [Copyright &y& Elsevier]

The factors of dyeing technology for PET knit fabrics using liquid flow dyeing machine include the dye exhaustion property of PET fiber and liquid flow parameters in the dyeing machine. This article is focused on: 1. The relationship between the concentration of disperse dyes and critical temperature zone, 2. The effect of pump flow on fabric running speed and even dyeing. As the results proved 1, the concentration of disperse dyes in the PET dyeing got lower with lower critical temperature zone 2. In the adjustment of dyeing pump flow and nozzle pressure, the running speed of pump at the same nozzle pressure did affect the dyeing flow with the differential rate of ± 10% while the fabric running rate with lower rate 3. The application of fabric running speed and nozzle pressure was influenced by the flow rate. Therefore, the optimization of dyeing process should combine the three components of fabrics, dyes and dyeing machine, in order to achieve the aims of energy saving and quality improvement. [ABSTRACT FROM AUTHOR]

A novel turbine-pump-driven device is proposed to supply driving force for the heat pipe operating under anti-gravity conditions. In this device, the turbine and the pump are linked together and driven by vapor; the mechanical pump pumps the condensate to the evaporator to achieve the circulation. Different from conventional capillary pumped loops, in which the low capillary force limits the heat transfer capacity, for the presented system, the maximum heat flux in the evaporator surface determined by the boiling limitation is generally more than 70-80 W · cm-2. According to thermodynamic analysis, this device can produce enough driving force on condition that the temperature difference between the evaporator and the condenser is greater than 10 °C. When the temperature uniformity of system is not exactly necessary, this new loop heat pipe will be a prospective solution for transporting large amount of wasted heat from energy consuming components. [ABSTRACT FROM AUTHOR]

Three levels pump configuration model is found to be nonconvex and the global optimality could not be ensured by all the traditional mixed integer nonlinear programming (MINLP) optimization methods. For solving such abstruse problem, an extended crowding genetic algorithm (ECGA) was presented. Distinguished from CGA algorithm, the concepts of species conserving and composite encoding are introduced in ECGA for maintaining the diversity of population more effectively and coping with the continuous and discrete variables in MINLP problem. Compared with the solutions solved from OA(Outer Approximation), ECP(Extended Cutting Plane) and MIN-MIN methods, the ECGA algorithm is proved to be effective in finding the global optimal solution of three levels pump configuration via using the problem-specific information. [ABSTRACT FROM AUTHOR]

This paper presents a comparison of manufacturing techniques used in the development of an axial blood pump impeller. In this development process the impeller was designed and its performance was evaluated with the aid of computational fluid dynamics (CFD). Prototypes of those designs where the CFD results show promise were needed in sufficient quantities at a low cost for experimental validation of the CFD results. As the impeller is less than 16 mm in diameter with a maximum blade thickness of about 1.5 mm, innovative manufacturing techniques are explored in this paper to determine the best process for quick fabrication of prototypes that are dimensionally accurate, structurally robust and low in cost. Four rapid prototyping techniques were explored. The completed parts were compared on the basis of manufacturing time, quality and strength of parts obtained, manufacturing cost and also in vitro performances. Based on these studies, it was concluded that selective laser sintering (SLS) is the most appropriate method for the quick production of prototype parts for evaluation of pump performance. [ABSTRACT FROM AUTHOR]

In this paper, a vector analysis is used to describe precisely the geometry of a hydrostatic gear pump from which full general parametric equations are deduced. A detailed kinematic analysis is made and theoretical solutions for sliding and mean velocity are obtained. The solution of the statically indeterminate system of multiple contacts between teeth is obtained. From this result, a thorough analysis in terms of sliding and mean speed, input torque, pressure contact and elastohydrodynamic film thickness is presented. [ABSTRACT FROM AUTHOR]

Electrical artifacts during continuous renal replacement therapy can make cardiac monitoring difficult and have, in the past, resulted in unnecessary and potentially harmful treatment when such artifacts are mistaken for arrhythmias. A case report illustrating such an artifact is described, as well as a simple method for grounding the fluid pathway which resulted in the disappearance of the pseudoarrhythmia seen during continuous renal replacement therapy. [ABSTRACT FROM AUTHOR]