Double Pump Research Articles

Analysis of double suction pumps in both pump and turbine modes using entropy factor

Pump as turbine (PAT) is one of the most extensively applied hydraulic machinery and play a prominent role in converting mechanical energy into electricity. However, choosing the suitable type of pump to use as a turbine is always a problem. Therefore, it is necessary to carry out a detailed analysis of these two operating modes. In this paper, a double suction pump is numerically simulated based on SST k- ω model in CFX. The hydraulic performance and internal flow are studied with different flow rates. The simulation results verified by experiments show that the flow rate at the best efficiency point of the turbine is approximately 1.7 times that of the pump, and the head is 2.22 times that of the pump. Besides energy loss is analyzed based on entropy production theory and the specific location of the energy loss of each domain is studied in detail. Analysis of entropy production proves that flow energy dissipation primarily concentrates within the volute casing in pump mode, with an average proportion of 45.6 %. While in the PAT mode, it is mainly concentrated in the impeller and suction chamber, accounting for 56 % and 25.2 % respectively.

Effect of baffles on internal flow characteristics of double-inhalation centrifugal pumps under low flow conditions

In order to investigate the impact of baffles in the inhalation chamber on the external characteristics and operational stability of a double inhalation centrifugal pump under low flow conditions, the flow field simulation software ANSYS CFX and the shear stress transport formulation were employed to numerically simulate the internal flow field of a double inhalation centrifugal pump with and without baffles. Two models were subjected to performance curve simulation and prediction, with the internal flow field, pressure pulsation, and impeller force of the two models being compared and analyzed under three small flow conditions of 0.6Qd (rated flow), 0.5Qd, and 0.4Qd. The velocity and vortex distribution inside the semi-spiral inhalation chamber, as well as their impact on the flow state in front of and inside the impeller, were analyzed. Research has demonstrated that the addition of baffles can enhance the pump head and efficiency in flow conditions of 0.5Qd–0.8Qd. However, there is a tendency for obstruction of flow in conditions below 0.5Qd. Baffles can reduce the amplitude of pressure pulsation within the impeller and the radial force exerted by the impeller as a whole. Consequently, the incorporation of baffles within the inhalation chamber during flow conditions of 0.5Qd–0.8Qd can enhance the operational efficacy of the pump. Nevertheless, within the flow range of <0.5Qd, the pump's performance will decline. This study serves as a foundation for the design of double inhalation centrifugal pumps with semi-spiral inhalation chambers.

Effect of volute structure on the performance of double suction centrifugal pump

Abstract This study aims to investigate the impact of the double volute structure on the internal flow dynamics and hydraulic performance of a double-suction pump. To achieve this, a double-suction centrifugal pump was selected as the research subject, and three-dimensional turbulence numerical simulations were conducted under various working conditions using the Reynolds average method (RANS) and RNG k-ε turbulence model. The results of the simulation are compared with the experimental data, which demonstrates the validity of the numerical simulation. This study analyzes the impact of the splitter on the flow field within the volute and impeller, as well as its effect on the radial force of the impeller. The results indicate that the water flow has a significant impact on the head of the splitter, resulting in a noticeable high-pressure zone on the pressure side of the blade in close proximity to the starting end of the splitter; Under off-design conditions, a significant recirculation zone exists between the end of the splitter and the pump outlet, and it increases as the deviation from the designed condition increases; In the case of a small flow rate, the flow inhomogeneity near the starting end of the splitter is serious, and there are large zones of low speed on the outside of the splitter; The double volute structure can make the inlet velocity of the volute more evenly distributed along the circumferential direction, and can be effectively utilized to reduce the radial force exerted on the impeller, thereby improving its performance.

Compact mid-infrared dual-wavelength optical parametric oscillator pumped by Yb-doped fiber lasers based on two PPMgLN crystals

A compact mid-infrared (MIR) dual-wavelength optical parametric oscillator (OPO) pumped by Yb-doped fiber lasers (YDFLs) based on dual-crystal with an L-shaped cavity structure is demonstrated. Two periodically poled MgO-doped lithium niobite (PPMgLN) crystals with polarization periods of 30.44 μm and 28.96 μm are pumped by two YDFLs, respectively. The dual-wavelength output at 3.45 μm and 4.00 μm is obtained synchronously by adjusting the double pump power. When the total power of double-end pumping is 28.98 W with a ratio of 2:3, the pulse width is 60.80 ns under the repetition frequency of 110 kHz, the output power is 1.483 W@3.45 μm and 1.703 W@4.00 μm, respectively. The total conversion efficiency is 10.99%. By utilizing this cavity structure, the gain and wavelength tuning of the two OPOs can be controlled separately. Meanwhile, the pulse width is 46.93 ns@3.45 μm and 39.38 ns@4.00 μm, respectively. The laser beam quality closely approaches the theoretical quality of the fundamental mode beam. Additionally, by independently adjusting the temperature of the two PPMgLN crystals from 20 °C to 150 °C, tunable mid-infrared laser outputs with wavelengths of 3.448–3.272 μm and 4.006–3.864 μm are achieved. The corresponding tuning bandwidths are 176 nm and 142 nm, respectively.

Optimization of rotor profile design and analysis of transient flow fields in an asymmetric singular double claw vacuum pump

The claw vacuum pump is widely used in vacuum industries due to its high-performance, compact structure, and oil-free operation. This study delves into the rotor profile and internal flow field characteristics of an asymmetric singular double claw vacuum pump. Theoretical profile equations for the male-female rotor of claw vacuum pumps were given, and a three-dimensional transient simulation of the internal flow field was carried out using the dynamic mesh reconstruction method. The simulation result was also verified by experiments. Analysis shows that: the radial clearance significantly affects the volumetric efficiency of the claw vacuum pump, with a larger effect than the axial clearance; the maximum instantaneous temperature corresponds to radial clearance, leading to maximum thermal deformation concentrated at the claw tip; thermal deformation is the predominant factor contributing to maximum deformation; the smaller the coefficient of thermal expansion, the less the rotor material affects the claw vacuum pump clearance. Based on these insights, we have innovatively optimized two elements of the theoretical claw vacuum pump rotor profile, i.e., the curvature of the cusp B and three optimized configurations of the complex EH section. The optimization results provide a solid theoretical basis for advancing the design and practical application of this pump type.

Technical and economic feasibility of a small vertical axis wind turbine in low wind conditions compared to other power sources for pumping water

In a global context, the significance of transitioning to renewable energy sources is paramount for sustainable development. This relevance is particularly evident in Brazil, where significant strides have been made in microgeneration of photovoltaic solar power and on-shore large-scale horizontal-axis wind power. Despite the country's extensive energy capacity from hydroelectric facilities, still approximately 38.5 million people reside in rural areas and surrounding areas, emphasizing the need for effective and affordable energy solutions for these regions. Based on this social and business opportunity of small-sized devices used in sustainable development, this practical experimentation explores the viability of initial studies from a prototyped small vertical-axis wind turbine (VAWT) system for water pumping, comparing its technical and economic feasibility with commercial off-the-shelf (COTS) photovoltaic solar pump (PV) and conventional electrical pump systems (EP). Two scenarios are investigated: (1) a patented transmission mechanism connected to a double effect pump and (2) the VAWT system designed to be connected to the same mechanism. Compared to PV ‘systems, scenario (1) offers 1.4x higher flowrate at a significantly lower cost (137% less) and consumes half the power. It offers a lower flowrate (2.6x) than EP systems but at a lower cost (36% less) and consumes one-third the power. Scenario (2) provides 2.7x less water flow than PV at a slightly lower cost (41% less). While less efficient in water flow (10 x) compared to EP, it has a slightly higher cost (15% more). This research builds upon existing knowledge and offers valuable insights for future small VAWT applications in low-wind remote areas for water pumping.

Study on the working characteristics of a double jet pump used for high sand content extraction in the oil and gas production

In order to fulfill the present need for downhole lifting pumps in various cutting-edge drilling techniques, a double jet pump is ingeniously devised. The internal three-dimensional characteristics of this pump are utilized to optimize its structural parameters through the flow field simulation method. Extensive evaluations are conducted to assess the alterations in jet performance under different parameters, including area ratios, throat lengths, nozzle exit positions, and nozzle area ratios. The pivotal structural parameters of the double jet pump are optimized as follows: area ratio ma=0.22, throat length Lh=84.5 mm, nozzle exit position Lc=6.76 mm, and nozzle area ratio mb=0.3. Furthermore, an experimental platform is meticulously erected to validate the principles of the double jet pump and to analyze its jet performance. This ascertains the feasibility of the double jet pump and validates the accuracy of the simulation and analysis results. This device can be effectively employed in the oil and gas production characterized by a high sand content extraction.

Research on working characteristics of composite two-stage ventilation heat recovery system with heat pipe and heat pump

In this paper, a composite two-stage ventilation heat recovery system with heat pipe and heat pump is proposed, heat pipe is used to recover the exhaust air energy to improve the operating performance of the system under all operating conditions. The split heat pipe heat exchanger is designed and manufactured, the working characteristics and performance of the composite heat recovery system under different working conditions are tested, and it is compared with the parallel-loop heat pump ventilation heat recovery system also. The results show that the optimal working fluid charge rate of the split heat pipe used in the composite system is 50 %–60 %, the temperature efficiency of the composite system in winter is higher than 64.31 %, the heating COP is up to 7.17, and the total heating capacity is 5.09 kW. Temperature efficiency and heating capacity of the system are 4.01 %–66.6 % and 7.68 %–67.19 % higher than that of the double loop heat pump heat recovery system, respectively.

Influence of Impeller Structure Parameters on the Hydraulic Performance and Casting Molding of Spiral Centrifugal Pumps

In order to study the influence of impeller structural parameters on the hydraulic performance and casting moulding of spiral centrifugal pumps, this paper selects a double vane spiral centrifugal pump with a specific rotation number of 170 as the research object. The Plackett–Burman experimental design is used to screen the influencing factors, and the results show that the vane thickness and the impeller outlet width are the significant influencing factors. Based on this result, five different scenarios were set for these two key parameters, numerical calculations were carried out using numerical simulation software for each of the five flow ratio cases, and casting simulations were carried out for the model of each scenario using AnyCasting6.0 to analyze the influence of these two factors on the hydraulic performance and casting forming of the spiral centrifugal pump. It was found that in terms of vane thickness, a moderate increase in vane thickness improved the hydraulic performance at small flow rates, but an excessive increase at large flow rates led to a decrease in efficiency and an increase in the probability of casting defects. In terms of impeller outlet width, increasing the outlet width caused the design point to be shifted, leading to a decrease in efficiency at small flow rates, but an increase in efficiency when the design flow rate was higher. At the same time, increasing the outlet width makes casting defects more likely to occur at the blade and back cover joint than on the blade surface. The study in this paper clarifies the significant effects of these two parameters on the performance and casting quality of spiral centrifugal pumps, and provides guidance for the optimal design of spiral centrifugal pumps.

Analysis of pressure pulsation in a multi-stage double suction centrifugal pump

Abstract Pressure pulsation is a common phenomenon, which results from different causes. The intenser pressure pulsation occurs in the pump, the severer the damage to the pump. In the paper, with the assistance of detached eddy simulation method, the characteristic of pressure pulsation in the multi-stage double suction centrifugal pump is studied to understanding the internal flow circumstance. The results reveal that the pressure pulsation intensity reaches the maximum at blade trailing edge, which propagates to the tongue region of forward flow channel and double-volute under the low rates. Furthermore, it can be concluded that the pressure pulsation of region with obvious rotor–stator interaction between rotating impeller and stationary volute is generally larger at low flow rates. The pressure pulsation near the suction side of blade trailing edge shows the feature of broadband frequency and with increasing flow rate the bandwidth of broadband decreases drops rapidly except BP1. Due to the influence of the number of impeller blades, the dominant frequency of monitoring points in the inter-stage flow channel and the volute is basically located at a frequency that is twice the blade frequency. Meanwhile, because of the symmetry of the geometric structure of the reverse flow channel, the pressure pulsation curve changes of its internal monitoring points are similar under the same flow rate.

Coherent structures decomposition of internal flow in the double-suction centrifugal pump impeller

Abstract In order to understand the unsteady flow phenomenon of the centrifugal pump, the dynamic mode decomposition method (DMD) is introduced to extract the three-dimensional coherent structure of the rotating flow field in the impeller passage under three different working conditions of the double-suction centrifugal pump. The time series collection of flow field is constructed by CFD numerical simulation, and the approximate matrix characteristic parameters and different modal data are solved. The analysis results show that the position, form and spatial-temporal evolution of the coherent structure can be accurately captured by DMD method corresponding to a single frequency in the double suction pump. For the temporal evolution, the coherent structure corresponding to low frequency is the most stable and dominate the unsteady flow. For the spatial evolution, the coherent structure corresponding to even-fold rotational frequency mostly occurs near the pressure side of the blade at the outlet of the impeller, and the coherent structure corresponding to odd-fold rotational frequency is mostly located in the flow field inside the impeller or near the blade surface.

Effect of Blade Thickening Law on the Internal Flow Field and Hydraulic Performance of Double Suction Pumps for Yellow River Pumping

Abstract The thickness of the blades is a fundamental parameter of the impeller and has a substantial impact on the performance of the pump. With the other geometric parameters of a centrifugal pump fixed, six kinds of impellers with different blade thickness were designed. Numerical simulations of the pumps were performed with Fluent under six different operating conditions based on the RNG k-epsilon equation and the SIMPLE algorithm. The hydraulic performance of the pump and its external characteristics were analysed based on the internal flow field to understand the relationship between blade thickness and performance. The results have showed that the hydraulic performance of the pump increases with the backward movement of the maximum thickness of the blade; Under the same sand concentration, the efficiency increases slightly with the increase of blade thickness within a certain range;With the increase of blade thickness, the turbulent kinetic energy loss of the pump under design operating conditions increases continuously; The thickening rules of schemes A1 and B can improve the hydraulic performance of the pump and the transport capacity of the sediment laden two-phase flow. That is, on the premise of meeting the structural strength of the blades, selecting a reasonable blade thickness can ensure that the double suction pump has good hydraulic performance.

Spin injection enhancement in CW VECSEL at room temperature using push-pull optical pumping.

We report the enhancement of spin injection efficiency in an external-cavity VCSEL based on a non-resonant pumping coupled with a polarized optical resonant illumination. This double pumping scheme allows both the injection of spin polarized electrons in the conduction band and the selection of the spin orientation for the electron/hole recombination laser process. Experimentally, a flip of the polarization state of the laser is achieved with an ellipticity of +31° (spin down) and -33° (spin up), so an increase of about 50% of the ellipticity is achieved in comparison to an optical non-resonant pumping alone.

OpSAVE: Eviction Based Scheme for Efficient Optical Network-on-Chip

For on-chip networks, nanophotonics has been considered a strong alternative owing to its high speed (due to low latency) and high bandwidth (due to wavelength division multiplexing). However, the major hurdle in the adoption of nanophotonic-based on-chip networks is their high static power consumption. Various proposals are there in the literature which try to reduce the static power consumption either by modulating the laser or by allowing the on-chip stations to share the photonic channels. In this paper, we propose OpSAVE— an optical NoC that combines the above two strategies to effectively reduce static power consumption. It proposes a superior prediction mechanism based on the eviction details from the private caches. It explains how shared channels can be used to dynamically balance the load and at the same time handle mispredictions. It allows the optical stations to share both the power and the available bandwidth to increase their utilization. Moreover, OpSAVE proposes to use a double pumping strategy to improve the system performance. We compared our scheme with the state-of-the-art proposals in this domain and the results show that our scheme consumes 4.4X less optical power and at the same time improves the performance by nearly 28%. In the evaluation, we have considered the multicore benchmarks from the Splash and Parsec benchmark suites.

Two-photon coherence in a DROP-FWM medium

In this work, we report experimental studies on coherence in a medium exhibiting DROP (Double Resonance Optical Pumping)-FWM (Four Wave Mixing). Here 5S1/2(F) → 5P3/2(F/) → 5D (F//) two photon transition of hot 87Rb atoms is used. The 5S→5P connection is modified by introducing an additional beam phase coupled to the original beam linking F = 2 → F/ transition. The frequency of the additional beam is offset from that of the original beam by ≈ +10Γ (Γ is natural linewidth). Such a two-beam configuration in F→F/ manifold effectively satisfies conditions of Vee (V) linkage or degenerate two-level connection (DTLC), depending on the detuning of the 780nm laser. This transformation profoundly affects the behavior of the ensuing Ladder (Ξ) system. While the (I) Ξ +V condition is favorable for Electromagnetically Induced Transparency (EIT), the (ii) Ξ + DTLC brings in the effect of Electromagnetically Induced Absorption (EIA). The EIT-dominated situation is helpful for FWM to take place, and the EIA effect augments the stronger presence of DROP. This condition is verified by monitoring the blue fluorescence emanating from the 5D→6P3/2→5S1/2 decay route. The DROP effect follows the Amplified Spontaneous Emission (ASE) pattern in the media. The origin of blue photons is also due to FWM under EIT conditions. In the case of EIA, the dominant condition increment in blue fluorescence is due to increased stimulated emission. The blue photons mainly contributed by (i) FWM and (ii) increased participation of stimulated emission are directional in nature and phase coherent.

A210 ESOPHAGEAL SQUAMOUS PAPILLOMATOSIS AFTER ENDOSCOPIC SUBMUCOSAL DISSECTION

Abstract Background Squamous papillomatosis is a rare benign epithelial finding, generally found incidentally in the distal esophagus. The pathophysiology is not well understood but felt to be secondary to reflux and chemical irritation leading to leukoplakia and verrucous hyperplasia of the epithelium and papilloma formation. Aims To present a case of esophageal squamous papillomatosis after endoscopic submucosal dissection (ESD) and radiofrequency ablation (RFA) of Barrett’s esophagus (BE) and early esophageal cancer. Methods Case report and review of the literature Results A 78-year-old male with C3M3 BE and previous band mucosectomy for nodular dysplasia was referred for ESD of an early esophageal cancer. ESD was successfully performed, with histopathology identifying a low-risk well-differentiated intramucosal adenocarcinoma without lymphovascular invasion and negative margins. Radiofrequency ablation was performed 3-months post-resection for residual BE. Subsequent surveillance gastroscopy 6 months post-resection identified extensive fleshy pink granulation tissue at the ESD scar, histopathology revealing SP. This was confirmed on subsequent repeat gastroscopy and biopsy. Compliance with double dose proton pump inhibitor therapy was confirmed. Conclusions To our knowledge, this is the first reported case of SP developing post-ESD and RFA; further expanding our knowledge of potential Barrett’s endotherapy-related adverse events. Funding Agencies None

Visual experimental study on cavitation performance of double-suction centrifugal pump

In this paper, the cavitation test results of double-suction centrifugal pump are further “visualized” and verified by using high-speed photography technology to photograph the development process and flow field of impeller inlet cavitation. By optimizing the impeller inlet parameters, the key geometric factors affecting the cavitation performance of the double suction pump were determined. The experimental results show that by optimizing the inlet parameters of the double-suction pump and combining the visualization test verification of cavitation, on the basis of ensuring the wide and efficient efficiency of the double-suction centrifugal pump, the optimization scheme of the experimental design greatly improves its cavitation performance, and provides a new design idea and reference for guiding the development and design of products with high cavitation performance.

Exploring the mechanism of improving the pressure fluctuation of double suction centrifugal pump by impeller stagger.

The pressure fluctuation in the volute can be effectively reduced when the impeller of the double-suction pump is staggered, but the mechanism of this reduction is still unclear. At the same time, the traditional analysis method cannot realize the visualization of pressure fluctuation. The purpose of this article is to explore the spatial distribution, propagation, and attenuation law of pressure fluctuation, and on this basis, to research the reason why staggered impeller reduce pressure fluctuation. A new method called Pulse tracking network (PTN) was used in this article. Compared with the traditional method, which only analyzes the pressure fluctuation at scattered points, this method greatly improves the spatial resolution of the pressure fluctuation. In particular, the phase analysis is a major highlight of the method. Staggered impeller significantly reduced the pressure fluctuation intensity dominated by blade passing frequency. At the same time, the propagation of the pressure fluctuation in the volute changed from radial to circumferential in the volute cross-section. Staggered impeller can effectively reduce pressure fluctuation, and the circumferential propagation caused by it is considered to be the main reason for it.

Visualization investigation of the motion of rags in a double blades pump

Accumulation of fibrous materials often leads to pump clogging in wastewater systems. Visualizing these clogging phenomena helps identify ways to reduce the risk. In this study, we analyze a double blades pump made of acrylic glass using a fast digital camera to record the motion of rags inside. Recordings at three rotational speeds investigate the impact of rag materials, sizes, and quantities on their passage through the pump. Results show that smaller rags pass through the pump more quickly. At the same rotational speed and with the same material, the maximum passage time increases by over 100% compared to the shortest passage time. Additionally, rags flow more rapidly at high impeller speeds. At low speeds, rags tend to linger inside the impeller or stick to the pump casing’s tongue. The passage time at high speed is about 10% less than at lower speeds. Furthermore, under the same mass concentration, larger rags with fewer quantities are more prone to clogging than smaller rags with greater quantities. The proportion of larger rags with fewer quantities smoothly leaving the pump is about 10% less than that of smaller rags with greater quantities.

Performance analysis of a novel combined open absorption heat pump and FlashME seawater desalination system for flue gas heat and water recovery

Thermal desalination processes generally consume a huge amount of thermal energy and industries release a large amount of latent waste heat in flue gas exhausts into the environment. In order to efficiently utilize this waste heat and to improve the energy efficiency of desalination process, this paper presents a novel combined system based on the open cycle absorption heat pump and low-grade thermal energy driven FlashME desalination. The proposed combined system is designed to recover the latent waste heat from flue gas exhausts in a parallel double stage open absorption heat pump which is driven by multiple energy sources and efficiently utilizes the recovered low temperature heat in FlashME for freshwater production. The validated process model of the combined system is developed in Aspen Plus and a parametric assessment is carried out to analyze its energy performance with the impact of various independent operational parameters by using HCOOK-H2O as an absorbent solution. The simulation results of the parametric study show that the combined system is capable of recovering the waste heat with an efficiency of 89.42 % by operating at a thermal performance coefficient of 2.21 and utilizes this heat in the form of hot seawater at 70 °C to drive FlashME desalination process for freshwater production at the performance ratio of 3.05. The critical analysis of the results highlights that the heat recovery performance of the absorption cycle is strongly dependent on the inlet parameters of flue gas and spray solution. In contrast, the water recovery performance of FlashME is dependent on regeneration pressure such that the water recovery rate varies from 9.19 % to 37.17 % with a pressure variation between 23.23 and 51.39 kPa which raises the seawater temperature 60–79 °C before the flashing stage. Furthermore, the system is flexible enough to operate with two heat sources of different temperature levels by adjusting the regeneration load in separate regenerators.