Pump Performance Research Articles

Experimental and numerical study on cavitation pulsating pressure of water-jet propulsion axial-flow pump.

Cavitation may occur in water-jet pump during operation of water-jet propulsion vessel, and once cavitation occurs, the tip clearance pulsating pressure of the impeller may be intensified, resulting in increased vibration of the water-jet propulsion unit. In this paper, the cavitation pulsating pressure characteristics at different positions in the pump are studied by experiment and numerical simulation, and the pulsating pressure characteristics in tip clearance are mainly researched. Based on Star-CCM+ commercial software, unsteady Reynolds-averaged Navier-Stokes equations(RANS) numerical simulation is carried out, and the feasibility of the numerical simulation method is verified by uncertainty analysis. The results show that the cavitation pulsating pressure near the leading edge of the impeller in the tip clearance is the largest. The variation of the tip clearance pulsating pressure with the intensification of cavitation is studied by numerical simulation, and its mechanism is revealed. A dimensionless coefficient of net positive suction head (CNPSH) is proposed, and the study shows that the cavitation pulsation pressure coefficients of pumps of different scales are equal when the working conditions are similar and the CNPSH are equal, which indicates that the cavitation pulsating pressure performance of full scale pump can be predicted by model scale. It is of great significance to evaluate the vibration performance of the full scale water-jet propulsion.

The Effect of Drive Signals on Output Performance of Piezoelectric Pumps

The output performance of piezoelectric pumps is not only affected by the structural design but is also related to the drive signal. To study the effect of different drive signals on the output performance of piezoelectric pumps, this paper takes dual-chamber serial piezoelectric pumps as the investigation object, theoretically deduces the effective value of the drive signal and the output performance of the piezoelectric pump, and tests the displacement of piezoelectric vibrator center, the output performance of the piezoelectric pump, and the operating noise within the range of 0–500 Hz, respectively, driven by square waves, sine waves, and triangular waves (the peak-to-peak values of which are all 300 V). The results show that at low frequencies, the piezoelectric vibrator’s center displacement curve matches the drive signal, which is sinusoidal and decreases with frequency. Under the square drive, the piezoelectric pump has the best performance, with a flow of 147.199 mL/min and pressure of 14.42 kPa, but the noise is also the highest. The output performance of the sine wave is better than that of the triangular wave, and the flow rate of the three signals shows a trend of first increasing and then decreasing.

Performance analysis of solar-assisted ground source heat pump in severe cold regions

ABSTRACT Long-term operation of a ground source heat pump (GSHP) in severe cold regions leads to a gradual decrease in subsurface soil temperature, affecting system performance. This paper proposes a solar assisted ground source heat pump (SAGSHP) system consisting of solar photovoltaic thermal (PV/T) and GSHP. Through TRNSYS software, the system was analyzed for 10 years of dynamic simulation in a severe cold region. The results are listed below: (1) The SAGSHP system is capable of effectively lessening the maximal temperature of photovoltaic (PV) modules in Changchun, Shenyang, and Harbin, China, by 21.73%, 13.67%, and 19.10%, respectively. The power generation efficiency of PV modules in these three locations can be maintained at about 22% year-round. (2) After ten years of operation, the coefficients of performance (COP) of the heat pumps have increased by 5.70%, 6.80%, and 5.01%, respectively, relative to the first year, showing good stability. (3) The soil temperatures at all three locations were stabilized during the ten years of operation. This study provides a theoretical basis for devising and installing SAGSHP in severe cold regions.

Design and Performance Test of Four-Chamber Series–Parallel Piezoelectric Pump

In order to improve the output performance of multi-chamber piezoelectric pumps, this paper proposes a novel design for a four-chamber series–parallel piezoelectric pump, based on the characteristics that the parallel chamber structure significantly increases the output flow rate, and the series chamber structure effectively improves the output pressure. The theoretical output flow rate and pressure of the four-chamber series–parallel piezoelectric pump were calculated, and a prototype was fabricated. Tests were conducted to compare the liquid transport performance of piezoelectric pumps with three different structures: series, parallel, and series–parallel. The results show that, when transporting liquid, the output flow rate of the four-chamber series–parallel structure increased by up to 13.3% compared to the four-chamber series structure, reaching a maximum of 767 mL/min. Additionally, the maximum output pressure of the series–parallel structure increased by 43.4% compared to the four-chamber parallel structure, reaching 42.3 kPa. The four-chamber series–parallel design combines the advantages of both series and parallel configurations, improving the output performance of the piezoelectric pump and providing a reference for the structural design of multi-chamber piezoelectric pumps.

Experimental Study on the Classification and Evolution of the Tip Cavitation Morphology in Axial Waterjet Pumps with Two Different Blade Numbers

Tip leakage flow and induced unstable cavitation can significantly damage the performance of axial waterjet pumps. This study investigated the impact of blade numbers on cavitating conditions in an axial waterjet pump by conducting tests of performance characteristics and high-speed photography experiments on three-blade and four-blade impellers. The results showed that the critical cavitation number σc of the three-blade impeller was larger, while the four-blade impeller flow pattern deteriorated more rapidly after σc. Various cavitation structures in the tip region were observed under different conditions, including clearance cavitation, shear layer cavitation, tip leakage vortex cavitation, and suction-side-perpendicular cavitating vortices (SSPCVs). Tip cavitation maps of the test impellers were drawn based on the flow rate coefficient and cavitation number variation. The three-blade impeller exhibited a wider range of severe cavitation, particularly with an increased occurrence of SSPCVs. With the cavitation number and flow rate coefficient decreased, the SSPCV generated from triangular cavitation cloud shedding presented an increased trend in scale and quantity. Conversely, in the case of the four-blade impeller, SSPCVs were often disrupted by the adjacent blade during migration and interfered with the tip cavitation in the neighboring flow passage.

Temperature-triggered liquid metal actuators for fluid manipulation by leveraging phase transition control

ABSTRACT Small-scale pumps for controlling microfluidics have promising applications in drug delivery and chemical assays. Liquid metal (LM) demonstrates excellent flow pumping performance due to its simple structure and the electrocapillary effect under an electric field. However, LM droplets risk escaping from constrained structures, which can lead to pump failure. Temperature regulation is also a critical parameter in optimizing chemical reactions in fluidic systems, however, integrating it into a compact system remains challenging. Here, we develop a temperature-triggered gallium-based actuator (TTGA) by introducing a gallium (Ga) droplet wetted on a copper (Cu) plate as the core element for flow actuation. The Cu plate prevents the Ga droplet from escaping the chamber and significantly increases the flow rate. By leveraging the electrochemical method to inhibit the supercooling effect of Ga, the TTGA enables activation/deactivation for flow actuation at different temperatures. We investigate the impact of electrode position, solution concentration, and applied voltage on TTGA’s pumping efficiency. By dynamically tuning the Ga droplet’s temperature to control phase transition, TTGA allows for accurate flow actuation control. Furthermore, placing Ga and eutectic Ga-indium (EGaIn) droplets in different channels enables the expected flow divergence for fluids with different temperatures. The development of TTGA presents new opportunities in microfluidics and biomedical treatment.

One-shot manufacturable soft-robotic pump inspired by embryonic tubular heart.

Soft peristaltic pumps, which use soft ring actuators instead of mechanical pistons or rollers, offer advantages in transporting liquids with non-uniform solids, such as slurry, food, and sewage. Recent advances in 3D printing with flexible thermoplastic polyurethane (TPU) present the potential for single-step fabrication of these pumps, distinguished from handcrafted, multistep traditional silicone casting methods. However, because of the relatively high hardness of TPU, TPU-based soft peristaltic pumps contract insufficiently and thus cannot perform as well as silicone-based ones. Improving the performance is crucial for fully automated, one-step manufactured soft pumps to lead to industrial use. This study aims to enhance TPU-based soft pumps through bioinspired design. Specifically, it proposed a design inspired by embryonic tubular hearts, in contrast to previous studies that mimicked digestive tracts. The new design facilitated long-axis stretching of an elliptical lumen during non-concentric contractile motion, akin to embryonic tubular hearts. The design was optimized for ring actuators and pumps 3D-printed with shore hardness 85 A TPU filament. The ring actuator achieved over 99% lumen closure with the best designs. The soft pumps transported water at flow rates of up to 218 ml min-1and generated a maximum discharge pressure of 355 mm Hg, comparable to the performance of blood pumps used in continuous renal replacement therapy.

Performance study of solar air collector-air source heat pump system inside the greenhouse

During the process of heating greenhouses, the phenomenon of inadequate heating installations is widespread. To address this issue, this paper proposed a solar air collector-air source heat pump (SAC-ASHP) system for greenhouses, combining solar technology with heat pump (HP) technology to provide sufficient heat during continuous cloudy days and winter. The heating capacities of the system on sunny, cloudy, and overcast days were 100.2 kWh, 112.3 kWh, and 157.8 kWh, respectively. The corresponding power was 30.1 kWh, 36.1 kWh, and 53.6 kWh. The coefficient of performance (COP) of the single air source heat pump (ASHP) for these days was 3.4, 3.2, and 3.0, respectively, while the COP of the solar heat pump (SHP) was 4.0, 3.5, and 3.1. Additionally, greenhouse employed heat and moisture recovery for humid air, aiming to provide a suitable environment for plant growth around the clock while conserving energy. The heat collection in the heat and moisture recovery combined HP mode was 66.7 % higher than in the heat exchanger (HE)-fan mode. This experimental study investigated the operational performance of the system in dynamic environments, revealing the stability of the system for greenhouse heating in cold regions, and providing new research ideas for greenhouse heating.

Bionic Strategies for Pump Anti-Cavitation: A Comprehensive Review

The cavitation phenomenon presents a significant challenge in pump operation since the losses incurred by cavitation adversely impact pump performance. The many constraints of conventional anti-cavitation techniques have compelled researchers to explore biological processes for innovative alternatives. Consequently, the use of bionanotechnology for anti-cavitation pumping has emerged as a prominent study domain. Despite the extensive publication of publications on biomimetic technology, research concerning the use of anti-cavitation in pumps remains scarce. This review comprehensively summarizes, for the first time, the advancements and applications of bionic structures, bionic surface texture design, and bionic materials in pump anti-cavitation, addressing critical aspects such as blade leading-edge bionic structures, bionic worm shells, microscopic bionic textures, and innovative bionic coatings. Bionic technology may significantly reduce cavitation erosion and improve pump performance by emulating natural biological structures. This research elucidates the creative contributions of biomimetic designs and their anti-cavitation effects, hence boosting the anti-cavitation performance of pumps. This work integrates practical requirements and anticipates future applications of bionic technology in pump anti-cavitation, offering a significant research direction and reference for scholars in this domain.

Efficiency improvement and pressure pulsation reduction of volute centrifugal pump through diffuser design optimization

To investigate the effects of load distribution parameters of the diffuser vanes on the efficiency and pressure pulsation of the volute centrifugal pump, the diffuser shape was designed using an inverse design method, and an optimization method was proposed for the diffuser blade load distribution based on the combination of Latin hypercubic sampling, artificial neural network, and non-dominated sorting genetic algorithm-II. Steady and unsteady simulations were performed by solving the three-dimensional Reynolds-averaged Navier–Stokes equations using the shear stress transport k−ω turbulence model. The results obtained from Pearson correlation analysis revealed that the slope values Ks and Kh of the shroud and hub load distribution curves had the most significant effect on the pump head and efficiency. Compared with those of the original model, the efficiency and head of the optimized volute centrifugal pump under the design conditions increased by 3.8 and 3.5 %, respectively. The pressure pulsation intensities in the vaneless regions were effectively mitigated for the optimized volute centrifugal pump. The pressure pulsation coefficients at three times the diffuser vane frequency (3fDIF) reduced by 58.5 and 43.8 % at monitoring points M1 and M2, in the impeller outlet, respectively. The pressure pulsation coefficients at the impeller blade passing frequency (fBPF) reduced by 6.5 and 14.4 % at monitoring points M3 and M4 in the diffuser inlet, respectively. The results showed that the optimized diffuser improved the overall performance of the volute centrifugal pump, and demonstrated the feasibility of the optimization method.

Rotor fault diagnosis of centrifugal pumps in nuclear power plants based on CWGAN-GP-CNN for imbalanced dataset

As a crucial device in nuclear power plants, centrifugal pumps undertake the critical role of cooling water circulation. Centrifugal pump rotor misalignment and unbalanced faults cause pump performance degradation, vibration increase, and equipment damage, thus seriously affecting the safety and reliability of nuclear power plants. In the process of centrifugal pump rotor fault, the difficulty in obtaining data samples and the limited amount of data can lead to an imbalance problem between the quantity of normal state and fault state samples in the dataset. In order to solve the problem, this paper proposed a CWGAN-GP model for generating rotor fault data based on CGAN and WGAN-GP models, and combined it with a two-stream CNN model to realize the rotor fault diagnosis with an imbalanced dataset. The quality and performance of the data generated by the proposed method were evaluated and validated in terms of visualization analysis, statistical indicators, and comparison with different data generation models. The results show that the CWGAN-GP model can generate high-quality data. Meanwhile, compared with other models on datasets with different degrees of imbalance, the two-stream CNN model is more effective in fault diagnosis on the expanded dataset by the CWGAN-GP model, and the improvement of fault diagnosis accuracy ranges from 1.40% to 13.33%.

On Leakage Flows In A Liquid Hydrogen Multi-Stage Pump for Aircraft Engine Applications

Abstract A comprehensive operational characterisation of a representative, Liquid Hydrogen (LH2) aircraft engine pump is presented in this work. The implications of leakage flows are investigated in a 2-stage, high-pressure pump for a wide range of flow rates and rotational speeds, through 3D (U)RANS simulations. Two configurations are compared: a baseline model comprising the primary flow path components - inducers, impellers and volutes and a realisable pump hardware that includes hub, shroud and power unit cavities. Performance metrics, including head changes and efficiencies, are extracted both at a component and system level. Leakage flow rates of 27.6% and up to 92.9% of the overall pump flow rate are recorded at design and lowest flow points respectively. The head loss in the mid to low flow rates does not exceed 4.5%, but the efficiency diminishes by up to 13.5% at off-design operation. The component analysis indicates significant penalties in impeller efficiency. At high flow rates, the presence of leakage flows improves the overall pump performance by 43% and 27% in head rise and efficiency, due to reduced losses in volutes and connecting ducts. The characterisation of pump behaviour described in this work is crucial for developing and designing safe and predictable LH2 aircraft pumps. Contrary to LH2 pumps utilized in rocketry and for cooling in nuclear industry, aircraft pumps are required to operate with wider turn-down ratios and often at low specific speeds. Therefore, this study addresses design considerations for this enabling technology.

Experimental and numerical study on transcritical CO2 air source heat pump water heater

As environmental problems become more and more serious, CO2 is widely used as a natural work material in heat pump water heaters. In order to better improve the performance of CO2 air-source heat pump water heater, a trans-critical CO2 quasi-two-stage compression heat pump system with ejector (TCIEJ) is proposed. And a transcritical CO2 air-source heat pump water heater experimental bench was built. The effects of parameters such as cooling water flow rate, high pressure and compressor frequency on the performance of the heat pump were tested. A simulation model of TCIEJ was also developed to simulate the system performance. The results show that when the cooling water flow rate is increased from 70 kg/h to 122.5 kg/h the COP is improved by 30 %, while the cooling water discharge temperature is reduced by 15.4 %. System performance can be enhanced by increasing the cooling water flow rate within the temperature range required to meet hot water demand. When the high-pressure pressure of the TCIEJ system was increased from 8.0 MPa to 10.4 MPa, the cooling water discharge temperature increased by 17.66 °C on average. Even in the ambient temperature of 0 °C high-pressure pressure of 10.4 MPa, the compressor discharge temperature is only 85.77 °C. It shows that the combination of make-up air technology and ejectors effectively reduces the compressor discharge temperature, which is conducive to improving the compressor’s service life.

Effect of clearance volume on the internal flow characteristics and output performance of oil-gas multiphase reciprocating pump

In the production of oil and natural gas, excessive clearance volume is an important factor affecting the normal operation of oil-gas multiphase pump. Currently, little research has been conducted on the effect of clearance volume on the output characteristics of multiphase pump at home and abroad, leading to extremely low efficiency in the field application of multiphase pump. Therefore, this study conducted numerical calculations on the internal flow characteristics and output performance of multiphase pump under different clearance volumes using FLUENT software. Results show that pressure and fluid velocity gradually decrease as the clearance volume increases. Simultaneously, the number and intensity of vortex flow gradually increase, media pressurization speed becomes slower, and the lag angle of the discharge valve opening becomes larger. Moreover, under conditions with a higher gas volume fraction, multiphase pump with larger clearance volumes experiences gas locking. Furthermore, this study provides a theoretical basis for the reasonable design of clearance volume for multiphase pump by drawing a relationship curve between gas volume fraction and clearance volume. These research findings can provide theoretical support for the performance optimization and design improvement of multiphase pumps.

Control strategy calibration of a direct-expansion solar-assisted heat pump

As known, the performance of a direct-expansion solar-assisted heat pump (DX-SAHP) is affected by environmental and operational parameters significantly, and the variable capacity system has distinct advantages. The calibration of the control strategy will be very useful for the thermal performance improvement of DX-SAHP systems. Based on the test rig which is used to supply domestic hot water, the original variable capacity control strategy has been calibrated with the quasi-dynamic mathematical model under different conditions. The calibration results show that the optimum range of the degree of superheat is 7–12 °C. For winter and spring/autumn conditions, the optimum range of operation duration are 360–420 min and 300–360 min, and the corresponding optimum range of average compressor speed are 3750–4500 r·min−1 and 2750–3750 r·min−1, respectively. Experiments prove that the actual operation parameters can be maintained at the optimum range well and the average coefficient of performance (COPm) during the whole heating process has been improved further. For winter and spring/autumn, the average operation duration and compressor speed are 395 min and 3970 r·min−1, 345 min and 3066 r·min−1, respectively. Moreover, the values of COPm could reach 3.44 and 4.67, respectively. Even at solar radiation intensity of 577.6 W·m−2 with ambient temperature of −9.1 °C, the COPm could reach 2.38.

Study on the Performance of a Novel Double-Section Full-Open Absorption Heat Pump for Flue Gas Waste Heat Recovery

Open absorption heat pumps are considered one of the most promising methods for efficiently utilizing low-grade waste heat, reducing energy consumption, and lowering greenhouse gas emissions. However, traditional heat pumps have significant limitations in the range of flue gas temperatures they can recover, and their relatively low system performance further restricts practical applications. In this study, we propose a novel double-section full-open absorption heat pump driven by flue gas from the desulfurization tower. By designing the absorber with a double-layer structure, the system can recover more latent and sensible heat from the flue gas, significantly enhancing its thermal recovery capability. Additionally, replacing the traditional LiBr/H2O working pair with LiCl/H2O significantly reduces the risks of solution crystallization and equipment corrosion. Through comprehensive research, the strengths and weaknesses of the system were explored. The results indicate that this system effectively recovers flue gas waste heat within the temperature range of 30–70 °C. Specifically, at a flue gas temperature of 70 °C and a flow rate of 3 kg/s, the system achieves a COP of 1.838, along with a heating capacity of 158.83 kW and a ROI of 34.1%. These metrics demonstrate that the system not only delivers high performance but also exhibits excellent economic viability. Additionally, when the solution temperature is lowered to 10 °C, the system’s maximum COP reaches 1.96, reflecting a significant 30.67% improvement over traditional heat pumps. These findings highlight the system’s potential for application in coal-fired power plants, where varying levels of power output can benefit from enhanced thermal recovery and efficiency.

Construction of Solid-Liquid Two-Phase Flow and Wear Rate Prediction Model in Multiphase Pump Based on Mixture Model-Discrete Phase Model Combination Method

Blade wear is the critical problem in the operation of multiphase pump. This paper presents a numerical study of the multiphase flow of multiphase pump. The trajectory of particles in the pump is calculated by the discrete phase model. Then, the simulation results are compared with the model test results of the pump to verify the correctness of the simulation method. The results show that the particles in the impeller domain are mainly near the hub, and the particles in the diffuser domain form a agglomerated area in the middle of the flow channel. The average wear rate of the impeller is more affected by the particle size than that of the diffuser. The maximum wear rate of blade surface increases first and then decreases with the increase of particle size. According to the wear data under different particle sizes, the regression model between particle size and wear rate is fitted to predict the wear of mixed transport pump in actual operation. The research results have important reference value for the prediction of the wear performance of the multiphase pump.

Experimental study of performance of building heating system based on HPS and equipped with thermal potential recovery system and heat load prediction

The results of experimental studies of the heating system performance of a building located in the area of temperate continental climate with temperatures in the heating period down to −30 °C are discussed. The studied heating system comprises an air–liquid heat pump, a liquid–liquid heat pump with a ground circuit, and an electric boiler for peak demands.The paper presents the results of the influence of the ground thermal potential recovery system on the liquid–liquid heat pump performance. Also the influence of the used method of heat load prediction on the system efficiency and indoor air temperature stability is shown.Implementation of the thermal potential recovery system allows to increase the average value of the transformation coefficient for the liquid–liquid heat pump from 2.7 to 2.9 during three years of operation.Heat load prediction leads to stable indoor air temperature in the range of 22 ± 1 °C. Also it allows to level out the dependence of indoor temperature fluctuations on outdoor air temperature fluctuations.

Process integration and electrification through multiple heat pumps using a Lorenz efficiency approach

This paper introduces a novel method for targeting the minimum shaft work required for process electrification employing principles of Pinch Analysis and detailed heat pump performance estimations. The method deviates from conventional Pinch Analysis by dividing the grand composite curve (GCC) into net heat sink and source profiles to enable the placement of heat pumps exploiting the heat pockets of the GCC. Additionally, it employs Lorenz efficiency over exergy efficiency, offering an accurate description of heat pump performance and highlighting the importance of integration between processes. The method is applied to two case studies. The first case, milk evaporator, focused on the placement of heat pumps in the heat pockets of the GCC. The results showed that while the maximum direct heat recovery was 20,447 kW, the optimal configuration limited the heat recovery to 12,199 kW, reducing the shaft work from 1,930 kW to 1,010 kW. The second, a spray dryer case, focused on the integration of electric boilers and the partial process electrification when available excess heat is limited. In this case, 1,520 kW out of 4,640 kW were covered by an electric boiler, with a biomass boiler replacing the electric boiler to cover 3,570 kW if available.

Turbulent flow field in maglev centrifugal blood pumps of CH-VAD and HeartMate III: secondary flow and its effects on pump performance.

Secondary flow path is one of the crucial aspects during the design of centrifugal blood pumps. Small clearance size increases stress level and blood damage, while large clearance size can improve blood washout and reduce stress level. Nonetheless, large clearance also leads to strong secondary flows, causing further blood damage. Maglev blood pumps rely on magnetic force to achieve rotor suspension and allow more design freedom of clearance size. This study aims to characterize turbulent flow field and secondary flow as well as its effects on the primary flow and pump performance, in two representative commercial maglev blood pumps of CH-VAD and HeartMate III, which feature distinct designs of secondary flow path. The narrow and long secondary flow path of CH-VAD resulted in low secondary flow rates and low disturbance to the primary flow. The flow loss and blood damage potential of the CH-VAD mainly occurred at the secondary flow path, as well as the blade clearances. By contrast, the wide clearances in HeartMate III induced significant disturbance to the primary flow, resulting in large incidence angle, strong secondary flows and high flow loss. At higher flow rates, the incidence angle was even larger, causing larger separation, leading to a significant decrease of efficiency and steeper performance curve compared with CH-VAD. This study shows that maglev bearings do not guarantee good blood compatibility, and more attention should be paid to the influence of secondary flows on pump performance when designing centrifugal blood pumps.