Pump Parameters Research Articles

Numerical Simulation of Solid Diverting Particles Transport and Plugging in Large-Scale Hydraulic Fracture

Diversion technology, also known as temporary plugging technology, has become an integral part of hydraulic fracturing in unconventional reservoirs. The solid diverting particles are a common type of chemical diverting agents used in horizontal well multistage fracturing. The transport and plugging of solid diverting particles within the fractures are crucial physical processes in the far-field diversion technology. In this study, in order to clarify the formation of the plugging layer by solid diverting particles in large-scale hydraulic fracture and to offer insights for the quantitative optimization of far-field diversion technology (FFD), an enhanced simplified two-fluid model within the Euler-Euler framework is employed to simulate the transport and plugging process of solid diverting particles within the fracture. And the numerical schemes of the front settlement region, the plugging layer formation region and the rear settlement region are also optimized. The proposed model is verified through comparison with experimental results from visual fracture test device. Based on the numerical results across various particle, pumping and fracture parameters, our findings indicate that: (1) The duration required to form a complete plugging layer can be reduced to 3% to 20% by increasing injection concentration, injection rate, and fracturing fluid viscosity; (2) Increasing the injection concentration (from 10kg/m3 to 30kg/m3) significantly enhances the length of the plugging layer by about 1 to 16 times, compensating for the inability to achieve a complete plugging layer with smaller particle sizes. Merely increasing the injection rate alone (from 0.35m3/min to 0.80m3/min) does not remedy the inability of small particles to form a complete plugging layer under identical plugging conditions. Excessive fracturing fluid viscosity (higher than 6mPa·s) impedes the formation of a complete plugging layer with smaller particles. High fracturing fluid leak-off rate (higher than 2.5×10-7m/s) markedly reduces the length of the plugging layer by about 37% to 44%; (3) Achieving a high close packing degree of particles within the plugging layer is facilitated by increasing injection concentration, increasing injection rate, and reducing fluid viscosity; (4) The abrupt variation in fracture width or height along the fracture length affects up to about 18% of the length of the plugging layer at the top of fracture. To ensure large length of the plugging layer at the top of fracture and high close packing degree of particles within the plugging layer, we recommend injection concentration above 10kg/m3, fracturing fluid viscosity below 6mPa·s, and injection rate exceeding 0.35m3/min. For particle size less than 1.8mm, we suggest injection concentration above 20kg/m3, and fracturing fluid viscosity not exceeding 3mPa·s.

Research on dynamic well control in riserless mud recovery system

In order to promote the development of RMR (Riserless Mud Recovery) system well control technology and ensure the safe operation of deep water drilling operations, the overflow control equation of RMR system considering the lifting force of subsea pump is established and verified, the conventional overflow monitoring method and the overflow monitoring method based on subsea pump parameter variation are compared and analyzed. the dynamic well control process of the RMR system after overflow under the two modes of constant subsea pump displacement and constant inlet pressure of subsea pump is simulated, and the influencing factors of inlet pressure of subsea pump are further analyzed. The results show that although the temperature effect is taken into account in the model established in this paper, the time error of the mud pool increment, the inlet pressure and the displacement of subsea pump after reaching the overflow criterion is less than 22.5% compared with Froyen's model. The conventional overflow monitoring method has fast response and small change, while the overflow monitoring method based on subsea pump parameter change is on the contrary, and the two should be used together. Both the constant inlet pressure of subsea pump mode and the constant subsea pump displacement mode can control overflow, but from the stability of subsea pump, service life and well control safety, the constant displacement mode is better. In the case of large formation pressure, low drilling fluid density, overflow criteria and circulating displacement, the pressure response adjustment speed of the subsea pump inlet is faster, and the back pressure load of the subsea pump inlet can be effectively alleviated by appropriately increasing the circulating displacement and drilling fluid density. This study has enriched the theoretical system of RMR system in overflow control, and has certain guiding significance for the development of deepwater and ultra-deepwater drilling safety technology.

Design and Optimization of a Permanent Magnet Synchronous Motor for a Two-Dimensional Piston Electro-Hydraulic Pump

A two-dimensional (2D) piston electro-hydraulic pump has been proposed further to enhance the power density of the electro-hydraulic pump. The 2D piston pump, characterized by high power density and a slender shape, is embedded within the stator of the motor in a co-rotor configuration where the piston and the motor’s rotor are in tandem. The intimate design of the hydraulic pump and the motor results in a coupling between the two, with intricate relationships and influences existing between the geometric parameters of the piston pump and the dimensions of the motor’s rotor. Based on the operational requirements and structure of the 2D piston pump, a permanent magnet synchronous motor (PMSM) designed for use with a 2D piston electro-hydraulic pump is developed. This study examines the impact of the motor’s stator iron core geometric parameters on both the electromagnetic and mechanical properties of a PMSM and completes the necessary performance validations. The optimization objectives of the motor are determined through an analysis of the influence of the key parameters of the rotor and stator on torque, torque ripple, and motor loss. A surrogate optimization model is constructed using a metamodel of optimal prognosis (MOP) to optimize the torque, torque ripple, and motor loss. Evolutionary genetic algorithms are utilized to achieve the multi-objective optimization design. A finite element simulation is used to compare the electromagnetic performance of the initial motor and optimal motor. Based on the optimal motor parameters, a 2.5 kW motor prototype is manufactured, and the experimental results validate the feasibility and effectiveness of the motor design and optimization.

Comparison between invasive cardiac output and left ventricular assist device flow parameter.

Evaluate the correlation between left ventricular assist device flow parameter and invasive cardiac output measurements. We retrospectively evaluated right heart catheterization examinations performed in left ventricular assist device patients from 2 tertiary medical centers. We evaluated the correlation between cardiac output measurement methods (indirect Fick and thermodilution) and pump flow parameter using linear regression, agreement was graphically displayed using Bland-Altman plot technique. Clinical, echocardiographic, pump and haemodynamic parameters were compared between patients with and without discordance, defined as at least 20% difference between measurements. The study population consisted of 102 patients (median age 58 [51-64], 86% males, 17 ± 12 months post left ventricular assist device implantation) with a total of 544 measurement compared. Discordance between measurements were present in 102 of 226 (45%) comparisons between indirect Fick and pump flow and in 72 of 161 (48%) between thermodilution and pump flow. A comparison of indirect Fick and left ventricular assist device exhibited a statistical correlation of R = 0.751, and that of thermodilution and left ventricular assist device of R = 0.789. Parameters associated with the presence of discordance between cardiac output measurements included a higher rate of aortic valve opening, lower indirect Fick and higher thermodilution cardiac output. After excluding the lowest tertile of indirect Fick cardiac output values, the correlation between measurements improved (thermodilution: R = 0.879 and indirect Fick: R = 0.843, p < 0.001). The current left ventricular assist device flow parameter provides an estimation of cardiac output that correlates well with indirect Fick and exhibits the strongest correlation with thermodilution. This correlation was stronger after excluding lower cardiac output values.

Совершенствование конструкций установок струйных насосов для добычи нефти

The characteristics of jet pump installations are given, which are used mainly for low-yield wells in oil production whose flow rate is less than 10 m3/day. It is noted that jet pump installations have a relatively low efficiency of not exceeding 0.35, and it is almost equal to the efficiency of electric drive pump installations and downhole rod pump installations when extracting oil from wells with low flow rates of up to 20 m3/day. The advantages of jet pump installations over other types of downhole pumping installations in difficult oil production conditions are shown. With flow rates up to 150 m3/day. Costs for oil production using jet pump installations are minimal compared to other installations. A brief analysis of the designs of jet pumps, their main overall dimensions and weight is provided. A brief overview of scientific, technical and patent literature on jet pump installations is given. By changing the design of nozzles, confusers, diffusers, working chambers of jet pumps, as well as improving the jet pump installations as a whole when used in tandem with other types of well installations, their productivity, operating efficiency and reliability can be increased. It is noted that the parameters of jet pumps can be obtained by calculation based on the theory of mixing two flows, the theory of jet propagation in a mass of stationary or moving liquid and the mechanics of bodies of variable mass. The main design parameters of jet pump units are feed, pressure, ejection coefficient, power and efficiency. These parameters can also be determined experimentally. A laboratory jet pump unit has been developed. Experiments have shown that with an increase in the flow rate of the working fluid, the flow rate of the mixture and the working pressure, the ejection coefficient and efficiency decrease. In the future, experiments will be continued with various designs of jet pump elements.

Self-sustained optomechanical state destruction triggered by the Kerr nonlinearity

Cavity optomechanics implements a unique platform where moving objects can be probed by quantum fields, either laser light or microwave signals. With a pump tone driving at a frequency above the cavity resonance, self-sustained oscillations can be triggered at large injected powers. These limit-cycle dynamics are particularly rich, presenting hysteretic behaviors, broad comb signals, and especially large motion amplitudes. All of these features can be exploited for both fundamental quantum research and engineering. Here we present low-temperature microwave experiments performed on a high-Q cavity resonance capacitively coupled to the flexure of a beam resonator. We study the limit-cycle dynamics parameter space as a function of pump parameters (detuning, power). Unexpectedly, we find that in a region of this parameter space the microwave resonance is irremediably destroyed: Only a dramatic power reset can restore the dynamics to its original state. The phenomenon can be understood as an optical instability linked to the Kerr nonlinearity of the cavity. A theory supporting this claim is presented, reproducing almost quantitatively the measurement. This remarkable feature might be further optimized and represents a new resource for quantum microwave circuits. Published by the American Physical Society 2024

Polarization self-modulation in a coaxially end-pumped orthogonally polarized laser

A scheme of orthogonally polarized laser (OPL) with polarization self-modulation (PSM) in the coaxial end-pumping configuration is proposed in this work. The gain medium consisted of two Nd:YVO4 crystals with orthogonal optical axes, and a quarter-wave plate served as a polarization-switching device. By rotating the electric vector during each cavity round trip, frequency degeneration and correlated operation of two polarization components were achieved. The polarization eigenstates in two orthogonal directions were analyzed using the Jones matrix and eigenequation. The spectral distribution was also briefly discussed based on thermal effects. The results showed that two eigenmodes located at 45° and 135° to the crystal axis, respectively, with a frequency difference equaled to half the free spectral range of the resonator. In the experiments, it was found for the first time that the modulation of eigenstates can be realized by adjusting pump parameters (including pump power, beam size, focusing position, and pump wavelength) and cavity anisotropy, which enables the manipulation of degree of polarization (DOP) and monitoring the resonator properties. Overall, tuning the laser polarization eigenstate offers a flexible method to switch the operational states of the OPL, including the longitudinal mode frequency difference, DOP, polarization angle, etc. It is believed this scheme provides a valuable reference to realize compact, high-beam-quality, and robust OPLs for applications such as dual-frequency light source development, precision measurement and polarization control.

Magnonic noise in the parametric spin-wave pumping process

This study investigates magnonic noise in the context of parametric spin-wave pumping in a yttrium iron garnet waveguide. By analyzing the input power dependence of parametric spin-wave spectra, we observed spectrum broadening and the emergence of additional pumping channels. A threshold power of 99.9 mW was determined based on spin-wave voltage. To elucidate magnon dynamics beyond the threshold, magnonic noise was examined, revealing its greater sensitivity to magnon scattering compared to spin-wave voltage. The detection of four-magnon scattering and its power-dependent behavior provides further insights into magnon interactions. Our findings contribute to a deeper understanding of magnon dynamics in parametric pumping, a critical process in magnonics.

Influence of axial distance between impeller and diffuser on the hydraulic performance and flow loss characteristics of bulb tubular pump

Abstract Bulb tubular pumps used in regional water transfer projects consume substantial power. Optimizing the geometric parameters of tubular pumps is crucial for enhancing efficiency and minimizing hydraulic losses. ANSYS CFX is used to investigate the axial distance between the impeller and the diffuser on the hydraulic performance and flow loss characteristics of the rear-bulb tubular pump, and the numerical simulation results are compared with the experimental data. Then, the entropy production theory is introduced to analyze flow losses. As the axial distance increases, the diffuser’s rectification effect on the flow at the impeller outlet deteriorates, leading to increased flow losses and decreased head and efficiency of the device. Flow losses in the bulb tubular pump are ranked from largest to smallest as follows: impeller, outflow channel, diffuser, inlet channel. The impeller exhibits the highest entropy production ratio, reaching 61.05% at an axial distance of 25 mm. By elucidating the energy loss distribution of each component under varying axial distances, this paper offers insights for the hydraulic optimization design of bulb tubular pumps.

Impact of extracorporeal blood pump gap sizes on the performance and hemocompatibility under off-design operation.

Hemocompatibility remains the dominant challenge in rotary blood pumps, and more information on the relationship between individual pump design features, hemodynamics, and blood trauma in various operation conditions is necessary. The study evaluated the variation of gap sizes in extracorporeal blood pumps concerning their influence on blood compatibility, particularly during off-design conditions. We developed a parametric generic blood pump framework for in-silico and in-vitro design feature analysis. Thirty-six designs with varying axial and radial gap sizes between 0.5 mm and 3 mm were generated. CFD was applied to calculate and compare device hemodynamics and evaluate the performance and hemocompatibility during off-design and target operation conditions. The following quantities were analyzed: pressure difference, hemolysis potential, residence times, hydraulic efficiency, and recirculation ratio. The in-vitro prototype showed excellent agreement with in-silico predictions regarding hydraulic performance (R2 = 0.996 with a RMSE = 2.07). Our results show a modest impact of gap size variations ±10% on key metrics. Domain-resolved analyses revealed a significant contribution of the gap regions to the device's overall hemolytic performance, with an increasing contribution for off-design flow rates. Overall elevated hemolysis levels were identified if at least one gap size was held minimal. We introduced and showed the feasibility of a parametric rotary blood pump framework to systematically investigate design feature impact. Results suggest, larger and uniformly sized gaps being overall beneficial regarding hemocompatibility.

Optomechanical entanglement manipulation and switching in a squeezed-cavity-assisted optomechanical system

Quantum entanglement is pivotal in modern quantum technologies, spanning applications from quantum networks to quantum metrology. Controllable quantum entanglement in cavity optomechanical systems has been an enduring pursuit. We propose a unique method for flexible manipulation and switching of optomechanical entanglement in a squeezed-cavity-assisted optomechanical system consisting of a χ(2)-nonlinear optical cavity and an optomechanical cavity. Squeezing the nonlinear optical cavity through parametric pumping allows effective control of light-light and light-vibration interactions within the system. This capability of the squeezed system plays a key role in manipulating quantum entanglement. We find that quantum entanglement between the unsqueezed cavity mode and the mechanical mode can be effectively regulated by adjusting the pump laser parameters. Furthermore, by turning the phase of the pump, we can achieve highly flexible quantum switching between entanglement and separability. Additionally, we demonstrate increased entanglement between the squeezed cavity mode and the mechanical mode when completely suppressing the pump-induced optical input noise. Our findings pave the way not only towards the manipulation and protection of fragile quantum entanglement but also to achieve photon-phonon quantum control by exploiting quantum squeezing.

Generation of strong mechanical squeezing through the joint effect of two-tone driving and parametric pumping

We propose an innovative scheme to efficiently prepare strong mechanical squeezing by utilizing the synergistic mechanism of two-tone driving and parametric pumping in an optomechanical system. By reasonably choosing the system parameters, the proposal highlights the following prominent advantages: the squeezing effect of the cavity field induced by the optical parametric amplifier can be transferred to the mechanical oscillator, which has been squeezed by the two-tone driving, and the degree of squeezing of the mechanical oscillator will surpass that obtained by any single mechanism; the joint mechanism can enhance the degree of squeezing significantly and break the 3 dB mechanical squeezing limit, which is particularly evident in range where the red/blue-detuned ratio is sub-optimal; the mechanical squeezing achieved through this distinctive joint mechanism exhibits notable robustness against both thermal noise and decay of mechanical oscillator. Our project offers a versatile and efficient approach for generating strong mechanical squeezing across a wide range of conditions.

Predictive modeling of flexible EHD pumps using Kolmogorov–Arnold Networks

We present a novel approach to predicting the pressure and flow rate of flexible electrohydrodynamic pumps using the Kolmogorov–Arnold Network. Inspired by the Kolmogorov–Arnold representation theorem, KAN replaces fixed activation functions with learnable spline-based activation functions, enabling it to approximate complex nonlinear functions more effectively than traditional models like Multi-Layer Perceptron and Random Forest. We evaluated KAN on a dataset of flexible EHD pump parameters and compared its performance against RF, and MLP models. KAN achieved superior predictive accuracy, with Mean Squared Errors of 12.186 and 0.012 for pressure and flow rate predictions, respectively. The symbolic formulas extracted from KAN provided insights into the nonlinear relationships between input parameters and pump performance. These findings demonstrate that KAN offers exceptional accuracy and interpretability, making it a promising alternative for predictive modeling in electrohydrodynamic pumping.

Topological pumping in an inhomogeneous Aubry-André model

The Aubry-André model is a fundamental theoretical model that exhibits interesting topological features. In this paper, we examine topologically protected boundary states in the inhomogeneous off-diagonal Aubry-André model. In contrast to the homogeneous case, the inhomogeneity triggers boundary states at phase boundaries that separate two distinct non-trivial topological domains. Remarkably, the topological character of the boundary states is predicted through topological pumping, where a boundary state is transferred from one boundary across the bulk region to the other by adiabatically tuning the pump parameter. Moreover, the role of the off-diagonal modulation strength (λ) on the transfer efficiency of the topological pumping is addressed. To support our results, we investigate the time evolution of a continuous-time quantum walk and show that its spread rate and λ are inversely related. Our work provides a new avenue to harness topological features of the Aubry-André model, where topological pumping can be used for robust quantum transport.

An Innovative Approach to Determine Programmed Intermittent Epidural Bolus Pump Settings for Labor Analgesia: A Randomized Controlled Trial.

Three settings are required on a programmed intermittent epidural bolus (PIEB) pump for labor analgesia: the PIEB next bolus (PIEBnb), PIEB interval (PIEBi), and PIEB volume (PIEBv). The ideal settings for these parameters are still unknown. We hypothesized a mathematical modeling tool, response surface methodology (RSM), could estimate 3 PIEB pump parameters while balancing 3 clinically important patient outcomes simultaneously. The study objective was to use RSM to estimate PIEB settings (PIEBnb, PIEBi, and PIEBv) while maximizing maternal satisfaction, minimizing the need for clinician-administered boluses, and optimizing the ratio of delivered/requested patient-controlled epidural analgesia (PCEA) boluses simultaneously. With institutional ethics approval, a double-blind randomized trial was completed in a tertiary care labor and delivery center. Nulliparous, English-speaking American Society of Anesthesiologists (ASA) physical status II patients aged 18 to 45 years at full term, single gestation in vertex presentation, in spontaneous labor and ≤7 cm cervical dilation were included. Patients with comorbidities, contraindications to neuraxial analgesia, using chronic analgesics, <152 cm, or body mass index (BMI) >45 kg/m 2 were excluded. After informed consent, labor analgesia was initiated using 10 mL ropivacaine 0.2% with 10 µg/mL fentanyl solution and PCEA (volume 6 mL every 10 minutes). Patients were randomized to predetermined PIEB settings. RSM identified 3 pump settings that represented a stationary point that best maximized or minimized 3 outcomes simultaneously: PCEA ratio (a ratio closest to 1), clinician bolus (optimal is 0), and maternal satisfaction (visual analog scale, 0-100, ideal response is ≥90). Of 287 potential participants, 192 did not meet inclusion criteria or declined to participate, and 26 were withdrawn, leaving 69 patients for study inclusion. Using RSM, the suggested PIEB settings for all the primary study outcomes were as follows: PIEBnb = 29.4 minutes, PIEBi = 59.8 minutes, and PIEBv = 6.2 mL. These PIEB settings corresponded to the following clinical outcomes: maternal satisfaction at 93.9%, PCEA ratio at 0.77, and need for clinician bolus at 0.29. The dermatome sensory score was between T10 and T5 in 89% of the patients. The median lowest Bromage score was 4. This novel study used a mathematical model to estimate PIEB pump settings while simultaneously maximizing 3 clinical outcomes. Equally weighted clinical outcomes prevent maximal outcome optimization and may not reflect patient priorities. Future studies or quality improvement endeavors could use RSM methodology to estimate PIEB pump settings targeting optimal values for a single clinical outcome of determined importance to parturients.

РЕЗУЛЬТАТЫ ЭКСПЕРИМЕНТАЛЬНЫХ ИССЛЕДОВАНИЙ НАСОСА-ПОНТОНА ДЛЯ ЛАГУН-НАВОЗОХРАНИЛИЩ

The main methods of preparing organic fertilizers from manure runoff coming from pigbreeding complexes are analyzed. In particular, one of the effective technologies is the technology of homogenization of runoff in lagoons-manure storages. The purpose of the article is to substantiate the design and parameters of the pontoon pump for homogenization and pumping of liquid organic fertilizers (LOF) from lagoons-manure storages. The analysis of studies on the problem of homogenization and pumping of LFO from lagoons-manure storages made it possible to formulate scientific prerequisites for improving the working process of mixing manure runoff in manure storages and pumping them to the place of application to the soil. Their essence lies in the substantiation of the design parameters of the transporting screw - length, diameter and frequency of its rotation. A new design of the pontoon pump is described and a diagram of its location when changing the depth of the lagoon-manure storage is presented. A diagram of the working process for the pontoon pump, consisting of three stages, is developed. The pump flow rate, the total specific energy of the pumped liquid at the pump outlet, and the pressure created by the conveying screw are determined. The analysis of the forces applied to a point in the conveying part of the pontoon pump is performed, which made it possible to determine the trigonometric functions of the angular parameter. Research is conducted using the multifactorial experiment technique. An analytical dependence of the change in the pump pressure on the diameter of the conveying screw casing and the length of the conveying screw at a constant screw rotation frequency is obtained. A graphical dependence of the response surface is constructed. The obtained design parameters ensure the efficient flow of the working process of pumping ZOU from the manure storage lagoon with the specified parameters of pressure and flow rate.

Theory and analytical solutions to wellbore problems with hardening/softening Drucker-Prager models

Recognizing and quantifying the elasto-plastic nature of underground formations is critical for various subsurface operations such as drilling, stimulation, production, injection, and storage. In the case of geological CO2 storage, for instance, it is key to identify storage sites characteristics and pumping parameters that lead to safe and perennial CO2 trapping. In this work, we investigate different rock hardening/softening behaviors with the Drucker-Prager model: cohesion hardening/softening, friction hardening/softening, and their combination, jointed hardening/softening. Our focus is to solve the elasto-plastic deformation analytically in the vicinity of a wellbore. The three hardening/softening formulations predict different mechanical responses and stress-paths for solving the same wellbore problem with excavation. The analytical solutions for 2D axisymmetric problems with different hardening laws are provided in this study and verified with corresponding numerical results. This approach can be used to interpret field observations and calibrate experimental data with more comprehensive models. These new laws are implemented and benchmarked in GEOS, an open-source advanced numerical simulator of subsurface formations. This study enhances our understanding of subsurface rock's elasto-plastic behavior and offer analytical references for interpretating experimental measurements and developing numerical simulations for solving wellbore problems.

Tunable Stochastic State Switching in 2D MoS2 Nanomechanical Resonators with Nonlinear Mode Coupling and Internal Resonance.

Coupled nanomechanical resonators have unveiled fascinating physical phenomena, including phonon-cavity coupling, coupled energy decay pathway, avoided crossing, and internal resonance. Despite these discoveries, the mechanisms and control techniques of nonlinear mode coupling phenomena with internal resonances require further exploration. Here, we report on the observation of stochastic switching between the two resonance states with coupled 1:1 internal resonance, for resonant two-dimensional (2D) molybdenum disulfide (MoS2) nanoelectromechanical systems (NEMS), which is directly driven to the critical coupling regime without parametric pumping. We further demonstrate that the probability of state switching is linearly tunable from ∼0% to ∼100% by varying the driving voltage. Furthermore, we gradually increase the white noise amplitude and show that the probability of obtaining the higher-energy state decreases, and the stochastic switching phenomenon eventually disappears. The results provide insights into the dynamics of coupled NEMS resonators and open up new possibilities for sensing and stochastic computing.

The Study Design of a Double-Action Plate Vacuum Pump

Rotary plate vacuum pumps have become widely used as a source of vacuum for milking systems. The main features of a plate vacuum pump include design simplicity, high efficiency, low cost and adaptability to climatic conditions. A plate vacuum pump requires the improvement of specific performance indicators. This refers to the indicator of specific productivity and specific energy intensity. It is possible to improve the vacuum pump by optimizing the design parameters and technological models of operation. The known studies allow the establishment of rational geometric parameters, the number of plates, the ratio of the main dimensions and eccentricity. However, the problem of reducing the degree of uneven air pumping from the vacuum system needs a scientific solution. The use of a vacuum cylinder in a vacuum line of an increased diameter partially solves the problem of vacuum pressure fluctuations. But such a decision requires additional material costs. In addition, the power of a vacuum pump increases to compensate for the pressure losses. In this study, the authors proposed the design of a double-action plate vacuum pump. It was proven that the simultaneous operation of combined rotors with plates shifted by 45° decreased the degree of air pumping by 7.8%. The research results indicated that the productivity of the developed vacuum pump increased by 13.6%. The drive power increased by 12%, and the specific energy intensity was 20% lower than that of vacuum pumps with similar geometric parameters. The relationship between rational kinematic and design parameters of a double-action vacuum pump was established.

A novel pump-thermal synergistic pressurization process for an efficient liquid hydrogen refueling station system

The traditional 70 MPa liquid hydrogen (LH2) refueling stations (HRSs) require LH2 pumps with high outlet pressures, leading to high initial investment, energy consumption, and difficulty in developing an LH2 pump meeting requirements. Existing LH2 HRSs using thermal compression eliminate the need for pressurization equipment but result in significant waste due to low-pressure hydrogen venting. Therefore, we have pioneered a novel pump-thermal synergistic pressurization process for an efficient LH2 HRS system. The process utilizes a 45 MPa LH2 pump and an electric heating method, allowing easily controllable heat input. This study constructs a thermodynamic model for this system that includes the dynamic operational processes of all core components. Based on the established model, the outlet parameters of the LH2 pump, characteristic parameters of the pressure vessel, the refueling process, and the operation of the entire system are investigated. By dynamic simulation of the whole HRS system with pump and thermal compression, it is found that the specific energy consumption for hydrogen refueling is reduced to 0.55 kWh/kg, with the pump consuming 0.2 kWh/kg while thermal compression consuming 0.35 kWh/kg. After optimizing control strategies, the cycle venting of the pressure vessel and the residual hydrogen gas after re-heating and pressurization account for only 11.6%, and further utilization through the pump pressurization cycle can achieve high utilization with no residuals. This system effectively reduces the initial investment and energy consumption for LH2 HRSs. It simplifies the structure, facilitating the retrofit of existing stations and promoting the construction and application of HRSs.