Pump Mode Research Articles

Pressure characteristics and force analysis of pump turbine in variable-pressure outlet pump mode

A nonstationary numerical simulation was performed on the outlet pressure stabilization and periodic variable-pressure condition of a pump turbine model in the pumping condition. The objective was to dissect the flow mechanism and force characteristics of components within the outlet variable-pressure pumping condition of the pump turbine and to probe into the stability of the pump turbine under such working conditions. Additionally, the alterations in the runner state, pressure distribution, pressure pulsation, as well as the forces exerted on the runner and top cover during this process were analyzed. The results demonstrated that the internal pressure and flow pattern of the pump turbine under variable-pressure conditions fluctuated periodically in accordance with the outlet pressure. An augmented frequency of the outlet pressure variation led to an elevation in the amplitude of the internal pressure change. Nevertheless, a hysteresis difference was observed in the changes of the flow channel pressure and flow pattern. The pressure pulsation in the runner area was influenced by the runner rotation, static and dynamic interferences in the lobe-free area, and the unsteady flow induced by the alterations in the outlet pressure.

Mathematical model of the system performance mode for simultaneous separate well operation

Relevance. The trend of oil production technology development is related to many relevant topics. One of such actual directions is the technology of simultaneous separate well operation, in particular, including two electric centrifugal pumps and double-sided submersible electric motor. The presence of two formations at the bottomhole implies the selection of the optimal layout, technological parameters of pumps pumping oil. Considering production from two independent formations in the well according to the mentioned technology, there is a high need in selection of correct parameters of installations at the design stage. In the absence of correct selection of technological parameters of units at the design stage, further operation of a well with two independent formations can be economically inexpedient, and in some cases unrealizable, which is due to a number of reasons. First, if the necessary underbalance is not provided for each particular formation, counterflow of fluid may occur and one of the pumps will not participate in the production process. Secondly, when operating an arrangement, which capacity significantly exceeds the capacity (fluid flow from the reservoir) of the well, there is a possibility of pumping failure and, as a consequence, there is a risk of potential failure. In this regard, an extremely urgent task at the moment is to ensure correct selection of technological parameters of electric centrifugal pump units used in simultaneous separate operation of wells with two independent formations. Aim. Development of a mathematical model that allows selecting the optimal technological parameters of the arrangement consisting of two electric centrifugal pumps and a double-sided submersible motor, used for simultaneous separate operation of wells with two independent formations. Methods. Numerical simulation methods for analyzing the operation mode of electric centrifugal pumps in conditions of oil production from two independent reservoirs. Results and conclusions. It was obtained that the developed mathematical model of the system operation mode for simultaneous separate operation of wells allows to estimate the potential of each individual selected pump during oil production (in time dynamics) by analyzing the depression on each individual reservoir, as well as modeling the process taking into account the potential backflow of liquid and supply failure.

In-situ analysis of water transport properties through a reinforced composite membrane in polymer electrolyte membrane fuel cells

This study presents a comprehensive in-situ analysis of water transport properties through an expanded polytetrafluoroethylene (ePTFE)-reinforced composite membrane, representing a notable advancement over previous studies that primarily focused on Nafion membranes. The membrane water content was measured using dynamic vapor sorption (DVS) isotherms, and the temperature dependence of sorption was investigated using a new dual-mode sorption (NDMS) model, which showed an excellent fit with an adjusted coefficient of determination (Radj2) greater than 0.96. By employing the hydrogen pumping mode and polymer electrolyte membrane fuel cells (PEMFC) mode, we established empirical correlations for the coefficients of water diffusion, electro-osmotic drag (EOD), and ionic conductivity as functions of water content and cell temperature. The correlation results exhibited a maximum relative error of less than 3.14 %. In addition, we isolated the water diffusion coefficients of the gas diffusion layer (GDL) and catalyst layer (CL) from the membrane to refine our analysis. This study enhances the understanding of water management in PEMFCs by establishing correlations for water diffusion, EOD coefficient, and ionic conductivity. These findings underscore the potential of reinforced composite membranes in advancing fuel cell technology by optimizing water transport, which is crucial for improving fuel cell performance and enabling more precise PEMFC modeling.

Investigation of ferromagnetic resonance heating of isotropic superparamagnetic on the example of biogenic ferrihydrite nanoparticles

Ferrihydrite nanoparticles have been synthesized and characterized. The dependences of the temperature increment of powders in the pumping mode by a high-frequency electromagnetic field in a constant magnetic field are studied. It is shown that the experimental dependence of the particle temperature on the dc magnetic field strength is in good agreement with the theory of ferromagnetic resonance for an isotropic superparamagnetic.

Laboratory Determination of Absorption Refrigeration Cycles

A methodology for experimentally particularizations and analyses of thermodynamically cycles of the binary mixture at laboratory diffusion absorption refrigerators is developed. It allows estimation of the performances of the unit at cooling and heat pump mode for scientifically and education purposes. Тhe developed approach will be used to educate students in the courses of thermodynamics and renewable energy systems about the applications of the absorption cycles for utilisation of solar or waste energy for cold and heat production.

ABSORPTION REFRIGERATION SYSTEMS FOR WASTE HEAT RECOVERY AT THE SILICATE INDUSTRY

The glass, ceramic and cement plants are energy intensive industrial systems, releasing high amounts of greenhouse gases. The dissipation of the waste heat reduces their profitability, energy and ecological efficiency. The absorption refrigeration systems are successful solutions for the recovery of thermal energy at different temperature levels to obtain useful cooling and heating powers for technological needs, and for air conditioning of administrative and industrial buildings. Although the absorption units in a heat pump and refrigeration cycle are currently used in building and industrial systems, they have not yet penetrated widely into the silicate factories. This paper discusses possibilities for the applications of basic types of absorption cycles at heat pump and refrigeration modes to utilize waste energy at different temperature levels in glass, ceramic and cement plants. The examined variants are demonstrated via examples, diagrams and analyses of the possible energy saving.

Preloading Clearance Effects on Hydrodynamic Characteristics of Preloading Spiral Case and Concrete in Pump Mode

Preloading Clearance Effects on Hydrodynamic Characteristics of Preloading Spiral Case and Concrete in Pump Mode

Chaotic Analysis of the Reversible Pump Turbine Exhaust Process in Pump Mode Based on a Data-driven Method

Due to the important strategic position of Pumped Storage Power Plants (PSPP) in global energy upgrading, conducting in-depth research on the various operating conditions of pump turbine units is important for their safe and stable operation. This study sought to clarify the gas–liquid phase motion and the nonlinear chaotic characteristics of the process of exhaust and pressurization in pump mode; with the simplified objective model proposed here, a visualization of the process is achieved using data-driven methods, and the nonlinear characteristics of gas–liquid phase motion during the process are theoretically demonstrated. A method that combines data-driven and chaotic analysis is proposed to qualitatively and quantitatively analyze the force and torque time-series signals of the runner under different exhaust rates. The results indicate that the chaotic characteristics of the force signals and torque signals of the runner are not in a single linear relationship with the exhaust rates. Therefore, this research also provides guidance on exhaust rates with the aim of informing actual engineering practice, the purpose of which is to reduce the vibration amplitude caused by repetitive torque and improve the stability of the unit operations.

Experimental characterization of a reversible heat pump – Organic Rankine cycle pilot plant as a thermally integrated Carnot battery

This paper reports a first detailed experimental characterization of a reversible heat pump – Organic Rankine Cycle pilot plant, presenting its potential as a thermally integrated Carnot battery for efficient energy storage. A total of 150 stationary operating points were investigated in both heat pump and ORC modes. The study analyzes and discusses the main trends and interactions on system and component level. As expected, heat pump and ORC operation show an opposing behavior. While heat pump operation yields a maximum COP of 9.5 at a 15 K temperature lift, the peak net ORC efficiency reaches 4.4 % with a 40 K temperature gradient. If additional storage losses are neglected, this leads to a power-to-power (round-trip) efficiency of up to 41.8 % for the Carnot battery. The absence of a liquid receiver in the ORC mode leads to notable subcooling and increased condensation pressures, impacting the expander’s power generation due to excess refrigerant accumulation. Moreover, the experimental results reveal that the reversible screw machine is the critical factor influencing efficiency. The screw machine’s maximum isentropic efficiencies are 78 % and 66 % in compressor and expander operation, respectively. The reliability of the results was verified by means of an energy balance and reference operating points, underlining high reproducibility. Additionally, potential system improvements were derived from the experimental results. Altogether, this paper successfully proofs the concept of reversible heat pump – ORC systems and provides experimental results for ongoing advancements in this field.

Comparison of measured and calculated high-viscosity crude oil temperature values in a pipeline during continuous pumping and shutdown modes

The paper investigates the stationary and non-stationary cooling processes of high-viscosity crude oil temperature in the Severnye Buzachi – Karazhanbas pipeline during both pump operations and pump shutdowns. To transport high-viscosity crude oil through pipelines, the hot pumping method is employed. During oil transportation and pump shutdowns, the oil temperature decreases due to heat exchange with the environment, leading to an increase in oil viscosity. As viscosity rises, more power is required from the pumps to move the thickened oil, resulting in higher electricity consumption. To avoid increased operational costs after pump shutdowns, it is crucial to accurately calculate the oil cooling temperature in order to determine the safe shutdown duration and a critical temperature threshold. The Shukhov formula is used to calculate oil temperature during transportation, while a modified version is applied during pump shutdowns. To verify the accuracy of the obtained oil temperature results, the calculated values were compared with the measured values from pipeline sensors in both stationary and non-stationary cases. The novelty of the work is in determining the methodology for calculating the safe shutdown time of a pipeline for high-viscosity oil. The proposed formula was validated using experimental data from SCADA system sensors in real-time.

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.

Spectro-spatial analysis of van der Pol-type phononic crystals

Abstract The application of phononic chains as metamaterials demonstrates their remarkable capability to manipulate the propagation of waves. These periodic structures yield frequency-dependent behavior of material comprising characteristics with many possible engineering applications. In this paper, we investigate the weak and general nonlinear behaviors of the van der Pol-type damped phononic chains. The analysis of wave propagation is initially conducted for a one-dimensional structure, and subsequently, is extended to consider the wave motion through two-dimensional and three-dimensional lattices. Results are obtained using the method of multiple scales and a Spectro-spatial analysis by employing the numerical method of the 4th-order Runge–Kutta. A new phase-diagram relation within the chain’s unit cell is also introduced aiming to enhance the numerical findings. Our results indicate that in the weakly nonlinear regime, the van der Pol-type damping closely follows the linear dispersion curve, regardless of the initial amplitude. This suggests a symmetry between energy pumping and dissipation modes, where hardening and softening behaviors align with linear characteristics of common damping mechanisms, such as viscous damping. Additionally, the formulation demonstrates the existence of limit-cycle stability in the motion of each mass. For the general damped system, it is observed that a special frequency exists where the system converges, for all wave numbers similar to the synchronization effect. Hence, the motion and the frequency of all masses are synced. Additionally, non-reciprocal wave propagation is observed, resulting in a bandgap structure with a symmetry breaking occurring near the limit cycle. These results are promising in the fields of wave emitters, wave filters, and signal encryption.

Modelling a low-head seawater-pumped hydro storage system's impeller for energy production within a small island developing state

ABSTRACT The proposed seawater pumped hydro storage (SPHS) is one option for providing a buffered energy storage system that will surely be required in the future. Given the fact that most small island developing states (SIDS) are isolated and surrounded by large bodies of water, the medium of seawater becomes an infinite supply. However, SIDS are also low lying and therefore only low heads will be available at high flows to maximize the energy efficiency of the system. The computational fluid dynamics (CFD) model, ANSYS Fluent, was used to simulate this SPHS pump turbine impeller at low heads and high flows. This pump turbine impeller was simulated to function as both a pump and as a turbine at various revolutions per minute (rpm). The performance of the system was evaluated based on the pressure and velocity distributions of the pump turbine impeller at varying rpm. It was found that there were less energy losses within the turbine mode compared to the pump mode. Furthermore, this study showcases that the CFD model ANSYS Fluent is an economical, efficient, and easily diagnosable technique for analysing an impeller in both pump and turbine modes.

Performance characteristics of a contra-rotating pump-turbine in turbine and pump modes under cavitating flow conditions

Recent studies have indicated the potential of a contra-rotating pump-turbine (CRPT) as a low-head design that enables pumped hydro storage in regions with flat topography. However, the effects of cavitation have scarcely been investigated for the CRPT. The current paper utilises computational fluid dynamics simulations to study a model scale CRPT subjected to cavitating flow conditions to determine how cavitation affects the machine’s operating performance in both pump and turbine modes. In total, eight operating conditions have been evaluated for each mode. The inlet flow rate is considered fixed at 0.27 m3/s, while the outlet pressure is gradually changed to induce cavitating conditions. The study demonstrates that the pump mode operation of the CRPT is more sensitive to cavitation compared to the turbine mode. The pump mode operation shows a steady decline in efficiency with decreasing inlet pressure, whereas in turbine mode the efficiency settles at a lower level. The 3% head drop occurs at a Thoma number of 1.0 in pump mode and at 0.6 in turbine mode. At the 3% head drop, a large cavitating region is already present at the runner blades’ suction side of the runner closest to the lower reservoir in both modes. The large cavitating region causes the flow to separate from the runner blade surfaces, which explains the reduced operating performance. To ensure an almost cavitating-free operating condition and unaffected performance, the Thoma number needs to be above 1.0 in turbine mode and at least 1.5 in pump mode. A frequency analysis reveals that the presence of cavitation affects the dominant pressure pulsations in the system. A dynamic mode decomposition analysis is carried out, demonstrating that the non-trivial pressure pulsations are connected to the support struts.

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.

Theoretical Study on Transverse Mode Instability in Raman Fiber Amplifiers Considering Mode Excitation.

Raman fiber lasers (RFLs), which are based on the stimulated Raman scattering effect, generate laser beams and offer distinct advantages such as flexibility in wavelength, low quantum defects, and absence from photo-darkening. However, as the power of the RFLs increases, heat generation emerges as a critical constraint on further power scaling. This escalating thermal load might result in transverse mode instability (TMI), thereby posing a significant challenge to the development of RFLs. In this work, a static model of the TMI effect in a high-power Raman fiber amplifier based on stimulated thermal Rayleigh scattering is established considering higher-order mode excitation. The variations of TMI threshold power with different seed power levels, fundamental mode purities, higher-order mode losses, and fiber lengths are investigated, while a TMI threshold formula with fundamental mode pumping is derived. This work will enrich the theoretical model of TMI and extend its application scope in TMI mitigation strategies, providing guidance for understanding and suppressing TMI in the RFLs.

Crystal growth, spectra and laser properties of Tm3+ and Ho3+ co-doped GdScO3 crystal

Tm,Ho:GdScO3 single crystal was grown by the Czochralski method. Its quality and effective segregation coefficient of crystal were characterized, and spectral properties of crystal (100) plane were studied. The absorption cross-section of Tm,Ho:GdScO3 at 793 nm is 1.61 × 10−20 cm2 and emission cross-section at 2020 nm is 1.39 × 10−20 cm2. The laser performance of the crystal by 793 nm LD end-pumped was investigated. The maximum output power of 240 mW was obtained with a slope efficiency of 9.1 % in CW(continuous wave) pump mode. In pulse mode, the maximum average output power of 507 mW was achieved. The maximum slope efficiency of 13.7 % was obtained with 100 Hz and 400 μs. The laser wavelength was 2096 nm. The beam quality factors Mx2/My2 were fitted to be 1.81/1.80. These results indicate that Tm,Ho:GdScO3 crystal is a promising candidate medium for near-infrared laser application.

Quantum Entanglement in Nonlinear Coupler with Raman Process

This paper examines the possible quantum entanglement generated in a coupler system consisting of two waveguides, where one waveguide is nonlinear and Raman-active, while the other waveguide only undergoes linear processes. The analytical-perturbative method is employed to investigate the production of entangled states in the given system. The Hillery-Zubairy criterion is employed to examine the possible quantum entanglement between the two fundamental pump modes propagating in both waveguides. We explore the generation of quantum entanglement under different initial conditions and critical design parameters. The simulation results suggest a continuous entanglement that remains until a particular distance of interaction is reached. As the linear coupling parameter increases, the relationship between the maximum reachable distance for entanglement and the degree of entanglement becomes more complex. The study reveals that entanglement experiences significant fluctuations when there is a substantial frequency mismatch between the modes.

Modal gain characteristics of few-mode erbium-doped fiber amplifiers with pump mode beating

Using the linear polarization (LP) mode decomposition method, we theoretically analyze the beat effect between the same polarization components of the vector pump modes and propose a pump beat model of few-mode erbium-doped fiber amplifiers (FM-EDFAs). The relationship of the overlap factor with the signal gain in the beat model is verified by the amplification of LP01 and LP11 modes for the first time, that is, the differential modal gain (DMG) is dependent on the integral of the overlap factor difference over the EDF length. We also simulate the effect of pump mode beating on signal amplification: the modal gain varies periodically with the pump mode phase, and the beat length can affect the fluctuation period and amplitude of the DMG. The DMG can further be reduced by controlling the initial phases of the vector modes and properly designing the beat length of the FM-EDF. The similar process can expand to more signal modes, such as the simultaneous amplification of LP01x, LP11ex, LP11oy, LP21ex and LP21oy modes. The LP mode decomposition method is also applied to the beat effect between signal modes or the amplification of orbital angular momentum (OAM) modes. One can expect to implement an experiment on the FM-EDFA amplification with pump mode beating by optimally designing the FM-EDF structure, using a properly narrow linewidth pump laser and precisely controlling the pump mode coherence.

Study on the influence of guide vane opening on pressure pulsation of pump-turbine under zero flow pump condition

Abstract Reversible pump-turbine is the key equipment of energy conversion in large pumped storage power station, and it is the core of stable operation of power station. Under the pump condition, the internal pressure pulsation law of the pump-turbine has an important influence on the stable operation of the pump. In order to study the pressure pulsation characteristics of pump-turbine in pump mode under zero flow condition, this study carried out unsteady numerical simulation on three kinds of guide vane openings, and analyzed the amplitude frequency characteristics of pressure pulsation in turbine under different head and the influence of internal flow characteristics on pressure pulsation. The research shows that in the pump mode, when the guide vane opening of the turbine increases, the influence of the blade frequency and the shaft frequency on the vaneless area increases, resulting in the maximum pressure fluctuation amplitude in the vaneless area under the pump condition, especially when GVO = 19 °. At the same time, due to the influence of dynamic and static interference, the larger turbulent kinetic energy appears in the vaneless area and the connection between the guide vane flow channel and the runner flow channel, resulting in an increase in hydraulic loss. Both the experimental and simulation results show that the guide vane opening of 19 ° should be avoided to reduce the hydraulic loss in the vaneless area when the turbine is operated under the zero flow pump condition.