Pump Energy Research Articles

Research on hybrid power load matching control method of new energy pumping machine

In order to improve the energy saving effect of new energy pumping machine, the power matching energy saving control of wind energy, electric energy and pumping machine load should be carried out when the actual wind speed is lower than the rated wind speed of the system. In this paper, according to the wind power hybrid transmission system, we study the load matching energy saving control strategy and method that takes into account the simultaneous change of wind speed and load, and propose the hybrid power load matching adaptive energy saving control strategy based on the cascade controller. In the strategy, the motor torque control method is used to eliminate the pressure deviation and realize the system pressure tracking load matching adaptive control, while keeping the motor output torque stable.

Nonlinear self-action of ultrashort guided exciton–polariton pulses in dielectric slab coupled to 2D semiconductor

Recently reported large values of exciton–polariton nonlinearity of transition metal dichalcogenide (TMD) monolayers coupled to optically resonant structures approach the values characteristic for GaAs-based systems in the regime of strong light-matter coupling. Contrary to the latter, TMD-based polaritonic devices remain operational at ambient conditions and therefore have greater potential for practical nanophotonic applications. Here, we present the study of the nonlinear properties of Ta2O5 slab waveguide coupled to a WSe2 monolayer. We confirm that the hybridization between the waveguide mode and the exciton resonance in WSe2 gives rise to the formation of guided exciton–polaritons with Rabi splitting of 36 meV. By measuring transmission of ultrashort optical pulses through this TMD-based polaritonic waveguide, we demonstrate the strong nonlinear dependence of the output spectrum on the input pulse energy. We develop a theoretical model that shows agreement with the experimental results and gives insights into the dominating microscopic processes which determine the nonlinear pulse self-action: Coulomb exciton–exciton interaction and scattering to an incoherent excitonic reservoir. Based on the numerical simulation of nonlinear phenomena in our polariton system, we conclude that it may support a quasi-stationary solitonic regime of pulse propagation at intermediate pump energies. Our results provide an important step for the development of nonlinear on-chip polaritonic devices based on 2D semiconductors.

An open superhydrophilic microchannel heat sink for thin film boiling with a high coefficient of performance

Currently, the existing two-phase boiling heat transfer technologies have limitations in extremely narrow spaces and cannot satisfy the high heat flux dissipation requirements of highly integrated and ultrathin devices. In this study, a high-efficiency and low-cost open superhydrophilic microchannel heat sink with a micro/nanocomposite structure, negligible pumping energy, and a high coefficient of performance (COP) was achieved. The wettability and microscopic morphology of the different heat sinks as well as the variation in the critical heat flux (CHF) and heat transfer coefficient (HTC) at different mass fluxes were discussed. When the mass flux was 0.05 kg/m2⋅s, the CHF of the microgrooved composite nanostructured copper (MCNC) heat sink was 173.90 W/cm2, which was 182.80% higher than that of the smooth copper (SC) heat sink and 20% higher than that of the microgrooved copper (MC) heat sink. In addition, the highest CHF of 325.90 W/cm2 was obtained for the MCNC at a 0.15 kg/m2⋅s mass flux. The high CHF of thin film boiling was achieved at a low inlet water pressure. This resulted in a COP of 695,600 for this boiling method, which is a larger value than that in most reports thus far. This study provides a preliminary investigation of the thin film boiling performance for an open microchannel. This may provide a new solution to the challenge of high heat flux dissipation in extreme spaces.

RESEARCH ON THE OPERATION OF THE ELECTROMECHANICAL SYSTEM OF AN AUTONOMOUS PHOTOELECTRIC PUMPING STATION

The work is dedicated to the investigation and analysis of the operation of the electromechanical system of an autonomous photovoltaic pumping station. Photovoltaic pumping stations are essential components of sustainable development, enabling efficient utilization of solar energy for independent water pumping. The study provides a detailed analysis of the structure and operation principles of the photovoltaic pumping station. Key components of the system, such as solar panels, electronic controllers, electromechanical pumps, and energy storage, were studied. Various methods for maximizing energy output from solar panels and optimizing the efficiency of pumping systems were examined. The research results revealed that the effective functioning of the photovoltaic pumping station depends on the precise balance of electromechanical components, optimal utilization of solar energy, and efficient management of electronic systems. Recommendations were put forth for improving the system's efficiency and reliability. Within the study, it was established that a crucial factor in the successful function of the photovoltaic pumping station is the selection of the optimal type of solar panels and their positioning to ensure maximum solar energy collection. The issue of storing excess energy to maintain system stability during periods of limited solar irradiation was also addressed. Moreover, the study included modeling and experimental research of various operational modes of the pumping station, including load variation and solar activity fluctuations. This provided crucial data regarding the dynamics and compliance of system operation with planned parameters. An important aspect of the research was evaluating the efficiency and economic viability of the photovoltaic pumping station in comparison with traditional energy sources for water supply. It was found that in some cases, the use of photovoltaic energy could be a more economically advantageous and environmentally cleaner solution. Overall, the results of this scientific work hold significant practical value for sustainable energy development and the utilization of renewable energy sources. The investigation of the operation of the electromechanical system of an autonomous photovoltaic pumping station contributes to a deeper understanding of the technological, economic, and environmental aspects of such systems. In conclusion, this research provides a deeper insight into the functioning principles of autonomous photovoltaic pumping stations and can serve as a foundation for further studies in the field of renewable energy utilization.

Thermal performance of cold plate based on phase change emulsion for Li-ion battery

A battery thermal management system (BTMS) is responsible for the safety performance of lithium-ion batteries. In this paper, different cooling methods based on phase change emulsion (PCE) containing 10 wt% to 40 wt% paraffin were investigated and compared with a water-cooling system. The three-dimensional thermal simulation results showed that the cooling performance of the mini-channel configuration was better than the baffle plate, fin cooling and jacket cooling methods. Based on the optimized structure of the mini-channel cold plate, the operation conditions for cooling Li-ion batteries were determined to keep the maximum temperature limit of 313 K and maximum temperature difference of 5 K at various discharge rates. There was advantage for the PCE cooling in reducing the pump energy consumption for high discharging rates compared with water cooling. The pump power declined by 24% and 36% for 2.0C discharging when applying the PCE with 25 wt% and 40 wt% paraffin as the coolant, respectively. The cooling with the PCE containing 25 wt% paraffin had 16% less energy consumption for 3.0C discharging.

Configuration mapping of thermally integrated pumped thermal energy storage system

The thermally integrated pumped thermal energy storage possesses the advantages of not being limited by geographical locations and small installation footprint as compared to other large-scale physical energy storage technologies. To promote the power-to-power efficiency of the thermally integrated PTES system, twenty-five kinds of pumped thermal energy storage systems are proposed and evaluated based on thermodynamics and economics. Since the power-to-power efficiency varies much with different system configurations and operating conditions, this paper focuses on developing a kind of configuration selection maps with different thermal storage methods, which can be employed as an effective and rapid decision-supporting tool for a general design of the thermally integrated pumped thermal energy storage system. Furthermore, the energy storage density and the levelized cost of storage of the mapping selected pumped thermal energy storage systems are also investigated. The results indicate that the energy storage density of the PTES with sensible thermal storage is usually lower than 5 kWh/m3, and increases up to 27.7 kWh/m3 when utilizes erythritol as the latent thermal storage material. Whereas the levelized cost of storage is more sensitive to the system configuration than the thermal storage methods, and ranges from 0.35 $/kWh to 0.55 $/kWh under different conditions. In terms of these performance indicators, the PTES system with latent thermal storage employing the double-stage heat pump cycle with flash tank or economizer as charging process and the single stage organic Rankine cycle with waste heat heater as discharging process would be an excellent option.

Design vacuum consolidation considering energy requirement

In designing a vacuum consolidation project, it is desirable to quantify the energy required. Explicit close form equations were derived for calculating energy consumptions during a vacuum consolidation in terms of extracting sealed-in air (Wair1), seepage consolidation of soils (Wsoil), draining out the water collected by PVDs (Wwater), and air-leaking rate into a vacuum consolidation system under a given level of vacuum. It is shown that for an ideal vacuum consolidation (no air-leaking), the energy required is higher but comparable with the work done by gravity force of the same magnitude of fill material induced consolidation. The results of the analysis using the design guides in China and/or Japan indicate that only a few percentages of the required effective pump energy are consumed on seepage consolidation and draining out of water collected by PVDs, and the other is for extracting the leaked-in air or possibly just wasted. Therefore, having a good sealing system, and setting a target range of vacuum pressure instead of a single value may increase the energy efficiency. Shortening the duration of a project by reducing the spacing between PVDs can also be a possible option for saving energy. Finally, a conceptual design flowchart was proposed.

Ecological function performance analysis and multi-objective optimization for an endoreversible four-reservoir chemical pump

Ecological function (E1) based on energy analysis is introduced into endoreversible four-reservoir chemical pump model. Optimization relationship between E1 and coefficient of performance (χ) is obtained. Effects of energy distribution ratio (a) of working fluid, chemical potential ratios (μH/μM and μO/μL) of material reservoirs and mass transfer coefficient ratios (b1, b2 and b3) on the optimal E1 performance are analyzed. Using NSGA-Ⅱ, taking intermediate parameter k (k=1−μ1/μH, where μ1 is chemical potentials of working fluid corresponding to reservoir μH) as optimization variable, and taking χ, dimensionless rate of energy pumping (Σ*), dimensionless E1 (E1*) and dimensionless entropy generation rate (σ*) as objective functions, multi-objective optimization (MOO) is performed, and Pareto frontiers under different optimization schemes are obtained. Deviation indices (D s) are introduced to compare the results of different MOO combinations with three decision-making methods. Trend of E1*−χ is parabolic-like one, there is an optimal χ (χE1*) to maximize E1* (E1max*); When a and μH/μM increase or μO/μL decreases, χE1* increases and E1max* decreases; When b1, b2 and b3 increase, E1max* decreases; When two-objective (σ* and E1*) optimization is carried out, the smallest D (0.3214) is obtained by TOPSIS. MOO can better balance the contradictory relationship of cycle performance parameters and improve the comprehensive performance of chemical pump.

Energy, economic, and environmental evaluation of a solar-assisted heat pump integrated with photovoltaic thermal modules using low-GWP refrigerants

Solar-assisted heat pumps integrated with photovoltaic thermal modules (PVT-HPs) have been extensively studied owing to their superior heating performance. However, the investigation of PVT-HPs using low global warming potential (GWP) refrigerants to replace R134a is required to comply with environmental regulations. This study aimed to investigate the substitutability of R1234yf, R1234ze(E), and R152a in PVT-HPs based on energy, economic, and environmental analyses. The heating performance of heat pumps using these low-GWP refrigerants was measured. Furthermore, transient simulations were performed using transient system simulation software to determine the annual performance of the PVT-HPs using low-GWP refrigerants. Based on the simulation results, the levelized cost of energy (LCOE) and Specific Life Cycle Climate Performance (SLCCP) were evaluated. R152a was the most economical refrigerant, showing a 50% reduction in LCOE compared to R134a because of its lower electricity purchase cost and higher sale cost. Furthermore, the SLCCPs of PVT-HPs using R1234yf, R1234ze(E), and R152a decreased by 16.8%, 17.5%, and 20.8%, respectively, compared to those using R134a. Accordingly, the refrigerant substitutability index of R152a was the highest at 1.431, owing to its superior economic and environmental performance. In conclusion, only R152a was deemed appropriate for replacing R134a in PVT-HPs.

A new static mixer concept for enhanced desalination performance in flow-electrode capacitive deionization (FCDI) systems

Poor electrical conductivity and high pumping energy cost are two major challenges that limit the desalination performance of flow-electrode capacitive deionization (FCDI) systems. In this study, we address these limitations by utilizing low carbon loading suspensions (≤2 wt%) with water-like viscosity in a novel static mixer design, referred to as a membrane-assisted static mixer (MASM). MASMs improved the electrical conductivity of the slurry by minimizing the charge transport distances between the active material and current collector as the ion-exchange membrane was compressed directly against the current collector surface (i.e., zero-gap flow field). Continuous mixing of the active material was achieved by controlling the displacement of the membrane via pressure fluctuations from the peristaltic pumps. A parametric study of three MASM flow field geometries was performed at varying flow rates of 1, 3, 5, 10, 15 and 25 mL min−1 and 0.5, 1, and 2 wt% activated carbon (AC). The best-performing flow configuration (2 wt% AC and 15 mL min−1) showed a high salt removal rate of 4.424 μg NaCl cm−2 s−1 with a total energy consumption of 98.95 kJ mol−1.

Replica symmetry breaking in a colloidal plasmonic random laser with gold-coated triangular silver nanostructures.

Plasmonic random lasers have drawn significant attention recently due to their versatility, low threshold, and the possibility of achieving tunable and coherent/incoherent outputs. However, in this Letter, the phenomenon of replica symmetry breaking is reported in intensity fluctuations of a rarely used colloidal plasmonic random laser (RL) illumination. Triangular nanosilver scatter particles produced incoherent RL action when used in a dimethylformamide (DMF) environment in a Rhodamine-6G gain medium. The use of gold-coated triangular nanosilver as the scatterer in place of triangular nanosilver offered a dual contribution of scattering and lower photo-reabsorption, which caused a reduction in the lasing threshold energy of 39% compared to that obtained with the latter. Further, due to its long-term photostability and chemical properties, a phase transition from the photonic paramagnetic to the glassy phase is observed experimentally in the RL system used. Interestingly, the transition occurs at approximately the lasing threshold value, which is a consequence of stronger correlation of modal behaviors at high input pump energies.

On the Efficiency of Mobile Hydraulic Power Packs Operating with New and Aged Eco-Friendly Fluids

With the increasing environmental awareness, in many applications, ranging from agriculture to industry and logistics, a wider and wider use of eco-friendly fluids is desirable. Although the chemical and biological aspects related to environmental compatibility have been extensively investigated by industries and researchers for obvious environmental reasons, not much literature is available on the performance of hydraulic components and systems operating with eco-friendly fluids, especially on the possible degradation of performance due to fluid aging. This work is aimed at studying the influence of eco-friendly fluids on the performance of external gear pumps for compact mobile hydraulic power units, which are among the most widespread hydraulic devices in the world, for their cost-effective and flexible construction. Once the experimental set-up is implemented to be well representative of the hydraulic power packs’ typical arrangement, pump performance is investigated. Pump energy performance is obtained in terms of volumetric efficiency and torque efficiency. Alongside the traditional fluid, two types of eco-friendly fluid available in the market are tested. Once the comparison is complete, the investigations are devoted to highlighting the impact of fluid aging on the pump performance. The fluids were aged through 2000 h operation under heavy-duty thermo-mechanical stress on a separate set-up and, afterwards, the pump performance was tested again with aged fluids. The results allow the assessment of the influence of different fluids on pump performance and a comparison of the impact of new versus aged eco-friendly fluids. The eco-friendly fluids exert a significant effect on the pump energy profile. The pump overall efficiency increases, marking an up to 5% improvement, depending on the cases. Fluid aging is found to reduce the pump’s overall performance. This paper addresses the key points defining the pump performance and provides new information on the topic. The results are original and represent a fundamental contribution to define the best practices for energy and maintenance management of hydraulic systems and to foster the deployment of further studies on models and simulation tools to catch the effect of the fluid condition.

Optimized terahertz pulse generation with chirped pump pulses from an echelon-based tilted-pulse-front (TPF) scheme.

We successfully demonstrated the generation of single-cycle terahertz (THz) pulses through tilted-pulse-front (TPF) pumping using a reflective echelon in a lithium niobate crystal. By optimizing the pump pulse duration using a chirp, we achieved a maximum pump-to-THz conversion efficiency of 0.39%. However, we observed that the saturation behavior began at a relatively low pump energy (0.37 mJ), corresponding to a pump intensity of 22 GW/cm2. To elucidate this behavior, we measured the near- and far-field THz beam profiles and found variations in their beam characteristics, such as the beam size, location, and divergence angle in the plane of the tilted pulse direction, with the pump energy (intensity). This nonlinear behavior is attributed to the reduced effective interaction length, which ultimately leads to the saturation of THz generation. The results obtained from our study suggest that it is feasible to develop an effective THz source using echelon-based TPF pumping while also considering the impact of nonlinear saturation effects.

Performance investigation and exergoeconomic optimization for a solar-driven direct heating and cooling system

Integrating solar energy with direct heating and cooling (DHC) systems can improve system efficiency and reduce polluting gas emissions. To assist buildings in better selecting a DHC system, an exergoeconomic analysis and optimization model combined with building loads and environmental parameters is proposed. The exergoeconomic optimization model is applied to a novel DHC system based on transcritical carbon dioxide heat pump (TCHP) and solar energy. The sold electricity ratio and operating time ratio are defined to transform the building loads and environmental parameters into specific operating conditions of the system. The compressor discharge pressure is optimized to obtain the lowest total unit exergy cost (UEC) of the DHC system. The exergy, energy, and exergoeconomic performance of the DHC system are analyzed under optimal conditions. The results indicate that when the compressor discharge pressure in the heating mode and cooling mode are 7.31 MPa and 8.93 MPa, respectively, the DHC system has the lowest UEC, 0.629 $/kWh. The total UEC is reduced by 43.56% compared to the reference system. Under optimal configuration, the exergy and energy efficiency of the DHC system are 1.81% and 40.30%, respectively. The sensitivity analysis shows that the exergy and energy efficiency, the total UEC, and the UEC in the heating and cooling modes are positively correlated with the sold electricity ratio. The above results demonstrate that the exergoeconomic optimization methods can provide better assistance in selecting the DHC system.

Study of Fe:ZnSe Laser Exited by Diode Side-Pumped Er:YAG Laser

The performance of a Fe:ZnSe laser was investigated in different schemes of excitation by a pulsed diode side-pumped Er:YAG laser. At the temperature of liquid nitrogen, the Fe:ZnSe laser, pumped by a free running 360-μs Er:YAG laser and demonstrated a pulse energy of 53 mJ with a slope efficiency of 42% relative to absorbed pump energy. When operating at room temperature, two optical schemes were considered. In the first one, the Fe:ZnSe laser crystal was pumped by a Q-switched Er:YAG laser with a passive shutter based on an additional Fe:ZnSe crystalline plate, and the cavities of both lasers were independent. In the second scheme, the cavities of the Fe:ZnSe and Er:YAG lasers were coupled, and the Fe:ZnSe crystal simultaneously served as an active element of the Fe:ZnSe laser and a passive shutter of the Er:YAG laser. Pulses with a duration of less than 200 ns and an energy of ~1 mJ were obtained from the Fe:ZnSe laser with a repetition rate of up to 50 kHz. The experimental waveforms of the laser pulses were approximated by rate equations.

Estimation of mixing efficiency of a small dimictic lake due to surface cooling

The paper presents the results of studying the mixing of the water mass of a small forest dimictic lake at the stage of summer heating. The wind effect is limited by the small area of the mirror (the size of the lake is 80–110 by 400 m) and the forested shores, so in summer the convective mixing mechanism prevails when the lake surface cools at night. Evaluation of the mixing efficiency η was carried out by the integral energy method, based on the calculations of energy pumping and changes in the background potential energy according to the temperature profile transformation. For this purpose, a chain with 13 highly sensitive temperature sensors was used; the measurements were carried out in the middle of summer 2022 for 35 days with a time interval of one minute. Acoustic current profiler’s data were used to estimate turbulent velocity fluctuations and calculate the energy dissipation rate, which made it possible to make an alternative assessment of the mixing efficiency. The value of η ~0,4 was obtained, which significantly exceeds the “canonical” value of 0,17 for the case of wind mixing.

Double-Tongue Worm Shell Structure on Plastic Centrifugal Pump Performance Study

Aiming at the problem of high vibration and high wear of centrifugal pump tongue, this paper proposes a double-tongue volute structure. Under the condition of ensuring the reliability of CFD results, the influence of various combinations of tongue and volute base circle on the turbulent kinetic energy of centrifugal pump and the radial force of impeller is explored. The traditional single-tongue volute centrifugal pump is compared with various characteristic indexes, and the unsteady numerical calculation is carried out based on different working conditions. It is concluded that the double-tongue volute structure can improve the pressure fluctuation at the monitoring points near the tongue. The results show that the double-tongue volute structure can improve the static pressure gradient and velocity gradient of the middle section of the centrifugal pump and reduce the maximum turbulent kinetic energy value at the tongue under small flow conditions. When the working condition is 1.0 Q, the radial force of the impeller of the C-type double-tongue volute reaches the minimum value of 3.03 N, which can effectively balance part of the radial force.

Threshold behavior and tunability of a diffusive random laser.

In this study, it is shown that the dynamics of the lasing threshold and the intensity saturation of a diffusive random laser can be visualized by one spectral feature: the peak wavelength shift (tunability). The varied ink concentration and pump energy were utilized to experimentally induce the peak shift and the lasing threshold dynamics. It was found that the peak wavelength progressively turns from blueshift to redshift upon crossing the lasing threshold. A unique random laser threshold regime instead of a threshold point is revealed. This threshold regime was also compared with those deduced from the replica symmetry breaking and the Lévy statistics, both are the state-of-the-art methods to predict the behavior of a complex system. All three results show the high agreement in terms of unveiling the lasing nature of the random lasers.

Integrating heat pumps into district heating systems: A multi-criteria decision analysis framework incorporating heat density and renewable energy mapping

The implementation of district heating (DH) projects necessitates a thorough and accurate evaluation and planning process. The availability of energy resources is often the key determinant in identifying the suitability of a specific location for district heating applications. Also, it is crucial to consider the other factors during the planning stage: the environment, economics, and technical parameters. This research aims to plan and implement a DH site selection model based on a geographic information system (GIS). This model employs Boolean and fuzzy toolboxes to analyze various layers, followed by the analytic hierarchy process (AHP) to identify the most appropriate locations for district heating in Gaziantep, Turkey. A mixed integer linear programming (MILP) approach is utilized to model proposed energy systems to achieve optimal operation and planning. The study's primary objective is to minimize the levelized cost of energy (LCOE), which encompasses initial costs, operations, maintenance, replacement expenses, and energy demand while also meeting the energy demand. A hybrid energy system that includes solar thermal/photovoltaic (ST, PV) energy, wind turbine (WT), and heat pump (HP) is considered, and its LCOE of optimal size is compared to other scenarios using HOMER simulation software. The results indicate that 270 km2 of the study area is suitable for DH implementation, with 83 km2 being highly suitable. Among the various scenarios, the hybrid energy system with a renewable energy penetration rate of approximately 78% achieves the best LCOE of 0.0442. The study concludes by providing a map of the potential for district heating and a discussion of the strengths and drawbacks of each scenario.

Tunable backward terahertz-wave parametric oscillator centered at a high frequency of 0.87 THz with injection seeding.

We report the first demonstration of a frequency tunable backward THz-wave parametric oscillator (BW-TPO) centered at a high frequency of 0.87 THz using a slant-stripe-type magnesium oxide-doped periodically poled lithium niobate (PPLN) crystal as the nonlinear medium. Down-converted THz and idler beams generate upon excitation of the PPLN with a sub-nanosecond pulsed source of λ = 1064.44 nm. The resulting first idler has a wavelength of 1067.75 nm, equivalent to an oscillation frequency of 0.872 THz as per the spectral line separation from the pump. We also present angle tuning of the BW-TPO frequency ranging from 0.836-0.905 THz through PPLN rotation. The threshold pump intensity for BW-TPO is determined to be 5.6 GW/cm2 while obtaining a conversion efficiency as high as 12.3% at a pump energy (intensity) of 15.25 mJ (8.90 GW/cm2). A reduction of the BW-TPO threshold energy and improved pump-to-idler energy conversion efficiency resulted from injection seeding with a CW laser at the same wavelength as the first idler. The THz output is also directly proportional to seed power.