Typical Operating Conditions Research Articles

Performance of a sedimentation tank for standing column wells coupled with geothermal heat pump systems

Performance of a sedimentation tank for standing column wells coupled with geothermal heat pump systems

Numerical and Experimental Investigations of a Double‐Suction Pump With a Middle Spacer and a Staggered Impeller

ABSTRACTDouble‐suction pumps are among the most commonly used mechanical devices in irrigation and drainage. To investigate the effects of the impeller configuration with a spacer and staggered arrangement on the internal flow field and radial force characteristics of a double‐suction centrifugal pump, a comparison investigation was conducted using the same type of pump with three different impeller configurations: a symmetrically arranged impeller without a spacer, a symmetrically arranged impeller with a spacer and a staggered 25° arrangement impeller with a spacer. This study employed a combination of experimental and numerical simulation methods to analyse changes in the head, efficiency, transient radial force and internal flow field under three typical operating conditions. The results indicate that the staggered 25° arrangement impeller with a spacer results in a higher head and efficiency than both the symmetrically arranged impellers without a spacer and those with a spacer across most working conditions. Furthermore, the efficiency improvement is most significant at low flow rates for the staggered 25° arrangement impeller with a spacer compared with the other configurations. In terms of the internal flow field, the addition of a spacer and staggered 25° arrangement impeller effectively reduces the high‐velocity flow, making the pressure distribution gradient more reasonable and the turbulent kinetic energy distribution more uniform. Additionally, adding spacers and employing staggered arrangements effectively reduces the steady‐state radial forces as well as the main frequency amplitude of the radial force fluctuations on the impeller. This improves both the high‐velocity flow structure attenuation rate and outlet flow stability for double‐suction impellers. By comparing and analysing the external characteristics, internal flow field and radial force characteristics of different impeller configurations, this study proposes an improved impeller scheme based on a spacer and staggered arrangement, which provides a new optimization idea for improving the efficiency and stability of double‐suction centrifugal pumps in irrigation systems.

Topological Scheme and Analysis of Operation Characteristics for Medium-Voltage DC Wind Turbine Photovoltaic Powered Off-Grid Hydrogen Production System

Renewable energy has high volatility in the traditional off-grid AC hydrogen (H2) production system, which leads to low reliability of the system operation. To address this issue, this paper designs the topology scheme of wind-photovoltaic generation powered off-grid H2 production system. Firstly, a DC off-grid system topology scheme with the wind turbine (WT) and photovoltaic (PV) is connected to the medium voltage DC bus by two-stage conversion is proposed. The power fluctuation of WT and PV generation systems and the power-adjustable characteristics of electrolyzers are taken into consideration. Meanwhile, the scheme of distributed access of energy storage (ES) to the WT side and PV side to provide the voltage support for the system is proposed. Secondly, the operating characteristics of DC microgrids and AC microgrids under abnormal operating conditions, such as the fault of the source side, the fault of the load side, and communication interruption, are analyzed in this paper. Finally, the electromagnetic transient simulation model of the DC off-grid H2 production system and the traditional AC off-grid H2 production system is established. The effectiveness of the proposed topology scheme is verified by simulation of typical operating conditions.

Prior Knowledge-Based Two-Layer Energy Management Strategy for Fuel Cell Ship Hybrid Power System

Implementing energy management is crucial in the fuel cell and battery or supercapacitor hybrid energy systems of ships. Traditional real-time energy management strategies often struggle to adapt to complex operating conditions; to address this issue and mitigate fuel cell fluctuations during real-time operations while extending the lifespan of lithium-ion batteries, this paper proposes a two-layer energy management system (EMS) based on prior knowledge of ship operation. In the first layer of the EMS, which operates offline, dynamic programming (DP) and low-pass filtering (LPF) are used to allocate power optimally for different typical ship operating conditions. Distribution results are then used to train an SSA-BP neural network, creating an offline strategy library. In the second layer, operating in real-time, the current load power is input into a support vector machine (SVM) to classify the current operating condition. The corresponding strategy from the offline library is then selected and used to provide energy distribution recommendations based on the real-time load and the state of charge (SOC) of the lithium-ion batteries and supercapacitors. The proposed EMS was validated using different ship load cycles. The results demonstrate that, compared to second-order filtering-based real-time energy management strategies, the proposed method reduces fuel cell power fluctuations by 44% and decreases lithium-ion battery degradation by 28%. Furthermore, the simulation results closely align with the offline optimization results, indicating that the proposed strategy achieves near-optimal energy management in real-time ship operations with minimal computational overhead.

Mathematical Models of Gas in Hydropneumatic Accumulators Used in Numerical Tests of Drive Systems with Energy Recovery

In recent years, multiple studies have been carried out on drive systems with energy recovery that are composed of hydropneumatic accumulators. In preliminary studies, these drive systems are frequently tested by computer simulation. Various mathematical models of gas in the accumulator have been used in different studies. It is not clear whether the results obtained by assuming various gas models can be directly compared with each other. In this study, the gas models most frequently used in practice are presented and evaluated in terms of the accuracy in predicting the efficiency of energy recovery from a hydropneumatic accumulator; five different gas equations of state are assessed, as well as various methods for calculating the specific heat capacity at constant volume. Typical methods used in mathematical models to describe the heat transfer between the hydropneumatic accumulator and the environment are discussed. The results of this study show that all real gas models can precisely predict the efficiency of energy recovery from the accumulator in typical operating conditions. However, neither the models based on the ideal gas law nor the models neglecting the heat exchange with the environment are accurate enough for studies in that field. In the last part of this paper, the models of gases in hydropneumatic accumulators implemented in selected commercial software are described and tested against the model developed by the author in Matlab.

Vibration Suppression of Concrete Pump Boom During Pumping by Feedforward Control Method

In this paper, boom of truck-mounted concrete pump is taken as the research object. Firstly, both mathematical and simulation models of the boom system are constructed, then vibration characteristics of the boom, especially vibration state of pump truck chassis are analyzed. According to the results of this theoretical analysis, a feedforward control method based on least mean square (LMS) algorithm and the finite impulse response (FIR) filtering algorithm is proposed to suppress the vibration of truck-mounted concrete pump boom which is mainly caused by the operation of pump system. After that, proposed feedforward control method simulation model is established; the effect on vibration suppression performance of it is analyzed. According to the simulation results conducted under three typical operation conditions, acceleration at the end of the boom decreases by 39.3% ~ 52.0% after the feedforward control force is applied. Therefore, it can be seen that the adaptive FIR-based feedforward vibration suppression algorithms designed in this paper can effectively suppress the vibration at the end of the boom.

Flow-Induced Stress Analysis of a Large Francis Turbine Under Different Loads in a Wide Operation Range

Francis turbines, being widely used in hydropower plants, operate under different loads which significantly affect their hydraulic characteristics and structural dynamics. It is essential to carry out the flow-induced dynamics analysis of the large prototype Francis turbines under different loads in a wide load operation range to optimize the hydraulic performance, ensure structural reliability, and prevent mechanical failure. This work analyzes the flow-induced dynamics of a large Francis turbine prototype with a rated power of 46 MW. Computer-aided design (CAD) models of the Francis turbine unit are first constructed, including the fluid and structural domains. After generating the computational meshes of the flow passages in the Francis turbine unit, Computational fluid dynamics (CFD) calculations are carried out under four typical operating conditions from 25% load to 100% load, and the pressure files obtained from CFD calculations are applied to the finite element model to analyze the flow-induced stresses of the runner. The results show that the pressure inside the Francis turbine runner decreases gradually from the spiral case to the draft tube under 25%, 50%, 75%, and 100% loads, but the local pressure distribution in the crown chamber of the Francis turbine unit varies under different loads. The locations of the maximum stress of the runner under the four different operating conditions vary with the power output. The flow-induced maximum stress of the runner at 25% load is located on the chamfer of the connection between the blade trailing edge and the crown. But from 50% load to 100% load, the maximum stress of the runner appears on the chamfer of the connection between the blade leading edge and the band. From 25% load to full load, the maximum stress of the unit is one-fifth of the yield stress of the runner material, and the runner will not be damaged during normal use. The calculation method with a fully three-dimensional fluid–structure interaction (FSI) method and the conclusions proposed in this study can provide important references for the design and evaluation of other hydraulic turbine units.

Calibration of hydroxyacetonitrile (HOCH2CN) and methyl isocyanate (CH3NCO) isomers using I− chemical ionization mass spectrometry (CIMS)

Abstract. The toxic reduced nitrogen compound methyl isocyanate (CH3NCO, MIC) has been reported as present in wildfire and biomass burning emissions, agricultural fumigation plumes, and indoor air. Its isomer, hydroxyacetonitrile (HOCH2CN, glycolonitrile, or HAN) has not been observed in the Earth's atmosphere to date. In this study, absolute sensitivity calibrations for these isomers using two I− chemical ionization mass spectrometry (I-CIMS) instruments, the time-of-flight (ToF) and quadrupole (Quad) instruments, commonly used in laboratory and field measurements, were performed, for the first time, over a range of ion-molecule reactor temperatures (10–40 °C) and I(H2O)− / I− ratio (0.01–1). This study demonstrates that I-CIMS, under typical operating conditions, is not sensitive to MIC with limits of detection (LOD) of > 860 and > 570 ppb for the ToF and Quad I-CIMS instruments, respectively. Both I-CIMS instruments are, however, highly sensitive to the HAN isomer with 0.3 and 3 ppt LODs for the ToF-CIMS and Quad-CIMS instruments, respectively. The present results show that several recent field studies using I-CIMS instrument detection have misattributed the C2H3NO signal to MIC. This study proposes that HAN rather than MIC was most likely the C2H3NO isomer observed in those field studies, although the source chemistry for HAN remains uncharacterized. This study demonstrates the importance of applying absolute calibration standards in the identification and quantification of isomeric compounds.

Assessment of Cyanotoxins Removal Efficiency Using a Simulated Drinking Water Treatment Process for Downstream Source Water of the Nakdong River

Objectives : This study aims to evaluate the removal rates of nine cyanotoxins produced by cyanobacteria using a laboratory-scale simulated drinking water treatment process (DWTP), providing useful data for DWTP operations during algal blooms.Methods : A lab-scale simulated DWTP was used to evaluate the removal rates of nine cyanotoxins under typical operating conditions, including specific chemical dosages and contact times. The study employed chlorine and ozone, as well as powdered activated carbon (PAC) and biological activated carbon (BAC).Results and Discussion : According to the experimental results of removal efficiency for chlorination and ozonation, microcystin-LR (MC-LR), MC-RR, MC-LA, MC-LF, MC-LY, MC-YR, cylindrospermopsin (CYN), and nodularin (NOD) were effectively removed within the typical ranges of pre- and post-chlorine and pre- and post-ozone concentrations in the DWTP. However, anatoxin-a (ANA) exhibited a significantly lower removal efficiency. The evaluation of removal efficiency for PAC treatment indicated that MC-LA, MC-LF, and MC-LY had low removal rates. In contrast, the other six cyanotoxins achieved over 50% removal when PAC concentrations were above 25 mg/L and contact times exceeded 30 minutes. The evaluation of removal rate for BAC treatment showed that under conditions with an empty bed contact time (EBCT) of more than 5 minutes, over 70% of the nine cyanotoxins were removed. When the EBCT exceeded 2 minutes, removal rates reached between 95% and 100%. In the BAC process, the removal of MC-RR was primarily facilitated by the biodegradation, while the removal of CYN was mainly achieved through adsorption.Conclusion : Due to climate change, the bloom periods of various cyanobacteria in domestic water sources are gradually increasing, resulting in a rising trend in both the frequency and concentration of detected cyanotoxins. This study evaluated the removal efficiency of various cyanotoxins in DWTPs, focusing on chlorine/ozone treatment (oxidation), PAC treatment (adsorption), and BAC (adsorption and biodegradation). The different DWTPs at the facility act as multiple barriers, effectively removing cyanotoxins upon their introduction.

Numerical Analysis of Operation Characteristics in Thermal Driven Adsorption Systems with Different Adsorbent Packing Method

Waste heat generated from industrial processes, such as data centers, is often discarded due to its low temperature, making reuse difficult. Adsorption systems have been proposed as a solution to utilize this low-grade waste heat. These systems consist of adsorption beds, an evaporator, and a condenser, with the adsorption bed—typically comprising a fin-tube heat exchanger and adsorbents—playing a central role in system operation. The adsorbent facilitates adsorption and desorption processes, driving system functionality. Two primary methods exist for packing the adsorbent into the adsorption bed: filling the void spaces around the heat exchanger with adsorbent particles, and coating the surface of the heat exchanger fins. These different packing methods affect the heat and mass transfer characteristics of the adsorption bed and, consequently, influence the overall system performance. This study presents a numerical analysis of the operational characteristics of an adsorption system using two distinct adsorbent packing methods, and evaluates their performance. Under typical operating conditions with a heat source temperature of 80°C, the coating model demonstrated a cooling capacity of 2.05 kW, an SCP of 0.117 kW/kg, and a COP of 0.333. Compared to the packing model, the coating model achieved 41% and 61% increases in cooling capacity and COP, respectively. Notably, the SCP showed a significant improvement of 153%. These results indicate that, despite using less adsorbent, the coating model not only offers better system performance but also presents a more economical approach to adsorption system development.AcknowledgementsThis work was supported by Korea Institute of Energy Technology Evaluation and Planning(KETEP) grant funded by the Korea government(MOTIE)(No. 20202020800200, Development and demonstration of smart design platform technology for thermal energy-intensive industrial facilities).

Proton Incorporation and Electrical Leakage in BaZrO3 and BaCeO3

Molecular hydrogen (H2) is a vital next-generation energy carrier, due to its high energy density, universal abundance, and ability to produce electricity in a fuel cell without greenhouse gas emissions. Critical to the adoption of hydrogen energy is the ability to produce H2 cleanly via the electrolysis of water. Solid oxide electrolyzer cells (SOECs) are attractive technologies to achieve this goal, as they can use excess thermal energy or other renewable energy sources to convert water into H2. However, the fundamental physics that determines the performance of SOECs—including sources of performance loss and degradation—is relatively poorly understood.Here, we describe first-principles calculations based on hybrid density functional theory (DFT) aimed at studying efficiency loss in proton-conducting SOECs based on the oxide electrolytes BaZrO3 (BZO) and BaCeO3 (BCO). These materials are acceptor-doped with a trivalent element such as yttrium to introduce protons; however, such doping can also increase electrical leakage in devices, which limits their Faradaic efficiency. Our calculations describe the properties of localized polarons in BZO and BCO: hole polarons form favorably in both materials, while electron polarons are only stabile in BCO and in Ce-containing alloys. Under typical operating conditions, large concentrations of hole polarons may be present; therefore, to limit the risk of p-type electrical leakage, it is advantageous to avoid extreme oxygen-rich conditions and high dopant concentrations [1].High ionic conductivity also requires large proton concentrations. We examine avenues to achieve this requirement by calculating the formation energy of protons and their concentrations under various conditions. Proton concentrations will be highest under wet conditions, with oxygen vacancies becoming more dominant under drier conditions. Encouragingly, higher protonation levels correlate with lower concentrations of hole polarons, implying lower electrical leakage with higher hydration levels. In addition to traditional protonation pathways, we also explore a novel hydrogenation mechanism via hydroxyl incorporation, which does not require acceptor doping. However, this process is unfavorable except under extremely wet conditions [2].These results provide crucial insights for understanding the complex behavior of these materials in situ. Determining how to promote ionic conductivity at the expense of electrical leakage is critical to optimizing their performance in SOECs and related devices.This work was performed under the auspices of the U.S. DOE by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.[1] A. J. E. Rowberg, M. Li, T. Ogitsu, J. B. Varley, Phys. Rev. Mater. 7, 015402 (2023).[2] A. J. E. Rowberg, M. Li, T. Ogitsu, J. B. Varley, Mater. Adv. 4, 6233-6243 (2023).

Modeling Analysis of the Impact of Platinum Oxides and Cerium Ion Migration on PEMFC Performance and Degradation Under a Realistic Driving Cycle

The sluggish oxygen reduction reaction (ORR) kinetics represents the major source of efficiency loss in a Proton Exchange Membrane Fuel Cell (PEMFC) [1]. In the potential range where fuel cells operate, several platinum (Pt) oxide species form on the catalyst surface [2]. Their formation and reduction is a dynamic process which strongly influences ORR activity and the loss of electrocatalyst active surface area (ECSA) [3]. PEMFC performance and durability are also significantly affected by Cerium (Ce) ions which, under typical operating conditions, are known to migrate through the polymer electrolyte membrane (PEM) and the catalyst layers (CLs) driven by concentration and potential gradients [4]. Such mobility reduces scavenging efficacy, thus accelerating PEM degradation. Moreover, it affects cell performance since the progressive build-up, during normal fuel cell operation, of Ce ions into the cathode CL is found to decrease proton conductivity [5] and hinder oxygen diffusion through the ionomer film [4], as highlighted by the most recent literature. In this scenario, a 1+1D multiphase dynamic non isothermal PEMFC model of performance is developed [6]: the close relationship between ORR reaction and Pt oxide dynamics is investigated by modeling oxides formation/reduction with a four-step oxidation mechanism which involves three different types of oxide species. Furthermore, based on the work of [2], the effects of ionomer sulfonate groups adsorption onto platinum surface and of local relative humidity are also included in the ORR kinetics. As visible in Figure 1(a), the proposed ORR formulation allows to properly capture cell voltage dynamics under the operating conditions of the automotive ID-FAST cycle [7]. The PEMFC model of performance also accounts for Ce ions mobility, both in the along-the-channel and through-the-membrane directions: for this purpose, a Nernst-Planck equation is adopted, where the diffusivity and migration coefficients are properly calibrated and validated (Figure 1(b)) by reproducing the Ce ions migration profiles reported in the literature for different current density [5].Lastly, the 1+1D multiphase dynamic non isothermal PEMFC model is coupled with a physical-based 0D model of platinum degradation [3]. The presented model framework is validated on experimental data gathered on a segmented hardware and representative of 600 cycles in the low power conditions of the automotive ID-FAST driving cycle load protocol [7]: as visible in Figure 1(c), the 67% of the initial ECSA is lost. Succeeding in the prediction, this modelling structure aspires to provide critical information for the development of proper mitigation strategies aimed at extending the lifetime of PEMFC stacks.This work received support from the Italian government Progetto PERMANENT - BANDO MITE PNRR Missione 2 Investimento 3.5 A - RSH2A_0O0012.[1] H.A. Gasteiger et al., Activity benchmarks and requirements for Pt, Pt-alloy, and non-Pt oxygen reduction catalysts for PEMFCs, Appl. Catal. B Environ. 56 (2005) 9–35. https://doi.org/10.1016/j.apcatb.2004.06.021.[2] A. Kongkanand et al., Platinum Surface Oxide and Oxygen Reduction Reaction Kinetics during Transient Fuel Cell Operation, J. Electrochem. Soc. 170 (2023) 094506. https://doi.org/10.1149/1945-7111/acfbbb.[3] E. Colombo, Understanding and mitigating degradation of PEMFC caused by real automotive operation, (2023). https://hdl.handle.net/2027.42/155288.[4] A.M. Baker et al., Cerium Ion Mobility and Diffusivity Rates in Perfluorosulfonic Acid Membranes Measured via Hydrogen Pump Operation, J. Electrochem. Soc. 164 (2017) F1272–F1278. https://doi.org/10.1149/2.1221712jes.[5] V.M. Ehlinger et al., Modeling proton-exchange-membrane fuel cell performance/degradation tradeoffs with chemical scavengers, JPhys Energy. 2 (2020). https://doi.org/10.1088/2515-7655/abb194.[6] F. Verducci et al., Dynamic Modeling of Polymer Electrolyte Membrane Fuel Cells Under Real-World Automotive Driving Cycle with Experimental Validation on Segmented Single Cell, Renew. Energy. (Currently under review).[7] E. Colombo et al., PEMFC performance decay during real-world automotive operation: Evincing degradation mechanisms and heterogeneity of ageing, J. Power Sources. 553 (2023) 232246. https://doi.org/10.1016/j.jpowsour.2022.232246. Figure 1

Stability Study of Doped-PrCoO3 Perovskites as Oxygen Electrodes in Proton Conducting Electrolysis Cells

Within the field of electrochemical systems, perovskite oxides are notable for their high catalytic activity, particularly when they are rich in oxygen vacancies. These materials exhibit oxygen vacancies that have a dual function. These vacancies can enhance targeted reactions by acting as active sites, thereby boosting the overall efficacy of the system. Conversely, they may also initiate a sequence of adverse reactions that weaken the material’s structure and reduce its stability, especially at high temperatures or exposure to high concentration steam or CO2, like the typical operation conditions in proton conducting electrolysis cells (PCECs). Although these materials are widely used as oxygen electrodes in PCECs, the specific structural mechanisms that determine their stability under operation conditions are not well understood. In this work, we employed layered double perovskite PrBa0.5Sr0.5Co1.5Fe0.5O5+δ and rhombohedral perovskite PrNi0.7Co0.3O3+δ to assess their structural stability. The challenging environments of high temperatures and exposure to high concentration steam accelerate potential structural degradation. Through density functional theory calculations and in situ Fourier transform infrared spectroscopy characterization, we demonstrate how lattice octahedra adapt to operational conditions, leading to anisotropic lattice stress and facilitating elemental segregation in different octahedral configurations. Our investigation delves into the atomic-scale intricacies of perovskite oxides, aiming to dissect the interplay between their structure and stability. This understanding could pave the way for developing more robust and effective materials.

Capacity configuration optimization of regenerative braking energy utilization system for electrified railways based on power sharing and energy storage

Capacity configuration optimization of regenerative braking energy utilization system for electrified railways based on power sharing and energy storage

Detecting Geothermal Operational Asset Anomalies Using the Locality-Sensitive Hashing (LSH) Algorithm

Geothermal power plants are crucial for sustainable energy generation, necessitating the reliable maintenance of their operating assets. This research proposes an approach for asset maintenance through anomaly detection using the Locality- Sensitive Hashing (LSH) algorithm. The accuracy and coverage of traditional anomaly detection approaches in geothermal power plants may be constrained by sensor monitoring systems. The LSH algorithm is used to improve detection skills and get a full understanding of the state of important assets. The proposed method utilizes historical sensor data collected during geothermal power plant operations. This data is transformed into hash codes using LSH, effectively capturing similarities between various operational states and asset conditions. By comparing the hash codes of the current operational state with a library of precomputed hash codes representing typical operating conditions, the LSH algorithm can identify deviations indicating potential irregularities. This facilitates early detection of anomalies, even in large-scale databases, enabling prompt maintenance interventions. The application of anomaly detection using the LSH algorithm provides benefits such as improved asset maintenance planning, reduced downtime, and increased operational safety. By leveraging data-driven analysis and the effectiveness of LSH, geothermal operators can detect faults early, enabling prompt interventions and optimizing reliability and efficiency. By leveraging historical sensor data and the efficient similarity approximation capabilities of LSH, the proposed approach enables early diagnosis of problems, improving maintenance planning and optimizing geothermal operations. Keywords: geothermal assets, locality-sensitive hashing, asset condition, fault detection, reliability

Data-driven ship typical operational conditions: A benchmark tool for assessing ship emissions

Data-driven ship typical operational conditions: A benchmark tool for assessing ship emissions

The aluminum and titanium-doped zinc oxide films with improved blocking effect on copper diffusion

The aluminum and titanium-doped zinc oxide films with improved blocking effect on copper diffusion

Optimal planning for hybrid renewable energy systems under limited information based on uncertainty quantification

Optimal planning for hybrid renewable energy systems under limited information based on uncertainty quantification

Computational Fluid Dynamics Analysis and Optimization of a Doublesuction Turbine Agitator

Background: As one of the essential pieces of chemical equipment, a reactor provides the necessary reaction space and conditions for the materials involved in the reaction during the stirring process. However, under typical operating conditions, issues such as uneven gas distribution, suboptimal gas-liquid mixing, and low product yield often arise in gas-liquid phase reactors. Purpose: To address the issues prevalent in current stirred reactors, a new design for a stirred reactor equipped with a double-suction turbine agitator was developed. Method: In this paper, a stirred reactor equipped with a double-suction turbine agitator was designed, and its three-dimensional modeling was conducted using SolidWorks. Computational Fluid Dynamics (CFD) simulations, based on the Euler-Euler two-phase approach with the RNG k −ε turbulence model, were performed to assess variables such as stirring speed, installation height, blade diameter and agitator inner diameter. The dispersion characteristics and flow field behaviors of the gas-liquid two-phase under varying conditions were comparatively analyzed. Optimizations were conducted across various parameters to enhance the gas mixing efficiency in the liquid phase. Result: The results show that a diameter of 370mm for the double-suction turbine agitator, an installation height of 640mm, a blade diameter of 500mm, and an inner hole diameter of 200mm yield optimal gas-liquid two-phase mixing performance. This configuration results in a broad and uniform gas distribution within the reactor, maintaining a desired high level of gas holdup at specific positions. Conclusion: The double suction turbine agitator is a type of radial agitator. During operation, it induces significant centrifugal forces in the liquid, exerts a robust shear effect, and enhances the mixing of the gas-liquid phases, thereby increasing the production efficiency of the product.

A new DC bus voltage control strategy for energy routers based on distributed coordination optimization

Abstract The types of power ports of energy routers at the side of the distribution network platform are complex and have different characteristics, which makes the operation conditions of energy routers complex and changeable. Although many pieces of literature have proposed more relevant control strategies to effectively realize the efficient and stable operation of energy routers under the two basic working conditions of grid-connected and isolated islands. However, when considering various complex operating conditions such as start-up, overload/overcharge, sudden failure of distribution network, grid-connected, and inter-island switching, the reliable operation of the existing energy routers is still faced with great challenges. In this paper, a DC bus voltage control strategy based on distributed coordination optimization is proposed for typical operating conditions of energy routers. Simulation results show that this strategy can effectively achieve the DC bus voltage control performance of energy routers under various burst operating conditions and strengthen the robustness of output voltage of energy routers under isolated islands.