Cycle Operation Research Articles

Eco-efficiency of power supply systems for offshore platforms

This study compared from an Eco-efficiency point of view three electricity supply alternatives for oil and gas extraction, preliminary treatment, and distribution activities that occur on floating production, storage, and offloading platforms (FPSO) operated off the coast of Brazil. The performance of autonomous systems (AS), in which independent open-cycle gas turbines generate electricity, was confronted with those achieved, respectively, by a Power Hub (PH) system and by an arrangement that associates the Power Hub system with an offshore wind farm (PHWE). The environmental dimension of the Eco-efficiency indicator was specified based on applying the Life Cycle Assessment technique for the impact categories of Global Warming Potential, Primary Energy Demand, and Fine Particulate Matter Formation. The economic dimension followed a similar approach based on Life Cycle costing (LCC) when considering the same units' construction, operation, maintenance, and dismantling costs. Given the characteristics of Brazilian oil fields, a comparison was made for three different stages of the operation cycle: C1: maximum extraction of oil and gas; C2: equity of volumes extracted from fuels and water + CO2; and C3: minimal extraction, but economically viable, of fuels. The results indicated that the PH and PHWE systems accumulate better environmental performance than the AS system, particularly regarding Global Warming Potential (35 % and 55 %, respectively) and Fine Particle Matter Formation (47 % and 59 % reduction). However, more than these gains are needed to compensate for the same systems' construction, operation, and maintenance investments, which were increased by up to 76 % in the case of PHWE. The study also concluded that the PH technology and its variation involving wind electrification are promising but that research efforts should be made to reduce costs. These results provide elements that can both subsidize designers from O&G companies in developing new extraction technologies and support decision processes conducted by other stakeholders and policy formulators linked to this segment.

Experimental Investigation of a Pulsation Reactor via Optical Methods

Material treatment in pulsation reactors (PRs) offers the potential to synthesize powdery products with desirable properties, such as nano-sized particles and high specific surface areas, on an industrial scale. These exceptional material characteristics arise from specific process parameters within PRs, characterized by the periodically varying conditions and the resulting enhanced heat and mass transfer between the medium and the particulate material. Understanding flame behavior and the re-ignition mechanism is crucial to controlling the efficiency and stability of the pulse combustion process. In order to accomplish this objective, an investigation was conducted into flame behavior within the combustion chamber of a Helmholtz-type pulsation reactor. The study was focused on primarily analyzing the flame propagation process and examining flame velocity throughout the operational cycle of the reactor. Two optical methods—natural flame luminosity (NFL) and particle image velocimetry (PIV)—were applied in related experiments. An analysis of the NFL measurement data revealed a correlation between the intensity of light emitted by the pulsed flame and the air-fuel equivalence ratio (range from 0.89 to 2.08 in this study). It is observed that a lower air-fuel equivalence ratio leads to higher flame luminosity in the PR. In addition, in order to study the parameters related to system stability and energy transfer efficiency, this study also focuses on the local velocity field measurement method and an example of a fluid flow result in a combustion chamber by using a phase-locked PIV measurement system upgraded from a classic PIV system. The presented results herein contribute to the characterization of flame propagation within a pulsation reactor, as well as in pulsatile flows over one working cycle in a broader context, with flow velocity in the center of the combustion chamber ranging from 1.5 m/s to 5 m/s. Furthermore, this study offers insights into the applicable experimental methodologies for investigating the intricate interplay between flames and flows within combustion processes.

Design and variable scale optimization of flare gas recovery process for hydrogen production

Flare systems are equipped in refining and petrochemical industries to ensure operation safety. However, flare gas sent directly to the flare system for combustion wastes energy and pollutes the environment, so it is of great significance to recover and comprehensively utilize flare gas. A new process of hydrogen production with flare gas recovery is proposed in this paper, which not only solves the problem of environmental pollution but also makes rational use of energy and improves economic benefit. Firstly, the flare gas recovery process for hydrogen production is designed by coupling the poly-refrigerant integrated cycle operation method with the chemical looping combustion sorption enhanced steam methane reforming method. Secondly, key parameters such as reactor temperature, H2O/CH4 molar ratio, and CaO/CH4 molar ratio are optimized through sensitivity analysis with CH4 conversion, H2 yield, H2 purity (dry basis), and CO2 capture rate as indicators. Thirdly, computational fluid dynamics simulation is carried out to validate the above macroscopic analysis results and further optimize the process at the mesoscopic level. The effects of different bed heights on hydrogen purity are analyzed to determine the optimal bed height for the reformer reactor, which strengthens the performance of the equipment. Finally, the process is probed by an economic analysis, which shows that 68.7 tons/year of hydrogen is produced when the recovery of methane from flare gas reaches 137.3 tons/year. This determines the economic feasibility of the process. The significance of this paper lies in: a novel green process using flare gas recovery to produce high-purity hydrogen with the conversion from waste gas to new energy realized with the concept of “turning waste into treasure”; a new way of combining meso-level and macro-level, variable-scale optimization of the process parameters; the recycling of other short-chain hydrocarbon-containing waste gases.

Environmental Risk Assessment of a Hydrocracker Unit in Abadan Oil Refinery Using the EFMEA Analysis

Background: The aim of risk assessment is to use a rational method to analyze risks and to identify the possible hazards and outcomes for people, equipment, materials, and the environment. Methods: The criteria and indices for assessing the environmental, health, and safety risks of the hydrocracker unit were determined by a Delphi questionnaire in this study. Then, an Environmental Failure Mode and Effects Analysis was applied to evaluate, score, and rank the risks based on their probability of occurrence, severity, probability of detection, extent of pollution, and potential of recycling. Results: According to the results of the Delphi process, 19 out of the 22 items were identified as the main criteria in the environmental, health, and safety risk evaluation of the hydrocracker unit at the Abadan Oil Refinery. However, the results indicated that 67% of the risks associated with the life cycle operation were low while 33% of them were high in terms of intensity. In contrast, 75% of the risks associated with control room operators were low and 25% were high in terms of intensity. On the other hand, 64, 7, and 29% of the risks associated with the activities of site employees were low, moderate, and high in terms of intensity, respectively, while the corresponding figures were 14, 29, and 57% in the case of risks associated with repairs. Conclusion: Based on the results of techniques of environmental failure modes and effects analysis (EFMEA) and Delphi, appropriate methods can be used to identify and reduce risks in similar industries.

Polynorepinephrine-regulated filler sulfonation toward interfacial reformation and conductive promotion of nanocomposite proton exchange membrane

Interfacial compatibility between filler and matrix substantially affects the overall morphology and performance of nanocomposites. Compared with bare montmorillonite (MMT), surface modified product such as sulfonated MMT (SMMT) has been known to render optimized interfacial compatibility in composite proton exchange membranes (PEMs) for proton exchange membrane fuel cells (PEMFCs) and direct methanol fuel cells (DMFCs). Nevertheless, in-depth understanding and investigation on the sulfonation of MMT are seldom focused, such as uniformity and sufficiency. Herein, these broadly neglected issues are proposed and resolved using an exemplary polynorepinephrine (PNE)-regulated SMMT (SNMMT). Rather than direct sulfonation utilizing the inherent hydroxyl groups of MMT, a PNE coating with ample hydroxyl groups is deposited on MMT beforehand, which results in more homogeneous and sufficient sulfonation of SNMMT. Compared with normal SMMT, this alteration on surficial geography of filler functionalization brings significant benefits when composited with Nafion matrix, including harmonized filler-matrix compatibility, improved mechanical stability and enhanced proton conduction. Moreover, the antioxidative ability of PNE layer enables improved chemical stability of nanocomposite PEM. The Nafion/SNMMT composite PEM achieves 0.275 S cm−1 proton conductivity at 95 °C in water, evidently beyond any previously reported composite PEMs using normal SMMT. Equipped with this reformed nanocomposite PEM, both PEMFC and DMFC display competitive peak power densities (1.121 W cm−2 with H2/O2 at 80 °C/100 % relative humidity (RH) for PEMFC, and 0.228 W cm−2 with 1.6 M methanol/100 % RH O2 for DMFC), and simultaneously show minor performance deteriorations in constant current density operation and RH cycle tests. It would be instructive the specific focus and reformation on the uniformity and sufficiency of filler modification may render significant interface and performance advancements for nanocomposites.

Factors Influencing the Decision-Making Process at the End-of-Life Cycle of Onshore Wind Farms: A Systematic Review

It is observed that the number of onshore wind farms that reach the end of their service life is continually increasing. The decision-making process that defines the future of the farm is a challenge for the owners. This systematic review aimed to identify which factors influence the decision-making process at the end-of-life cycle of onshore wind farms. In accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) protocol, a research strategy was developed and used the Scopus, Web of Science and EMBASE databases. Initially, 2767 articles were identified, but, after double-blind screening, 26 articles were analyzed in full. The scarcity of studies on this topic and little elucidation are limitations of this review. The results include (i) a systematization of six options for decision making, (ii) thirteen factors influencing the decision-making process associated with categories of external factors (logistics and infrastructure aspects, regulatory aspects and public policies, national energy guidelines, the technological development of the sector); and internal factors (economic/financial, operational and environmental aspects). It is concluded that most of the publications consist of simulations and theoretical studies highlighting a bottleneck in experiences and feasible data to support decisions at the end of service life. It is highlighted that most of the studies showed that partial decommissioning with partial repowering, as well as total decommissioning, were the most feasible options for the end-of-life cycle, with aspects related to public policies and regulatory aspects, as well as environmental, operational and economic/financial aspects, being the most influential, especially due to the wake effect, operation and maintenance costs (OPEX) and the protection of guarantees and incentives for operation in a new operating cycle.

Автоматизация расчета реактора для синтеза серосодержащего сорбента, предназначенного для извлечения из сточных вод ионов тяжелых металлов

An automated algorithm for calculating the time of the full cycle of operation, the stages of thermal stabilization and cooling of the reaction mixture in a reactor designed for the synthesis of a sulfur-containing sorbent produced on the basis of waste products from metallurgy, petrochemistry (sulfur), epichlorohydrin (1, 2, 4-trichloropropane) and the pulp and paper industry (lignin) for extraction from wastewater of heavy metal ions. The use of algorithms and a program for automated calculation of the reactor helps to reduce the complexity of production costs and the cost of the finished sorbent, increases the reliability of calculations and the quality of design solutions. The developed algorithms and program include the following calculation routines: physico-chemical properties of the components of the reaction mixture and the choice of a mixing device (propeller three-bladed agitator), taking into account the viscosity of the mixture; hydrodynamic calculation of the mixing device and heat transfer when heating the mixture from 20 to 45 °C; heat transfer during thermal stabilization and cooling of the working mixture, as well as the time of the full cycle of the reactor. The proposed algorithm of heat transfer during thermal stabilization of the reaction mass is based on the determination of the temperature range of water heating, compensating for heat losses. For this purpose, the inverse problem of heat transfer with unknown temperatures over a hot heat carrier is formulated and solved, such that the average value between them is a thermostabilizable value. An algorithm for calculating the cooling process of the reaction mixture in a sulfur-containing sorbent synthesis reactor, taking into account heat losses to the environment in the amount of 5%, is presented. A program has been developed that implements the presented algorithms in C#, designed to automate the calculation of a sulfur-containing sorbent synthesis reactor designed to extract heavy metal ions from wastewater.

Proposal of Multicriteria Decision-Making Models for Biogas Production

While biogas production offers promising solutions for waste management, energy diversification, and sustainable development, effective project implementation requires comprehensive evaluation criteria that encompass diverse aspects, such as the problem to be addressed, biodigester technology selection, business model development, investment considerations, and final product utilization. A preliminary study involving an integrative review of 58 articles yielded 499 unique criteria. These criteria were categorized into four groups: economic, environmental, social, and technical, encompassing a total of 39 subcriteria. Six stages of the biogas production cycle were considered in the analysis: project, initiation, biodigester type selection, location determination, operational cycle definition, and final product utilization. The analysis revealed that existing decision-making models often prioritize technical and economic considerations while neglecting broader social and environmental perspectives. This paper addresses this gap by proposing, for the first time, stage-specific, multicriteria decision-making (MDCA) models tailored to each phase of a biogas production cycle. These models empower project managers and policymakers to optimize resource allocation, minimize the environmental impact, maximize social benefits, and ensure project viability and profitability. The models’ adaptability allows for tailored prioritization based on specific project requirements and contexts. This groundbreaking research fills a critical void in biogas decision making by bridging the gap between existing technical and economic model limitations and the growing need for truly sustainable project development.

A single‐source nine‐level solar‐PV inverter with quadruple voltage boosting and high reliability

SummaryAn increase in generation from distributed energy sources like solar PV has motivated researchers to explore better electrical energy conversion solutions. Multilevel inverters with fewer component count and boosting capabilities contribute to a reliable and efficient single‐stage solution. This work proposes a reliable single‐source switched capacitor multilevel inverter capable of producing nine‐level boosted AC voltage with its stand‐alone and grid‐connected operation. It employs 11 switches, three diodes, and three switched capacitors. The main feature of the proposed topology is its ability to produce quadruple boosting with respect to the DC input voltage. Another advantage is the exhibition of low capacitor currents due to frequent charging durations in one operational cycle. The selection criterion for the switched capacitors is also presented. The topology's performance is evaluated in MATLAB/Simulink under various conditions and in PLECS environments for its efficiency. It was then realized on an experimental prototype in stand‐alone mode. The topology is then modified in terms of topology and modulation to mitigate the leakage current, thus making it suitable for grid‐connected operation. This operation is validated on the hardware‐in‐the‐loop platform. Further, the reliability analysis explores a high total mean time to failure (MTTFT) of nearly 253,164 hours/failures compared to recent switched capacitor topologies and an efficiency of above 95%. The low inrush currents, high MTTFT value, and better efficiency make it a suitable topology for renewable microgrids' stand‐alone and grid‐integrated operation.

Multistage dynamic optimisation of ore flow for underground metal mines

ABSTRACT The purpose of transportation dispatching in underground mines is to achieve efficient connection and operation cycles between different stopes while ensuring efficient ore transportation from stopes to a mill. The transportation system of large underground mines is a typical complex transportation network with large-scale transportation equipment, which involves both continuous and batch transportation succession and the blending of ore with different grades. The equipment dispatching has an important impact on the ore flow rate, grade, and transportation costs. Therefore, the ore flow needs to be optimally controlled from the perspective of multistage dynamic ore blending. A new model is presented to optimise the ore transportation process considering the ore flow rate, grade, equipment, and transportation network constraints, which aims at minimising transportation costs. The model is verified through a case study of the Sanshandao gold mine in China.

Study on the influence of injection pressure and frequency on the deformation and damage law of the surrounding rock in the old cavity of salt mine

AbstractThe long‐term cyclic gas injection and production mode of the gas storage will lead to accelerated deformation of the surrounding rock of the old cavity, and even the instability and failure of the cavity. Considering the geological conditions and cavity measurement data of the old cavity of the horizontal butted‐well in China, the deformation and failure characteristics of the long‐term cyclic injection‐production process of the surrounding rock of the old cavity under different internal pressure difference and injection‐production frequency are studied. The long‐term stability of the gas storage is predicted by six indexes: the deformation of surrounding rock, dilatancy safety factor, volume shrinkage rate, plastic zone volume, equivalent strain, and no tensile stress. The results show that with the increase of operation duration and cycle times, the deformation, volume shrinkage rate, and plastic zone volume of the surrounding rock gradually increase after the old cavity is reconstructed into the gas storage and the difference of results under different UGS and CAES gradually expands. The stability of the surrounding rock of the old cavity under the cycle action of CAES will be lower. The number of cycles has a limited impact on the stability of the surrounding rock of the old cavity, while the operation duration and injection‐production pressure are the main determinants of the stability of the surrounding rock of the old cavity. If the old cavity of the salt mine is reconstructed into CAES, the parameters such as the number of cycles, the operation duration, and the injection‐production pressure still need to be considered comprehensively. The research results can provide reference value for the reasonable design of the gas storage pressure range of the old cavity and the safety and stability evaluation of the surrounding rock.

Theoretical foundations for creating a quantum photon computer

Currently, significant results have emerged in the field of creation and application of quantum computers. We are talking about the Chinese quantum photonic computers Jiuzhang, Jiuzhang-2 (Jiuzhang 2.0), Jiuzhang-3 (Jiuzhang 3.0), which appeared respectively in 2020, 2021 and 2023, as well as the Canadian quantum photonic computer Borealis, which appeared in 2022. All these computers belong to the class of so-called quantum simulators – variants of quantum computers that solve one problem or a narrow class of problems. In addition to narrow specialization, quantum simulators have another important feature. In quantum simulators, controllable quantum objects simulate and effectively predict the behavior of real quantum systems. For example, in the quantum photonic computers Jiuzhang, Jiuzhang-2, Jiuzhang-3 and Borealis, the photons supplied to the inputs of these computers imitate the behavior of a “system of non-interacting identical bosons.” The Jiuzhang, Jiuzhang-2, Jiuzhang-3, and Borealis quantum simulators solve the problem of sampling bosons from a given distribution. Together they represent a significant scientific, technical and technological breakthrough in the development and creation of quantum computers. However, beyond what has been achieved, a number of important issues that are of interest both theoretically and for the field of practical applications remain unexamined. Among them are the following: about the architecture and composition of the elements of a quantum photonic computer, their number and connection diagram, as well as setting parameters that determine the required probability distribution from which boson samples are taken. The scientific problem addressed in the article is to obtain answers to the above questions by developing the theoretical foundations for creating a quantum photonic computer that solves the problem of sampling bosons from a given distribution in the most general case without restrictions on the distribution. The following results were obtained: the theoretical basis for the creation of a quantum photon computer (called in the article the Fuzuli boson sampler, briefly bsF) was developed that solves the problem of sampling bosons from a given distribution, for use as a quantum computing subsystem of a hybrid computing system to solve the problem of estimating matrix permanents; its constituent elements have been identified and studied, their numbers have been determined, and inter-element connection diagrams have been developed; an algorithm has been developed for tuning the bsF quantum photon computer to solve the problem of estimating matrix permanents; The functioning process of bsF is described. The article assumes that physically, in each cycle of operation of the bsF computer, the process of supplying photons to the inputs of the computer, their “movement” to the detectors, as well as the registration of photons by detectors is organized in such a way that the set of these photons imitates the behavior of a system of non-interacting identical bosons. Physical and engineering issues of ensuring such behavior of photons are not considered in this work. At the same time, the feasibility of such a possibility in practice (experimentally) is assumed to be undeniable. Examples confirming this position are the already created prototypes of quantum photonic computers in China (Jiuzhang, Jiuzhang-2, Jiuzhang-3) and in Canada (Borealis).

Dynamics of heat release in a dual-fuel engine

The increasing attention to the use of dual-fuel engines with compression ignition leads to the need to study the thermal engineering processes occurring in them. A model for calculating the thermal engineering stages in a cylinder of a dual-fuel engine with a refined composition of the working fluid is presented, including the determination of fuel supply characteristics, fuel injection and evaporation functions and allowing theoretically to determine with high accuracy the pressure function, cycle operation, power, efficient and thermal criteria for the operation of a dual-fuel engine. The paper attempts to show the mutual relationship between the individual processes of heat generation, their influence on the design parameters under the operating conditions characteristic of a dual-fuel engine, as well as on the operating conditions of components and parts.

A Data-Model Interactive Remaining Useful Life Prediction Approach of Lithium-Ion Batteries Based on PF-BiGRU-TSAM

Accurate remaining useful life (RUL) prediction of lithium-ion batteries is critical for energy supply systems. In conventional data-driven RUL prediction approaches, the battery's degradation mechanism is difficult into incorporate in the RUL prediction. Furthermore, there are notable limitations in reflecting the significance of different time instances, and the uncertainty in the degradation process. Consequently, a novel data-model interactive remaining useful life prediction approach based on particle filter-temporal attention mechanism-bidirectional gated recurrent unit (PF-BiGRU-TSAM) is proposed. Specifically, BiGRU-TSAM is trained offline through historical data, which assigns corresponding significance to battery capacities at different time instances. Moreover, regarding the interactive data-model for the online prediction phase based on PF-BiGRU-TSAM, the advantages of data-driven and model-based approaches are integrated, which accomplishes the purpose of modifying each other. The proposed PF-BiGRU-TSAM approach is validated with a real-world battery dataset. Experimental results demonstrate the proposed approach is better than some published approaches. Taking the 50th operational cycle of the four batteries B0005, B0006, B0007, and B0018 in the dataset as an instance, the absolute errors of the proposed PF-BiGRU-TSAM are 0, 1, 3, 3, respectively, which represents the proposed approach has an excellent performance.

Research on the mixing characteristics of the bottom blowing molten pool based on flow characteristics and mixing uniformity

In this study, a new method of combining lance–liquid flow characteristics and mixing uniformity is proposed to evaluate the stirring characteristics in the bottom blowing copper molten pool. A fluid simulation model of a bottom blowing molten pool was established, water was used to simulate the melt environment, and an experimental platform was set up for verification. The effects of swirl, multi-channel, and straight pipe spray on the lance–liquid stirring characteristics of the bottom-blown copper molten pool are compared through quantifying the flow characteristics and mixing uniformity. In addition, digital image processing technologies, such as image entropy variance and eddy current map entropy increase, are introduced. Through numerical simulation research, it is found that the transverse velocity of the swirl spray lance is the largest, which makes the rise time of the bubble increase to the greatest extent. Compared with the straight pipe spray, the swirl spray reduces the liquid splash height by 0.054 m, and the degree of vortex flow is higher. The lance phase stability is increased by 37.87%, and the maximum turbulent kinetic energy can be increased by 8.73%. The spray effect of the multi-channel spray is between the two. It is shown that the swirling spray lance can improve the stability of gas in the molten pool, enhance the uniformity of gas–liquid mixing, and improve the operation cycle and the smelting efficiency of the molten pool.

A comprehensive modeling framework for coupled electricity and carbon markets

AbstractThe carbon market plays a critical role in promoting the transition toward renewable energy sources and reducing greenhouse gas emissions in the electricity generation and transmission. Extant research has overlooked the dynamic bilateral causality that exists between electricity and carbon markets. Moreover, these studies have frequently treated the macroeconomic effect as exogenous. To bridge this research gap, this paper presents a holistic modeling framework that comprehensively captures the intertwined nature of electricity and carbon markets and their concomitant interactions with the overarching economy. The suggested modeling framework is an integration of three principal modules, namely, a carbon market, an electricity market, and economic system. This synergistic blend provides an exhaustive understanding of the entire market operation cycle. It offers detailed clearance rules, and most importantly, it adopts a macroeconomic systematic modeling approach for evaluating the impact emanating from the interconnected electricity and carbon markets. To illustrate the practicality and effectiveness of the proposed approach, a case study anchored on empirical data sourced from the electricity and carbon markets in China is conducted. The empirical findings underscore the fact that incorporating a green certificate market into the modeling framework can precipitate a reduction in greenhouse gas emissions. Additionally, the results indicate that expanding the scale of the green certificate market from 1.9% in 2021 to 33% by 2023 will increase the generation of green electricity by 10%.

Performance and Emission of the Aircraft with Hybrid Propulsion During Take-Off Operation Cycle

Performance and Emission of the Aircraft with Hybrid Propulsion During Take-Off Operation Cycle

ОБОСНОВАНИЕ ПРИМЕНЕНИЯ КОМПОЗИТНЫХ БАЛЛОНОВ В КОММУНАЛЬНО-БЫТОВОМ ОБЕСПЕЧЕНИИ ПОТРЕБИТЕЛЕЙ ГАЗОМ

The introduction of new advanced materials into gas supply practice leads to the creation of new products with improved qualities. For domestic use, along with traditional metal cylinders for liquefied petroleum gas, composite cylinders have recently been offered. Possessing a number of undeniable advantages, composite cylinders annually increase their share of presence in the field of bottled gas supply. However, the transition from traditional metal cylinders for the consumer should not be accompanied by a banal change of vessels, but requires a comprehensive, competent approach with justification for decisions made on the formation of a gas supply system for the consumer based on cylinders made of composite materials. Using the basic principles characterizing changes in the states of gas mixtures included in liquefied hydrocarbon gas, the characteristics of heat exchange, the vessels under study, the principles of operation of gas-using equipment for the consumer, parameters are determined that form the basis for the competent use of composite cylinders for the consumer using liquefied gases of various brands. As a result of the research, the mass of gas for filling cylinders was determined, taking into account the seasonality of operation and brands recommended for domestic consumption, the process of heat exchange between the cylinder and the environment was studied, taking into account its operating mode and the uneven generation of the vapor phase in the daily cycle of operation to ensure food preparation and hot water supply to consumers, the optimal periods of continuous operation of an individual cylinder installation with different capacities of a sin-gle composite cylinder and the number of cylinder replacements in the annual operating cycle were determined.

Dynamics of the Main Indicators Correlated to the Cycles of Operations at an Entity’s Level

Dynamics of the Main Indicators Correlated to the Cycles of Operations at an Entity’s Level

Optimizing slug bubble size for application of the ultra-thin flat sheet membranes in MBR: a comprehensive study combining CFD simulation and experiment.

Optimizing the slug bubble size specifically for ultra-thin flat sheet membranes in MBR systems can effectively enhance the scouring force and improve fouling control efficiency, thereby further advancing their targeted and widespread application. In this study, a three-dimensional model was developed based on the practical application to investigate the impact of slug bubbles on scouring performance in ultra-thin flat sheet MBR systems, encompassing their evolution, disturbance level, and shear stress. A membrane fouling probability index for quantifying the distribution of membrane fouling, along with a turbulence intensity index have been proposed. The findings revealed that the 20-mL slug bubble induced the highest disturbance level in the surrounding fluid, characterized by an instantaneous peak velocity of 0.63m/s at the local system level, conducive to bubble scouring. And exerted the greatest shear stress effect, achieving the most effective reduction in membrane contamination, with a maximum shear stress of 1.82Pa. The experimental validation conducted during the operational cycles confirmed that the scouring effect of 20-mL slug flow yielded in a maximum proportion of 48.16% within the low fouling probability region. The results provided evidence supporting the assertion that specific aeration conditions producing 20mL of bubbles resulted in minimal membrane fouling, ensuring a more pronounced scouring effect. The combination anythsis of slug bubble characteristics and behaviors, integrating theoretical and experimental approaches, implied that 20mL was the optimal bubble size in ultra-thin flat sheet MBR, which fulfilled the optimal air scouring effect.