Effects Of Operating Parameters Research Articles

Photo-Oxidation in Three-Phase Flow with Continuous Photosensitizer Recycling

Microreactors have emerged as a promising platform for conducting photo-oxidations, offering green routes to facilitate significant chemical transformations. In this study, the sustainability of photo-oxidations is improved by a three-phase gas/liquid/liquid flow reaction in a photo-microreactor with continuous recycling, which is applied to a model reaction. Recycling is enabled by the photosensitizer and the substrate, which are in immiscible phases. The effect of various operational parameters on the reaction and the contact pattern among phases is explored, and the interplay between the flow pattern and photo-oxidation is discussed. The highest conversion is detected for flow conditions that display significantly lower diffusion distance between the dispersed photosensitizer slug and the oxygen bubble, highlighting the link between the flow pattern and mass transfer. Furthermore, phase separation was automated using a liquid–liquid separator where the photosensitizer and organic substrate were recycled continuously to achieve full conversion. The proposed approach eliminates the downstream purification step and provides a sustainable pathway toward photo-oxidations in microreactors.

Operation analysis and its performance optimizations of the spray dispersion desulfurization tower for the industrial coal-fired boiler

As a relatively new type of desulfurization system, long-term high-efficiency desulfurization is a critical issue for commercial spray dispersion system applications. To analyze the coupling effects of different operation parameters, a series of operation performance predictions with their optimizations are implemented. Through the analysis of the operating influencing factors based on artificial intelligence, the key influencing factors of the operation performance are determined. For instance, the tube immersion depth accounts for 46% of the factors that affect the desulfurization efficiency. Moreover, the system stability analysis determines not only the system's fine operation stability, but also identifies several factors, such as the PH and inlet gas temperature, that require key control for operational stability. For instance, the phase margin of the PH, flue gas temperature, and SO2 concentration in flue gas is greater than 0 when the amplitude margin reaches 1 point, allowing the PH control system to demonstrate excellent system operating stability. Then, after a systematic analysis of the operation, several optimizations of the operation are provided. Finally, in recent applications, the optimized spray dispersion has demonstrated excellent desulfurization performance: the desulfurization efficiency was greater than 99%, and the outlet SO2 concentration was less than 15 mg/m3 in three years of operation, which means that near-zero SO2 emissions in long cycles were essentially achieved, and 1/3 and 1/5 of the energy and cost consumption were reduced.

Optimization of Process Parameters for Pellet Production from Corn Stalk Rinds Using Box–Behnken Design

In the current study, corn stalk rinds were used as feedstock for the production of solid-fuel pellets. In an effort to comprehensively analyze the effects of different operational parameters on the physical properties of pellets, response surface methodology (RSM) was employed in conjunction with a Box–Behnken experimental design (BBD). By assessing multiple variables simultaneously and examining their interactions, BBD facilitates the development of a reliable response model that can predict how changes in independent variables will impact response variables. The recorded responses included relaxed density, mechanical durability, and compressive strength. Based on the results, greater R2 values of 0.9467, 0.8669, and 0.9196, could be, respectively, attained for the quadratic regression models. The analysis of variance revealed that all independent variables had significant effects on the responses. The optimal processing condition for the pellets was established by determining the ideal combination of operational parameters. The process entailed the choice of a particle dimension measuring 0.5 mm, a moisture level of 11.35%, the application of heat at 125.7 °C on the die, and the utilization of a molding pressure of 154.2 MPa. Based on these factors, the predicted response values were determined to be 1639.61 kg/m3 for relaxed density, 97.95% for mechanical durability, and 10.18 MPa for compressive strength. The values obtained experimentally under the optimized conditions were similar to the predicted values with a desirability value of 1.00.

Tri-objective optimization of a waste-to-energy plant with super critical carbon dioxide and multi-effect water desalination for building application based on biomass fuels

In the present research, an innovative biomass-based energy system for the production of electricity and desalinated water for building application is proposed. The main subsystems of this power plant include gasification cycle, gas turbine (GT), supercritical carbon dioxide cycle (s-CO2), two-stage organic Rankine cycle (ORC) and MED water desalination unit with thermal ejector. A comprehensive thermodynamic and thermoeconomic evaluation is performed on the proposed system. For the analysis, first the system is modeled and analyzed from the energy point of view, then it is examined similarly from the exergy point of view, and then an economic analysis (exergy-economic analysis) is performed on the system. Then, we repeat the mentioned cases for several types of biomasses and compare them with each other. Grossman diagram will be presented to better understand the exergy of each point and its destruction in each component of the system. After energy, exergy and economic modeling and analysis, the system is analyzed and modeled using artificial intelligence to help the system optimization process, and the model obtained with genetic algorithm (GA) to maximize the output power of the system, minimize the cost system and maximizing the rate of water desalination is optimized. The basic analysis of the system is analyzed inside the EES software, then it is transferred to the MATLAB software to optimize and check the effect of operational parameters on the thermodynamic performance and the total cost rate (TCR). It is analyzed and modeled artificially and this model is used for optimization. The obtained result will be three-dimensional Pareto front for single-objective and double-objective optimization, for work-output-cost functions and sweetening-cost rate with the specified value of the design parameters. In the single-objective optimization, the maximum work output, the maximum rate of water desalination, and the minimum TCR will be 55,306.89 kW, 17216.86 m3/day, and $0.3760/s, respectively.

Construction of Ag/Ag2S/CdS Heterostructures through a Facile Two-Step Wet Chemical Process for Efficient Photocatalytic Hydrogen Production

We have demonstrated a two-step wet chemical approach for synthesizing ternary Ag/Ag2S/CdS heterostructures for efficient photocatalytic hydrogen evolution. The CdS precursor concentrations and reaction temperatures are crucial in determining the efficiency of photocatalytic water splitting under visible light excitation. In addition, the effect of operational parameters (such as the pH value, sacrificial reagents, reusability, water bases, and light sources) on the photocatalytic hydrogen production of Ag/Ag2S/CdS heterostructures was investigated. As a result, Ag/Ag2S/CdS heterostructures exhibited a 3.1-fold enhancement in photocatalytic activities compared to bare CdS nanoparticles. Furthermore, the combination of Ag, Ag2S, and CdS can significantly enhance light absorption and facilitate the separation and transport of photogenerated carriers through the surface plasma resonance (SPR) effect. Furthermore, the Ag/Ag2S/CdS heterostructures in seawater exhibited a pH value approximately 2.09 times higher than in de-ionized water without an adjusted pH value under visible light excitation. The ternary Ag/Ag2S/CdS heterostructures provide new potential for designing efficient and stable photocatalysts for photocatalytic hydrogen evolution.

Self-rotation induced regeneration of filter media to enhance the oil-water separation in a microchannel filter

The regeneration of filter media was crucial to the filtration performance of the oily wastewater. Herein, a novel hydrocyclone-induce approach was proposed for filter media regeneration, followed by an exploration of oil desorption feasibility and mechanism. The effect of structural and operation parameters of a hydrocyclone on the particle self-rotation was extensively analyzed by numerical simulation, and its feasibility for oil desorption from the filter media was subsequently investigated. A hydrocyclone-intensified filtration method that combined by the unit of filtration and hydrocyclone self-rotation regeneration was proposed, and the effect of hydrocyclone-induced filter media regeneration on the subsequent oily wastewater filtration was also explored. The ideal specifications of the hydrocyclone were concluded to be an overflow pipe insertion of 120 mm, and a cone angle of 60° for the optimal self-rotation velocity. The hydrocyclone-induced regeneration presents a remarkable oil desorption efficiency, and the oil concentration of filter media reduced from 9.43 % to 6.94 %, 4.33 %, and 3.43 % as the flowrate increased from 1.8 × 105 L·m−2·h−1 to 5.4 × 105 L·m−2·h−1. The adhered oil was exfoliated due to the centrifugal force caused by the revolution and self-rotation of the media particles, while the filter media spun in a hydrocyclone. The average effluent oil concentration in the raw oily wastewater was reduced to 12.2 mg/L during the pilot-scale test, indicating that the hydrocyclone regeneration benefits the continuous oil-water separation. It is believed that this work might provide a unique and efficient method for oily wastewater treatment with the integration of filtration and hydrocyclone regeneration.

Anion exchange membrane water electrolysis: Numerical modeling and electrochemical performance analysis

In this paper, a three-dimensional numerical model is developed for an anion exchange membrane electrolyser cell (AEMEC) with a double serpentine flow field pattern. The focus on the AEMEC is due to its benefits, including the solid membrane, inexpensive catalysts and membrane, and high stability. The effect of important operating parameters, i.e. cell temperature and cathode pressure, on the performance of the electrolyser is numerically modeled by considering different causes of performance degradation. The polarization curve, uniformity index, and the distribution of the hydrogen concentration, current density, temperature, and pressure in different operating conditions are presented. By increasing the operating temperature and decreasing the cathode pressure, the voltage of the elctrolyser decreases. Due to the higher concentration of water at the inlet of the cathode channel, more hydrogen is produced, and the current density is higher. The maximum current density and hydrogen concentrations are 7868Am2 and 0.898molm3, respectively, when the operating condition is set to the temperature of 343 K, the pressure of 1 bar, and the cell voltage of 1.85 V.

Thermal-hydraulic-mechanical-chemical modeling and simulation of an enhanced geothermal system based on the framework of extended finite element methods - Embedded discrete fracture model

The thermo-hydro-mechanical-chemical (THMC) coupling process plays a crucial role in Enhanced Geothermal System (EGS), particularly during long-term heat extraction. However, most models for fractured reservoirs are computationally expensive, with very dense grids required, especially near fractures, limiting their practical use in EGS research. The embedded discrete fracture model (EDFM) can construct fracture and matrix grids independently, significantly reducing computational complexity while maintaining high accuracy. Although it is suitable for efficiently evaluating the long-term performance of heat extraction in fractured reservoirs, there are few THMC-coupled models based on EDFM, and THMC coupling effects have often been overlooked in evaluations of the environmental benefits of EGS. To address this, a fully THMC-coupled model based on EDFM and the extended finite element method (XFEM) is proposed and verified. The evolution of heat production and environmental benefits of an EGS over 30 years are presented. The results show that the production temperature and electric power remain highly efficient in the first 5 years and decrease by 7.8% and 15.4% respectively over 15 years. Moreover, the total amount of extracted heat during this period is 6.52 × 1012 kJ, which is equivalent to saving 22.26 × 108 kg of coal consumption and reducing CO2 emissions by 5.83 Mt, SO2 emissions by 189.22 × 105 kg, and NOx emissions by 166.96 × 105 kg. These findings highlight the significant potential of geothermal energy for energy supply and environmental benefits. Additionally, the study investigates the effects of critical operating and physical parameters on the production performance of EGS, including injection temperature, injection flow rate, initial reservoir temperature, and initial reservoir permeability. This work serves as a reference for both the theoretical THMC coupled model and practical EGS engineering.

Lipid extraction and CO2 capture with switchable polarity solvent

In this study, lipid extraction and CO2 capture are combined using N, N-dimethylcyclohexylamine (DMCHA) as switchable polarity solvent. The effects of operation parameters are discussed according to the CO2 absorption/desorption and lipid/DMCHA recovery results. A triphasic models considering lipid, water, and gas phases are established to analyze the kinetic behaviors. The results show that DMCHA is reversible through CO2 absorption/desorption, and the enhanced dispersion of droplets and bubbles in water phase improves the lipid/DMCHA recovery and CO2 absorption/desorption. The triphasic kinetic models fit well with experimental data, and gas–liquid mass transfer is regarded as the rate-determining step. The lower interfacial areas result in the poorer gas–liquid mass transfer for the DMCHA recovery than lipid recovery process.

Evaluation of atrazine degradation by iron persulfate activation process in aqueous phase using Taguchi approach

Atrazine (ATZ) is one of the most widely used herbicides for the control of annual broadleaf and grassy weeds in the world. Its residual in the environment is of great concern. This research work primarily focused on examining ATZ degradation by the ferrous ion activated persulfate (PS) oxidation process (Fe2+-AP process) and the influence of oxidative parameters on the degradation of ATZ in aqueous phase. The Taguchi Design of Experiment methodology was used to explore the effects of various operational parameters, including ATZ concentration, dosage of Fe2+, dosage of PS, and pH condition (Taguchi L9 orthogonal array). The optimal operational conditions were then determined based on the results of ANOVA statistical analysis. Operational conditions included ATZ at an initial concentration of 5 mg/L, with initial concentrations of 1 mM Fe2+, 10 mM PS, and pH = 3, at 20oC, for a reaction time period of 3 h. The sensitivity of factors for the ATZ degradation followed the decreasing order: PS concentration, pH, ATZ concentration and Fe2+ dosage. The results of this study provide useful operational conditions for the Fe2+-AP process, for application to field remediation of ATZ contamination.

A simulation study on the condensation flow and thermal control characteristics of mixed refrigerant in a dimpled tube

In this study, the condensation flow and heat transfer characteristics of ethane/propane in the dimple tube have been numerically investigated, and the liquid droplet entrainment caused by the dimple structure was considered. The effects of operation and structure parameters on flow and heat transfer were analyzed, including different dimple depths, helical pitch, and dimple pitch. The results showed that the dimple tube had a higher heat transfer coefficient compared to the smooth tube, which increased with the increase in the mass flow rate and the decrease in the saturation temperature. The effect of dimple depth on heat transfer is greater than that of the dimple pitch or helical pitch, and the dimple depth will cause the local mass transfer rate to increase under high vapor quality. Meanwhile, the existing heat transfer correlations for smooth tubes were compared, and a condensation heat transfer correlation suitable for the mixed refrigerant in the dimple tubes was proposed with an average deviation of 6.3%.The conclusions obtained can provide support for the optimization design of liquefied natural gas plants.

Effects of cold-rolling operation parameters on the surface quality of stainless steel and titanium strips with oil pits

Effects of cold-rolling operation parameters on the surface quality of stainless steel and titanium strips with oil pits

Use of Pitzer’s model to calculate thermodynamic properties of aqueous electrolyte solutions of sulfuric acid

Over this study we calculated the coefficients of activity of different species and the concentration in the presence of H+ ion when H2SO4 is alone in solution. The coefficient of average activity was calculated using the model of Pitzer. The constants of dissociation of these reactions were calculated from the values of the free standard energies. The reaction reaches a balance while producing H+, HSO4- and SO42-. The research reported here concentrated on the effect of some important operational parameters on dissolution process. The parameters were investigated and their ranges are as follows: initial molality ranging from 0.001 to 5 mol.kg-1 and temperatures between 25 and 200°C. Fortran 90 (Mathematical formula translating system) was used to perform all mathematical calculations. The numerical code can be used to calculate the molarity of ion H+ of an aqueous solution of sulfuric acid. The objective of the present work is to optimize the parameters of leaching such as activity of sulfuric acid on the dissociation phenomena.

Molybdenum Carbide/Ni Nanoparticles Embedded into Carbon Nanofibers as an Effective Non-Precious Catalyst for Green Hydrogen Production from Methanol Electrooxidation.

Molybdenum carbide co-catalyst and carbon nanofiber matrix are suggested to improve the nickel activity toward methanol electrooxidation process. The proposed electrocatalyst has been synthesized by calcination electrospun nanofiber mats composed of molybdenum chloride, nickel acetate, and poly (vinyl alcohol) under vacuum at elevated temperatures. The fabricated catalyst has been characterized using XRD, SEM, and TEM analysis. The electrochemical measurements demonstrated that the fabricated composite acquired specific activity for methanol electrooxidation when molybdenum content and calcination temperature were tuned. In terms of the current density, the highest performance is attributed to the nanofibers obtained from electrospun solution having 5% molybdenum precursor compared to nickel acetate as a current density of 107 mA/cm2 was generated. The process operating parameters have been optimized and expressed mathematically using the Taguchi robust design method. Experimental design has been employed in investigating the key operating parameters of methanol electrooxidation reaction to obtain the highest oxidation current density peak. The main effective operating parameters of the methanol oxidation reaction are Mo content in the electrocatalyst, methanol concentration, and reaction temperature. Employing Taguchi's robust design helped to capture the optimum conditions yielding the maximum current density. The calculations revealed that the optimum parameters are as follows: Mo content, 5 wt.%; methanol concentration, 2.65 M; and reaction temperature, 50 °C. A mathematical model has been statistically derived to describe the experimental data adequately with an R2 value of 0. 979. The optimization process indicated that the maximum current density can be identified statistically at 5% Mo, 2.0 M methanol concentration, and 45 °C operating temperature.

Investigating the Planarization of Al0.5CoCrFeNi2 High-Entropy Thin Films Through Chemical Mechanical Polishing

High-entropy alloys (HEAs) exhibit a variety of characteristics and provide industries with more options in high-end applications, as HEAs differ from the design concept of conventional alloys. In semiconductor manufacturing processes, HEAs are potential candidates for diffusion barrier layers due to their sluggish diffusion behavior. As a functional interlayer inside three-dimensional integrated circuits (3D-ICs), this material should be prepared as a thin-film with wafer-level flatness. Chemical mechanical polishing (CMP) is a common process used to planarize ICs; however, very little literature has reported its development in complex alloys, and CMP has not been applied to HEAs. In this study, Al0.5CoCrFeNi2 HEA was prepared as thin films of different crystallinities to investigate the effects of CMP operation parameters in planarizing these complex concentrated alloys. The HNO3-based slurry mainly causes the oxidation of Ni, Cr, and Fe in HEA films and then causes the film surface to soften, creating a surface more conducive to mechanical grinding. Both chemical and mechanical forces can enhance the material removal rate (MRR) in the CMP process; more importantly, a moderate rotation speed of 40 rpm and a low down force of 50 g/cm2 are necessary to achieve nanoscale flatness. Additionally, a useful prediction relationship, the Preston equation, for the CMP process applied to HEA systems was established.

Intensification of esterification reaction microbubble mediated reactive distillation

The current study is based on the microbubble mediated reactive distillation by converting conventional homogeneous liquid-liquid system into a heterogeneous vapour-liquid system. Microbubbles owing to their higher surface area to volume ratio provides better mass transfer as well increasing the conversion and rate of reaction. To prove the hypothesis, production of methyl acetate was investigated because of its industrial importance. The experimental plan was designed using Response Surface Methodology (RSM). It allowed analysing the effects of operational parameters simultaneously. The kinetics investigation demonstrated that the esterification reaction occurs, indeed, on the vapour liquid interface at the skin/surface of the bubble and follows pseudo-first order kinetics. The maximum conversion of the process was found to be 91% in 20 min which is significantly higher than any previous study. Furthermore, RSM and Gated Recurrent Unit (GRU) were employed to develop models to analyse the correlations among parameters and to predict the responses. The GRU produced higher R2 = 0.9981 as compared to R2 = 0.9715 produced by RSM. The results depict that GRU model is more robust and reliable than Response Surface Methodology for parameter interaction study and response prediction.

Removal of Colour and COD from vegetable tannery wastewater onto bone char– Effect of process parameters, adsorption mechanism, kinetics and equilibrium modelling

ABSTRACT In this study, bone char derived from head bones of cattle was used as an adsorbent in the removal of Chemical Oxygen Demand (COD) and colour from vegetable tannery wastewater. The char was characterized by proximate analysis, pHpzc, FTIR, BET surface area analysis and SEM-EDX spectroscopy. The effects of operational parameters (pH, contact time, adsorbent mass and temperature), the kinetics and isotherms of the adsorption process were investigated. Optimal conditions for maximum adsorption of COD (77.4%) and colour (98.01%) occurred at pH 2 after 60-minute contact time with 50 g of adsorbent at 25°C. The adsorption kinetics were analyzed using Elovich and the pseudo-first and – second-order models. The pseudo-second order model gave the best fit for the kinetic data. Application of the intra-particle diffusion and Boyd models to the kinetic data revealed that COD and colour adsorption onto the bone char were predominantly controlled by film diffusion. The Langmuir, Freundlich, Temkin and Redlich-Peterson isotherm models were applied. The Freundlich model best described the adsorption of COD and colour. The maximum monolayer adsorption capacities for COD and colour were 559.61 mg/g and 2011.76 Pt-Co/g, respectively. These results indicate that bone char can be an effective low-cost adsorbent in wastewater treatment.

Configurations and Operation Methods of Diesel-Based Solid Oxide Fuel Cell System

Solid oxide fuel cell (SOFC) can use a wide variety of carbon-based fuels. Diesel can act as a high-quantity fuel because of its high heat value and ease of transport. In this study, three different system configurations were proposed by a model in ASPEN PLUS V12 and fitted by data measured in the large size cell. The effects of key operation parameters, including reforming temperature, steam-to-carbon ratio (S/C) and recycling rate of the anode off-gas, were studied, which were characterized by the system efficiency and output power. As a result, the highest system efficiency was gotten with a water condenser and an anode off-gas recycling module in the system. The best operation method occurs when the thermal load of the diesel reformer is compensated by the heat released by anode off-gas combustion. This research will lay a theoretical foundation for the upcoming design of a physical diesel-based SOFC system.

Study of the Adsorption Efficacy of Cr(III) on a Metal Oxide-Based Material Derived from the Quartz Sand Enrichment Process

In the present study, the efficacy of chromium removal from water media was studied. For this purpose, a metal oxide based material, derived from the enrichment process of quartz coastal sand was used as possible adsorbent of chromium (III) ions. Following additional modification of the adsorbent, the effect of operational parameters including pH, contact time and Cr(III) concentration were studied according to one-factor-at-a-time procedure. Adsorption efficacy was assessed by the measurement of the remaining chromium concentration in solution, after adsorption. Atomic absorption spectroscopy technique, with flame atomization was used for the determination of chromium concentration in solution. Obtained results revealed that selected material exhibited higher adsorption efficacy in alkaline solution (pH = 6-9). The maximum removal efficacy (>93%) was achieved after 180 minutes of contact time, with an adsorbent dosage of 5 g/L and initial chromium concentration 20 mg/L. The adsorption process for Cr(III) follow the Freundlich isotherm and gives high correlation coefficient R². Calculations performed based on the Langmuir isotherm showed that the maximum adsorption efficiency of Cr³⁺ in the natural metal-oxide material has resulted 10 mg/g or 10000 μg/g. Pseudo second order reaction kinetics has provided a realistic description for removal of Cr(III) from solution with high correlation coefficient R² of (0.999). The adsorption isotherms were better described by the Freundlich equation (R² = 0.934). Adsorption of trivalent chromium ions onto selected material followed the pseudo second order model (R² = 0.996). Hence, the residual materials derived from the enrichment processes of quartz sand can be used as alternative adsorbent for the removal of trivalent chromium ions from aqueous solutions.

Effect of Operating Parameters on O3, O3/UV, O3/UV/PS Process Using Bubble Column Reactor for Degradation of Reactive Dyes

Effect of Operating Parameters on O3, O3/UV, O3/UV/PS Process Using Bubble Column Reactor for Degradation of Reactive Dyes