Iranian Journal of Chemical Engineering (IJChE)

Abstract Polysulfone-zinc oxide mixed matrix membrane (MMM) was fabricated. A polyamide layer was formed on the top surface of the membranes using interfacial polymerization process. The properties and structure of the membranes were investigated and the membranes were used for desalination in reverse osmosis process. Cross-sectional images of the membranes substrate showed that the addition of zinc oxide to the polymer matrix resulted in a denser structure and increased the thickness of the sponge-like layer near the lower surface of the membrane. The addition of zinc oxide to the polymer matrix decreased the surface contact angle of the membrane with water, thereby increasing the hydrophilicity of the membrane. The pure water flux of all membranes reduced at the beginning of the process and after 60 min remained almost constant at the values of 19.50 (Lm-2h-1) and 30.20 (Lm-2h-1) for the membrane made with plain polymer and the MMM, respectively. In the reverse osmosis process, the water flux of the membrane fabricated using plain polymer was 9.70 (Lm-2h-1) which increased by 39% and reached to 13.50 (Lm-2h-1) by the addition of zinc oxide nanoparticles. The salt rejection of plain polysulfone membrane was 92.5% which increased to 97.21% with the addition of zinc oxide to the polymer matrix. The addition of zinc oxide nanoparticles to the polymer matrix significantly decreased the water permeability to salt permeability ratio (B/A) from 40.54 to 14.35 (kPa).

Abstract Nowadays, increasing demand for sustainable energy sources has led to a growing interest in using biomass as a renewable feedstock for producing hydrogen and methanol. The main objectives of this study involve simulation and economic analysis and evaluation of synthesis gas, hydrogen, and methanol production processes from various biomass sources using Aspen HYSYS software. Three lignocellulosic sources were waste wood biomass (WWB), thin hardwood chips biomass (THWCB), and almond shells biomass (ASB). In the first part of the simulation, the unrefined synthesis gas was produced through a multi-stage biomass gasification process. The outcomes reveal that the yield and composition of synthesis gas were increased by raising the steam-to-biomass ratio (SBR). Subsequently, an integrated model for hydrogen production from various biomass sources was examined through gasification in the presence of steam and oxygen through a water-gas shift (WGS) reaction and the separation and purification of the produced hydrogen using a pressure swing adsorption (PSA) unit. Finally, the hydrogen produced in the previous step was fed to the methanol synthesis unit. The results of the simulation of the gasification process of various lignocellulosic biomasses showed that the use of WWB, THWCB, and ASB can yield annual hydrogen production of 261,000, 349,344, and 361,656 kg, respectively. Consequently, the economic analyses indicated that hydrogen and methanol production from biomass is associated with significant efficiency and profitability. Furthermore, the comparison of synthesis gases' heating values derived from three biomasses revealed that the highest heating values were generated from ASB, THWCB, and WWB, respectively.

Abstract The pyrolysis of polyethylene terephthalate (PET) was investigated across a broad range of final temperatures, from 478°C to 640°C, yielding various products. Infrared radiation was employed as the heat source in this study. To minimize experimental deviations, each test under fixed conditions was repeated twice, and the results were compared for consistency. The primary objective was to evaluate the quantitative and qualitative differences in the products generated through this novel heating method, aiming to enhance the understanding of the pyrolysis process and the influence of the heating rate on the final outputs. Pyrolysis was conducted in a vertical tubular reactor housed within an infrared furnace. The average heating rates varied significantly, ranging from approximately 20.61°C/min in the slowest test to 161.12°C/min in the fastest one. The solid residue (char) resulted from PET pyrolysis was analyzed. The yields of 87.5% and 91% were recorded for the slowest and fastest heating rates respectively. These char samples were assessed using Differential Thermal Analysis (DTA) and Thermogravimetric Analysis (TGA) to compare their quantity and quality. The findings revealed that the heating rate during the infrared pyrolysis of PET has a direct correlation with the quantity of valuable products, but an inverse relationship with their quality. 

Abstract Most industrial operating units are basically in contact with two gas and liquid phases. Bubble characteristics over the last years have been determined through different methods. In this project a mass transfer system has been designed for absorbing gas bubbles by liquid phase. The mass transfer and hydrodynamic behavior in the wake of single rising air bubbles were investigated by using an image analysis method and empirical relations. By considering these methods, the overall bubble properties including the size of single bubble, shape, path, rising velocity and mass transfer coefficient were studied and measured. The investigation was developed with 0.15×0.15×0.35 m3 bubble column and nozzle diameter (0.5, 1, 1.5, 2, 2.5 mm) in different liquids considering viscose changes. Moreover, from the results obtained, it can be concluded that the increase of nozzle diameter increases the bubble diameter which results in reduction of velocity and mass transfer coefficient. This is a fact that, by raising the viscosity of liquid phase the bubble diameter stands at the highest level and on the contrary velocity and mass transfer coefficient stand at the lowest level. So according to these outcomes we can conclude that, the diameter of bubble depends on physical properties of fluids and has a direct relation with nozzle diameter.

Abstract Amine gas sweetening is a process in which acidic gases including hydrogen sulfide (H₂S) and carbon dioxide (CO₂) are removed by a solution of water and amines. Many parameters influence the sweetening process. Knowledge about the important parameters and their degree of importance is of great interest to achieve the optimum condition. Nine effective parameters including the CO₂ and H₂S contents of the feed, the temperature and pressure of the feed, the tray number and pressure of the absorber, the lean amine temperature, and the concentrations of Methyl Diethanol Amine (MDEA), and Piperazine (PZ) have been chosen as effective variables, while CO₂/H₂S recovery and total process energy have been considered as response variables.  After the verification of the present study with real plant data, the experimental layout was designed by the Plackett-Burman approach, and the model validation has been confirmed by ANOVA. The results of the present study showed that the most effective parameters in the CO₂ recovery are the absorber tray number and PZ concentration, while in the H₂S recovery, the absorber tray number is the most important variable. Regarding the total energy of the proces, feed temperature, PZ concentration, absorber tray number, lean amine temperature, and feed pressure are obtained as important variables. The optimum condition has been obtained in the feed and absorber pressures of 5758.9, and  1458.9 kPa respectively, with the feed and lean amine temperature of 0.11 and 50  respectively, the concentrations of 17.57 and 3.8 wt.% of MDEA and  PZ respectively, the absorber tray number of 20 and the mass flow rates of 792 and 103.6 kg/h of CO₂ and H₂S respectively. Under the mentioned conditions, the CO₂ and H₂S recovery were achieved at 99.99 % while the total energy of the process was 3.56 Mw.

Abstract Polymer chains- tethered membranes exhibited a technic to improve membrane surface, and can be commonly used to change the inherent surface physico-chemical properties of materials. So, the grafting of poly(methyl methacrylate) (PMMA) chains onto poly(vinylidene fluoride) (PVDF) substrate was carried out via surface initiated atom transfer radical polymerization (SI-ATRP) at room temperature. Surface coverage and grafting density were controlled by adjusting the  concentration of the initiator. The attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR) and thermogravimetric analysis (TGA) results indicated that the PMMA brush was successfully synthesized on the substrates. The study examined the alterations in the physical characteristics of a the PVDF membrane modified with polymer brushes using the scanning electron microscopy. The results showed that PMMA brushes were attached not only to the outer surface of the membrane but also to the surfaces of its pores. Results from the atomic force microscopy and water contact angle measurements confirmed the homogeneous grafting of PMMA chains onto the substrate.

Abstract The chemical interesterification (CIE) process is a promising approach to modifying and improving oils and fat structure. In this study, CIE of fully hydrogenated soybean oil (FHSO) and sunflower oil (SFO) was performed. Different initial blends with various mass ratios of 20-45% FHSO (coded as S1, S2, S3, and S4) were converted to interesterified samples (Si-1, Si-2, Si-3, and Si-4, peer-to-peer). The interesterified samples (60% content) were used in different margarine formulas with 40% palmolein PO (M1, M2, M3, M4), and margarines enriched with beta-carotene, to compensate for the reduction of carotene during the oil decolorization process during refining. Esterification caused a significant decrease in the solid fat content (SFC) of initial fat blends and fatty acid profile analysis confirmed just less than 0.17-0.3% of trans fatty acid content (According to the definition of zero trans less than 0.5 g/12 g serving). Differential scanning calorimetry (DSC) measurement indicated that the interesterified samples possess lower melting points while showing binary or ternary crystallization peaks. The Polarized light microscopy (PLM) confirmed the presence of fine, desirable β´spherulite crystals, which are effective in creating the proper texture in margarine. Formulated margarines were evaluated and compared with one type of commercial margarine (as a control sample). According to the texture profile analysis (TPA) and organoleptic results, the M3 formula was chosen as the best formulation for margarine preparation (using Si-3 blending with the 35: 65 ratios of FHSO to SFO).

Abstract Nisin is a natural heat resistance preserver with wide applications in food industries. The main drawback of nisin is its weak activity against most Gram-negative bacteria. In this study, the antibacterial activities of nisin against Salmonella typhimurium, Klebsiella pneumoniae, Citrobacter freundii, and Escherichia coli improved via the Maillard reaction with xanthan. The nisin-xanthan conjugates analyzed by the ultraviolet, fluorescence, and Fourier transform infrared spectroscopies. The results showed temperature, reaction duration, and nisin-to-xanthan ratio affected the quality of the obtained conjugates. In relevant to the results, the antibacterial activity of 100 mg L-1 of the conjugates was increased against S. aureus, S. typhimurium, and E. coli when the nisin to xanthan ratio was increased from 1:1 to 4:1 and reached 88.8, 98.7, and 97.7%, respectively. The increase in temperature from 90 ᵒC to 110 ᵒC enhanced the antibacterial effects against all test bacteria, especially for persistent Gram-negative cells, namely C. freundii and K. pneumoniae. The longer Maillard reaction after 110 min at 110 ᵒC did not improve the antibacterial activity of the conjugates against all test bacteria. The best antibacterial activity was observed at a temperature of 110 ᵒC for 110 min for a nisin-to-xanthan ratio of 4:1.

Abstract In the current research, heat transfer within a pilot scale shell and tube heat exchanger is investigated. The heat exchanger consist of a shell and five copper tubes. Water as the cold stream and Boehmite-water nanofluid as the hot stream passes through the shell and tube side, respectively. The effect of nanofluid concentration (0.35, 0.7, and 1.5 %wt.), volume flowrate of the cold stream (0.6, 3, and 6 L/min), and the inlet temperature of the hot stream (40, 50, 60  were investigated on the overall heat transfer coefficient. Moreover, the computational fluid dynamics (CFD) modeling of heat transfer within the pilot scale was performed to study the hydrodynamics of flow inside the heat exchanger. The experimental results and CFD predictions indicates that as the concentration of the nanofluid increases, the overall heat transfer coefficient will increase. This can be attributed to higher thermal conductivity of nanoparticles and the Brownian motion of the particles in the base fluid. Moreover, when the volume flowrate of the fluid increases, Reynolds number will increase, which cause the convection heat transfer coefficient and consequently the overall heat transfer coefficient to be enhanced. Also, at higher inlet temperature of the hot fluid, higher overall heat transfer coefficient was resulted. The maximum deviation between the overall heat transfer coefficients evaluated base on the CFD predictions and its value based on experimental measurements was 16.7%. This proves the ability of CFD technique in pursuing the experimental data. CFD simulation provide a meaningful knowledge about the hydrodynamics of each stream in the heat exchanger, which help us to optimize the performance of heat exchanger.

Abstract Nanostructured SAPO-34 zeolites were synthesized using TEA/morpholine as dual templates through a hydrothermal approach, with the crystallization time as a key parameter. Different characterization methods of XRD, FESEM, EDX-dot mapping, BET, and FTIR were used to analyze these materials. The results demonstrated that the crystallization time was an efficient factor for determining the crystalline phase and uniformity of the final products. Additionally, the size and uniformity of cubic SAPO-34 particles enhanced in longer crystallization times. It was found that the SAPO-34 catalyst synthesized in the crystallization time of 72 h had an optimal distribution of silicon within the crystal lattice structure, resulting in a significant enhancement of its catalytic performance. This catalyst demonstrated the moderately stable production of highly desired olefins, maintaining the selectivity of 58% for ethylene and 38% for propylene over 10 h on stream. The possible reaction mechanism for the MTO process utilizing the prepared SAPO-34 material is proposed. 

Abstract Potassium superoxide tablets can be used in respiratory air regeneration systems within confined spaces such as spacecraft, submarines, coal mines and individual and collective masks. These tablets react with moisture and carbon dioxide in air and release oxygen. In this study, The effect of five parameters; the pressing pressure (0.5, 2, 4 and 5 bar), humidity (10, 15, 20, 25 %), Catalyst additives (CuSO₄.5H₂O, (Cu₂(OH)₃Cl₂)₂, CuO, TiO₂), H₂O Absorbent additives  (SiO₂, LiCl, CaO, SiO₂.Al₂O₃) and CO₂ Absorbent additives (LiOH, NaOH, KOH, Ca(OH)₂) were investigated in four levels using the Taguchi method. The carbon dioxide absorption and Surface Erosion were selected as criteria for optimizing the performance of Potassium Superoxide tablets based on the analysis of variance and the optimal conditions of each were evaluated separately and simultaneously. The optimal conditions for the higher carbon dioxide absorption and smaller Surface Erosion include the Humidity of 15 %, pressing pressure of 4 bar, CuSO₄.5H₂O as the Catalyst, SiO₂ as the H₂O absorbent and Ca(OH)₂ as the CO₂ absorbent. Experiments performed in the performance test show that the optimized tablets in this study show a 28 % and 79 % increase in the carbon dioxide absorption compared to commercial tablets and pure potassium superoxide respectively. The results showed that the catalysts with copper cation had the greatest effect on the performance of the tablets.
 

Abstract Biodiesel, as a renewable and environmentally friendly fuel, is a feasible alternative to fossil diesel, which has gained great popularity in recent years. However, due to some undesirable properties such as higher viscosity, biodiesel must be blended with diesel in order to be utilizable in a diesel engine. Therefore, a reasonable approach is required for predicting the diesel-biodiesel blend properties. This study tries to estimate two substantial properties of blend, i.e. kinemattic viscosity (KV) and cetane number (CN), through neural network (NN) and empirical models which use pure properties of biodiesel (kinematic viscosity, boiling point, evaporation point, flash point, pour point, heat of combustion, cloud point, and specific gravity) as independent variables. In this regard, a three-layer feed-forward network with varying input parameters, training algorithms, transfer functions, and hidden neurons has been examined to predict the KV and CN of the diesel-biodiesel blend. Besides, the prediction capability of thirty empirical equations is investigated to determine the top equations describing blend properties. The result reveals that an ANN with three input parameters of biodiesel concentration (%), the CN of biodiesel, and biodiesel cloud point has the best prediction quality of CN with an R-value of 0.9961. Moreover, NN estimates the KV of blend with the highest correlation coefficient of 0.9985. The results corresponding to empirical equations also indicate that fractional-exponential equations are the best describer of the CN and KV of blend with R-values of 0.9947 and 0.9980, respectively.

Abstract  This study investigates the two-phase flow simulation in a Y-type  micromixer with a circular pit at the junction with a 1.7 MHz ultrasonic (US) transducer. A CFD simulation is conducted on the micromixer under varying fluid flow rates. Initially, the simulation is performed without US waves, and subsequently, the US waves are applied. The influence of US waves on flow behavior, mass transfer coefficient (KLa), and extraction efficiency (E) is assessed and contrasts with the same in the scenario where no ultrasound is applied. The simulation outcomes exhibit strong agreement with the experimental findings of a reliable reference. The findings indicate that the flow pattern for both aqueous and organic phases is parallel within the micromixer when ultrasound is absent.   However, applying the US waves alters the flow pattern and enhances the mixing. Under the US field, the interface between the two phases is completely disrupted and the contact between them increases. It is concluded that applying US waves into the liquid medium enhances turbulence, mixing, and the mass transfer rate inside the micromixer.  The influence of the flow rate of the aqueous phase at different US powers on KLa and E was investigated. The decreasing trend of KLa is observed. The effect of the power of ultrasound (P=3.5, 5.25, and 7W) on KLa and E is investigated and results show that P= 7 W has the more ability to enhance the mass transfer rate. The maximum error that is obtained for KLa is 5.43 %, which shows the high accuracy of the CFD model.

Abstract Given the high share of energy consumption in the building sector and the need to enhance thermal performance in cold climates, this study investigates the effect of the paraffin-based phase change material RT22HC on improving the thermal efficiency of a double-skin building facade. This material has a melting temperature in the range of 20–23°C (peak 22°C) and a latent heat storage capacity of about 190 kJ/kg, which enables storing and releasing heat at an approximately constant temperature. The aim of the study is to analyze the impact of removing thermal insulation and replacing it with an air cavity containing PCM on heating and cooling loads during cold periods in the city of Tabriz. Energy modeling was performed using DB software, and the heat transfer analysis was conducted with the Finite Difference algorithm. Three scenarios were examined: a base facade; a double-skin facade with PCM and thermal insulation; and a double-skin facade with PCM and an air cavity. The results showed that in the third case, the melting and solidification mechanism of RT22HC reduced heat flux and increased temperature stability; such that the annual sensible heat load decreased from 27276.61 kWh to 9985.8 kWh (equivalent to 63%). Moreover, indoor temperature fluctuations and mean radiant temperature differences decreased, improving thermal comfort conditions. Overall, the low thermal conductivity (0.2 W/m·K) and high heat capacity of PCM led to proposing this material as an effective substitute for conventional thermal insulations in DSF facades in cold climates.

Abstract This study evaluates the effectiveness of the aluminum sulfate coagulation in treating the wastewater from thermal power plants to efficiently remove pollutants. Key operational parameters—the pH of the wastewater (5 to 9), dosage of coagulant (10 to 40 mg/L), and mixing time (10 to 30 minutes)—were systematically investigated for their impact on the removal of chemical oxygen demand (COD) and total dissolved solids (TDS). The coagulation mechanism involves the hydrolysis of aluminum sulfate, generating charged species that neutralize particle charges, followed by adsorption, bridging, and floc formation, which together promote the aggregation and sedimentation of pollutants. Utilizing the response surface methodology (RSM) with the Design Expert software, the process was optimized, revealing that a pH near 7.4, dosage of approximately 40 mg/L of the coagulant, and mixing time of around 22 minutes maximize the treatment efficiency. Under these conditions, the removal of COD and TDS reached 71.1% and 97.3% respectively, demonstrating the potential of this approach for the sustainable and cost-effective wastewater treatment in thermal power plant operations.

Abstract Ultrasonic distillation has been implemented as a green technology for desalination of saltwater due to its low energy consumption. It has also been proposed as an alternative to conventional distillation for separating water-ethanol mixtures, offering easy operating conditions and significant reduction in energy consumption (up to 80%). The Response Surface Methodology (RSM) was employed to optimize key parameters that influence ethanol enrichment, which includes initial ethanol concentration, solution height, and the quantity of ultrasonic modules. A central composite design (CCD) was utilized to reduce the number of experimental trials while formulating a predictive mathematical model. The findings suggest that elevated initial ethanol concentrations and an augmented number of modules significantly improved the ethanol concentration in the collected mist. Under optimal conditions—65% ethanol concentration, 2.5 cm solution height, and three modules—the purity of ethanol attained was akin to that achieved through conventional distillation techniques, accompanied by markedly diminished energy consumption. This research illustrates the potential of ultrasonic distillation for ethanol separation, offering operational efficiency and reduced energy demands.

Abstract This study employs classical molecular dynamics simulations using the OPLS-AA force field to systematically investigate the influence of the length of alkyl chain on the structural, thermodynamic, and dynamical properties of a homologous series of pyridinium-based ionic liquids (methyl- to pentyl-pyridinium bromide). The main objective is to elucidate how the gradual elongation of the alkyl chain affects intermolecular interactions and ion transport behavior at the molecular level. The model demonstrates good agreement with available experimental density data, confirming its reliability for predicting physicochemical trends in these systems. The results indicate that increasing the length of the alkyl chain weakens electrostatic interactions and enhances free volume, leading to a systematic reduction in density and cohesive energy density. The structural analysis reveals well-defined cation–anion coordination shells, reflecting strong local ionic organization across all systems. The dynamical analysis shows a consistent decrease in the ionic mobility with the elongationof chains, due to stronger van der Waals interactions and steric effects, which in turn reduce diffusion and ionic conductivity. Importantly, the ionic transference numbers calculated from ion mobilities clearly demonstrate that cations contribute more to charge transport than anions in all investigated systems. This cation-dominated transport behavior provides a direct molecular-level explanation for the observed decrease in ionic conductivity by increasing the length of chains.

Abstract The membrane bioreactor (MBR) is a combination of biological and membrane systems. It utilizes advanced technologies in the treatment of various types of wastewater, having unique advantages such as the high-quality effluent and improved efficiency. The primary limiting factor for the utilization of this bioreactor  is the  membrane fouling phenomenon, which increases operational costs. In this study, four membrane bioreactors were used, with the first MBR (R1) serving as the control bioreactor. In the second MBR (R2), an adsorption process was employed, while in the third (R3) and fourth MBR (R4), in addition to the adsorption process, the electrochemical process was applied with voltages of two and one volts respectively. For the four bioreactors, the percentages of the Chemical Oxygen Demand (COD) were recorded as 86%, 91.2%, 90.7%, and 95.3% respectively. The levels of the total Extracellular Polymeric Substances (EPS) in R1, R2, R3, and R4 were about 260, 155, 177, and 98 mg/gVSS respectively. The R4 exhibited significantly lower EPS (98 mg/gVSS) compared to R1 (260 mg/gVSS), possibly due to the adsorption of EPS by nanoparticles and its subsequent removal during the electrochemical process. The role of voltage was evident in R3, where the higher voltage (2V) resulted in the less removal of EPS (155 mg/gVSS) compared to the same in R4 (98 mg/gVSS). The study found that the values of the Soluble Microbial Products (SMP) for R4, R3, R2, and R1 were about 15, 65, 55 and 139 mg/L respectively. Particularly in the most effective MBR, R4, where the addition of the zeolite adsorbent alongside metal ions demonstrated the best performance in the removal of SMP.

Abstract The cementation reaction of Ni-Cd occurs on the surface of zinc powder, and the Ni-Cd ions in the zinc sulfate solution (make-up) change into a solid metal deposit during the process. The primary purpose of this study is to evaluate the effect of the particle size of zinc powder on the operational parameters of cementation, such as the quantity of the zinc powder used, the reaction temperature, and the contact time. These parameters are influential on cost reduction as well as the manufacturing rate of zinc ingot. Results indicated that providing that the zinc powder, -325 mesh, is used, the consumption of zinc powder used in the industry can be reduced by an average of 40%. It was also confirmed that the best times for the cementation of Ni-Cd for all studied sizes were 75 and 60 minutes respectively. The Ni and Ca were removed in -325 mesh to the optimal values at 85℃ and 65℃ respectively. By optimizing the evaluated parameters, the concentrations of Ni and Cd impurities were obtained at the lowest possible and acceptable levels for transferring the make-up solution to the electrolysis stage.

Abstract pH control is crucial in biological and water treatment processes, yet it poses significant challenges due to its nonlinear characteristics. Conventional Proportional-Integral-Derivative (PID) controllers, although operator-friendly, often struggle to maintain satisfactory performance in highly nonlinear systems, especially when subjected to disturbances, measurement delay, and measurement noise. On the other hand, gain scheduling is a technique to cope with the process nonlinearity while maintaining the PID simplicity for the operators. In this paper, a gain-scheduled digital proportional-integral (PI) controller is presented for pH control, where the parameters of the controller are adapted using fuzzy logic. The control error and its numerical derivative are fed to the fuzzy inference unit with 7 membership functions, fuzzifying the severity of the control deviation. Then, the PI proportional and integral gains are updated in the defuzzification step. A simulation of a benchmark pH process with measurement delay was carried out under various scenarios. The results show that the proposed fuzzy-PI controller significantly outperforms the conventional PI controller. This is especially true in cases of feed disturbance and considerable changes in the setpoint, where the nonlinear process deviates significantly from the nominal point. In a combined disturbance/setpoint change scenario, the fuzzy-PI controller reduces the integral of the absolute error by 54%.

Abstract Methanol is an important industrial chemical, and its synthesis and purification units are among the most widely used processes in the field of energy. The two-column separation unit of methanol has been analyzed from the thermodynamic and energy points of view in the present study. The simulation has been done by Aspen Hysys V11 and the SRK equation has been regarded as the most appropriate equation of state (EOS) for this simulation with the mean relative error (MRE) of 2 %. Then, the design of the heat exchanger network (HEN) has been calculated using the Aspen Energy Analyzer V11. Both distillation towers have been analyzed using pinch technology. As a result, the amount of hot and cold utilities used has been LP=1.482×〖10〗^8, MP=1.57×〖10〗^4, and Air =1.423×〖10〗^8, respectively. Besides, the total heating and cooling target of the process has been 1.482×〖10〗^8 and 1.423×〖10〗^8, accordingly. Then, the 〖∆T〗_min (minimum allowable temperature difference between hot and cold currents) and its effect on the annual cost have been investigated. The optimum value 〖∆T〗_min is determined to have better-operating conditions and to meet the design of the HEN economically. Reducing 〖∆T〗_min increases operating costs and reduces energy costs.

Abstract Ejectors offer a cost-effective and practical solution for recovering flare gases, thereby reducing greenhouse gases. Improving the entrainment rate of the secondary fluid can enhance ejector performance. The objective of this research is to identify the optimal ejector geometry to maximize the absorption rate of the secondary fluid. Computational fluid dynamics is used to evaluate a two-phase ejector. Geometric parameters such as throat diameter and length, nozzle diameter, and converging and diverging angles impact the absorption rate of the secondary fluid. Using a multi-objective genetic algorithm, the optimal values for each parameter are obtained. The results show that reducing the throat length and angle of the converging section, as well as nozzle diameter, leads to increased absorption. In contrast, the throat and angle of the divergent section increase absorption. Additionally, energy efficiency is investigated under basic and optimized geometries. The findings reveal that increasing the soak range does not necessarily enhance energy efficiency.

Abstract In this research, gold nanoparticles (AuNPs) were synthesized for the first time utilizing the extract of Teucrium polium. The study evaluated the antimicrobial potential of both methanolic and aqueous extracts of T. polium, alongside the synthesized AuNPs. Furthermore, the impact of varying AuNP concentrations on the phytochemical characteristics of the plant extract was analyzed. The successful fabrication of AuNPs was verified through a comprehensive suite of characterization techniques, including UV-Vis spectroscopy, XRD, TEM, SEM, and FTIR. Morphological analysis via SEM and TEM revealed spherical nanoparticles with a mean diameter of 22.89 nm, while the UV-Vis spectrum exhibited a characteristic surface plasmon resonance (SPR) peak at 420 nm. The reaction reached its optimum efficiency at pH 5. Antimicrobial assays indicated that the methanolic extract possessed superior antibacterial and antifungal properties compared to the aqueous version, yielding maximum inhibition zones for Escherichia coli (14±1.4 mm) and Aspergillus niger (15±0.7 mm). Additionally, the AuNPs demonstrated notable efficacy against gram-negative bacteria, with the highest inhibition observed for E. coli (18±0.7 mm) and A. niger (20±0.9 mm). Regarding the antioxidant capacity and reducing power (phenolic flavonoid content), a concentration-dependent increase was observed up to 60 ppm (IC50=9.94 µg/mL; reducing power= 16.85 mMFe2+/mg sample), followed by a decline at concentrations exceeding this threshold.

Abstract Modern steam turbines employ extended low-pressure blades, subjecting root connections to severe centrifugal and thermal loads. As a result of these loadings, various and severe dynamic stresses are formed in the structure. Understanding the distribution of these stresses and conducting studies on it will greatly help determine the lifespan of items and how to manage them. This study evaluates stress and strain distributions in Ti-6Al-4V turbine roots, specifically comparing BLISK and fir-tree designs under operational conditions. Using the nonlinear Finite Element Analysis (FEA) and Local Plastic Stress and Strain Analysis (LPSA), the peak von Mises stress was identified as 890.76 MPa for the BLISK and 390.82 MPa for fir-tree roots. Advanced damage frameworks, including the Modified Mohr-Coulomb and Lemaitre's CDM models, are discussed conceptually to identify critical stress triaxiality states, thereby establishing a reliable baseline for subsequent fracture analyses. The findings establish a reliable baseline for fatigue studies, identifying root-blade transition fillets as critical sites for low-cycle fatigue failure. Understanding the behavior of materials under fatigue loading can help in better determining the scope of application of the design and optimizing it.