Iranian Journal of Chemical Engineering (IJChE)

Abstract Centrifugal pumps are extensively employed in mining, petrochemical, and wastewater treatment industries, where handling solid–liquid two-phase flows often results in the erosive wear of internal components. This study investigates slurry-induced erosion in a single-stage centrifugal pump through a three-dimensional CFD model developed in COMSOL Multiphysics. The model integrates Lagrangian particle tracking with an empirical erosion correlation and is validated with experimental data reported in the literature, showing good agreement with an average relative error of below 5%. Parametric simulations were conducted to examine the effects of two key operating parameters: flow rate and particle concentration. The results indicate that at sub-design flow rates, the prolonged particle residence time increases impact frequency, leading to severe localized erosion near the blade leading edges. Conversely, operating at rates close to the design flow rate and up to 1.4 Qd reduces erosion intensity and promotes a more uniform wear distribution. Increasing particle concentration produces a nearly linear rise in the maximum erosion rate—from approximately 3 mm/year at 0.5% to over 22 mm/year at 3%—while also expanding the affected blade area. Moreover, larger particles intensify erosion severity and shift erosion zones toward the downstream blade regions, altering the wear mechanism. Overall, the validated CFD framework provides a robust and predictive tool for evaluating both erosion intensity and spatial distribution in slurry-handling centrifugal pumps. The findings emphasize the importance of optimizing operational parameters and applying wear-resistant materials to enhance pump durability and reduce maintenance costs. 

Abstract The Fe₃O₄/MW-CNT composite was prepared for a hybrid photo-catalyst-assisted electrochemical process for the removal of BTX contamination from wastewater. Oxidation of multi-walled carbon nanotube was conducted by different treatments including acid treatment and hydrogen peroxide. The XRD, FTIR, SEM, TEM, and BET analyses were performed to characterize both the MW-CNT and the synthesized composite. Simultaneous photo-catalyst and electrochemical processes were conducted to evaluate the performance of a new hybrid process for wastewater treatment. The effect of current density, photo-catalyst loading, and BTX initial concentration was investigated experimentally. The characterization results of the synthesized composite show that a mixture of strong nitric acid and sulfuric acid treatment at a high exposure time and low temperature is the best route for MW-CNT oxidation. The removal efficiency of BTX compounds from wastewater using the hybrid photo-electrochemical process was found to be in the range of 28 to 43% for different conditions. The optimum condition for maximum removal of BTX was found by mathematical modeling of experimental data. The results indicate that a combination of photo-catalyst and the electrochemical process can enhance the BTX removal efficiency.

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 In this study, the fluid flow together with solid particles has been studied using Computational Fluid Dynamics (CFD). The gas-solid flow (air and sand particles with the size of 150 µm) inside a 76.2 mm diameter pipe with various bend angles including 45, 60, 90, 120, 135, and 180° was modelled at the fluid flow velocity of 11 m/s. The k-ω turbulence model was employed to model the flow turbulence and the E/CRC erosion model have been used to predict erosion rates. The hydrodynamics of the flow, the particles motion as well as the probable erosion regions were predicted. The CFD simulation results showed that increasing the curvature angle increases the erosion rate. While, increasing the pipe diameter, decreases the erosion rate. The maximum erosion rate was predicted at the end part of the curvature for 45 and 60 ° angles, while it was observed in the middle region for 120 and 135 ° curvatures. Finally, the maximum erosion rate for the 180 ° curvature was observed in two regions at the end of the first and second half. Using these results, precautionary considerations for the erosion, and the suitable plans for the repair and maintenance of the equipment can be offered.

Abstract The Fe3O4/MW-CNT composite was prepared for a hybrid photo-catalyst-assisted electrochemical process for the removal of BTX contamination from wastewater. Oxidation of multi-walled carbon nanotube was conducted by different treatments including acid treatment and hydrogen peroxide. The XRD, FTIR, SEM, TEM, and BET analyses were performed to characterize both the MW-CNT and the synthesized composite. Simultaneous photo-catalyst and electrochemical processes were conducted to evaluate the performance of a new hybrid process for wastewater treatment. The effect of current density, photo-catalyst loading, and BTX initial concentration was investigated experimentally. The characterization results of the synthesized composite show that a mixture of strong nitric acid and sulfuric acid treatment at a high exposure time and low temperature is the best route for MW-CNT oxidation. The removal efficiency of BTX compounds from wastewater using the hybrid photo-electrochemical process was found to be in the range of 28 to 43% for different conditions. The optimum condition for maximum removal of BTX was found by mathematical modeling of experimental data. The results indicate that a combination of photo-catalyst and the electrochemical process can enhance the BTX removal efficiency.

Abstract The central composite design (CCD) was employed to investigate the adsorption of Pb(II) and Zn(II) metal ions as well as methylene blue (MB) as an aromatic anion by a new EDTA/MnO₂/CS/Fe₃O₄ synthesized nanocomposite. The effect of possible affective factors including the contaminant concentration (20-200 mg/L), pH (2-8), adsorbent content (0.1-0.9 g/L), and contact time (10-110 min) on the adsorption of the metal ions using response surface methodology (RSM) were studied. The highest removal percentages predicted by the model were 100.776 % and 87.069 %, respectively, for the removal of Pb(II) and Zn(II), that the value of more than 100 % in the case of Pb(II) was due to the model’s error. The effect of the simultaneous presence of methyl blue (MB) and the metal ions in the aqueous solution on the adsorption rate of each metal ion was investigated. The study of the adsorption isotherms in the single-component adsorption showed the dominance of Langmuir isotherm over the adsorption process of each pollutant (R² > 0.99). The maximum adsorption capacities according to the Langmuir model were 310.4 and 136 mg/g for lead and zinc ions, respectively, and 421.1 mg/g for methyl blue. The results showed that the studied nanocomposite still had high efficiency after five consecutive adsorption-desorption cycles

Abstract In the present study, Choline hydroxide (ChOH) as an ionic liquid catalyst was used for transesterification of soybean oil into biodiesel in a microchannel reactor. The effects of three variables i.e. reaction temperature, catalyst dosage and total flow rate on fatty acid methyl ester (FAME) content (wt. %) were optimized using Box–Behnken experimental design. In order to predict the FAME content a quadratic polynomial model was obtained. The optimal conditions from the model were reaction temperature of 53.53 °C, catalyst dosage of 2.6 wt. % and total flow rate of 11.82 mL/min. At these conditions, the predicted FAME content was 96.45 wt.% and the experimental FAME content was obtained 97.6 wt. %. The proximity of the experimental results and predicted values showed that the regression model issignificant. Using the ionic liquid catalyst in the studied microreactor for transesterification leads to diminish the reaction time to the order of seconds compared to conventional batch systems. In addition, the reusability of ChOH catalyst was investigated. The results revealed that the catalyst had perfect utility after several runs without much loss in the activity.

Abstract Abstract
In this work, the role of appropriate mixing for mercaptan removal from Kerosene using caustic soda has been investigated in the pilot scale. Static mixer at different condition has been used as a passive mixing tool to achieve proper mixing and consequently high performance of mercaptan removal. Two lengths of static mixer including 20 and 40 cm as well as two pitches 1 and 3 mm were considered in a straight line. NaOH was injected to the Kerosene line to remove ( convert it to disulfide) the mercaptan. The effect of mixer length, mixer element pitch at different flow rates of Kerosene, including 2, 18 and 30 mL/s was investigated on the mercaptan removal. The experimental results showed that the concentration of mercaptan in the pilot line outlet will decrease as the flow rates of Kerosene decreases. Also, at a fixed flow rate of Kerosene, increasing the length of the static mixer and decreasing its element pitch caused the mercaptan to decrease due to proper mixing. Computational Fluid Dynamics (CFD) modeling technique was employed to describe the experimental results, fluid flow pattern, and mixing performance. Qualitative predicted results of CFD modeling show a good agreement with the experimental data.

Abstract "> Despite numerous studies of shell and helically coiled tube heat exchangers, a few investigations on the heat transfer and flow characteristic consider the geometrical effects like coil pitch. Moreover, this scarcity is highlighted for the shell side of this type of heat exchangers. This study reports experimental and Computational Fluid Dynamics (CFD) investigations on heat transfer and flow characteristics of a shell and helically coiled tube heat exchanger. The experiments were carried out using a helically coiled tube, which was placed in a cylindrical shell. Hot and cold water were used as the process fluids on the tube and shell side, respectively. The CFD modeling technique was employed to describe the experimental results, fluid flow pattern, and temperature profiles as well as dead zones in the heat exchanger. Quantitative predicted results of CFD modeling show a good agreement with the experimental data for temperature. The effect of the coil pitch on heat transfer rate was numerically studied and it was found that the heat transfer coefficient intensifies with an increase in coil pitch. The average turbulent kinetic energy (k) for the old coil tube and twice coil pitch heat exchanger was computed as 2.9×10-3 and 3.3×10-3 m 2 /s2, respectively. This indicates an increase of about 14% in flow turbulent kinetic energy. Nusselt numbers were compared with those estimated using published correlation and a mean relative error (MRE) of 14.5% was found between the experimental and predicted data. However, a good agreement was obtained in lower shell Reynolds numbers (lower than Re=200).