Iranian Journal of Chemical Engineering (IJChE)

Abstract This study presents a neuro-fuzzy inference system for predicting the pressure loss in coiled flow inverter (CFI) tubes. Computational fluid dynamics (CFD) simulations were conducted to obtain the amounts of the pressure loss across nine distinct configurations of CFI. The neuro-fuzzy model utilized three key input parameters of the Reynolds number (Re), number of 90° bends (N), and tube-to-coil diameter ratio (L/D). Following CFD validation, the dataset was partitioned into training (two-thirds) and testing (one-third) subsets. The model achieved an outstanding mean relative error (MRE) of 0.549%, demonstrating its high predictive accuracy and reliability for the estimation of the pressure loss in coiled flow inverter systems. These results highlight the neuro-fuzzy approach as a suitable tool for optimizing CFI designs in industrial applications. This study ultimately demonstrates how the strategic combination of numerical simulation and machine learning can accelerate development cycles while maintaining rigorous accuracy standards, providing engineers with a powerful tool for system design and optimization. 

Abstract Although not listed on the United States Pharmacopeia (USP), like standard USP 2, small volume USP 2 dissolution apparatus has gained a great deal of attention, especially for cases where small amount of drug product is available for testing in research and design step or evaluations are to be made on a tablet containing trace amounts of the active pharmaceutical ingredient. In this work, firstly, small volume USP 2 apparatus was designed and manufactured using downscaling rules and considering standard USP 2 as a reference. Then, velocity profile, flow patterns, and shear rate were obtained by PIV and COMSOL simulation software at paddle speeds of 66 and 133 rpm, corresponding to agitation speed of 50 and 100 rpm, respectively, in the standard USP 2. Comparison between experimental and computational results showed acceptable adaptation. Instantaneous velocity data showed eddies and secondary flows in different zones of the vessel, which is desirable for micro-mixing but undesirable in terms of system consistency and reproducibility, as sampling from these zones are known to lead to inconsistent data. Furthermore, increased agitation rate led to the disappearance of rotational zones around the paddle. The magnitude of velocity and shear rate increased by 35% with an increment of paddle stirring from 66 to 133 rpm.

Abstract In the study, the thermal-hydraulic performance of the zigzag channels with circular cross-section was analyzed by Computational Fluid Dynamics (CFD). The standard K-Ꜫ turbulent scalable wall functions were used for modeling. The wall temperature was assumed constant 353 K and water was used as the working fluid. The zigzag serpentine channels with bend angles of 5 - 45° were studied for turbulent flow from 4000 to 40,000 Reynolds number (Re). The thermal performance of the zigzag 45° channel was better than the other channels and also it had the highest friction factor (f). The bends caused secondary flow, and as the bend angle increased, the secondary flow increased. This Phenomenon had a positive effect on thermal performance and a negative effect on hydraulic performance by increasing the friction factor. The obtained CFD data used to develop correlations for predicting the Nu and f as the functions of Re and bend angles. The correlation constants were optimized by the genetic algorithm method which leads to the mean relative errors of 3.32% and 6.94% for Nu and f estimation, respectively.

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 In this paper, drag coefficient of infinite quadralobe catalytic particle with non-circular cross sections has been investigated by Computational Fluid Dynamics (CFD) methods and for this purpose FEMLAB Multiphysics V2.3 based on finite element methods have been used. A new simple correlation for drag coefficient of infinite quadralobe particle
has been established over the range of Reynolds numbers from 0.01 up to 1000. A comparative study has been made between the numerical results of this study and the available data in the literature. The predicted drag coefficient of infinite cylinder shows good agreement with experimental data within a converging quantitative error of less than 7% up to Reynolds number of 1000. The drag coefficient results for cross flow on infinite quadralobe particle shows higher value in comparison with cylindrical particle. In addition, influence of different number of particles (single, two, three and four particles) and orientation angle of particles on drag coefficient have been investigated.