A numerical model for simulating Residence Time Distribution (RTD) of turbulent flows in helical Static mixers is proposed and developed to improve the understanding of Static mixers. The results of this model is presented in terms of different volumetric flow rate to illustrate the complicated flow patterns that drive the mixing process in helical Static mixers. The computed results are also used to predict the amount of mixing that occurs within a mixing device. Such theoretical estimates need, however, always to be thoroughly checked against observations in Static mixer. To check the reliability of the theoretically estimated RTD from the simulation by the application of the model equation, a comparison of the same with those obtained from observed data experiments in Static mixer using statistical characteristics is done. Comparison between RTD curves shows that motionless mixture can improve the performance of reactor.

The laminar flow pattern and mixing behavior of incompressible Newtonian fluids in different modified mixer ‎configurations were numerically investigated using Computational Fluid Dynamics (CFD) simulations in the range of ‎Re=0. 15-100. The governing equations were solved by ANSYS Fluent 14 using the second-order finite volume method ‎‎(FVM) and the SIMPLE algorithm scheme. The computational model is assessed by comparing the predicted pressure ‎drop results to empirical correlations in the literature. The effects of incorporated helical overlapped mixer elements and ‎the diameter aspect ratio (C) on the mixing efficiency for different mixer geometries were examined and evaluated by ‎characteristics measures of Intensity of Segregation (IOS), pressure drop, extensional efficiency, and G-factor. The ‎performance of new modified mixers is evaluated via comparison with the standard industrial Kenics Static mixer. The ‎Static mixers with modified internal geometry achieved fast mixing and better mixing quality than the Kenics mixer. ‎Besides, an increase in diameter aspect ratio C benefited from a decrease in pressure drop within the Static. The ‎modified mixer: C=1. 5 was found to have the highest mixing efficiency, concerning short mixing length with marginally ‎higher pressure drop than the other mixers. In contrast, the mixer: C=2 is the most efficient based on low pressure drop ‎and energy requirement with slightly greater mixing length‎‎.

Oil droplet size distribution of an emulsion produced by Sulzer Chemtech's Static SMX Static mixer under flow condition was experimentally studied and reported. The dispersed phase of vegetable oil-in-water (O/W) emulsion produced through Static mixer by varying the concentration from 1 to 4 vol % oil in water, flowrate of dispersed and continuous phase and operating time. The effect of run time on oil drop sizes is characterized using the spectra obtained from the particle size analyser. The Static mixer with 9 perpendicular elements made of teflon is stacked against each other had a void fraction of 0. 93. The sauter mean diameter of oil droplet decreases from 8 μ m to 4 μ m with an increase in Reynolds number. The emulsion droplets of mean sauter diameter in the range 4. 1 μ m to 4. 7 μ m were produced by increasing the concentration of the dispersed phase from 1: 100 to 1: 25, within a span value of between 30 to 240 sec, at atmospheric pressure and room temperature. Performance equation for sauter mean oil droplet diameter is developed based on the experimental data has ± 0. 2 rms deviation.

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 in different conditions has been used as a passive mixing tool to achieve proper mixing, thus 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 effects of mixer length and mixer element pitch at different flow rates of Kerosene, including 2, 18 and 30 mL/s were 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 decrease. 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 good agreement with the experimental data.

Background and Aim: The aim of the present study was to investigate the effect of the Hand Static Rest Splint on reducing the pain and other compliance of Rheumatoid Arthritis (RA). Materials and Methods: In the present clinical trial, 12 patients, aged 35-50 (average: 39 years) with RA, referring to the Occupational Therapy Unit of Taleghani hospital and meeting America College of Rheumatology diagnostic criteria, were included. Visual Analogue Scale (VAS) was administered and swelling, tenderness and morning stiffness were assessed. Moreover, assessments of active range of motion using goniometry and grip strength with Jamar dynamometer in both hands were performed. Statistical analysis of data was performed using t-test and Mann-Whitney Test for two independent samples and willcoxon tests and paired t-test for paired samples run in SPSS, version 18. The level of significance was set at p˂ 0. 05. Results: The findings showed that the Static Rest Splint led to improvement in the wrist range of motion (flexion p=0/005, extension p=0/03) when the two groups were compared, but it did not have a significant effect on Morning Stiffness (p=1), pain (p=0/1), Swelling (p=0/06), and Tenderness (p=0/2). However, when compared between after and before intervention in hand with splint, pain (p=0/02) and wrist range of motion (p=0/004) improved. Conclusion: Based on the findings of the current study, and since using splints only improve range of motion in the wrist compared between two groups and pain relief before and after the intervention, it seems that using hand Static Rest Splint to reduce other symptoms need further investigation and also given that the use of this position without stress on the tendon can be effective in reducing the causes deformity, further studies are needed to more delineate these points.

The laminar flow of non-Newtonian fluids through a Kenics Static mixer is investigated by using the CFD (Computational Fluid Dynamics) tool. The working fluids have a shear thinning behavior modeled by the Ostwald De Waele law. We focus on the effect of Reynolds number, fluid properties, twist angle and blade pitch on the flow characteristics and energy cost. The pressure drop information obtained from the simulations was compared to several experimental correlations and data available in the literature. The numerical results were found in good agreement with the experimental values. From the obtained results, the twist technique is confirmed to be very useful to enhance the mixing with less power consumption and at low Reynolds numbers. A faster axial mixing has been achieved with increased blade length and decreased twist angle. However, the good mixing near the tube walls was obtained with increased twist angle. The power consumption expressed in power drop was found to be increase with increased CMC concentrations, Reynolds number, twist angle and decreased blade length.

This paper proposes a 2.4 GHz active mixer without passive inductor for the transceiver system. Taking into account the design requirements of the mixer, a double-balanced down-conversion structure with active inductor and negative resistance is designed. The proposed mixer with 130 nm CMOS technology is designed and simulated using Cadence software at 1.5 V supply voltage. Although we had to compromise conversion gain with linearity, we were able to achieve very high conversion gain with average linearity. Based on the results of post-layout simulations, the conversion gain of 27.57 dB, IIP3 equal to -7.88 dBm, 1-dB compression point equal to -17.34 dBm and IIP2 equal to 44.22 dBm with power consumption of 2.5 mW was obtained for the proposed mixer. The chip size without input and output pads is 95.18 µm × 117.68 µm, which leads to a chip area of 0.0112mm2.