MASS TRANSFER IN CROSS-FLOW PARALLEL-PLATE DIALYZER WITH INTERNAL RECYCLE FOR IMPROVED PERFORMANCE

The internal reflux effect on dialysis through the retentate phase of a countercurrently cross-flow rectangular module is investigated. Theoretical analysis of mass transfer in cross-flow devices with or without recycling is analogous to heat transfer in cross-flow heat exchangers. In contrast to a device without reflux, considerable mass transfer is achievable if cross-flow dialyzers are operated with reflux, which provides an increase in fluid velocity, resulting in a reduction in mass-transfer resistance. It is concluded that reflux can enhance mass transfer, especially for large flow rate and feed-concentration operated under high reflux ratio.

In this study, modeling investigation of mass transfer in concurrent-flow chemical extraction process is carried out. Continuum Model is used to describe mass transfer process. Concentration curves in organic droplet and aqueous liquid film are firstly calculated and rate-limiting step is determined to be mass transfer of solute in aqueous phase. Mass transfer performance in aqueous phase is further calculated. Volumetric mass transfer coefficient and volumetric mass transfer coefficient during mass transfer time before solute concentration decreases to 5%, are calculated for evaluating mass transfer characteristics. The effect of organic droplet size is studied. The result demonstrates that increase in aqueous/organic volume ratio significantly decreases mass transfer performance, decrease in droplet size enhances mass transfer process through both reducing mass transfer resistance and increasing contacting area.

Mass transfer between microbubbles

Parametric studies of coupled vibration of cylindrical pipes conveying fluid with the wave propagation approach

Modeling investigation of mass transfer of gas–liquid concurrent flow processes

Swirl flow agitation for scale suppression

Use of axial membrane vibrations to enhance mass transfer in a hollow tube oxygenator

Mass transfer in gas—liquid slurry reactors

The article focuses on the influence of Hall current, radiation, heat source, and Dufour effects on the unsteady magnetohydrodynamic (MHD) natural convective parabolic flow over a vertical plate fixed within a porous medium. The study involves examining the heat transfer and substance accumulation dynamics when an incompressible fluid flows over a vertically oriented plate. The plate is uniformly heated and undergoes increased velocity due to rotational motion. The researcher applied the Laplace Method to find solutions for the relevant mathematical equations. In this analysis, specific parameters were considered, including Prandtl, Schmidt, Grashof values for heat transfer, and the Grashof value for substance accumulation. The results indicated that factors such as heat source, Hall current, permeability, and Grashof values lead to a corresponding increase in fluid velocity. Conversely, an increase in radiation levels is associated with a decrease in fluid velocity. Temperature, on the other hand, rises with a higher heat source and decreases with an increase in radiation levels.

The effect of some environmental parameters on surface colonization by microorganisms

The increased demand for energy has led to the development of innovative drilling methods and technologies in the oil and gas industry. Inefficient transportation of cuttings causes downhole cleanliness issues, which have drawn widespread attention. One way to overcome cuttings transport inefficiency is to use suitable modeling methods to determine capable drilling parameters that will ensure the effective removal of cuttings particles. In this paper, Computational Fluid Dynamics (CFD) and Discrete Element Method (DEM) are combined to deeply investigate the impact of various drill parameters on cutting transport. The effects of cuttings particle size, eccentricity, fluid velocity, drill pipe/bit rotation speed, and bit offset angle are analyzed by studying the velocity of cuttings particles and the spatial distribution of particles in the annulus and bottom-hole. The results show that an increase in eccentricity and particle size reduces the velocity of cuttings particles, with the velocity decreasing more significantly when the eccentricity is greater than 0.5 and the particle size exceeds 2 mm. An increase in fluid velocity and speed of drill pipe/bit significantly increases the velocity of cuttings particles, which has a positive feedback effect on the migration of cuttings particles in the downhole. Bit offset angle leads to changes in the bottom-hole spatial structure and reduces the cuttings transport efficiency. These findings provide a useful strategy for improving cuttings migration and downhole cleaning.

A mass transfer model for hydrate formation in bubbly flow considering bubble-bubble interactions and bubble-hydrate particle interactions

To explore the effect of dual-frequency ultrasound combined vacuum drying (DUVD) on non-Newtonian fluid food, the experiments of DUVD on Pangasius bocourti surimi (PBS) were carried out, and the dehydration, water migration, microstructure and rheological properties of PBS were studied under different ultrasonic powers and frequency combinations. The results showed that the drying times were shortened by 43.48 %–86.97 % with applying dual-frequency ultrasound in vacuum drying process. The low-field nuclear magnetic resonance results illustrated that the content of free water decreased continuously during drying, and higher ultrasonic power could cause faster free water reduction rate, while semi-bound water content increased first and then decreased. The scanning electron microscope results demonstrated that increasing ultrasonic power was beneficial to the formation of dense micropores and the reduction of mass transfer resistance. The rheological properties examinations revealed that PBS remained the characteristics of pseudoplastic fluid and elastic fluid after DUVD treatment, the shear stress and apparent viscosity, energy storage modulus and loss modulus of the composites were increased at different degrees. The study clarified that DUVD technology could achieve faster and better drying of PBS.

Effects of net-type spacers on heat and mass transfer in direct contact membrane distillation and comparison with ultrafiltration studies

Mass transfer in a symmetric sinusoidal wavy-walled channel for oscillatory flow