Mathematical Study of Nonlinear Mixed Convection Unsteady Flow in a Parallel Plate Inclined Channel in the Proximity of Time Periodic Boundary Conditions: Flow Reversal

This report is executed to examine the task of assimilating parameters on bipartite convection stream structure in a sloped pipeline while certain plate is disorderly warmed. The dictating motivation and energy identifications are ascertained and consequent expressions for thermal reading, liquid movement, fanning friction and stress flatten are acquired. The purpose of non-linear Boussinesq simulation is to escalate liquid movement, inverse stream generation at the channel plates, stress flatten, and fanning factor. In particular, the liquid motion escalates at the channel left portion and depletes at the channel right portion with the progress of time. A particular case of our development shows an excellent compromise with the previous consequences in the literature.

On the existence of global solution of the system of equations of liquid movement in porous medium

The initial-boundary value problem for the system of one-dimensional isothermal motion of viscous liquid in deformable viscous porous medium is considered. Local theorem of existence and uniqueness of problem is proved in case of compressible liquid. In case of incompressible liquid the theorem of global solvability in time is proved in Holder classes. A feature of the model of fluid filtration in a porous medium considered in this paper is the inclusion of the mobility of the solid skeleton and its poroelastiс properties. The transition from Euler variables to Lagrangian variables is used in the proof of the theorems.

Estimating fouling and hydraulic debottlenecking of a clarifier piping system in the expansion of a chemical manufacturing plant

Debottlenecking and estimating fouling in a clarifier piping system for the expansion of an existing chemical manufacturing facility in the U.S. Gulf Coast was analyzed and modified. The existing clarifier piping system fitting data was gathered for the real-world operation from the field. This data was used in the Applied Flow Technology (AFT) Fathom, a program used to study hydraulic systems. The hydraulic results with and without recommended piping modifications along with changing piping roughness factors were also analyzed. The two piping roughness factor cases tested were roughness of 0.152 mm and fouling of 25.4 mm. The AFT Fathom results showed that without piping modifications and specifying fouling of 25.4 mm, required flow cannot be established due to insufficient driving force for liquid movement. The measured field flow data confirmed that the reduced clarifier capacity was due to high pressure losses in the hydraulic system. Also, it was found that the existing clarifier nozzle was inadequately designed originally, and replacing the nozzle showed an increase in the clarifier capacity due to reduced entrainment of the air. These modifications were further adapted in the plant expansion and operations were validated using the actual plant data. The plant data matched closely with the estimated capacities of the clarifiers. AFT Fathom hydraulic software was effective in predicting a fouling severity in the clarifier piping system and debottlenecking of the clarifier capacity was done. The conclusions derived from this study can be used all over the world where clarifiers are utilized.

Closable Valves and Channels for Polymeric Microfluidic Devices

This study explores three unique approaches for closing valves and channels within microfluidic systems, specifically multilayer, centrifugally driven polymeric devices. Precise control over the cessation of liquid movement is achieved through either the introduction of expanding polyurethane foam, the application of direct contact heating, or the redeposition of xerographic toner via chloroform solvation and evaporation. Each of these techniques modifies the substrate of the microdevice in a different way. All three are effective at closing a previously open fluidic pathway after a desired unit operation has taken place, i.e., sample metering, chemical reaction, or analytical measurement. Closing previously open valves and channels imparts stringent fluidic control—preventing backflow, maintaining pressurized chambers within the microdevice, and facilitating sample fractionation without cross-contamination. As such, a variety of microfluidic bioanalytical systems would benefit from the integration of these valving approaches.

An effect of fabrics thickness and structure on moisture management properties of 3D spacer fabrics

Purpose Polyester multifilament is used to produce the face and back layer of warp knitted spacer fabric (WKSF) and these two layers are connected by polyester monofilament as a middle layer. This fabric has unique and extraordinary characteristics, and different possibilities of fabric structure and the middle layer thickness are tried to find out the moisture management properties. The paper aims to discuss these issues. Design/methodology/approach This study investigates the influence of fabric thickness and structure on moisture management properties. Findings Polyester monofilament quickly up takes the water molecule from the water reservoir and transfers it by capillary action. The gravitational force and the availability space between the two outer surface layers restrict the movement of water molecules, although the pressure develops to push the molecules from the water reservoir. As a result, all the spacer fabric samples attain the equilibrium state very quickly. WKSF and the hexagonal net structure prove to be better in vertical wicking. Originality/value The liquid movement is quick in the front side of the spacer fabric, and the rate of wicking is higher in open structure than in the closed structure. It confirms that the hexagonal net structure produces high pore size on fabric and it reaches maximum wicking values. Fabric thickness does not have much influence on the vertical wicking properties of all fabric samples, and the rate of liquid movement produces a similar trend. In in-plane wicking, the polyester monofilament in the middle layer of spacer fabric plays a major role rather than the outer surface layers of fabric.

CHANGING INTENSITY OF HEAT TRANSFER IN THE PIPE SECTION DURING REFREGERANT BOILING IN THE EVAPORATORS OF SHIP REFRIGERATING PLANTS

The article describes the experimental evaporator as a research object, the evaporator model being given with boiling refrigerant R4O6A inside the pipe. The experiment in heat transfer was performed on a special stand inside a smooth pipe made of 1X18H9T grade steel with a diameter of 0.013 mm, a length of 3.3 m, and a wall thickness of 0.5 mm. There has been studied the influence of the two-phase regimes of the working medium movement on heat exchange where it is boiling both along the length of the pipe and in its section. The comparison between heat transfer coefficients has been given. The visual observations over the flow structure were held. There were determined four regimes of two-phase flow: emulsion, slug, wavy, and stratified. Changing heat transfer coefficients in the upper, medium and bottom parts of the tube section has been shown. Changing of heat transfer was identified in the dependence of developing of the regimes. There has been proved the existence of dry wall in the upper part of the pipe under wave and stratified regimes, where the minimal heat transfer was recorded. Graphic dependences of changing the heat transfer coefficients in the pipe section for various regimes are presented. It has been stated that the intensity of heat transfer to steam depends on the speed of its movement, and the heat transfer to a boiling liquid depends on two components: boiling intensity and speed of the liquid movement. It has been inferred that the refrigerant enters the evaporators of the ship refrigeration units after throttling with initial mass of steam content from 0.1 to 0.15 kg/kg, which corresponds to the projectile or wave mode; emulsion mode is possible only in pumping circuits; the length of the stratified regime with low heat transfer intensity will be the most significant.

Modeling an Airlift Reactor for the Growing of Microalgae

Objective: The flow dynamics of an airlift reactor for the growing of microalgae is modeled using Computational Fluid Dynamics (CFD). The model is applied to the operation and optimization of the reactor, giving a valuable picture of the liquid movement and carbon dioxide trajectory at different air injection flow rates. Methods: A novel aspect of the model is that air and carbon dioxide are injected at separated locations. Air is injected at the bottom of the reactor and CO2 injection takes place in the downcomer region of the reactor to obtain longer CO2 paths, improving its transference. Results: The results show modeling is a useful tool in the control of the reactor operation; for example, in avoiding the sedimentation of microalgae or for detecting the existence of zones with extremely low CO2 concentrations.