Effect of the wavy tank wall on the characteristics of mechanical agitation in the presence of a Al2O3-water nanofluid

The enhancement of the heat transfer in the stirred tank is a much-desired objective for accelerating certain physical and chemical parameters in the industrial field. From this basis, an attempt is made in this paper to investigate the effect of the wavy wall of a stirred tank on the hydrodynamic, thermal, and energetic behavior of an Al2O3-Water nanofluid. The stirred tank has a flat bottom, and it is equipped with an anchor stirrer. A hot temperature has been imposed on the tank wall, and the agitator has been assumed adiabatic, where the nanofluid has a cold temperature at the initial instant. The laminar flow was governed by the equations that describe the forced convection, and it was solved by the finite element method. The numerical simulation results showed a considerable acceleration in the heat transfer inside the stirred tank by increasing the amplitude of the wavy wall and increasing the nanoparticle concentration. However, there has been a remarkable increase in the stirring power number. This contribution aims to increase thermal efficiency, especially in the chemical and petrochemical fields, to obtain a better yield of certain chemical reactions and mass transfer depending on the heat

Management and valorisation of wastes through use in producing alkali-activated cement materials

There is a growing global interest in maximising the re-use and recycling of waste, to minimise the environmental impacts associated with waste treatment and disposal. Use of high-volume wastes in the production of blended or novel cements (including alkali-activated cements) is well known as a key pathway by which these wastes can be re-used. This paper presents a critical overview of the urban, agricultural, mining and industrial wastes that have been identified as potential precursors for the production of alkali-activated cement materials, or that can be effectively stabilised/solidified via alkali activation, to assure their safe disposal. The central aim of this review is to elucidate the potential advantages and pitfalls associated with the application of alkali-activation technology to a wide variety of wastes that have been claimed to be suitable for the production of construction materials. A brief overview of the generation and characteristics of each waste is reported, accompanied by identification of opportunities for the use of alkali-activation technology for their valorisation and/or management

Optimization of the Performance of a Biomedical Micro-Pump

This paper discusses the optimization of a micro-pump composed by deformable polymeric membrane in contact with reservoir and examines the effect of the materials property at the performance and the functionality of the system. The Neo Hookean  hyperelastic material model is used to simulate the deformation of polydimethylsiloxane (PDMS) elastomer and compared with Poly methyl methacrylate (PMMA). The results of simulation by finite element are presented and discussed.  In second steps we study the power to inject by active membrane a Newtonian and a non Newtonian fluid in microcanalization, the power law is used to model the variation of the blood viscosity and precise the maximum value of flow rate at minimum applied pressure and control the fluid transportation. This type of micropump appears to be suitable for biomedical applications and demonstrate the versatile use of active membrane as moving parts to inject the fluids us blood or glucose

Mechanical Behavior of Polymeric Membrane: Comparison between PDMS and PMMA for Micro Fluidic Application

AbstractThe list of polymers is long each it presents very interesting mechanical advantages. In this paper we interest more especially to two polymers extensively used in the MEMS and more especially in micro-valve actuators, the PDMS and PMMA. Our goal is to study the mechanical behavior of the two polymeric membrane subjected to equal pressure could drag deformation. We have simulate the mechanical behavior by hyper elastic model of Neo- Hookean and linear elastic in order to compare between the two materials in view of amplitude deformation on one hand, and on the other hand we present the numerical conditions thus (the effect of the step, thickness, number of mesh) in order to optimize the dimensionality of the membran

Numerical simulation of heat transfer through the building facades of buildings located in the city of Bechar

This study deals with the transient heat transfer in a multi-layered building wall through the facades of the buildings located in the city of Bechar (south-west Algeria). The physical model is presented to find the variation of the transient temperature in these structures and the heat flux through these elements, which depends on the air temperature of the inner surface and the instantaneous climatic conditions of the air outside. Comsol Multiphysics based on the finite element method is designed to perform numerical simulations. The measured hourly ambient air temperatures and the solar radiation flux on the horizontal surface for the city of Bechar Algeria are using during the hottest period (July 2015), and also using the properties Thermodynamics of each component of the structure. The validation of the analytical model with this simulation is verified in this document. The calculations carried out for different multilayer building walls which are commonly used in the south of Algeria to determine the thermal behavior of these structures and the influence of radiation heat flux on these elements

Numerical simulation heat transfer by natural convection in liquid metal with a sinusoidal temperature

This study focuses on the numerical simulation of heat transfer by natural convection in a rectangular enclosure, filled with a liquid metal (low Prandtl number) partially heated from below with a sinusoidal temperature. The value of the study lies in its involvement in the crystal growth for the manufacture of semiconductors and electronics cooling. Indeed, the occurrence of convection during crystal growth can lead to in homogeneities that lead to striations and defects that affect the quality of the crystals obtained by the Bridgman techniques or Chochrawlski. Temperature of the oscillations, due to the instabilities of the convective flow in the liquid metal, also induces non-uniform cooling in the solidification front. Convection is then studied in order to reduce it. A modelling of the problem in two dimensions was conducted using Comsol computer code that is based on the finite element method, by varying the configuration of the control parameters, namely, the Rayleigh number, the nature of fluid (Prandtl number) and amplitude of temperature on heat transfer rate (Nusselt number) on convective structures that appear

Numerical simulation heat transfer by natural convection in liquid metal with a sinusoidal temperature

This study focuses on the numerical simulation of heat transfer by natural convection in a rectangular enclosure, filled with a liquid metal (low Prandtl number) partially heated from below with a sinusoidal temperature. The value of the study lies in its involvement in the crystal growth for the manufacture of semiconductors and electronics cooling. Indeed, the occurrence of convection during crystal growth can lead to in homogeneities that lead to striations and defects that affect the quality of the crystals obtained by the Bridgman techniques or Chochrawlski. Temperature of the oscillations, due to the instabilities of the convective flow in the liquid metal, also induces non-uniform cooling in the solidification front. Convection is then studied in order to reduce it. A modelling of the problem in two dimensions was conducted using Comsol computer code that is based on the finite element method, by varying the configuration of the control parameters, namely, the Rayleigh number, the nature of fluid (Prandtl number) and amplitude of temperature on heat transfer rate (Nusselt number) on convective structures that appear

Numerical Study of Mechanical Stirring in Case of Yield Stress Fluid with Circular Anchor Impeller

In this work the characterization of hydrodynamic fields of incompressible yield stress fluid with regularization model of Bercovier and Engelman in a cylindrical vessel not chicaned equipped with circular anchor stirrer was undertaken by means of numerical simulation using computational fluid dynamics. Simulations flow of a Bingham fluid agitated by straights blades anchor was used to validate the rheological model implemented of the fluid treated. The flow structures, and especially the effect of inertia, the plasticity and the yield stress, are discussed. We have analyzed also the influence of rheological parameters on the hydrodynamic flow behaviours, such as the velocity components and the global characteristic like power consumption