Search

The present study deals with numerical investigation of mixed convection of Al2O3-water nanofluid with consideration of variable properties inside a rectangular inclined multi-vented cavity heated from one side. Effects of variations of volume fraction of nanoparticles and the positions of outlet port of the cavity on flow and temperature field and rate of heat transfer are studied. The obtained results show that the existence of nanoparticles in the base fluid leads to a significant heat transfer increase. Moreover, a better cooling inside the cavity was found by a displacement of the outlet port from the left to the right of wall. [ABSTRACT FROM AUTHOR]

The main purpose of this work is to studied a dynamic thermal simulation for prediction of the thermal and energy performance of an Earth-to-Air Heat Exchanger (EAHX), depends on various factors, installed in individual building including an area of 109 m2 multi-zone in the city of Beni Mellal Morocco. The climate is temperate, with temperature varying between 2 °C and 44.8 °C. This study was performed using TRNSYS simulation software during a typical year. Our simulation consists in developing a comparative study with or without an earth-air heat exchanger (EAHX), in order to analyze the energy efficiency and thermal performance within the building. As a result, an EAHX may improve the thermal comfort inside a building or even reduce the energy destined for heating or cooling. Moreover, the results show that the passive air conditioning of the building envelope is among the most effective solutions that give a significant reduction in energy requirements. [ABSTRACT FROM AUTHOR]

This paper focused on analytic modeling of the effective thermal conductivity of bio-composite building materials. The analytic model adopted in this paper is the homogenization method. The principal idea of this method is to characterize the effective thermal conductivity from a microstructural description of the heterogeneous material and the knowledge of the local behavior of constituents (matrix and fiber) using a micromechanical approach. A three schemes (the dilute scheme, Auto-coherent scheme and the Mori-Tanaka scheme) are introduced and compared with Voigt-Reuss and Hashin-Shtrikman bounds and with experimental data at low fraction. A good agreement between the three schemes and Voigt-Reuss and Hashin-Shtrikman bounds and experimental values was revealed. The maximum deviations remain lower than 4.4% between Mori-Tanaka scheme and experimental data. [ABSTRACT FROM AUTHOR]

In the present paper, numerical computations have been carried out to investigate the mixed convection developing within a cavity ventilated by injection / suction of a cold jet of isothermal air, interacting with the external environment through two openings arranged in the middle of the left and right vertical walls. The remaining portions of the left vertical wall are subjected to a constant heat flux, while, the remaining walls of the cavity are perfectly insulated. The combined effects of the basic parameters namely the Reynolds number, 20≤Re≤3000, the walls emissivity, 0≤ε ≤ 0.85, and the imposed external flow mode (injection or suction) on the flow characteristics and heat transfer are examined. The results revealed that, for both modes of ventilation, the contribution of radiation to the total heat transfer is significant even for a predominant forced convection regime particularly for high values of wall emissivity. [ABSTRACT FROM AUTHOR]

The present study is aimed to investigate the effect of the 3D printing temperature on the mechanical behavior of polymer materials. For this purpose, three levels of 3D printing temperature were chosen according to the polymer melting temperature range. The commercial polylactic acid PLA 3D870 was used as polymer filaments. The effect of the processing temperature on the mechanical elasticity and resistance was studied using 3-point bending test. In addition, two other process parameters were taken into account to determine the interaction effect of each of them with the printing temperature. The experimental results show a considerable effect of temperature on the stiffness and strength of printed polymer parts. The mechanical properties were maximum for the low temperature levels. Moreover, the resistance presents a significant interaction effect between temperature and feed rate on the one hand, and deposit angle on the other hand. For the rigidity, no significant interaction was found. [ABSTRACT FROM AUTHOR]

A numerical investigation is carried out for mixed convection fluid flow and heat transfer in a discretely heated lid-driven square cavity. The fluid in the cavity is a water-based nanofluid containing Al2O3 nanoparticles. The bottom and left walls are discretely heated while the right wall is cooled. The top wall is considered adiabatic and moving at a constant speed. The numerical resolution of the studied problem is based on the lattice Boltzmann method (LBM). The simulations have been carried out for the effects of various controlling parameters, such as Grashof number being fixed at 104, Richardson number ranging from 0.05 to 10, inclination angle ranging from 0° to 90° and the solid volume fraction of nanoparticles between 0 and 0.07. The obtained results are presented as streamlines, isotherms, average Nusselt numbers and average temperature inside the cavity. Results show that the nanoparticles effect contributes to an enhancement on heat transfer rate. Also, it is found that Ri involves a heat transfer reduction on both left and bottom walls. [ABSTRACT FROM AUTHOR]

A numerical study has been executed to analyze the effects of thermal radiation and Prandtl number on mixed convective flow and heat transfer characteristics inside a lid driven square cavity. Where the cavity is heated uniformly from the left wall and cooled from the right side while thermal insulation is imposed on horizontal walls. The finite difference method is used to solve the full governing equations for which the Boussinesq approximation is adopted. The results are explored over a range of Prandtl number, Pr, (1, 7 and 50), radiation parameter, Rd, (0 ≤ Rd ≤ 10), and for constant Grashof number of 104. The results indicate that the flow and thermal fields as well as the heat transfer rate and the flow intensity in the square cavity depend significantly on the mentioned parameters. [ABSTRACT FROM AUTHOR]

This paper reports a numerical study on mixed convection of thermo-dependent shear-thickening fluids combined with thermal radiation effect in a lid-driven square cavity. The cavity is uniformly heated / (cooled) from the left / (right) while the horizontal walls are thermally insulated. The finite difference method is used to solve the full governing equations for which the Boussinesq approximation is adopted. Effects of the governing parameters, namely, Richardson number and the Pearson number on the flow and heat transfer are analyzed. It has been found that the augmentation of Richardson number decreases the heat transfer and enhances the convective flow. [ABSTRACT FROM AUTHOR]

This work is focused on the numerical modeling of steady laminar mixed convection flow in a Ventilated inclined enclosure filled with water-Al2O3 nanofluid and heated from one side. A parametric study is conducted and a set of graphical results is presented and discussed to illustrate the effects of volume fraction of the nanoparticles (0 ≤ ϕ ≤ 0.05), aspect ratio of the cavity (0.5 ≤ A ≤ 4) and mode of imposed external flow (injection or suction) on the flow and heat transfer characteristics. The obtained results showed that the presence of nanoparticles increases the heat transfer and the mean temperature within the cavity. In addition, a better cooling inside the cavity was found for a rectangular enclosure (A = 2). [ABSTRACT FROM AUTHOR]