Natural convection heat transfer was investigated experimentally in a concentric-cylinders annulus. To enhance the rate of heat transfer, pin fins were installed on the surface of the inner cylinder. Two fin arrangements were employed, namely, staggered and in-line arrangements. The length of the fins varied from 2 to 8 cm and the Rayleigh number Ra changed in the range from 5 x 105  to 5 x 106...

Laminar natural convection in differentially heated (β = 0°, where β is the inclination angle), inclined (β = 30° and 60°), and bottom-heated (β = 90°) square enclosures filled with a nanofluid is investigated, using a two-phase lattice Boltzmann simulation approach. The effects of the inclination angle on Nu number and convection heat transfer coefficient are studied. The effects of thermophor...

A numerical study is carried out to investigate the laminar forced convection heat transfer from a circular cylinder. The fluid is assumed to be incompressible, the Reynolds number ranged from 0.1 to 1000, and the Prandtl number was equal to 0.7. The range of study includes heat transfer in creeping flow (Re40). The equations were discretized by a control-volume-based finite difference techniqu...

in this paper, mixed convection of al2o3-eg-water nanofluid in a square lid-driven enclosure is investigated numerically. the focus of this study is on the effects of variable thermophysical properties of the nanofluid on the heat transfer characteristics. the top moving and the bottom stationary horizontal walls are insulated, while the vertical walls are kept at different constant temperature...

Several approaches to numerical modelling of liquid droplet heating and evaporation by convection and radiation from the surrounding hot gas are discussed. The finite thermal conductivity of liquid, recirculation in droplets, and time dependence of gas temperature and the convection heat transfer coefficient are taken into account. For the constant and almost constant convection heat transfer c...

Laminar free convection flow of viscous, incompressible fluid with variable viscosity and viscous dissipation through two horizontal parallel walls embedded in a porous medium is studied. Arrhenius model is used in which the variable viscosity is used to be decreasing exponentially with temperature. An approximation technique is defined to obtain the solution of the coupled non-linear equations...

In this article, mixed convection heat transfer of alumina-water nanofluid in an inclined and baffled C-shape enclosure is studied. It is assumed that the flow is laminar and steady. There is no energy production, energy storage and viscous heat dissipation. Furthermore, the nanofluid is considered as a continuous, Newtonian and incompressible fluid. Governing equations are discretized by finit...

in this paper, the problem of turbulent forced convection flow of water- alumina nanofluid in a uniformly heated pipe has been thoroughly investigated. in numerical study, single and two-phase models have been used. in single-phase modeling of nanofluid, thermal and flow properties of nanofluid have been considered to be dependent on temperature and volume fraction. effects of volume fraction a...

Natural convection heat transfer has many applications in different fields of industry; such as cooling industries, electronic transformer devices and ventilation equipment; due to simple process, economic advantage, low noise and renewed retrieval. Recently, heat transfer of nanofluids have been considered because of higher thermal conductivity coefficient compared with those of ordinary fluid...

The forced convection heat transfer in high porosity metal-foam filled tube heat exchangers are studied in this paper. The Brinkman Darcy momentum model and two energy equations for both solid and fluid phases in porous media are employed .The study shows that using metal-foams can significantly improve the heat transfer in heat exchangers. Keywords—metal foam, Nusselt number, heat exchanger, h...