Print ISSN: 1681-6900

Online ISSN: 2412-0758

Keywords : square enclosure

Natural Convection Heat Transfer in Enclosure with Uniformly Heated Inner Elliptic Cylinder and Outer square Cylinder

Akeel Abdullah Mohammed

Engineering and Technology Journal, 2012, Volume 30, Issue 19, Pages 3435-3456

Experimental and numerical simulation study for natural convection heat
transfer formed by uniformly heated inclined elliptical cylinder concentrically
located in an enclosed square cylinder subjected to the ambient have been
investigated. Experiments have been carried out for Rayliegh number ranges from
0.9×106 to 3.3×106. The enclosure angles of inclination are f =0o (horizontal), 45o
(inclined), and 90o (vertical), and for axis ratio of elliptic cylinder
(minor/major=b/c) of 1:2, while the dimensions of outer square cylinder was
0.5×0.5×2 m. A numerical simulation was conducted by using commercial
Fluent CFD code to investigate the steady laminar natural convective heat
transfer for air between a heated elliptic cylinder and its square enclosure. It
covered a range of hydraulic radius ratios (HRR) of 1.97, 2.62, and 3.93 and
for orientation angles j = 0o (the major axis is vertical), 30o, 45o. Two
values of Rayligh number were taken: 0.9×106 and 3.3×106. The experimental
results showed that the heat transfer process improves as Rayliegh number
increases and is better in f =0o than other angles of inclination at the same
heat input. Theoretical results showed that the HRR, Rayligh number, and
angle of orientation have significant effect on the physical behavior of
stremlines and isotherms inside the equivalent annular gap.

An Investigation of Natural Convection Heat Transfer in a Square Enclosure Filled with Nanofluid

Ayad M. Salman

Engineering and Technology Journal, 2011, Volume 29, Issue 12, Pages 2346-2363

In this research, numerical solution of natural convection heat transfer of nanofluids in two-dimensional square enclosures is obtained for different values of Rayleigh numbers and volume fraction of nanofluids. Numerical simulation has then been undertaken for the mixture of Cu-water as nanofluid. The stream–vorticity form of the Navier–Stokes equations and energy equation are used in this study. The present model is utilized to obtain results in the range of Rayleigh number 103–105 and volume fractions of nanofluids (0.025-0.1). The enclosure which represent two-dimensional square enclosure with heated left side wall, while the right side was cold, the top and bottom walls were adiabatic. The governing equations are solved with finite-difference technique by central difference scheme. A computer program in (FORTRAN 90) was used to carry out the numerical solution. The results are a remarkable increase in the average Nusselt number with an increase in the volume fraction. An increase in the Rayleigh number results an increase in the average Nusselt number for a certain nanoparticle. In order to validate the numerical model, the results of two previous works for square enclosure filled by water based Al2O3 nano-particles as nanofluids. The first work was variation of average Nusselt number and volume fraction for Ra number Ra=103. There are excellent agreement in results and the maximum difference between these results reach 4.2%. A relation between average Nusselt number and Ra number also compared for other previous work. There are agreement in results and found the maximum difference between results reach to 6.5% approximately at Ra=105 which validate the present computational model.

Buoyancy Heat Transfer In Staggered Dividing Square Enclosure

Ali L. Ekaid; Ayad F. Hameed; Ahmad F. Mehde

Engineering and Technology Journal, 2010, Volume 28, Issue 4, Pages 639-663

In this research, the Buoyancy heat transfer and flow patterns in a partially
divided square enclosure with staggered partitions have been studied numerically.
The partitions were distributed on the lower and upper surfaces of the box in
staggered manner. The height of the partitions was varied. The conduction heat
transfer through the fins (partitions) was also included. It is assumed that the
vertical walls of enclosure were adiabatic and its horizontal walls were maintained
at uniform but in different temperature. The problem was formulated in terms of
the stream function-vorticity procedure. The numerical solution based on the
transformation of the governing equations by using finite difference method was
obtained. The effect of increasing the partition height and Rayleigh number on
contour maps of the stream lines and temperature were reported and discussed. In
addition, the research presented and discussed the results of the average Nussult
number of the enclosures heated wall at various Rayleigh number and
dimensionless partition heights. The results showed that the mean Nussult number
increases with the increasing of Rayleigh number and decreases with the
increasing of partition heights. The distributed heat by conduction through the
partition increases with the increasing of the partition height especially at
(H/L ≥ 0.3). A comparison between the obtained results and the published
computational studies has been made and it showed a good agreement with
percentage error not exceed (0.54%).