A heatline analysis of natural convection in a square inclined enclosure filled with a CuO nanofluid under non-uniform wall heating condition

Abstract

a b s t r a c tHeatline visualization technique is used to understand heat transport path in an inclined non-uniformly heated enclosure filled with water based CuO nanofluid. The cavity has square cross-section and it is nonuniformly heated from a wall and cooled from opposite wall while other walls are adiabatic. The governing equations which are continuity, momentum and energy equations are solved using finite volume method. The dimensionless heatfunction for nanofluid heat flow is defined and solved to determine heatline patterns. Calculations were performed for Rayleigh numbers of 10 3 , 10 4 and 10 5, inclination angle of 0°, 30°, 60°and 90°, and nanoparticle fraction of 0, 0.02, 0.04, 0.06, 0.08 and 0.1. It is observed that heat transfer in the cavity increases by adding nanoparticles. The rate of increase is greater for the enclosures with low Rayleigh number. Visualization of heatline is successfully applied to nanoparticle convective flows. Based on the heatline patterns, three heat transfer regions are observed and discussed in details.

Numerical simulation of natural convection and mixed convection of the nanofluid in a square cavity using Buongiorno model

“…As seen, the effects of increasing volume fraction of nanoparticles are more pronounced at lower Rayleigh numbers where conduction heat transfer is dominant. Similar observations were reported by Oztop et al [14] and Abu-Nada and Oztop [20]. Besides, Table 3 (20) These correlations can estimate Nu within average error of 2.6% and maximum error of 5.3%.…”

“…Abu-nada and Oztop [20] investigated numerical simulation of natural convection in an inclined cavity filled with Cuwater nanofluid when 10 3 <Ra< 10 5 to report that the effects of increasing nanoparticles volume fraction on heat transfer rate are more pronounced at low Rayleigh numbers similar to Oztop et al. [14]'s findings.…”

“…The former assumes that the continuous phase and the nanoparticles are in thermal equilibrium and move with the same velocity; the method is used for both natural convection [11][12][13][14][15][16][17][18][19][20] and mixed convection [21][22][23][24][25] of nanofluids. Parvin et al [15] investigated natural convection heat transfer in an odd-shaped cavity using the Brinkman [8] and Maxwell-Garnetts [9] models to estimate the effective viscosity and thermal conductivity of the nanofluid.…”

Water-Based Nanofluids for Natural Convection Cooling of a Pair of Symmetrical Heated Blocks Placed Inside a Rectangular Enclosure of Aspect Ratio Two

“…The collective influence of non-uniform nanoparticle diameters, nanoparticles volume fractions, Prandtl number, and Grashof number on the flow and temperature distributions was analyzed exhaustively. In synthesis, it can be attested that natural convective heat transfer in enclosures filled with water can be enhanced by adding nanoparticles of copper, Cu [17][18][19][20], copper oxide CuO [21][22][23], silver Ag [24], alumina Al2O3 [25] and titanium TiO2 [26]. Natural convection heat transfer in closed enclosures having a heated block inside and filled with nanofluids has received considerable attention in recent years due to its practical applications, such as thermal insulation and/or building design.…”

Numerical Analysis of Nanofluids in Differentially Heated Enclosure Undergoing Orthogonal Rotation

“…They showed that heat transfer coefficient increases with increasing Cu nanoparticles concentration. Oztop et al [13] observed the heat transfer coefficient increases by adding CuO nanoparticles concentration in an inclined nonuniformly heated enclosure. On the other hand, Hwang et al [14], Santra et al [15] and Abu-Nada [16] reported a decrease in the heat transfer by increasing the nanoparticles concentration for a particular Rayleigh number.…”