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Numerical evaluation of laminar heat transfer enhancement in nanofluid flow in coiled square tubes.

Sasmito AP, Kurnia JC, Mujumdar AS - Nanoscale Res Lett (2011)

Bottom Line: The two nanofluid suspensions examined in this study are: water-Al2O3 and water-CuO.The flow behavior and heat transfer performance of these nanofluid suspensions in various configurations of coiled square tubes, e.g., conical spiral, in-plane spiral, and helical spiral, are investigated and compared with those for water flowing in a straight tube.Laminar flow of a Newtonian nanofluid in coils made of square cross section tubes is simulated using computational fluid dynamics (CFD)approach, where the nanofluid properties are treated as functions of particle volumetric concentration and temperature.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Mechanical Engineering, National University of Singapore, 9 Engineering Drive 1, Singapore, 117576 Singapore. jc.kurnia@nus.edu.sg.

ABSTRACT
Convective heat transfer can be enhanced by changing flow geometry and/or by enhancing thermal conductivity of the fluid. This study proposes simultaneous passive heat transfer enhancement by combining the geometry effect utilizing nanofluids inflow in coils. The two nanofluid suspensions examined in this study are: water-Al2O3 and water-CuO. The flow behavior and heat transfer performance of these nanofluid suspensions in various configurations of coiled square tubes, e.g., conical spiral, in-plane spiral, and helical spiral, are investigated and compared with those for water flowing in a straight tube. Laminar flow of a Newtonian nanofluid in coils made of square cross section tubes is simulated using computational fluid dynamics (CFD)approach, where the nanofluid properties are treated as functions of particle volumetric concentration and temperature. The results indicate that addition of small amounts of nanoparticles up to 1% improves significantly the heat transfer performance; however, further addition tends to deteriorate heat transfer performance.

No MeSH data available.


Related in: MedlinePlus

Computational domain for (a) straight tube, (b) conical spiral tube, (c) in-plane spiral tube, and (d) helical spiral tube.
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Figure 2: Computational domain for (a) straight tube, (b) conical spiral tube, (c) in-plane spiral tube, and (d) helical spiral tube.

Mentions: The computational domains (see Figure 2) were created in AutoCAD 2010; the commercial pre-processor software GAMBIT 2.3.16 was used for meshing, labeling boundary conditions and determines the computational domain. Three different meshes, 1 × 105, 2 × 105, and 4 ×105, were tested and compared in terms of the local pressure, velocities, and temperature to ensure a mesh independent solution. It is found that mesh number of around 2 × 105 gives about 1% deviation compared to mesh size of 4 × 105; whereas the results from mesh number of 1 × 105 deviate by up to 8% compared to those from the finest one. Therefore, a mesh of around 2 × 105 (20 × 20 × 500) elements was considered sufficient for the numerical investigation purposes; a fine structured mesh near the wall to resolve the boundary layer and an increasingly coarser mesh in the middle of the channel to reduce the computational cost.


Numerical evaluation of laminar heat transfer enhancement in nanofluid flow in coiled square tubes.

Sasmito AP, Kurnia JC, Mujumdar AS - Nanoscale Res Lett (2011)

Computational domain for (a) straight tube, (b) conical spiral tube, (c) in-plane spiral tube, and (d) helical spiral tube.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3211469&req=5

Figure 2: Computational domain for (a) straight tube, (b) conical spiral tube, (c) in-plane spiral tube, and (d) helical spiral tube.
Mentions: The computational domains (see Figure 2) were created in AutoCAD 2010; the commercial pre-processor software GAMBIT 2.3.16 was used for meshing, labeling boundary conditions and determines the computational domain. Three different meshes, 1 × 105, 2 × 105, and 4 ×105, were tested and compared in terms of the local pressure, velocities, and temperature to ensure a mesh independent solution. It is found that mesh number of around 2 × 105 gives about 1% deviation compared to mesh size of 4 × 105; whereas the results from mesh number of 1 × 105 deviate by up to 8% compared to those from the finest one. Therefore, a mesh of around 2 × 105 (20 × 20 × 500) elements was considered sufficient for the numerical investigation purposes; a fine structured mesh near the wall to resolve the boundary layer and an increasingly coarser mesh in the middle of the channel to reduce the computational cost.

Bottom Line: The two nanofluid suspensions examined in this study are: water-Al2O3 and water-CuO.The flow behavior and heat transfer performance of these nanofluid suspensions in various configurations of coiled square tubes, e.g., conical spiral, in-plane spiral, and helical spiral, are investigated and compared with those for water flowing in a straight tube.Laminar flow of a Newtonian nanofluid in coils made of square cross section tubes is simulated using computational fluid dynamics (CFD)approach, where the nanofluid properties are treated as functions of particle volumetric concentration and temperature.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Mechanical Engineering, National University of Singapore, 9 Engineering Drive 1, Singapore, 117576 Singapore. jc.kurnia@nus.edu.sg.

ABSTRACT
Convective heat transfer can be enhanced by changing flow geometry and/or by enhancing thermal conductivity of the fluid. This study proposes simultaneous passive heat transfer enhancement by combining the geometry effect utilizing nanofluids inflow in coils. The two nanofluid suspensions examined in this study are: water-Al2O3 and water-CuO. The flow behavior and heat transfer performance of these nanofluid suspensions in various configurations of coiled square tubes, e.g., conical spiral, in-plane spiral, and helical spiral, are investigated and compared with those for water flowing in a straight tube. Laminar flow of a Newtonian nanofluid in coils made of square cross section tubes is simulated using computational fluid dynamics (CFD)approach, where the nanofluid properties are treated as functions of particle volumetric concentration and temperature. The results indicate that addition of small amounts of nanoparticles up to 1% improves significantly the heat transfer performance; however, further addition tends to deteriorate heat transfer performance.

No MeSH data available.


Related in: MedlinePlus