![Sample our Engineering & Technology journals, sign in here to start your access, latest two full volumes FREE to you for 14 days]({"type":"image" , "src" : "/sda/5933/TOC-Subject-Sample-2021-Engineering-Tech.jpg"})
ABSTRACT
Numerical investigations on the thermal and hydraulic characteristics of pulsating laminar flow in a three-dimensional helical microchannel heat sink (HMCHS) model are performed using Al2O3-water-based nanofluid. The simulation is performed in the laminar regime for Reynolds number ranging from 6 to 25. The two-phase mixture model with modified effective thermal conductivity and viscosity equations is employed to solve the problem numerically. The detailed results for thermal and flow fields are reported for the effects of amplitude (1–3), frequency (5–20 rad/s), and nanoparticle concentration (1%–3%). The results indicate that the heat transfer performance improves significantly for sinusoidal velocity inlet conditions compared with steady flow conditions.
Nomenclature
| A | = | dimensionless amplitude |
| Cp | = | heat capacity, (J/kg · k) |
| Dh | = | hydraulic diameter, (2 WchD/Wch + D), (m) |
| De | = | Dean number |
| h | = | heat transfer coefficient, (W/m2 · K) |
| λ | = | thermal conductivity, (W/m · K) |
| q | = | heat transfer rate, W |
| M | = | molecular weight, (mol) |
| N | = | Avogadro number |
| Nu | = | Nusselt number, (Nu = hDh/k) |
| P | = | pressure, (Pa) |
| r | = | inner tube radius, (m) |
| Rc | = | curvature ratio |
| Re | = | Reynolds number, (Re = ρVDh/µ) |
| T | = | temperature, (K) |
| t | = | time, (s) |
| V | = | velocity, (m/s) |
| Greek Symbols | = | |
| α | = | aspect ratio (height/width) |
| κ | = | Boltzmann constant |
| ρ | = | density, (kg/m3) |
| μ | = | dynamic viscosity, (kg · m/s) |
| Ø | = | volume fraction of nanoparticle |
| f | = | frequency, (rad/s) |
| Subscript | = | |
| bf | = | base fluid |
| eff | = | effective |
| m | = | mixture |
| nf | = | nanofluid |
| np | = | nanoparticle |
Nomenclature
| A | = | dimensionless amplitude |
| Cp | = | heat capacity, (J/kg · k) |
| Dh | = | hydraulic diameter, (2 WchD/Wch + D), (m) |
| De | = | Dean number |
| h | = | heat transfer coefficient, (W/m2 · K) |
| λ | = | thermal conductivity, (W/m · K) |
| q | = | heat transfer rate, W |
| M | = | molecular weight, (mol) |
| N | = | Avogadro number |
| Nu | = | Nusselt number, (Nu = hDh/k) |
| P | = | pressure, (Pa) |
| r | = | inner tube radius, (m) |
| Rc | = | curvature ratio |
| Re | = | Reynolds number, (Re = ρVDh/µ) |
| T | = | temperature, (K) |
| t | = | time, (s) |
| V | = | velocity, (m/s) |
| Greek Symbols | = | |
| α | = | aspect ratio (height/width) |
| κ | = | Boltzmann constant |
| ρ | = | density, (kg/m3) |
| μ | = | dynamic viscosity, (kg · m/s) |
| Ø | = | volume fraction of nanoparticle |
| f | = | frequency, (rad/s) |
| Subscript | = | |
| bf | = | base fluid |
| eff | = | effective |
| m | = | mixture |
| nf | = | nanofluid |
| np | = | nanoparticle |