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ABSTRACT
Forced convection in a combined entry developing length of a convergent pipe under constant wall heat flux boundary condition is performed in this work. Influences of the convergence angle, Reynolds, and Prandtl numbers on the heat transfer and flow field have been investigated. The numerical results are obtained for a wide range of convergence angles (0°–25°), Reynolds numbers (700–2100), and Prandtl numbers (0.707, 5.83). Compared to a traditional pipe, a substantial increase in heat transfer has been achieved with an increase in the pressure drop as the convergence angle increases. In this work, the effect of convergence angle, Reynolds number, and Prandtl number on the overall flow and thermal performance for the aforementioned configuration is investigated. To the best of authors’ knowledge, this investigation has been done for the first time, and it provides new and significant information regarding heat transfer enhancement utilizing a convergent pipe.
Nomenclature
| A | = | area, m2 |
| Cp | = | specific heat at constant pressure, J/kg K |
| D | = | conduit diameter, m |
| h | = | convective heat transfer coefficient, W/m2 K |
| k | = | thermal conductivity, W/m K |
| L | = | conduit length, m |
| = | mass flow rate, kg/s | |
| Nu | = | Nusselt number |
| P | = | pressure, Pa |
| Pr | = | Prandtl number |
| p | = | perimeter, m |
| q | = | heat flux, W/m2 |
| Re | = | Reynolds number |
| r | = | conduit radius, m |
| S | = | slant length, m |
| T | = | temperature, K |
| U | = | uniform velocity, m/s |
| V | = | velocity vector, m/s |
| x | = | local x-direction, m |
| α | = | thermal diffusivity, m2/s |
| θ | = | taper, convergence or divergence angle, degree |
| μ | = | viscosity, Ns/m2 |
| ρ | = | density, kg/m3 |
| Subscripts | = | |
| i | = | in |
| m | = | mean |
| o | = | out |
| s | = | surface |
| x | = | local |
Nomenclature
| A | = | area, m2 |
| Cp | = | specific heat at constant pressure, J/kg K |
| D | = | conduit diameter, m |
| h | = | convective heat transfer coefficient, W/m2 K |
| k | = | thermal conductivity, W/m K |
| L | = | conduit length, m |
| = | mass flow rate, kg/s | |
| Nu | = | Nusselt number |
| P | = | pressure, Pa |
| Pr | = | Prandtl number |
| p | = | perimeter, m |
| q | = | heat flux, W/m2 |
| Re | = | Reynolds number |
| r | = | conduit radius, m |
| S | = | slant length, m |
| T | = | temperature, K |
| U | = | uniform velocity, m/s |
| V | = | velocity vector, m/s |
| x | = | local x-direction, m |
| α | = | thermal diffusivity, m2/s |
| θ | = | taper, convergence or divergence angle, degree |
| μ | = | viscosity, Ns/m2 |
| ρ | = | density, kg/m3 |
| Subscripts | = | |
| i | = | in |
| m | = | mean |
| o | = | out |
| s | = | surface |
| x | = | local |