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ABSTRACT
In this paper, a comprehensive transient three-dimensional model for heat transfer performance and flow resistance is applied to investigate the characteristics of a fin-and-tube heat exchanger with an H-typed fin. The overall and local dynamic response performance of Nu number and Eu number under volatile flow conditions are analyzed in detail. The results indicate that for the H-typed fin-and-tube heat exchanger, both the heat transfer and the fluid flow are influenced by volatile flow, which consists of three key parameters, time-averaged velocity, volatile amplitude, and the cycle time. Correlations of Nu number and Eu number for each case of volatile flow conditions are presented.
Nomenclature
| a | = | thermal diffusivity, m2 s−1 |
| A | = | heat transfer area, m2 |
| Ac | = | cross-sectional area, m2 |
| Au | = | oscillation amplitude |
| cp | = | fluid specific heat, J kg−1 K−1 |
| D | = | tube outside diameter, m |
| De | = | equivalent diameter, m |
| Fp | = | fin pitch, m |
| Ft | = | fin thickness, m |
| h | = | heat transfer coefficient, W m−2 K−1 |
| H | = | fin height, m |
| N | = | tube row number |
| p | = | pressure, Pa |
| P | = | wetting perimeter, m |
| qm | = | mass flow rate, kg s−1 |
| Q | = | heat transfer rate, W |
| S1 | = | spanwise tube pitch, m |
| S2 | = | longitudinal tube pitch, m |
| t | = | time, s |
| T | = | temperature, K |
| ΔTm | = | logarithmic-mean T difference, K |
| Tu | = | oscillation period, s |
| u, v, w | = | x, y, z velocity components, m s−1 |
| U | = | velocity magnitude, m s−1 |
| W | = | slit width, m |
| x, y, z | = | Cartesian coordinates |
| Greek symbols | = | |
| λ | = | thermal conductivity, W m−1 K−1 |
| ν | = | kinematic viscosity, m2 s−1 |
| ρ | = | fluid density, kg m−3 |
| Dimensionless numbers | = | |
| Re | = | Reynolds number |
| Nu | = | Nusselt number |
| Eu | = | Euler number |
| Subscripts | = | |
| in, out | = | channel inlet and outlet |
| w | = | fin surface |
| max | = | maximum value |
| min | = | minimum value |
Nomenclature
| a | = | thermal diffusivity, m2 s−1 |
| A | = | heat transfer area, m2 |
| Ac | = | cross-sectional area, m2 |
| Au | = | oscillation amplitude |
| cp | = | fluid specific heat, J kg−1 K−1 |
| D | = | tube outside diameter, m |
| De | = | equivalent diameter, m |
| Fp | = | fin pitch, m |
| Ft | = | fin thickness, m |
| h | = | heat transfer coefficient, W m−2 K−1 |
| H | = | fin height, m |
| N | = | tube row number |
| p | = | pressure, Pa |
| P | = | wetting perimeter, m |
| qm | = | mass flow rate, kg s−1 |
| Q | = | heat transfer rate, W |
| S1 | = | spanwise tube pitch, m |
| S2 | = | longitudinal tube pitch, m |
| t | = | time, s |
| T | = | temperature, K |
| ΔTm | = | logarithmic-mean T difference, K |
| Tu | = | oscillation period, s |
| u, v, w | = | x, y, z velocity components, m s−1 |
| U | = | velocity magnitude, m s−1 |
| W | = | slit width, m |
| x, y, z | = | Cartesian coordinates |
| Greek symbols | = | |
| λ | = | thermal conductivity, W m−1 K−1 |
| ν | = | kinematic viscosity, m2 s−1 |
| ρ | = | fluid density, kg m−3 |
| Dimensionless numbers | = | |
| Re | = | Reynolds number |
| Nu | = | Nusselt number |
| Eu | = | Euler number |
| Subscripts | = | |
| in, out | = | channel inlet and outlet |
| w | = | fin surface |
| max | = | maximum value |
| min | = | minimum value |