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ABSTRACT
In the present work, an experimental investigation of heat transfer enhancement parameters of the oscillating flow heat exchanger under different frequencies, tidal displacement, and heat fluxes is carried out. The effect of different parameters on experimental effective thermal conductivity and convective heat transfer coefficient in cooling region is studied using correlations given by different researchers. A correlation for experimental effective thermal conductivity in terms of S2√ω is derived based on experimental data. This correlation is useful for predicting the optimum value of S2√ω before onset of turbulence.
Funding
Financial support for this research was provided by the Board of College and University Development, Savitribai Phule Pune University (Research grant Proposal no: 13ENG001096, Duration: 2013–15). The authors are grateful for this financial support.
Nomenclature
| a | = | half channel width or d/2 (m) |
| Ac | = | cross-section area of pipe (m2) |
| Asc | = | pipe outer surface area for cooling region (m2) |
| Cp | = | specific heat at constant pressure (J/kg K) |
| d | = | diameter of flow tube (m) |
| f | = | oscillation frequency (Hz) |
| h | = | convective heat transfer coefficient (W/m2 K) |
| k | = | thermal conductivity (W/m K) |
| keff | = | experimental effective thermal conductivity (W m–1 K–1) |
| keffk | = | theoretical effective thermal conductivity using Kurzweg’s correlation (W m–1 K–1) |
| keffn | = | theoretical effective thermal conductivity using Nishio’s correlation (W m–1 K–1) |
| L | = | length of cooling tube in tube side of shell and tube heat exchanger (m) |
| m | = | mass flow rate of shell side cooling water (kg/s) |
| Pr | = | Prandtl number |
| P(Wo) | = | ratio of enhanced thermal diffusivity to molecular diffusivity normalized in such way that it is function of Wo only |
| Q | = | heat rate (W) |
| Qout | = | heat output (W) |
| Re | = | Reynolds number |
| r | = | tube radius (m) |
| S | = | oscillation tidal displacement (m) |
| T1–T10 | = | temperature at different test points as shown in (°C or K as stated) |
| Tc | = | mean temperature of hot water inlet to heat exchanger (°C or K as stated) |
| Th | = | mean temperature of copper tube near heater (°C or K as stated) |
| Tmcs | = | mean of inlet and outlet temperature of water on shell side (°C or K as stated) |
| Ts | = | mean surface temperature of tube of shell and tube heat exchanger (°C or K as stated) |
| umax | = | peak velocity in (m/s) |
| Wo | = | Womersley number |
| Δx | = | distance between heat source and heat sink (m) |
Greek symbols
| α | = | thermal diffusivity (m2/s) |
| β | = | transition number |
| ν | = | kinematic viscosity (m2/s) |
| ω | = | angular frequency of oscillation (rad/s) |
| ρ | = | density of water (kg/m3) |
Subscripts
| Th | = | Theoretical |
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