Pressure drop and convective heat transfer of Al2O3/water and MWCNT/water nanofluids in a chevron plate heat exchanger

Heat transfer and pressure drop characteristics of Al2O3/water and MWCNT/water nanofluids flowing in a chevron-type plate heat exchanger were experimentally investigated and compared with those of water. Results showed that heat transfer seemed to be improved by using nanofluids at constant Reynolds number. However, little heat transfer enhancement was observed based on a constant flow velocity. The heat transfer deterioration of MWCNT/water nanofluids was more intensive than Al2O3/water nanofluids due to the relatively large viscosity increase of MWCNT/water nanofluids. A new heat transfer correlation was proposed based on the experimental data of water and it predicts the experimental data of nanofluids accurately when the measured nanofluid properties (thermal conductivity and viscosity) were adopted for calculation. Besides, the pressure drop of nanofluid was reasonably higher than that of water and seemed to increase with increasing particle volume concentrations due to the increase in viscosity. However, there was not much difference between the pressure drop of nanofluids and that of water at low particle volume concentrations. A correlation for predicting the friction factor was obtained and it fitted the experimental data very well.