Investigation and optimization of heat transfer coefficient of MWCNTs-Water nanofluids in a plate heat exchanger

This article reports an experimental study of heat transfer characteristics of multi-walled carbon nanotubes (MWCNTs). These nanofluids, consisting of water with different weight concentrations of nanofluid (0.0.1–0.145% wt.), have flown in counter flow plate heat exchanger under turbulent conditions (the range of Reynolds numbers 2500-6500) for cooling applications. The nanofluid was prepared by dispersing MWCNT nanoparticles in the presence of sodium dodecyl sulfate (SDS) and water as base fluid. The results showed that the convective heat transfer coefficient (HTC) of nanofluid was higher than that of the base fluid at an equal mass flow rate and inlet temperature. The heat transfer coefficient of nanofluid increased by mass flow rate and temperature rising. Also, the heat transfer coefficient and the concentration of MWCNTs nanofluid showed a positive association at the same temperature.  At a constant weight concentration, the heat transfer coefficient increased when the Reynolds number increased. The slope weight concentration tended to rise as the heat transfer coefficient growing. The increase in Reynolds numbers (or mass flow) was less than the increase in the concentration of carbon nanotubes. According to the performed experiments and software analysis (QUALITEK 4), the heat transfer coefficient and concentration both multiplied at the same time. But there was an inverse relationship between the heat transfer coefficient and flow rate.