The Non-Dimensional Analysis of Heat Transfer and Fluid Flow in Wavy Mini Channel Heat Exchangers

In this research, the heat transfer behavior of a wavy mini-channel heat exchanger was studied. Using the experimental data of heat transfer, the convective heat transfer coefficients were estimated. Among numerous trials, the Nusselt number (Nu) best correlation is a linear function of Reynolds number (Re) independent of Prandtl number (Pr), and similar correlationsfor hot and cold sides were obtained. The coefficient range is 0.01 to 0.03 for different fluids. The previous experimental works verify this conclusion. Also, in the case of non-Newtonian fluids and nanofluids, the definition of Re is related to its rheological behavior. However, if the velocity profile is specified, it can be used to derive the relation between the Fanning friction factor (Cf) and Re. Here, a suitable velocity profile for wavy configuration is used, and the experimental valuesof Re are estimated by the experimental pressure drop data. It is shown that the application of the derived relation between Cf and Re is preferred compared to the assumption of a circular pipe that is convenient for fluid mechanics studies. In addition, it is proved that if experiments with different fluids or relative waviness are done at similar flow rates, the U versus the Re plot can be used to compare heat exchanger performance.