Numerical Analysis of Nanofluid Flow and Heat transfer in a Heat Exchanger with Different Arrangements of Turbulator Inserts

In this experimental study, the effect of using a heat exchanger with louvered strip inserts louvered strip inserts on flow and heat transfer utilizing various types of nanofluids is studied numerically. The continuity, momentum and energy equations are solved by means of a finite volume method (FVM). The top and the bottom walls of the pipe are heated with a uniform heat flux boundary condition. Two different louvered strip insert arrangements (forward and backward) are used in this study with a Reynolds number range of 10,000, 15,000, 20,000, 25,000, 30,000. The effects of various louvered strip slant angles and pitches are also investigated. Three different types of nanoparticles, Al2O3, CuO and ZnO with different volume fractions in the range of 1% to 4% and different nanoparticle diameters in the range of 20 nm to 50 nm, dispersed in a base fluid (water) are used. The numerical results indicate that the forward louvered strip arrangement can promote the heat transfer by approximately 77 % at the lowest slant angle of α=10° and largest pitch of S=50 mm. The maximal skin friction coefficient of the enhanced tube is around 5.7 times than that of the smooth tube and the value of performance evaluation criterion (PEC) lies in the range of 1.34–1.57. It is found that Al2O3 nanofluid has the highest Nusselt number value, followed by ZnO, and CuO while pure water has the lowest Nusselt number. The results show that the Nusselt number increases with decreasing the nanoparticle diameter and it increases slightly with increasing the volume fraction of nanoparticles. The results reveal that there is a slight change in the skin friction coefficient when nanoparticle diameters of Al2O3 nanofluid are varied.