Improvement of heat transfer in helical HX with multiple-head ribbed using water-based nanofluids

Abstract

This study shows the comparison between the helical and straight tube heat exchangers with multiple-head ribbed geometries. A computational fluid dynamics model with constant wall temperature condition was developed for the study and validated against a numerical study and particular experimental correlations. Two, three, and four head ribbed geometries were used for both the helical and straight tubes. Also, different revolutions of ribbed geometry were taken into consideration while designing the HXs for the comparison of heat transfer. Number of 10, 20, and 30 coil revolutions were used in this study. Four different water-based nanofluids, such as Al2O3, CuO, SiO2, ZnO used in the best heat exchanger. Results have been shown in terms of the effect of ribbed geometry, coil revolutions, velocity, and temperature distribution along the pipe and the effect of nanofluid in the heat exchanger. Helical tube heat exchangers are more effective than straight tube heat exchangers in terms of heat transfer. It was found that the lesser the number of ribbed heads, the higher the heat transfer for both helical and straight heat exchangers. On the other side, when the number of coil revolution of ribbed profile increases, the heat transfer is also increased for both helical and straight heat exchangers. So, the two head ribbed with 30 coil revolutions helical heat exchanger ensures the highest amount of heat transfer rate. And four head ribbed with 10 coil revolution straight tube heat exchanger has got the lowest value of heat transfer rate. In the nanofluid study, it is found that the Al2O3 water-based nanofluid has the highest heat transfer rate among the four nanoparticles. Finally, this study represents the perfect comparison to choose the right type of heat exchanger and the nanoparticle.