Boiling is considered an important mode of heat transfer (HT) enhancement and has several industrial cooling applications. Boiling has the potential to minimize energy losses from HT devices, compared with other convection or conduction modes of HT enhancement. The purpose of this review article was to analyze, discuss, and compare existing research on boiling heat transfer enhancement techniques from the last few decades. We sought to understand the effect of nucleation sites on plain and curved surfaces and on HT enhancement, to suggest future guidelines for researchers to consider. This would help both research and industry communities to determine the best surface structure and surface manufacturing technique for a particular fluid. We discuss pool boiling HT enhancement, and present conclusions and recommendations for future research.

The fundamentals of heat transfer and its applications, the classification of heat transfer technology and different heat transfer techniques, and the needs for augmentation and its benefits and the different combinations of two or more inserts and integral roughness elements for heat transfer augmentation purpose have been introduced and discussed in this chapter. It is shown that most of the compound techniques performed better than the individual inserts for heat transfer enhancement. This chapter has also been dedicated to understanding the basic concepts of vortex generators for heat transfer enhancement in plate-fin heat exchangers. The performance of transverse, longitudinal, and wing-type vortex generators has been discussed as well.

Present study reports a computational investigation on heat transfer and pressure drop characteristics for flow through a heat exchanger tube fitted with novel hybrid ribs by using magnetic nanofluid (Fe3O4). Effects of different rib geometry on heat transfer and pressure drop characteristics have been investigated for Reynolds number ranging from 3 000 to 22 000. Until now, there is little information available in the literature on the method of quantifying the effect of forced convection on the heat transfer and pressure drop of hybrid rib (HR) inserts by using magnetic nanofluid (MNF). The transition SST models along with governing equations (continuity, momentum, and energy equations) are numerically solved with ANSYS Fluent 19.2. The simulation results are validated with established correlations and excellent agreement was found. Heat transfer coefficient is more in combined arrangement (HR and MNF) compared to acting alone arrangement (only MNF).

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