A Brief Review of Techniques of Thermal Enhancement in Tubes

Heat transfer enhancement in tubes is not a novel idea. These tubes are used in several engineering devices like heat exchangers, boilers, evaporators, refrigerators, and air conditioners, to name a few. To date, these tubes are undergoing an evolutionary period, since engineers are trying new ways to improve the heat transfer (or enhance the heat transfer). The main cause is the pressure loss that occurs due to friction and the limitation of the surface area of the tube. The passive techniques to overcome this loss are more common due to cost-effectiveness. Thus, common passive techniques include grooves inside the tube surface, grooves on both the inner and outer surface, or putting inserts within the tube. Modern techniques are utilizing nanofluids, that carry nano-materials inside the heat transfer fluid to enhance heat transfer. To quantitatively gauge the heat transfer enhancement, the heat transfer effectiveness is computed. This chapter deals with the study of the above-mentioned techniques in some detail and discusses minimizing entropy generation rate in groove tube(s). Also, a bird’s-eye view of the nanofluids and their usage for heat transfer enhancement has been seen