Advances in triple tube heat exchangers regarding heat transfer characteristics of single and two-phase flows in comparison to double tube heat exchangers part 2

Abstract Triple concentric-tube heat exchangers are often used in a variety of industries, including HVAC, food and beverage manufacturing, and chemical processing. They may also be utilized in applications requiring thermal homogeneity, such as food and pharmaceutical production. They are appropriate for a number of applications since they may be constructed to withstand a range of temperatures and pressures. The purpose of this study is to examine the most current papers, covering single- and two-phase flows having pure and nanofluids with a particular emphasis on the heat transfer and hydrodynamic properties. The use of advanced surfaces improves heat transfer with respect to smooth surfaces, and the use of nanofluids has a positive influence on heat transfer characteristics with the increase in nanoparticle volume concentration since nanoparticles rise thermal conductivity, heat transfer area, and Brownian motion. The practical calculation methodologies, proposed correlations for calculating the Nusselt number and friction factor in triple ones are shown. There are insufficient studies to comment on pressure drop features, and correlations for Nusselt numbers and friction factors that are only known for single-phase flows. The research indicates that the heat transfer characteristics of triple concentric-tube heat exchangers surpass those of double tube heat exchangers. Important progress is supposed to occur for the design and utilization of triple ones as a substitute for double ones soon. Finally, there are a limited number of experimental two-phase flow studies in triple ones. It is essential to work on this topic to meet the important lack in open sources.