Heat transfer of water-based carbon nanotube nanofluids in the shell and tube cooling heat exchangers of the gasoline product of the residue fluid catalytic cracking unit

In this study, a series of low-concentration carbon nanotubes (CNT) water-based nanofluids (0.0055, 0.055, 0.111 and 0.278 vol%) were used as coolants in a shell and tube cooler of the residue fluid catalytic cracking gasoline product to analyze their effects on heat performance of the heat exchanger. The coolants and gasoline flow in tube side and shell side, respectively. This work was performed through simulating the heat exchanger by ASPEN HTFS+ 7.3 software. The performance of the nanofluids to heat transfer was analyzed in comparison with cooling water. Results illustrated that 0.055% CNT concentration could enhance heat transfer properties of the heat exchanger such as Nusselt number, total heat transfer coefficient and heat transfer rate more than other concentrations. Therefore, the lowest temperature of outlet shell-side fluid was also observed at this concentration. Moreover, increment in mass flow rates of both the tube-side and shell-side fluids caused enhancement of the heat transfer, especially with 0.055 vol% CNT. Although there is an optimum concentration among the studied CNT volume fractions, all nanofluids exhibit better thermal performance of the heat exchanger than cooling water, whereas pressure drop increases with CNT loading.