Enhancement of Heat Duty in Heat Exchangers Using Nanofluids

A nanofluid is a suspension of ultrafine particles in a conventional base fluid which tremendously enhances the heat transfer characteristics of the original fluid. In this paper, application of nanofluids for enhancement of heat transfer in an industrial scale heat exchanger (for condensing saturated vapor to subcool water) hasbeen studied. Nanoparticles such as Fe, Cu, Ag, Al, Al2O3, Cuo, Si and SiC with 10 nm diameter added tocooling water or ethylene glycol as cold stream in heat exchanger. Nanoparticles concentration increases from 0.05% - 3% volume percent in cooling water. The heat exchanger is simulated by Aspen Plus softwareand results show that for all nanoparticles, by increasing volume percent of nanoparticles, heat duty of heatexchanger increases up to 9.9%. In addition, results illustrate that the best improvement of duty, when wateracts as the cold stream, is for Ag with 3% volume fraction while this improvement is for SiC with 3% volume fraction when ethylene glycol is as cold stream. Also, the worst case for water occurs for Si and Alwith 0.05% volume percent whereas Ag is considered as the least improvement for ethylene glycol.Moreover, results indicate that the performance of water as fluid base of cold stream excel from ethylene glycol because water physical properties such as thermal conductivity, specific heat and viscosity are more suitable in comparison with ethylene glycol for heat transfer. However, enhancement of heat duty due to nanoparticle addition for ethylene glycol is far better than water.

Keywords:

Nanofluids , Forced convective heat transfer , Effective thermal conductivity , Heat transfer enhancement , Nanoparticles