A second law analysis on flow of a nanofluid in a shell-and-tube heat exchanger equipped with new unilateral ladder type helical baffles

Abstract

The irreversibility characteristics of a shell and tube heat exchanger (STHE) fitted with the unilateral ladder type helical baffle are investigated. A boehmite nanofluid having different nanoparticle shapes is used as the hot fluid in the tube-side with a constant Reynolds number. The pure water is applied for the cold fluid, which passes inside the shell with various Reynolds numbers. The thermal and frictional entropy productions of both fluids intensify by the Reynolds number amplification. Thereby, the plural entropy production rates of the hot fluid and cold fluid, in the condition of utilizing the platelet nanoparticles, respectively demonstrate 8.4% and 20.9% increases by the Reynolds number variation from 5000 to 20,000. The nanofluid containing the platelet nanoparticles causes the maximum thermal entropy production. All in all, the minimum irreversibility for the whole STHE occurs for the nanofluid containing the oblate spheroid particles, which is recommended for use in this STHE.