Investigation of turbulent entropy production rate with SWCNT/H2O nanofluid flowing in various inwardly corrugated pipes

Abstract

AbstractThis paper presents turbulent heat transfer performance and entropy production rate in different inwardly corrugated pipes with single‐walled carbon nanotube (SWCNT)/H2O nanofluid as a working fluid using the finite volume method approach. The configurations considered were circular, triangular, and trapezoidal. The SWCNT/H2O nanofluid was modeled using a single‐phase approach and the model was used to simulate the turbulent flow. A parametric study was carried out on the effect of Reynolds number (5 × 103 ≤ Re ≤ 3 × 104) and nanoparticle volume ratio (0% ≤ φ ≤ 0.25%) on hydrodynamic, heat transfer performance, thermal entropy production rates (TEPRs; due to mean and turbulent temperature gradients), and viscous entropy production rates (VEPRs; due to mean and turbulent velocity gradients). The results showed that the mean temperature gradient contributes most to the TEPR, compared with the turbulent temperature gradient. However, the opposite was the case for the VEPR. Furthermore, the presence of corrugation decreases the TEPR but enhanced friction factor, Nusselt number, and VEPR. For example, at a Reynolds number of 2.5 × 104, the normalized friction factor, average Nusselt number, TEPR, and VEPR (referencing a smooth pipe) in circularly, triangularly, and trapezoidal corrugated pipes are {3.86, 1.39, 0.80, 3.88}, {3.80, 1.41, 0.72, 3.98}, and {4.34, 1.55, 0.69, 4.19}, respectively.