Aggregation Effects on Heat Transfer in Viscoplastic Nanofluid Entrance Flows

TL;DR

This paper numerically examines how nanoparticle aggregation influences heat transfer and flow characteristics in viscoplastic nanofluids within a heated entrance region, considering various models and parameters.

Contribution

It introduces a comprehensive numerical analysis of aggregation effects on heat transfer in viscoplastic nanofluids using multiple property models and flow conditions.

Findings

Aggregation affects heat transfer efficiency and flow resistance.

Optimal nanoparticle volume fraction enhances heat transfer performance.

Yield stress and volume fraction significantly influence pressure drop and Nusselt number.

Abstract

This study numerically investigates heat transfer enhancement in laminar, incompressible viscoplastic nanofluid flow through the entrance region of a circular cylinder with a uniformly heated wall, including the effects of both, non-aggregation and aggregation of nanoparticles. Nanofluid properties are modeled using Brinkman and Maxwell models in the case of non-aggregation, and Krieger-Dougherty, Maxwell-Bruggeman models in the case of aggregation, while the viscoplastic behavior is described by the Bingham-Papanastasiou model. The governing boundary layer equations are solved using a finite-difference method. The effects of yield stress and nanoparticle volume fraction (up to 5%) on friction, pressure drop, and Nusselt number are analyzed, and performance evaluation criteria are evaluated to identify the optimal volume fraction for maximum efficiency.