Nanoparticle aggregation effects on radiative heat transport of nanoliquid over a vertical cylinder with sensitivity analysis

Abstract

A sensitivity analysis is performed to analyze the effects of the nanoparticle (NP) aggregation and thermal radiation on heat transport of the nanoliquids (titania based on ethylene glycol) over a vertical cylinder. The optimization of heat transfer rate and friction factor is performed for NP volume fraction (1% ⩽ φ ⩽ 3%), radiation parameter (1 ⩽ Rt ⩽ 3), and mixed convection parameter (1.5 ⩽ λ ⩽ 2.5) via the face-centered central composite design (CCD) and the response surface methodology (RSM). The modified Krieger and Dougherty model (MKDM) for dynamic viscosity and the Bruggeman model (BM) for thermal conductivity are utilized to simulate nanoliquids with the NP aggregation aspect. The complicated nonlinear problem is treated numerically. It is found that the temperature of nanoliquid is enhanced due to the aggregation of NPs. The friction factor is more sensitive to the volume fraction of NPs than the thermal radiation and the mixed convection parameter. Furthermore, the heat transport rate is more sensitive to the effect of radiative heat compared with the NP volume fraction and mixed convection parameter.