Numerical Study of Heat Transfer Characteristics of Nanofluid Flow in the Finned Pipe Subjected to Variable Heat Flux

Abstract

Attempts for investigation of flows forced convective heat transfer using nanofluids have been made by numerous researchers in the recent years‎. ‎Utilizing nanofluid as a working fluid in lots of the literatures is greatly recommended To achieve higher efficiency in cooling systems. ‎ The present study surveys laminar flow forced convective heat transfer of Al‎₂‎O‎₃-‎water nanofluid, numerically under variable heat flux‎. Classical models which have been widely utilized for evaluating thermophysical characteristics of a nanofluid are used in the study and the effects of nanofluid heat transfer characteristics are assessed‎. ‎Two types of the pipe consist of finless tube and finned pipe are investigated‎. ‎Effects of the parameters such as variable heat flux parameter‎, ‎nanoparticle concentration‎, ‎and the Reynolds number are also assessed‎. ‎The numerical results demonstrate that the convective heat transfer coefficient of nanofluid in the both type pipes increases in accordance with volume concentration as well as Reynolds number of nano‎-particles. Furthermore‎, ‎the average convective heat transfer coefficient in the finless pipe is the same as the constant heat flux case; but‎, ‎thermal efficiency of the finned pipe under variable heat flux has higher value in comparison with the constant heat flux case‎.