A numerical simulation validated experimentally for thermally developing convection characteristics of a phase change nanofluid flow in a circular tube

摘要

The present work aims to examine the heat transfer effectiveness of laminar forced convection for water-based Nano-PCM emulsion ?ow through a pipe. Over a fnite length of the wall, the pipe is uniformly heated with a uniform heating ?ux. An approximate enthalpy model is employed for the formulation of the energy equation to present the phase-change process of the Nano-PCM emulsion. Effciency of utilizing the water-based Nano-PCM emulsion to substitute its base ?uid as the working ?uid in a uniform heating pipe was then demarcated quantitatively for different dimensionless parameters including the mass concentration of the Nano-PCM particles, ω pcmp, and the modifed Stefan number,Ste*bf. Predicted results show that the surface-averaged cooling effciency of the nano?uid appears increasingly promoted with its Nano-PCM particle fraction under decreasingSte*bf . The local heat transfer coeffcient can be improved more than 20 times as the phase change ?uid with ωpcmp = 10% and Ste*bf = 0.01 is used. The local heat transfer improvement for the phase change nano?uid over the water is directly related to the mass fraction of Nano-PCM particle. The averaged heat transfer effectiveness of water-based Nano-PCM emulsion ?ow is considerably increased with its Nano-PCM particle fraction under decreasing Ste*bf.