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

The present work aims to examine the heat transfer effectiveness of laminar forced convection for water-based Nano-PCM emulsion flow through a pipe. Over a finite length of the wall, the pipe is uniformly heated with a uniform heating flux. An approximate enthalpy model is employed for the formulation of the energy equation to present the phase-change process of the Nano-PCM emulsion. Efficiency of utilizing the water-based Nano-PCM emulsion to substitute its base fluid as the working fluid in a uniform heating pipe was then demarcated quantitatively for different dimensionless parameters including the mass concentration of the Nano-PCM particles, omega(pcmp), and the modified Stefan number,Ste*(bf). Predicted results show that the surface-averaged cooling efficiency of the nanofluid appears increasingly promoted with its Nano-PCM particle fraction under decreasingSte*(bf). The local heat transfer coefficient can be improved more than 20 times as the phase change fluid with omega(pcmp) = 10% and Ste*(bf) = 0.01 is used. The local heat transfer improvement for the phase change nanofluid 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 flow is considerably increased with its Nano-PCM particle fraction under decreasing Ste*(bf).

Automated summary

The study investigates the heat transfer effectiveness of water-based Nano-PCM emulsion flow in a pipe, showing that as the Nano-PCM particle fraction increases, the heat transfer efficiency also improves; under certain conditions, using phase change fluid can significantly enhance the local heat transfer coefficient.