Parametric Analysis of Enhanced Heat Transfer for Laminar Flow of Microencapsulated Phase Change Suspension in a Circular Tube with Constant Wall Temperature

Abstract

A novel phase change microcapsule with compound crust is briefly introduced in this paper, and the heat transfer enhancement due to a microencapsulated phase change material is investigated parametrically for laminar convective heat transfer in a circular tube with constant wall temperature. The size of the phase change mushy region and the phase change interface locations are given for the various governing parameters. Two enhancement ratios, the traditional enhancement ratio and a modified enhancement ratio, were used to quantify the enhanced heat transfer characteristics of the microencapsulated phase change suspension for six major parameters. The six parameters are the bulk Stephan number, the volumetric concentration of the solid-phase, the particle-to-tube radius ratio, the dimensionless initial subcooling, the dimensionless phase change temperature range, and the bulk Reynolds number. The simulations show that the bulk Stephan number and the volumetric concentration are the most important parameters influencing the heat transfer enhancement of the microencapsulated suspension. The influence of the microcapsule diameters on the heat transfer enhancement comes from the microconvection, instead of the latent heat release due to the phase change. In addition, the combined effect of changes in all of these parameters on the heat transfer enhancement was examined.

ACKNOWLEDGMENTS

This project was funded by the National Nature Science Foundation of China (grant 50276044).