Heat transfer characteristics of a rectangular natural circulation loop containing solid‐liquid phase‐change material suspensions

Abstract

Purpose

To examine the heat transfer characteristics of soild‐liquid phase change material (PCM) suspensions in a rectangular natural circulation loop.

Design/methodology/approach

A continuum mixture flow model is used for the buoyancy‐driven circulation flow of the PCM suspensions together with an approximate enthalpy model to describe the solid‐liquid phase change (melting/freezing) process of the PC particles in the loop. Numerical simulations via a finite difference method have been conducted for the pertinent physical parameters of a loop with fixed geometrical configuration in the following ranges: the modified Rayleigh number Ra*=10⁹‐10¹³, the modified Stefan number Ste*=0.05‐0.5, the particle volumetric fraction C_v=0‐20 percent and the modified subcooling factor Sb*=0‐2.0.

Findings

The melting/freezing processes of the PCM particles at the heated/cooled sections of the loop are closely interrelated in their inlet conditions of the suspension. The influences of the modified Rayleigh number, the particle fraction, the modified Stefan number, and the modified subcooling factor on the heat transfer behavior, as well as the thermal efficacy of the PCM suspensions are elucidated. There could be a flow regime in the parametirc domain where heat transfer performance of the suspension circulation loop is significantly enhanced, due to contribution of the latent heat transport associated with melting/freezing of PCM particles.

Research limitations/implications

Future work to address effects of the geometric parameters such as the aspect ratio; the lengths and locations of, as well as the relative height between the heated and cooled sections is definitely needed, which are necessary steps towards developing more reliable predictive tools for system design of a circulation loop containing PCM suspension.

Originality/value

This work has explored the feasibility and quantified the efficacy of incorporating the PC suspensions as the heat transfer enhancement medium in a natural circulation loop, which has not been examined previously.

Citation

Ho, C.J., Chiu, S.Y. and Lin, J.F. (2005), "Heat transfer characteristics of a rectangular natural circulation loop containing solid‐liquid phase‐change material suspensions", International Journal of Numerical Methods for Heat & Fluid Flow, Vol. 15 No. 5, pp. 441-461. https://doi.org/10.1108/09615530510593639