Melting performance of nano-enhanced phase change materials in a triple-tube heat exchanger with zigzag-shaped tubes

Abstract

This study aims at evaluating the melting behavior of nano-enhanced phase change materials (NePCM) inside a triple-tube heat exchanger with a zigzag-shape channel configuration. To assess the performance of the proposed geometry, a zigzag tube with different angles and heights is numerically simulated and the results are compared with the conventional triple-tube heat exchanger. Cu, CuO, Al2O3 and Ag nanoparticles with various concentrations are used to improve the thermal conductivity of NePCMs. The main finding of this research is a significant improvement in the melting performance of a triple-tube heat exchanger by employing a middle zigzag tube. The zigzag configuration with a 67.5° angle and 15 mm height is found as the optimum case with a great potential to (i) reduce the melting time from 4654 s in the case of a straight tube to just 827 s and (ii) increase the heat retrieval rate from just ∼47 W in case of a straight tube to ∼185 W. Among the type of nanoparticles analyzed in this research, Al2O3 has the highest melting performance with ∼14 % increase in the melting rate and heat charge rate at 4 % concentration. Increasing the concentration of Al2O3 nanoparticles from 2 % to 6 % improves the heat charge rate by ∼2.3 %.