Experimental effect of inclination on the process of melting paraffin in a square cavity

Hocine Guellil,Abdel Illah Nabil Korti

doi:10.18186/thermal.1025925

Abstract

Phase change material PCM is a promising strategy for reducing energy consumption in various applications. Among the large number of PCMs studied in the literature, paraffin are considered to be promising for latent heat thermal energy storage LHTES due to its appropriate thermal properties and their chemical stability. The interest of this work is to carry out an experimental procedure to visualize the phase change process of paraffin in a square cavity at different inclination angles. This article reveals how the melting rate could be affected by changing three orientations 90° (vertical heating), 0° (bottom horizontal heating) and 45° (inclined heating). The enclosure is heated on one side while the other walls are thermally insulated. The numerical photos, infrared thermal image and thermocouples-temperatures recorded during the melting processing are used to calculate the melting fractions and to estimate the intensity of heat transfer in different angles. The results show that the inclination angle has a great influence on the behavior of natural convection, affecting the front melting propagation and heat transfer rate. When the inclination angle decreases from 90° to 0° the convection currents in the cavity progressively evolve from a dominant single-cell movement to an unstable Rayleigh-Benard movement. The total melting time for the bottom and inclined heating cavities were, on average, 56% and 45% less than that of the vertical heating, respectively.

Highlights

Using PCM in the thermal industries has become a key area of research over the past three decades
In order to see the effect of the inclination of the cavity on the thermal behavior of the paraffin melting front, three configurations are adopted: vertical heating on the right (θ = 90°), horizontal heating on the bottom (θ = 0°) and inclined heating (θ = 45°)
The development of the buoyancy force leads to the formation of an increasing mono-cellular current in the molten paraffin that provides the heat to rise through the hot wall and accelerates the melting at the top, and subsequently causes the descent of liquid through the melting front and delays the melting at the bottom (50 and 80 min)

Summary

INTRODUCTION

Using PCM in the thermal industries has become a key area of research over the past three decades. In a third study, [7] performed a comparative analysis of experimental results and numerical simulations of fusion of the tetracosane PCM contained in a cube and heated from bottom, while all the other sides are assumed to be adiabatic They observed the behavior of the solid/liquid interface throughout the experiment, characterized by an irregular shape. The study examines the effects of porosity (70–90%), the mass flow (0.03–0.07 kg/s), the solar intensity (514–714 W/m2) and spacing glass-absorber-insulation (7–10 cm) on the dynamic and thermal behavior of double-pass solar collectors He concludes that the presence of the porous media at the bottom of the absorber is the best configuration and allow increasing the outlet temperature. Based on the numerical simulation, the obtained results can be used as a benchmark model for the future work

EXPERIMENTAL PROCEDURE

AND DISCUSSION

CONCLUSION