Numerical and experimental study of inverse natural convection heat transfer for heat sink in a cavity with phase change material

Abstract

This study examines the fluid flow and heat transfer characteristics of rectangular fins positioned within a square cavity through the use of the inverse three-dimensional computational fluid dynamics (CFD) method, experimental analysis, and the constant heat transfer rate assumption. This paper proposes a heat sink that uses a phase change material (PCM) made of paraffin within a small cavity. The inverse CFD method, combined with the least squares method, root mean square error, and excessive experimental data, is adopted to predict the unknown heat transfer rate Q and absorption heat Qab. One of the objectives of this study is to investigate the effect of the PCM heat sink on fluid flow and heat transfer characteristics within a cavity. A sequence of tests on various flow models indicates that employing the RNG k-epsilon turbulence model with the standard wall function is the most suitable choice for all scenarios in the three-fin model. Conversely, the zero-equation model proved to be a more adequate fit for the PCM heat sink. Another objective of this study is to study the effect of the height of the PCM heat sink on Q and Qab. The incorporation of a PCM heat sink results in a further improvement in the efficiency of heat dissipation. Part of the heat created is absorbed by the PCM heat sink, which absorbs 22.5 % of the thermal energy. Under the same volume, the PCM heat sink with a lower height (Hp = 0.012 m) absorbs 14 % more heat compared to Hp = 0.02 m. Thus, a lower-height PCM heat sink has a better heat dissipation effect.