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• Thermal behavior of rectangular fins located within a square cavity were analyzed. • Inverse CFD method and experimental data were adopted for heat transfer prediction. • Suitable turbulence model based on the RMSE of the flow model were selected. • Effect of fin geometry on the flow and heat transfer within a cavity was evaluated. • Effect of PCM heat sink on the flow and heat transfer within a cavity was studied. 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 Q ab. 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-ε 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 Q ab. 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 (H p = 0.012 m) absorbs 14 % more heat compared to H p = 0.02 m. Thus, a lower-height PCM heat sink has a better heat dissipation effect. [ABSTRACT FROM AUTHOR]

An investigation into the effect of mass flow rate oscillation on the R-134a evaporation heat transportation in a horizontal annular duct was experimentally conducted. The experiments were performed at different amplitudes (10, 20, and 30%) and periods (20, 30, 60, and 120 s) of the mass flux oscillation in a duct with different gap sizes (1.0, 2.0 and 5.0 mm). In this regard, the time variations of evaporation heat transportation coefficient and the heated wall temperature were also analyzed for the thermal characteristics of the oscillatory evaporation heat transfer. Measured results showed that the amplitude and period of the mass flux oscillation insignificantly affected the time-average heat transportation coefficient for the R-134a oscillatory evaporation heat transfer. However, the larger amplitudes and longer periods of the mass flux oscillation led to stronger wall temperature oscillations. [ABSTRACT FROM AUTHOR]