The global demand of the heating and cooling applications gives a larger potential to study the thermal energy storage system. Phase change materials (PCM) that are used to charge, store, and discharge the heat energy are inferior in heat transfer characteristics. The properties of PCM can be improved by adding nanoparticles, changing the orientation of the enclosure or both. Two-dimensional transient numerical analysis on the effect of Grashoff number (5000, 13000, and 20000), nanoparticle type (Al2O3, CuO, and MWCNT), and volume concentration (0%, 1%, 3%, and 5%) added in RT 42 PCM and orientation of square enclosure (30, 45, and 60°) to enhance the heat transfer rate is carried out. The thermophysical properties of the nano-PCM are evaluated and presented. From the results, it is affirmed that the melt fraction of the PCM rises with the increase in Gr and volume concentration of the nanoparticles up to an optimum level. The MWCNT-based nano-PCM attained a larger portion of melt fraction followed by Al2O3, CuO, and pure PCM. It is noted that an orientation of 60° and 45° will convert more quantities of pure PCM and nano-PCM into liquid fraction, respectively. The (3% MWCNT/RT-42 PCM) filled in 45° oriented container attained the highest melt fraction by 3.4%, 2.04%, and 2.94% than (3% Al2O3/RT-42 PCM), (1%CuO/RT-42 PCM), and pure PCM. The variation in the maximum melt fraction of the nanomaterial is because of the change in thermophysical characteristics of the nano-PCM.
With the recent trends in the manufacturing techniques of semiconductor chips, the compactness of electronic devices is getting improved. Though the computational speed is improved extensively, overcoming the heat dissipation remained the most challenging task. Buoyancy based convection in the heat sink alone is not sufficient to extract this huge amount of heat. Therefore, better heat transfer enhancement methods are essential to designing thermal efficient electronic devices. One of these techniques is the induction of forced convection by driving one of the lids of the sink. In this work, a 2-Dimensional steady-state thermal analysis of a moving lid enclosure provided with water/ (water + CuO) nanofluid for different Grashof numbers (5000, 13000, and 20000), Reynolds numbers (100, 200, 300, 400, and 500), and volume fractions (1%, 3%, and 5%) is carried out. The impact of Gr, Re, and volume concentrations on Nusselt number is studied. The design of the solid zone is studied by considering three different orientations (Frontward step, Zero step, and Rearward step). The maximum amount of heat transfer is achieved with the Frontward step for Gr = 20000, Re = 500, and 5% CuO volume concentration in pure water. For Re = 100 and Gr = 20000, Nuavg is improved by 5.49% for mixed mode of heat convection as compared to forced mode of heat convection. A heat transfer enhancement of 42.75% more than pure water is attained with a 5% CuO volume fraction of nanofluid at Re = 500 for frontward stepped geometry. However, there is a reduction in the rate of increment of (12.98% vs 16.54%) upon further addition of nanoparticles from 3 to 5% as compared to 1 to 3%.
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