Melting Enhancement in a Triple-Tube Latent Heat Storage System with Sloped Fins

Abstract

Due to the potential cost saving and minimal temperature stratification, the energy storage based on phase-change materials (PCMs) can be a reliable approach for decoupling energy demand from immediate supply availability. However, due to their high heat resistance, these materials necessitate the introduction of enhancing additives, such as expanded surfaces and fins, to enable their deployment in more widespread thermal and energy storage applications. This study reports on how circular fins with staggered distribution and variable orientations can be employed for addressing the low thermal response rates in a PCM (Paraffin RT-35) triple-tube heat exchanger consisting of two heat-transfer fluids flow in opposites directions through the inner and the outer tubes. Various configurations, dimensions, and orientations of the circular fins at different flow conditions of the heat-transfer fluid were numerically examined and optimized using an experimentally validated computational fluid-dynamic model. The results show that the melting rate, compared with the base case of finless, can be improved by 88% and the heat charging rate by 34%, when the fin orientation is downward–upward along the left side and the right side of the PCM shell. The results also show that there is a benefit if longer fins with smaller thicknesses are adopted in the vertical direction of the storage unit. This benefit helps natural convection to play a greater role, resulting in higher melting rates. Changing the fins’ dimensions from (thickness × length) 2 × 7.071 mm2 to 0.55 × 25.76 mm2 decreases the melting time by 22% and increases the heat charging rate by 9.6%. This study has also confirmed the importance of selecting the suitable values of Reynolds numbers and the inlet temperatures of the heat-transfer fluid for optimizing the melting enhancement potential of circular fins with downward–upward fin orientations.

RETRACTED: Improving the melting performance in a triple-pipe latent heat storage system using hemispherical and quarter-spherical fins with a staggered arrangement

“…As the PCMs have the inherent capability of high latent heat energy storage density, they also have low thermal conductivity, which reduces the heat transfer capability of either conduction or convection modes while charging and discharging the PCM. Several thermal conductivity enhancement methods have been introduced, such as metallic fins and foams ( Abdulateef et al, 2018 ; Mohammed et al, 2020 ; Mahmoud et al, 2021 ; Hashem Zadeh et al, 2022 ; Mohammed, 2022 ), metallic and carbon-based nanomaterials ( Arshad et al, 2020 ; Arshad et al, 2021b ; Kalidasan et al, 2022 ), heat pipes, and metallic matrices ( Eisapour et al, 2022b ).…”

Improved Melting of Latent Heat Storage Using Fin Arrays with Non-Uniform Dimensions and Distinct Patterns

“…Nevertheless, the most significant inconsistency that almost all PCMs today suffer from is their intrinsically low heat conduction, which has a negative impact on the system’s thermal reaction to the cyclic heat charging/discharging operations. To overcome this issue, researchers identified different approaches for the thermal enhancement of TES systems, such as porous matrices [ 16 , 17 , 18 , 19 ], extended fins [ 20 , 21 , 22 , 23 , 24 , 25 ], and heat pipes [ 26 , 27 ] along with utilizing good performing casing for PCM containment. Boosting the thermal performance of PCM-based storage devices by applying extended fins to the tubes transporting the heat-transfer fluid (HTF) is often considered as one of the most effective enhancement methods in energy storage systems [ 23 , 28 ].…”

Utilization of Carbon-Based Nanomaterials and Plate-Fin Networks in a Cold PCM Container with Application in Air Conditioning of Buildings

“…They concluded that this method leads to up to 15% energy saving compared to the conventional insulation techniques. Mahmoud et al [ 11 ] worked on the melting enhancement of RT-35 wax in a triple-tube (TT) unit with sloped circular fins. They evaluated the influence of fins with various sizes and orientations with the same fin volume fractions.…”