Grooved single-channel dual media tank thermal energy storage systems to improve overall thermal performance: Numerical analysis

In this study, a numerical analysis of a single-channel structured dual media tank ( DMT ) thermal energy storage (TES) system is done to investigate the effect of grooves on thermo-hydraulic performance. Due to computational complexity, a single channel is considered, and results are validated by the numerical results of other studies. The study encompasses the analysis of unsteady temperature distribution, heat transfer coefficient, and friction factor by varying the groove size ratio with the diameter of the pebbles. The φ ratio (grooves diameter/pebbles diameter) is varied from 3.15 to 4.73, and the effect of the Re for different widths of the channel is studied. The numerical result reveals a 50 % increase in heat transfer coefficient when φ is varied from 3.15 to 4.73 at a Reynolds number of 22.4. Similarly, a small variation in the frictional factor can be observed. amounts to 22 % while keeping a Reynolds number of 22.4 and a diameter ratio (φ) ranging from 3.15 to 4.73. Furthermore, research is done on how Reynolds number affects volumetric heat transfer (ℎ v ). The results indicate a 31 % decrease in ℎ v at φ = 3.15. on the other hand, a larger value of φ is observed to result in a lesser drop in ℎ v . Additionally, the computation performance improvement factor (PEF) shows greater values for φ = 3.15, indicating that the ideal groove diameter to achieve maximum heat transfer rate and minimum pressure drop is smaller.