Effects of instabilities and coherent structures on the performance of a thermocline based thermal energy storage

Manu, K. V.; Anand, Prateek; Chetia, Utpal Kumar; Basu, Saptarshi

doi:10.1016/j.applthermaleng.2015.05.072

Cited by 17 publications

(9 citation statements)

References 15 publications

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“…Viscous fingering is a commonly observed phenomenon in dual media (porous filled) tanks and Kelvin-Helmholtz instability (shear instability) can generate vortices inside the TES. These vortices evolve and disrupt the thermocline region [3,4]. The resultant undesirable mixing of fluids disturb the thermal stratification inside the tank [5].…”

Section: Introductionmentioning

confidence: 99%

“…The resultant undesirable mixing of fluids disturb the thermal stratification inside the tank [5]. These types of interface-collapses are observed during the charging cycle when the temperature of the incoming fluid is lower than that of the stored hot-fluid temperature [3,4]. Slight variations in density can also cause Rayleigh-Taylor instability, leading to formation of vortices.…”

Section: Introductionmentioning

confidence: 99%

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Spatio-temporal disruption of thermocline by successive laminar vortex pairs in a single tank thermal energy storage

Tinaikar

Advaith

Chetia

et al. 2016

Applied Thermal Engineering

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The stratification efficiency of single tank thermal energy storage is affected by the internal mixing processes, especially in the thermocline region due to disturbances of different kinds. To study the mixing dynamics at the interface, we have conducted detailed numerical and supporting experimental studies for different Atwood numbers (stratification levels). Numerical experiments were conducted with two successive vortex pairs with three different time-lags (short, medium and long). For the short time-lag case, the preliminary vortex pair merges with the ensuing vortex pair. The merged single vortex pair peels back the thermocline layer causing mixing of the hot and cold fluids. The thermocline thickness increases as a result of the entrainment of the cold fluid into the hot fluid. The peeling process continues until buoyant forces leads to plume like structures that penetrate into the lighter fluid. For the medium and large time-lag cases, such merging of vortices was not observed. The vortex pair interacts separately with the thermocline region. The plume structure created by the first vortex pair interacts with the ensuing vortex pair. The altered interface (thermocline) thickness strongly depends on the nature of the vortex-thermocline interaction mechanisms. The thermocline effectiveness decreases consequent to such interactions and have been quantified in details in the current work.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Spatio-temporal disruption of thermocline by successive laminar vortex pairs in a single tank thermal energy storage

Tinaikar

Advaith

Chetia

et al. 2016

Applied Thermal Engineering

Self Cite

View full text Add to dashboard Cite

show abstract

“…Previous numerical studies of Rayleigh-Taylor instabilities in thermocline tanks were focused on analyzing the effect of Reynolds number and inflow temperature on thermal stratification [10]. However, these studies did not quantify the spatio-temporal dynamics of the thermocline during and after vortical interactions; furthermore, the impact of the disturbances on the overall storage efficiency has not been investigated.…”

Section: Introductionmentioning

confidence: 99%

“…Rayleigh-Taylor instabilities are observed under such circumstances inside thermocline tanks without filler material. Numerical simulations performed by Manu et al [10,11] have shown that Rayleigh-Taylor instabilities arising from random perturbations can cause temporary break-down of the thermocline region. The disturbances initially grow exponentially, followed by non-linear stages during formation of mushroom-like and falling spikes-like structures.…”

Section: Introductionmentioning

confidence: 99%