Comparative study of the transient natural convection in an underground water pit thermal storage

Review on Solar Thermal Stratified Storage Tanks (STSST): Insight on stratification studies and efficiency indicators

High temperature solar receiver and thermal storage systems

Experiments on comparative performance of water thermocline storage tank with and without encapsulated paraffin wax packed bed

Cyclic characteristics of water thermocline storage tank with encapsulated PCM packed bed

https://docs.lib.purdue.edu/cgi/viewcontent.cgi?article=1313&context=coolingpubs

Short and long-term sensitivity of lab-scale thermocline based thermal storage to flow disturbances

This work experimentally investigates the dynamics of interaction between a propagating vortex ring and density stratified interface of finite thickness. The flow evolution has been quantified using a high speed shadowgraph technique and particle image velocimetry. The spatial and temporal behaviours of the vortex in the near and far field of the interface and the plume structure formed due to buoyancy are investigated systematically by varying the vortex strength (Reynolds number, Re) and the degree of stratification (Atwood number, A(t)). Maximum penetration length (Lp(max)) of the vortex ring through the interface is measured over a range of Reynolds (1350 <= Re <= 4600) and Richardson (0.1 <= Ri <= 4) numbers. It is found that for low Froude number values, the maximum penetration length varies linearly with the Froude number as in the study of Orlandi et al. ''Vortex rings descending in a stratified fluid,'' Phys. Fluids 10, 2819-2827 (1998)]. However, for high Reynolds and Richardson numbers (Ri), anomalous behaviour in maximum penetration is observed. The Lp(max) value is used to characterize the vortex-interface interactions into non-penetrative, partially-penetrative, and extensively penetrative regimes. Flow visualization revealed the occurrence of short-wavelength instability of a plume structure, particularly in a partially penetrative regime. Fluid motion exhibits chaotic behaviour in an extensively penetrative regime. Detailed analyses of plume structure propagation are performed by measuring the plume length and plume rise. Appropriate scaling for the plume length and plume rise is derived, which allows universal collapse of the data for different flow conditions. Some information concerning the instability of the plume structure and decay of the vortex ring is obtained using proper orthogonal decomposition. Published by AIP Publishing.

Interaction of vortex ring with a stratified finite thickness interface

The evolution of vortex rings in isodensity and isoviscosity fluid has been studied analytically using a novel mathematical model. The model predicts the spatiotemporal variation in peak vorticity, circulation, vortex size and spacing based on instantaneous vortex parameters. This proposed model is quantitatively verified using experimental measurements. Experiments are conducted using high-speed particle image velocimetry (PIV) and laser induced fluorescence (LIF) techniques. Non-buoyant vortex rings are generated from a nozzle using a constant hydrostatic pressure tank. The vortex Reynolds number based on circulation is varied in the range 100–1500 to account for a large range of operating conditions. Experimental results show good agreement with theoretical predictions. However, it is observed that neither Saffman’s thin-core model nor the thick-core equations could correctly explain vortex evolution for all initial conditions. Therefore, a transitional theory is framed using force balance equations which seamlessly integrate short- and long-time asymptotic theories. It is found that the parameter , where is the vortex half-spacing and denotes the standard deviation of the Gaussian vorticity profile, governs the regime of vortex evolution. For higher values of , evolution follows short-time behaviour, while for , long-time behaviour is prominent. Using this theory, many reported anomalous observations have been explained.

Aashay Tinaikar

Papers

Short and long-term sensitivity of lab-scale thermocline based thermal storage to flow disturbances

Interaction of vortex ring with a stratified finite thickness interface

Understanding evolution of vortex rings in viscous fluids

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

Understanding evolution of vortex rings in viscous fluids