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

Tinaikar, Aashay; Advaith, S.; Chetia, Utpal Kumar; Manu, K. V.; Basu, Saptarshi

doi:10.1016/j.applthermaleng.2016.04.105

Cited by 14 publications

(7 citation statements)

References 14 publications

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“…The power density is largest at low frequencies that are less than the Brunt-Väisälä frequency. Similar behavior was observed in case of successive multi-vortex interaction (with different vortex generation mechanism) with thermocline [21]. The peak frequency values and the Brunt-Väisälä frequency values, tabulated in Table 3, increase with Atwood number.…”

Section: Thermocline Responsesupporting

confidence: 60%

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

Hatte

Mira-Hernández

Advaith

et al. 2016

Applied Thermal Engineering

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Section: Thermocline Responsesupporting

confidence: 60%

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

Hatte

Mira-Hernández

Advaith

et al. 2016

Applied Thermal Engineering

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“…Turbulent diffusivities could easily be one or two orders of magnitude higher than the molecular thermal diffusivity assumed here depending on the scale and intensity of turbulence. Thus turbulence has the potential to significantly degrade the effectiveness of a liquid thermocline, and many complex studies of this have been carried out for example by Tinaikar et al [4].…”

Section: Resultsmentioning

confidence: 99%

“…In this case the thermal storage media can also act as the heat exchange fluid transferring heat directly with the Wind-TP thermal pumping circuit. However it is important to avoid perturbing the delicate thermocline [4] by adding turbulence or non-uniform momentum at the inlet as this can be a source of significant exergy destruction. Fig.…”

Section: Liquid Thermoclinementioning

confidence: 99%

The cold store for a pumped thermal energy storage system

Davenne

Garvey

Cárdenas

et al. 2017

Journal of Energy Storage

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A B S T R A C TIn recent years several proposals for thermodynamic cycles involving the compression and expansion of gas and thermal storage have been put forward as effective ways of storing energy. These include the work of Desrues [1] who proposed a thermal energy storage process for large scale electric applications, Isentropic Ltd [2] who were working on a pumped thermal energy storage system and Garvey who proposed storing wind energy using a wind driven thermal pumping system known as Wind-TP [3]. All these systems require a hot and a cold store capable of storing thermal energy which can later be used to generate electricity. The efficiency and ultimately the successful adoption of pumped thermal energy storage will depend on the effectiveness of the thermal stores. In this paper we compare the performance of a packed bed and a liquid thermocline as the cold store for an off-shore Wind-TP system. Simulations are used to compare the exergetic performance of the two options leading to the conclusion that a liquid thermocline has potential to be significantly more effective than a packed bed thermocline. An addition to a liquid store involving a sliding divider separating warm and cold fluid is proposed as a way of avoiding exergy losses associated with the smearing of a thermocline front. Crown Copyright © 2017 Published by Elsevier Ltd. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/). The wind driven thermal pumping cycleIn recent years several pumped thermal energy storage (PTES) systems have been put forward as efficient methods to store energy [1,2,3]. The efficiency achieved will depend on the efficiency of the constituent thermo-mechanical components. In this paper we focus on the efficiency of the thermal stores and in particular the cold store. We use the example of a wind driven thermal pumping system to evaluate the relative performance of a liquid and a packed bed cold store. The thermal pumping cycle consists of a closed circuit of working gas passing through a compressor and an expander and exchanging heat with a hot store and a cold store as shown in Fig. 1.The cycle can operate in various modes including the following principle modes 1. Direct power transmission (no heat or coolth being transferred to stores) 2. Charging mode (heat and coolth being stored, small electrical output compared to input power) 3. Discharge mode (heat and coolth being recovered, large electrical output compared to input power)For illustrative purposes each mode is represented in the T-S diagrams shown in Figs. 2-4 . For simplicity the compressor and expander are assumed to be isentropic and the heat exchange to and from thermal stores perfect. The working gas in the main circuit is taken to be hydrogen [3] and the pressure ratio is 25:1 with a minimum pressure of 20 bar and maximum pressure of 500 bar. The minimum temperature of the working hydrogen is 120 K and the maximum is 753 K.An off shore wind-TP system would have a large wind turbine with rated power of a...

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“…Matulka et al [16] used the number to quantify the initial state of a stratified tank before the inclusion of entrainment. Tinaikar et al [17] used the Atwood number in a model to include successive laminar vortex pairs in which the Atwood number described the stratification strength. The Atwood number includes less information than the Archimedes and is simpler to calculate.…”

Section: Literature Overviewmentioning

confidence: 99%

A Flow Rate Dependent 1D Model for Thermally Stratified Hot-Water Energy Storage

et al. 2021

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Stratified tank models are used to simulate thermal storage in applications such as residential or commercial hot-water storage tanks, chilled-water storage tanks, and solar thermal systems. The energy efficiency of these applications relates to the system components and the level of stratification maintained during various flow events in the tank. One-dimensional (1D) models are used in building energy simulations because of the short computation time but often do not include flow-rate dependent mixing. The accuracy of 1D models for plug flow, plug flow with axial conduction, and two convection eddy-diffusivity models were compared with experimental data sets for discharging a 50-gal residential tank and recharging the tank with hot water from an external hot-water source. A minimum and maximum relationship for the eddy diffusivity factor were found at Re <2100 and >10,000 for recirculation of hot water to the top of the tank and vertical tubes inletting cold water at the bottom. The root mean square error decreased from >4 °C to near 2 °C when considering flow-based mixing models during heating, while the exponential decay of the eddy diffusion results in a root mean square error reduction of 1 °C for cone-shaped diffusers that begin to relaminarize flow at the inlet.

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

Cited by 14 publications

References 14 publications

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

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

The cold store for a pumped thermal energy storage system

A Flow Rate Dependent 1D Model for Thermally Stratified Hot-Water Energy Storage

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