Transient calculation of charge and discharge cycles in thermally stratified energy storages

Steinert, Philipp; Göppert, Stefan; Platzer, Bernd

doi:10.1016/j.solener.2013.08.039

Cited by 21 publications

(8 citation statements)

References 23 publications

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“…The main mechanisms influencing the transient development of the temperature profile in a Thermal Energy Storage are heat transport process, mixing of the charging fluid with stored fluid, and local turbulence because of stratification [17]. From the temperature distribution inside of the storage it can be seen that the region above to the heater outlet doesn't show a significant mixing.…”

Section: Resultsmentioning

confidence: 99%

Numerical Investigation of Effective Heat Conductivity of Fluid in Charging Process of Thermal Storage Tank

Taheri¹,

Schmidt²,

Gabi³

2015

OJFD

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This paper presents a numerical case study of heat transfer mechanisms during the charging process of a stratified thermal storage tank applied in a specific adsorption heat pump cycle. The effective thermal conductivity of the heat transfer fluid during the charging process is analyzed through CFD simulations using Unsteady Reynolds-averaged Navier-Stokes equations (URANS). The aim of the study is to provide an equivalent thermal conductivity for a one-dimensional storage tank model to be used in a system simulation of the complete adsorption heat pump cycle. The influence of the turbulent mixing and also the advection effect due to fluid bulk motion are investigated. The results show that in the case considered here, the turbulence effect on the effective thermal conductivity is more considerable than the advection effect.

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Section: Resultsmentioning

confidence: 99%

Numerical Investigation of Effective Heat Conductivity of Fluid in Charging Process of Thermal Storage Tank

Taheri¹,

Schmidt²,

Gabi³

2015

OJFD

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“…Analytical [54,55] Empirical [56] [11,57,58] HWSTs can shift thermal loads to off-peak hours and increase energy flexibility, providing up to a 7.5% energy saving potential and 5.5% emission reduction potential.…”

Section: Hot Water Storage Tank (Hwst)mentioning

confidence: 99%

A Review of Mathematical Models of Building Physics and Energy Technologies for Environmentally Friendly Integrated Energy Management Systems

2022

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The Energy Management System (EMS) is an efficient technique to monitor, control and enhance the building performance. In the state-of-the-art, building performance analysis is separated into building simulation and control management: this may cause inaccuracies and extra operating time. Thus, a coherent framework to integrate building physics with various energy technologies and energy control management methods is highly required. This framework should be formed by simplified but accurate models of building physics and building energy technologies, and should allow for the selection of proper control strategies according to the control objectives and scenarios. Therefore, this paper reviews the fundamental mathematical modeling and control strategies to create such a framework. The mathematical models of (i) building physics and (ii) popular building energy technologies (renewable energy systems, common heating and cooling energy systems and energy distribution systems) are first presented. Then, it is shown how the collected mathematical models can be linked. Merging with two frequently used EMS strategies, namely rule-based and model predictive controls, is discussed. This work provides an extendable map to model and control buildings and intends to be a foundation for building researchers, designers and engineers.

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“…Models for hot-water tanks have been studied by many authors over the past halfcentury, and a few successful approaches are the momentum decomposition based on buoyancy and jet momentum by Steinert et al [2], discharge efficiency by Lavan and Thompson [3], maximum analytical efficiency of stratification by Homan [4], and exergybased analysis for cooling of a cylindrical tank, which found that a 1:1 aspect ratio had the highest exergy efficiency, Bai et al, [5]. Njoku et al [6] reviewed energy and exergy modeling methods in which the entropy generation number was suggested as being superior to energy-based modeling.…”

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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Transient calculation of charge and discharge cycles in thermally stratified energy storages

Cited by 21 publications

References 23 publications

Numerical Investigation of Effective Heat Conductivity of Fluid in Charging Process of Thermal Storage Tank

Numerical Investigation of Effective Heat Conductivity of Fluid in Charging Process of Thermal Storage Tank

A Review of Mathematical Models of Building Physics and Energy Technologies for Environmentally Friendly Integrated Energy Management Systems

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

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