Modeling of Heat Transfer and Energy Efficiency Performance of Transient Cold Storage in Phase Change Thermal Storage Components

Helmns, Dre; Carey, Van P.

doi:10.1115/ht2016-7237

Cited by 4 publications

(7 citation statements)

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“…The primary differences between the aforementioned papers and that of Helmns are largely related to methodology. Helmns has established a numerical solver using a simple, explicit method [6,7]. The present paper adds a layer of complexity to the original model developed by Helmns by modifying the calculation for overall heat transfer coefficient, U, to account for the change in melt front location rather than using a constant, average value.…”

Section: Introductionmentioning

confidence: 99%

Exploration of Variable Conductance Effects During Input and Extraction of Heat From Phase Change Thermal Storage

Theroff

Helmns

Carey

2018

Volume 8A: Heat Transfer and Thermal Engineering

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Previous efforts to model the effectiveness of heat input and extraction from a thermal storage unit have generally been based on the definition of a constant conductance of heat from the working fluid to the phase change storage material. In order to capture the effects of changing thermal resistance between the working fluid and melt front location, this paper presents a method using a resistor network analogy to account for thermal conductance as a function of melt fraction. This expression for thermal conductance is then implemented in an existing numerical framework. Results are validated by comparing calculations for a single unit cell using a quasi-steady Stefan problem approach, a finite difference scheme, and more general form solutions from literature. The variable approach is then compared with an average value for overall thermal conductivity, U, to characterize the performance of a thermal energy storage unit consisting of a series of these unit cells. Overall effectiveness in the thermal energy storage device is found to be within 0.6% agreement when comparing these methods, though local percent deviation can be as high as 113%. Depending on the needed accuracy and use case for such a numerical framework, suggestions are provided on whether an average value for U is sufficient for characterizing such a thermal energy storage device. Discussion is also provided on the flexibility of the computation schemes described by testing the sensitivity of the results via changes in dimension-less input parameters.

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Section: Introductionmentioning

confidence: 99%

Exploration of Variable Conductance Effects During Input and Extraction of Heat From Phase Change Thermal Storage

Theroff

Helmns

Carey

2018

Volume 8A: Heat Transfer and Thermal Engineering

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“…Drawing upon the previous work, we can formulate the governing energy balance equations using dimensionless numbers and use these to resolve the temperature and melt fraction fields within the TES device [11]. The transport equations are written in terms of dimensionless position, time, and temperature.…”

Section: Thermal Energy Storage Governing Equationsmentioning

confidence: 99%

Multiscale Transient Modeling of Latent Energy Storage for Asynchronous Cooling

Helmns

Carey

2018

Journal of Thermal Science and Engineering Applications

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This paper establishes a multiscale design evaluation framework that integrates performance models for a thermal energy storage (TES) unit and a subsystem heat exchanger (HX). The modeling facilitates the analysis of transient input and extraction processes for the TES device which uses solid-liquid phase change to store thermal energy. We investigate sensible and latent heat transfer through the unit's matrix structure which contains phase change material (PCM) in the interstitial spacing. The heat transfer is driven by a temperature difference between fluid flow passages and the PCM matrix which experiences sensible heat transfer until it reaches the PCM fusion point; then it undergoes melting or solidification in order to receive, or reject, energy. To capture these physics, we establish a dimensionless framework to model heat transfer in the storage device much like effectiveness-number of transfer units (NTU) analysis methods for compact HX. Solution of the nondimensional governing equations is subsequently used to predict the effectiveness of the transient energy input and extraction processes. The TES is examined within the context of a larger subsystem to illustrate how a high efficiency design target can be established for specified operating conditions that correspond to a variety of applications. The general applicability of the model framework is discussed and example performance calculations are presented for the enhancement of a Rankine power plant via asynchronous cooling.

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“…In previous works, we established a dimensionless first-principles framework to model transient heat transfer in a TES device, similar to effectiveness-NTU analysis methods for compact heat exchangers. We began by deriving a non-dimensional framework in order to analyze thermal energy storage and characterize its performance [23]. During that examination, we found that we would need to focus our efforts on quantifying the spaceand time-varying conductance inherent in the transient melting and freezing processes of latent thermal storage.…”

Section: Introductionmentioning

confidence: 99%

Development and Validation of a Latent Thermal Energy Storage Model Using Modelica

et al. 2021

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An abundance of research has been performed to understand the physics of latent thermal energy storage with phase change material. Some analytical and numerical findings have been validated by experiments, but there are few free and open-source models available to the general public for use in systems simulation and analysis. The Modelica programming language is a good avenue to make such models available, because it is object-oriented, equation-based, declarative, and acausal. These characteristics have enabling the creation of component model libraries that can be used to build larger system simulations for design analysis. The authors have previously developed a numerical framework to model phase change thermal storage and have validated model predictions with experiments. The objectives of this paper are to describe the transfer of the numerical framework to an implementation in a Modelica component model and to validate the Modelica model with data from the experiment and the original numerical framework.

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Modeling of Heat Transfer and Energy Efficiency Performance of Transient Cold Storage in Phase Change Thermal Storage Components

Cited by 4 publications

References 0 publications

Exploration of Variable Conductance Effects During Input and Extraction of Heat From Phase Change Thermal Storage

Exploration of Variable Conductance Effects During Input and Extraction of Heat From Phase Change Thermal Storage

Multiscale Transient Modeling of Latent Energy Storage for Asynchronous Cooling

Development and Validation of a Latent Thermal Energy Storage Model Using Modelica

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