Comparison of RC-model and FEM-model for a PCM-plate storage including free convection

Neumann, Hannah; Gamisch, Sebastian; Gschwander, Stefan

doi:10.1016/j.applthermaleng.2021.117232

Cited by 14 publications

(6 citation statements)

References 45 publications

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“…Heat exchangers are characterized experimentally and optimized by simulations based on FEM and simplified capacity–resistor (RC) models. [ 37–39 ]…”

Section: Introductionmentioning

confidence: 99%

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Thermal Storage: From Low‐to‐High‐Temperature Systems

et al. 2023

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Different technologies of cold and heat storages are developed at Fraunhofer ISE. Herein, an overview of ongoing research for sensible and latent thermal energy storages is provided. Phase change emulsions are developed supported by molecular dynamic simulations. A narrow temperature range of the phase change is crucial for the applicability. By the simulations, a nucleation additive is identified that reduces supercooling by up to 9 K. The long‐term stability of phase change material is investigated by degradation experiments. Thermal cycling and ageing of materials at elevated temperature are applied. The change of melting enthalpy and characteristic temperatures are evaluated. Among erythritol, adipic acid, and myristic acid, the smallest degradation is observed for the latter. For sensible storage, the reduction of thermal oil by low‐cost filler materials and their compatibility is investigated at elevated temperature. It can be concluded that the materials are compatible up to 320 °C. At the component level, different macroencapsulations and immersed heat exchangers are tested for phase change materials. The investigated configurations achieve similar values of thermal power during (dis‐)charge. Compared to water as storage medium, the capacity increases by a factor of 2.2 and 4.1 for the macroencapsulation and the immersed heat exchanger, respectively.

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“…Heat exchangers are characterized experimentally and optimized by simulations based on FEM and simplified capacity–resistor (RC) models. [ 37–39 ]…”

Section: Introductionmentioning

confidence: 99%

“…Heat exchangers are characterized experimentally and optimized by simulations based on FEM and simplified capacity-resistor (RC) models. [37][38][39] For macroencapsulated PCM, the material is stored in capsules with a size in the centimeter range. [13] Multiple capsules are arranged in a storage container.…”

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confidence: 99%

Thermal Storage: From Low‐to‐High‐Temperature Systems

et al. 2023

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“…Multiple heat exchanger plates passed by a HTF are arranged in parallel while PCM is located in between the plates. Neumann et al developed validated models for parallel arranged aluminum roll-bond plates with bionically inspired FracTherm ® HTF channel structure, developed by Fraunhofer ISE [5]. Saeed et al.…”

Section: Introductionmentioning

confidence: 99%

Numerical and Experimental Investigation of Wire Cloth Heat Exchanger for Latent Heat Storages

2021

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Latent thermal energy storages (LTES) offer a high storage density within a narrow temperature range. Due to the typically low thermal conductivity of the applied phase change materials (PCM), the power of the storages is limited. To increase the power, an efficient heat exchanger with a large heat transfer surface and a higher thermal conductivity is needed. In this article, planar wire cloth heat exchangers are investigated to obtain these properties. They investigated the first time for LTES. Therefore, we developed a finite element method (FEM) model of the heat exchanger and validated it against the experimental characterization of a prototype LTES. As PCM, the commercially available paraffin RT35HC is used. The performance of the wire cloth is compared to tube bundle heat exchanger by a parametric study. The tube diameter, tube distance, wire diameter and heat exchanger distance were varied. In addition, aluminum and stainless steel were investigated as materials for the heat exchanger. In total, 654 variants were simulated. Compared to tube bundle heat exchanger with equal tube arrangement, the wire cloth can increase the mean thermal power by a factor of 4.20 but can also reduce the storage capacity by a minimum factor of 0.85. A Pareto frontier analysis shows that for a free arrangement of parallel tubes, the tube bundle and wire cloth heat exchanger reach similar performance and storage capacities.

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“…In [20], a simplified 3D model is constructed by using an empirical equation for the heat delivered by the PCM, according to the calorimetric measurements at the material level. Another approach, proposed in [21], is the use of a RC model (resistance-capacitance), which was then compared to the 1D-3D coupled model developed in [19]. The deviation of both models from the experiments was in the order of 1 K, but the RC model had a two to three times shorter computational time, which makes it suitable for fast and reliable design.…”

Section: Introductionmentioning

confidence: 99%

A Fast-Reduced Model for an Innovative Latent Thermal Energy Storage for Direct Integration in Heat Pumps

Palomba

Frazzica

2021

Applied Sciences

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In the present paper, the numerical modeling of an innovative latent thermal energy storage unit, suitable for direct integration into the condenser or evaporator of a heat pump is presented. The Modelica language, in the Dymola environment, and TIL libraries were used for the development of a modular model, which is easily re-usable and adaptable to different configurations. Validation of the model was carried out using experimental data under different operating modes and it was subsequently used for the optimization of a design for charging and discharge. In particular, since the storage unit is made up of parallel channels for the heat transfer fluid, refrigerant, and phase change material, their number and distribution were changed to evaluate the effect on heat transfer performance.

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Comparison of RC-model and FEM-model for a PCM-plate storage including free convection

Cited by 14 publications

References 45 publications

Thermal Storage: From Low‐to‐High‐Temperature Systems

Thermal Storage: From Low‐to‐High‐Temperature Systems

Numerical and Experimental Investigation of Wire Cloth Heat Exchanger for Latent Heat Storages

A Fast-Reduced Model for an Innovative Latent Thermal Energy Storage for Direct Integration in Heat Pumps

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