Conductive heat transfer in lamellar phase change material composites

Hoe, Alison; Deckard, Michael; Tamraparni, Achutha; Elwany, Alaa; Felts, Jonathan R.; Shamberger, Patrick J.

doi:10.1016/j.applthermaleng.2020.115553

Cited by 16 publications

(18 citation statements)

References 65 publications

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“…Solidliquid PCMs require engineering measures in the form of specially-engineered metallic fin structures and additives to provide mechanical support, accommodate large solid-to-liquid volumetric changes (10-15% typical), prevent liquid phase PCM leakage, and enhance the inadequate PCM thermal conductivity (typically 0.1 to 1 Wm -1 K -1 [11]); in particular, poor thermal conductivity results in large time constants and inhibits fast, high power operation. The need for encapsulation and the goal of increasing power by adding high thermal conductivity sensible heating materials has come at the expense of reduced module energy capacity [12] [13], as described schematically in Figure 1. In many cases, this reduces the mass and volume of active PCM material by well over half.…”

Section: Highlightsmentioning

confidence: 99%

Solid-state thermal energy storage using reversible martensitic transformations

Sharar

Donovan

Warzoha

et al. 2019

Applied Physics Letters

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The identification and use of reversible Martensitic transformations, typically described as shape memory transformations, as a new class of solid-solid phase change material is experimentally demonstrated here for the first time. To prove this claim, time-domain thermoreflectance, frequency-domain thermoreflectance, and differential scanning calorimetry studies were conducted on commercial NiTi alloys to quantify thermal conductivity and latent heat. Additional Joule-heating experiments demonstrate successful temperature leveling during transient heating and cooling in a simulated environment. Compared to standard solid-solid materials and solid-liquid paraffin, these experimental results show that shape memory alloys provide up to a two order of magnitude higher Figure of Merit. Beyond these novel experimental results, a comprehensive review of >75 binary NiTi and NiTi-based ternary and quaternary alloys in the literature shows that shape memory alloys can be tuned in a wide range of transformation temperatures (from -50 to 330°C), latent heats (from 9.1 to 35.1 J/g), and thermal conductivities (from 15.6 to 28 W/m·K). This can be accomplished by changing the Ni and Ti balance, introducing trace elements, and/or by thermomechanical processing.Combining excellent corrosion resistance, formability, high strength and ductility, high thermal performance, and tunability, SMAs represent an exceptional phase change material that circumvents many of the scientific and engineering challenges hindering progress in this field. MAIN TEXTThermal energy storage (TES) using phase change materials (PCMs) offers tremendous benefits in a diverse array of technology spaces, ranging from large scale power generation to more

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Section: Highlightsmentioning

confidence: 99%

Solid-state thermal energy storage using reversible martensitic transformations

Sharar

Donovan

Warzoha

et al. 2019

Applied Physics Letters

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“…Specifically, we utilize 2D finite difference, a 1D fin approximation, and an effective medium approximation as described in a previous work. [ 40 ] Figure shows the temperature rise as a function of lamellar pitch for a volume fraction of 0.5, where the high thermal conductivity phase is 3D printed AlSi12, and the PCM is octadecane (see Experimental Section for thermophysical properties of each). The boundary conditions for the heated surface are a constant heat flux

q_{0}^{″} = 1

W cm −2 , and the other boundary condition is adiabatic.…”

Section: Design Rules For Optimizing Tes Composite Performancementioning

confidence: 99%

“…For the case of constant temperature boundary conditions, the heat flux is no longer constant and is given by the following for an effective medium

Q_{q, rate}^{″} = \int_{0}^{t} q^{″} d t

where the heat flux for constant temperature boundary condition is given in Equation () from previous studies [ 40 ]

q^{″} = \frac{e_{eff} Δ T}{erf (λ) \sqrt{π t}}

with

λ = c_{eff} Δ T / 2 L_{normalm}

for small values of

Δ T

. The resulting total heat absorption per unit cross‐sectional area is then found by integrating Equation () into (), resulting in Equation () as follows.

Q_{q, rate}^{″} = \frac{e_{eff} Δ T \sqrt{t}}{2 erf false(λ false) \sqrt{π}}

…”

Section: Design Rules For Optimizing Tes Composite Performancementioning

confidence: 99%

“…Previously, analytical expressions for lamellar PCM composites were developed and tested numerically for 1D conductive heat transfer. [ 40 ] Lamellar PCM composites were investigated as a homogenous composite using effective medium approximation for particular length and time scales, where the properties of the lamellar geometry can be described by effective properties of high conductivity and PCM components. [ 41 ] Such simplifications, if valid, would provide a tractable framework for developing design rules for PCM composites.…”

Section: Introductionmentioning

confidence: 99%

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Design and Optimization of Lamellar Phase Change Composites for Thermal Energy Storage

et al. 2020

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Phase change materials offer thermal energy storage (TES) and are often integrated with high conductivity materials to increase power density. However, the design and optimization of such composites are historically based on intuition, as the computational techniques used to predict behavior in these systems are generally too expensive to perform parametric studies. Herein, a general design framework is developed and demonstrated that is optimized for TES in parallel lamellar structures, to identify the critical pitch required to treat the composite as a single effective medium and the optimum volume fraction of high conductivity material in the lamellar composite. The optimization criteria is tested experimentally using 3D printed AlSi12 alloy and octadecane. The composite system exhibits a critical pitch between a lamella of 1 mm and the optimum volume fraction for the high conductivity material is 0.6–0.8. The design principles demonstrated here show that the size and volumes of conductive materials are much larger than the current state of the art, and this framework provides a holistic approach to design for such future materials for TES applications.

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“…Beyond geometric basis and length scale, the key design variable within thermal PCM‐based composites is the volume fraction of the constituents within the system. This is most often studied within the literature using numerical or experimental methods or empirical analyses [2d,5c,9] . While these studies are useful for rough characterization of the design space, the sparse nature of the datasets involved in comparison to the complete degrees of freedom within the design space prevents the development of generally applicable design rules.…”

Section: Introductionmentioning

confidence: 99%

Design of Radially Variant Phase‐Change Material Composites

et al. 2022

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Phase‐change materials (PCMs) and high‐conductivity elements can be combined to form highly compact and efficient composite heat sinks. However, the design challenge presented by thermal composites composed of PCMs and high‐conductivity elements remains unresolved. Herein, design guidelines are presented for radially varying cylindrical PCM composites. Numerical and analytical techniques are utilized to explore the utility and limits of optimal composite designs selecting for 1) temperature minimization, 2) specific effective heat capacity maximization, and 3) volumetric effective heat capacity maximization. Significant increases in each metric are observed when implementing radially variant designs in cylindrical geometries, especially for metrics of heat capacity. Furthermore, a hybrid approach to variant composite design is presented, allowing for the balancing of different design objectives. The utilization of a variable design under high heat flux (10 ± 1.4 W cm−2) and short melting periods (up to 50 s) is experimentally demonstrated, directly resulted in a 65% decrease in total system mass and a 200% increase in specific heat capacity while maintaining strong temperature dampening performance. In a second case study, a 23% decrease in mass is demonstrated while maintaining strong specific heat performance, emphasizing the broad utility of this approach.

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Conductive heat transfer in lamellar phase change material composites

Cited by 16 publications

References 65 publications

Solid-state thermal energy storage using reversible martensitic transformations

Solid-state thermal energy storage using reversible martensitic transformations

Design and Optimization of Lamellar Phase Change Composites for Thermal Energy Storage

Design of Radially Variant Phase‐Change Material Composites

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