Elsevier

Thermochimica Acta

Volume 662, 10 April 2018, Pages 75-89
Thermochimica Acta

Experimental study on the thermal storage performance and non-isothermal crystallization kinetics of pentaerythritol blended with low melting metal

https://doi.org/10.1016/j.tca.2018.02.007Get rights and content

Highlights

  • A solid-solid PCM, Pentaerythritol (PE), added with 0.1, 0.3 and 0.5 wt% of Indium, a low melt metal, for energy storage.

  • Thermal conductivity enhancement of about 12.74% for PE added with 0.5 wt% of In.

  • Reduction of about 20.75% in energy storage and release time of PE added with 0.5 wt% of indium.

  • Enthalpy of solid-state transition of PE decreases by 3.42% corresponding to 0.5 wt% of indium.

  • The time for half crystallization of PE decreased with the increase in weight fraction of indium.

Abstract

This paper discusses the thermal cycling characterization, properties, and crystallization kinetics of pentaerythritol (PE) added with 0.1, 0.3 and 0.5 wt.% of indium (In). The TG and FTIR analysis confirmed the thermal and chemical stability of the PCM samples after 100 thermal cycles. DSC results indicated that the enthalpy of transition of PE with 0.1, 0.3 and, 0.5 wt.% of indium decreased by 9.4, 10.4 and, 11.4% after 100 thermal cycles. The onset temperature and transition enthalpy of PE decreased from 181.4 to 181.1 °C, and 264 to 255 kJ/kg respectively due to the addition of 0.5 wt.% of indium. The T-history analysis showed that the thermal conductivity of PE enhanced from 0.106 to 0.1189 W/m­K due to the addition of 0.5 wt.% indium. The non-isothermal crystallization kinetics revealed that the time for crystallization of PE decreased due to the addition of indium.

Introduction

Phase change materials (PCM) permit large amounts of thermal energy to be stored in comparatively small volumes, resulting in some of the lowest costs of any storage concepts [[1], [2], [3]]. The organic materials are more chemically stable than inorganic substances, they melt congruently, and supercooling is not a significant problem [4]. Most organic compounds contain Csingle bondH and Csingle bondC covalent bonds. Covalent bonds are typically harder to break, and hence organic materials react at a slower rate compared to inorganic substances. In addition to that, the reaction in organic materials involves first breaking of existing bonds, and then the formation of new bonds and additional energy is required to break bonds. Therefore, reactions are relatively slow. Inorganic substances, on the other hand, are formed by transfer of an electron from one atom to another, and so they contain ions. They get easily ionized and do not to expend energy to break bonds since they are already dissociated and therefore show a faster reaction. A PCM is reliable if it is thermally, chemically and physically stable after repeated heating and cooling cycles. So it is imperative to carry out cycling stability test to ensure the long-term performance of a thermal energy storage system [5]. PCM those involve phase transition from solid to liquid and back to the solid state are the most commonly used latent heat storage materials [6]. Paraffin and fatty acids are organic solid-liquid PCM that has been investigated by numerous researchers for lower thermal energy storage applications because of their desirable characteristics like good heat storage density with negligible supercooling, chemical stability and low cost [[7], [8]]. Sugar alcohols (also known as polyalcohols or polyols) are organic materials and considered as PCM for thermal energy applications in the temperature range from 30 °C to 200 °C [9]. Sugar alcohols, such as Erythritol and Mannitol have inherently sizeable thermal storage densities compared with other organic compounds [10]. The literature reported many on the suitability of polyalcohols with solid-liquid phase transition as thermal storage media. Aran et al. [11] experimentally studied the thermal and chemical stability of D-mannitol, Myo-inositol, and Galactitol using DSC and FTIR techniques. They reported polymorphic changes for Myo-inositol in the temperature range of 50 °C–260 °C. Their study also showed poor cycling stability for Galactitol. The experimental research of Kumaresan et al. [12] reported that the significant difference between the melting and decomposition temperature makes D-mannitol suitable for medium temperature applications. Kaizawa et al. [13], in their study, reported that Erythritol, Xylitol, and D-Mannitol are reliable PCM for high-temperature applications. Metallic alloys are used as high-temperature PCM as they offer high thermal reliability and repeatability [14]. The solid-liquid PCM used in the field of thermal energy storage and heat transfer applications suffer from critical issues such as volume change and leakage in their liquid phases. A more straightforward solution that eliminates the problems of leakage and volume change is to use a PCM that undergoes a solid-solid phase transition. Solid-solid PCMs undergo a solid/solid phase transition associated with the absorption and release of large amounts of heat. These materials change their crystalline structure from one lattice configuration to another at a fixed and well-defined temperature, and this transformation can involve latent heats comparable to the most efficient solid/liquid PCM [15]. Polyalcohols such as pentaerythritol [PE], pentaglycerine [PG], and neopentylglycol [NPG] are known to have solid-solid transition enthalpies which are comparable to the fusion enthalpies of many types of paraffin [16]. At low temperature, polyalcohols and their amine derivatives have the body-centered tetragonal molecular structure (α-phase). At solid-solid phase transition temperature, they change into a face-centered cubic crystalline structure (γ-phase) accompanied with the absorption of the hydrogen bond energy [17]. Many studies on polyalcohols and amine derivative as potential solid-solid PCM have been reported in the literature [[18], [19], [20], [21]]. Barrio et al. [22] studied the phase change mechanism in polyalcohols and stated that the reformation of the hydrogen bonds during cooling takes place at a lower energy than the breaking of the bonds during the heating transition thereby causing subcooling in polyalcohols. Most PCM have typically low thermal conductivity leading to an inadequate heat transfer and slow charging and discharging rates. Therefore, heat transfer enhancement techniques such as dispersion of high conductive materials into PCM, the impregnation of high conductivity porous material with the PCM, microencapsulation are employed to improve thermal storage performance of PCM. Improving the thermal conductivity of PCM by dispersing thermally conductive nanoparticles is one of the ways to enhance the effectiveness of the PCM-based TES systems. The literature reported many such research works that investigated the thermal energy storage performance of organic as well as inorganic PCM with different nanoparticles additives. The literature indicated that the addition of nanoparticles affects the phase change properties of PCM in addition to the enhancement of thermal conductivity [23]. Among the different nanoparticles, carbon nanotubes (CNT) and carbon nanofibers (CNF) have exhibited excellent thermo-physical properties that make them suited to the field of PCM based LHTES. Elgafy and Lafdi [24] analytically and experimentally investigated the performance enhancement of Paraffin wax based LHS system by adding carbon nanofibres (CNF) with the mass fraction of CNF ranging from 1 to 4%. Their study showed an almost linear increase in thermal conductivity with increase in the mass ratio of carbon nanofibres. Wang et al. [25] conducted an experimental study of enhancement of thermal conductivity of palmitic acid based phase change materials with carbon nanotubes as fillers. Tun-Ping Teng and Chao-Chieh Yu [26] reported the production of nanocomposite-enhanced phase-change materials using the direct-synthesis method by mixing paraffin with alumina (Al2O3), titania (TiO2), silica (SiO2), and zinc oxide (ZnO) in three concentrations of 1.0, 2.0, and 3.0 wt.%. Their experimental results demonstrated that TiO2 was more efficient than the other additives in enhancing both the heat conduction and thermal storage performance of paraffin for most of the experimental parameters. Mettawee and Assassa [27] conducted a study on thermal conductivity enhancement of paraffin wax by incorporating with 0.1, 0.3, 0.4 and 0.5% mass fractions aluminum particles. Their study showed a 60% reduction in charging time with an aluminum mass fraction of 0.5% compared to pure paraffin wax. Zhiwei Ge et al. [28] studied the use of carbonate-salt-based composite materials for medium- and high-temperature thermal energy storage applications. Advanced nanocomposite phase change material based on calcium chloride hexahydrate with aluminum oxide nanoparticles for thermal energy storage was proposed and studied by Xiang Li et al. [29]. They conducted thermal cycling test of the composite PCM with 1% weight fraction of alumina particles and observed from the characterization study that the chloride hexahydrate/aluminum nanocomposite PCM possesses acceptable thermal reliability, chemical stability, and heat transfer characteristics which makes them suited for low-temperature (25–35 °C) solar thermal energy storage applications. D K Singh et al. [30] conducted an experimental study on Myo-Inositol based nano PCM for solar thermal energy storage. In their research, they have reported the thermal cycling characterization of Myo-Inositol added with CuO and Al2O3 (mass fractions of 1%, 2%, and 3%) nanoparticles using DSC, TGA and FTIR methods. They recommended myo-inositol based nano-PCM as a potential material for solar thermal energy storage applications in the temperature range 160 °C–260 °C.

Many studies on potential solid-solid PCM have been reported in the literature [[31], [32], [33], [34], [35]]. Recent studies on PCM have stated the use of additives such as nanoparticles to improve the performance of thermal energy storage systems. Additives are being used to enhance the thermophysical properties of the storage materials. Studies show that nanoparticles can naturally promote the heterogeneous nucleating of the solid-liquid organic PCM and improve their crystallization rates. However, few such studies have reported for solid-solid organic PCM [[36], [37], [38], [39], [40]]. Polyalcohols used as solid-solid PCM have low heat transfer characteristics due to their poor thermal conductivity values. So additives such as nanoparticles are used to improve the thermal properties of polyalcohols. Hu et al. [41] have done an experimental investigation on solid-solid phase change properties of pentaerythritol (PE)/nano-AlN composite for thermal storage. They have reported that the addition of nano-AlN can accelerate the crystallization rate and reduce the supercooling degree of PE during the cooling process.

Pentaerythritol is a solid-solid PCM that has a very high heat of transition associated with the breakage and reformation of hydrogen bonds during the crystal structure change at a higher temperature. However, being an organic material, pentaerythritol has low thermal conductivity. The thermal conductivity of the metal caused by the electron motion is much higher than that of the organic materials. Therefore, metal (or its alloys) with a low melting point used as a PCM will exhibit a much stronger heat transfer capacity than that of traditional PCM. Based on this point, authors have attempted to study the use of low melting metal (LMM) as a useful additive for improving the thermal performance of organic PCM. In our previous work [42] we have studied the thermal and chemical stability of pentaerythritol blended with a low melting alloy of In, Sn, Bi, and Zn for potential PCM for latent heat storage. In this experimental investigation, we have experimented a new solid-solid organic-low melt metal composite PCM with an improved thermal performance for energy storage application. The experiments conducted for studying the feasibility of indium (In), a low melt metal, as an additive for improving the thermal storage performance of pentaerythritol in the temperature range 30–200 °C. For this, PE samples with 0.1 wt.%, 0.3 wt.% and 0.5 wt.% of indium were prepared using a laboratory ball mill. Thermal cycling study of the developed PCM samples was carried out in a thermal cycling experimental unit. The PCM samples before and after 100 thermal cycles were characterized using the DSC, TGA-DTA and FTIR methods. Thermal conductivity and specific heat changes of pentaerythritol due to LMM additives were studied using T-history method [[43], [44]]. Thermal energy storage/release performance of pentaerythritol added with indium was also examined in this experimental study. We have also investigated the non-isothermal crystallization kinetics of pentaerythritol added with 0.1 wt.%, 0.3 wt.% and 0.5 wt.% of indium by DSC analysis at different cooling rates of 5 °C/min, 10 °C/min, 20 °C/min and 40 °C/min. Authors have done a thorough survey on experimental works using organic solid-solid PCM, and till now, no research that investigates the thermal storage performance and non-isothermal crystallization kinetics of an organic solid-solid PCM added with low melt metal have reported in the literature.

Section snippets

Materials

Pentaerythritol [2,2-bis (hydroxymethyl)-1, 3-propanediol], is an organic compound with the formula C5H12O4. This polyalcohol shows a phase transition in the solid state between 187 and 189 °C (tetragonal to cubic structural change). As shown in Fig. 1(a), PE molecule consists of four methylenic carbon atoms surrounding the central carbon atom in a tetrahedral arrangement. The PE molecule is comparatively flexible, and its branches can rotate about Csingle bondC or Csingle bondO single bonds. At ambient pressure and

Thermal property measurement

Fig. 6 shows the cooling curves obtained from the T-history method for PE, PE + 0.1 wt.% In, PE + 0.3 wt.% In and PE + 0.5 wt.% In before and after 100 thermal cycles displayed in black, red, blue and dark cyan color. The cooling curve of glycerin, the reference material, is shown in magenta color. The cooling curves obtained for PCM samples and that for glycerin, reference material, were compared to determine the thermal properties such as thermal conductivity and specific heat of PCM. It is

Uncertainty analysis

The primary parameter monitored during the thermal cycling and thermal storage performance tests were the PCM sample temperatures, where K type thermocouples connected to a multi-channel data acquisition system (KEYSIGHT 34972A LXI) were used to record the sample temperatures. These K-type thermocouples were calibrated using a handheld dry-well calibrator (Fluke 9100S) having temperature accuracy of ±0.25 °C. The root sum squares (RSS) method was used to evaluate the uncertainty in the

Conclusions

An experimental investigation was performed to study the effect of the addition of indium, a low melting metal (LMM), on the heat of absorption and release associated with the breakage and reformation of hydrogen bonds during the thermal cycling of pentaerythritol (PE). Initially, PE samples with 0.1%, 0.3% and 0.5% weight fractions of indium were prepared using a laboratory ball mill. Thermal cycling study of the developed PCM samples was carried out in a thermal cycling experimental unit. The

Acknowledgement

The authors wish to thank DST-SERI (Sanction number: DST/TM/SERI/DSS/275 (G) dated 14.09.2015) for the financial support provided for the experimental work reported in this paper.

References (56)

  • E. Murrill et al.

    Solid-solid phase transitions determined by differential scanning calorimetry: part I. Tetrahedral substances

    Thermochim. Acta

    (1970)
  • M. Barrio et al.

    Applicability for heat storage of binary systems of neopentylglycol, pentaglycerine, and pentaerythritol: a comparative analysis

    Sol. Energy Mat.

    (1988)
  • A. Elgafy et al.

    Effect of carbon nanofibres additives on thermal behavior of phase change materials

    Carbon

    (2005)
  • J.F. Wang et al.

    Enhancing thermal conductivity of palmitic acid based phase change materials with carbon nanotubes as fillers

    Sol. Energy

    (2010)
  • E.B.S. Mettawee et al.

    Thermal conductivity enhancement in a latent heat storage system

    Sol. Energy

    (2007)
  • Zhiwei Ge et al.

    Carbonate-salt-based composite materials for medium- and high-temperature thermal energy storage

    Particuology

    (2014)
  • D.K. Singh et al.

    Myo-inositol based nano-PCM for solar thermal energy storage

    Appl. Therm. Eng.

    (2017)
  • D.K. Benson et al.

    Solid state phase transitions in pentaerythritol and related polyhydric alcohols

    Sol. Energy Mater.

    (1986)
  • Q.Y. Yan et al.

    The thermal storage performance of monobasic, binary and triatomic polyalcohols systems

    Sol. Energy

    (2008)
  • W. Li et al.

    Study of solid-solid phase change of (n-CnH2n+1 NH3)2MCl4 for thermal energy storage

    Thermochim. Acta

    (1999)
  • E. Landi et al.

    Metal-dependent thermal behavior Ln (n-CnH2n+1 NH3)2MCl4

    Thermochim. Acta

    (1975)
  • X. Ruiyun et al.

    Studies of solid-solid phase transitions for (n-C18H37NH3)2MCl4

    Thermochim. Acta

    (1990)
  • J.G. Tang et al.

    Effects of organic nucleating agents and zinc oxide nanoparticles on isotactic polypropylene crystallization

    Polymer

    (2004)
  • P. Hu et al.

    Experimental study on solid-solid phase change properties of pentaerythritol (PE)/nano-AlN composite for thermal storage

    Sol. Energy

    (2014)
  • K.P. Venkitaraj et al.

    Experimental study on the thermal and chemical stability of pentaerythritol blended with low melting alloy as possible PCM for latent heat storage

    Exp. Therm. Fluid Sci.

    (2017)
  • Aran Sole et al.

    Review of the T-history method to determine thermophysical properties of phase change materials (PCM)

    Renew. Sustain. Energy Rev.

    (2013)
  • P. Ramamoorthy et al.

    Vibration spectrum of pentaerythritol

    Spectrochim. Acta Part A: Mol. Biomol. Spectrosc.

    (1997)
  • Nandini Garg et al.

    Investigations of pressure induced structural phase transformations in pentaerythritol

    Solid State Commun.

    (2005)
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