Non-isothermal crystallization kinetics of paraffin wax as a phase changing energy storage material

Louanate, Amal; Otmani, Rabie El; Kandoussi, Khalid; Boutaous, Mhamed

doi:10.1088/1402-4896/abb49f

Cited by 16 publications

(17 citation statements)

References 44 publications

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“…The peak 1 ranging from 30 °C to 40 °C was caused by solid-solid (SS) phase transition in PW, which generally implicates a rotational motion at the molecular level from the rotator phase a to the non-rotating phase b. [32] The peak 2 ranging from 50 °C to 60 °C was caused by solid-liquid (SL) phase transition in PW during heating/cooling cycles. The details related to phase transition and thermal energy storage were given in shown in Table 1 and Table 2.…”

Section: Resultsmentioning

confidence: 99%

“…Two peaks including peak 1 and peak 2 were observed for PW, PWV and UPWV. The peak 1 ranging from 30 °C to 40 °C was caused by solid‐solid (SS) phase transition in PW, which generally implicates a rotational motion at the molecular level from the rotator phase

α

to the non‐rotating phase

β

[32] . The peak 2 ranging from 50 °C to 60 °C was caused by solid‐liquid (SL) phase transition in PW during heating/cooling cycles.…”

Section: Resultsmentioning

confidence: 99%

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Nanofibrous Membranes in Multilayer Fabrics to Avoid PCM Leakages

et al. 2022

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Incorporating phase change materials (PCMs) into textiles is one facial method to realize personal thermal management (PTM). Despite the significant progress of PCM‐incorporated textiles, the incorporation of PCMs into textiles remains an outstanding challenge. In this work, we described a sandwich‐like multi‐layer PCM fabric, which consisted of nanofibrous membranes as barrier layers and PCM‐loaded viscose fabric as a PCM‐loaded layer. Three common organic PCMs including polyethylene glycol (PEG), paraffin wax (PW) and myristic acid (MA), and the polyurethane (PU) nanofibrous membranes was used. As a result, we achieved that weak interfacial adhesion between melting PCMs and PU nanofibrous membranes accounted for leakage phenomena. Only the sample (UPWV) with PU nanofibrous membranes as barrier layers and paraffin wax (PW) as PCMs had no leakage. Little confinement of PW crystallization in the UPWV was found. Besides, thermal energy storage, phase transition, and thermal buffering effect of UPWV supported various applications.

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Section: Resultsmentioning

confidence: 99%

α

to the non‐rotating phase

β

[32] . The peak 2 ranging from 50 °C to 60 °C was caused by solid‐liquid (SL) phase transition in PW during heating/cooling cycles.…”

Section: Resultsmentioning

confidence: 99%

Nanofibrous Membranes in Multilayer Fabrics to Avoid PCM Leakages

et al. 2022

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“…At the crystallization/melting point, the heat flow curve demonstrates a sharp maximum/minimum. As for paraffin samples, it was repeatedly shown that cooling/heating rate could affect their thermophysical and structural properties [3][4][5][6][7]. In particular, Hammami et al reported an increase in the crystallization temperature for a series of seven n-alkanes upon decreasing the cooling rate from 10 to 1 K/min [4,5].…”

Section: Introductionmentioning

confidence: 99%

“…Lazaro et al showed that for a n-octadecane sample the heating rate should be lower than 0.5 K/min to eliminate the effects of heating rate on the results [7]. Louanate et al studied non-isothermal crystallization behavior of technical grade paraffin wax and showed that the peaks of the crystallization curves became broader and shifted to lower temperatures, when the cooling rate was increased from 0.3 to 20 K/min [3]. Lastly, Abdi et al focused on the thermophysical properties of n-octadecane and n-eicosane and varied the cooling/heating rates from 0.025 to 0.5 K/min [6].…”

Section: Introductionmentioning

confidence: 99%

Cooling-rate computer simulations for the description of crystallization of organic phase-change materials

Nazarychev

Glova

Larin

et al. 2022

Preprint

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A molecular-level insight into the phase transformations is of great demand for the molecular systems for which the phase transition is a key process from the point of view of practical applications, organic phase-change materials being one of the most prominent examples. Such a detailed insight can be gained through cooling-rate computer simulations, i.e. simulations in which cooling is applied to a system at a constant rate. However, the ability of the simulations to give an accurate description of the phase transition process is an open question, since the cooling rates accessible in atomic-scale computer simulations are many orders of magnitude larger than those in experiments. In this paper we present the first computational study that systematically explores as to how the cooling rate affects the crystallization of organic phase-change materials such as paraffins. To this end, we performed a series of atomistic molecular dynamics simulations in which the cooling rate was varied over four orders of magnitude. Our computational results clearly show that a certain threshold in the values of cooling rates exists. When cooling is performed with the rates smaller than the threshold, computer simulations are able to qualitatively reproduce the crystallization process in paraffins. This includes an abrupt change in the temperature dependence of the density, enthalpy, and thermal conductivity upon crystallization. The crystallization enthalpy for these cooling rates was found to agree quantitatively with experiment. However, beyond this threshold, when cooling is too fast, the paraffin’s properties in simulations start to deviate considerably from experimental data: the faster the cooling, the larger part of the system is trapped in the super-cooled liquid state. As a result, one can observe a systematic decrease in the fraction of crystalline domains in a paraffin sample with cooling rate, leading eventually to a complete lack of crystallization at low temperatures. Both the crystallization temperature and the crystallinity decrease with cooling rate in line with experimental data. All the above strongly supports the conclusion that a proper choice of a cooling rate is of tremendous importance in computer simulations of organic phase-change materials such as paraffins. Cooling with the rates that are too high can lead to a completely inaccurate description of the crystallization process, as well as the thermophysical and structural properties.

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“…Phase change materials (PCMs) are essential thermal mass materials for storing and releasing thermal energy during a phase transition, they also have several advantages that make them appropriate for building applications: PCMs are non-corrosive, nontoxic and compatible with traditional buildings material (Rathore and Shukla, 2019). For more than 30 years, PCMs have been studied by many researchers around the world and many types of PCMs for building applications are therefore available in literature (Alqahtani et al, 2020;Kumar et al, 2019;Louanate et al, 2020a;Singh Rathore et al, 2020;Soares et al, 2013). These materials have two main roles: reducing energy consumption by narrowing fluctuations of indoor temperature and shifting peak loads to the off-peak period for supply of electricity.…”

Section: Introductionmentioning

confidence: 99%

Energy saving potential of phase change materials-enhanced building envelope considering the six Moroccan climate zones

Louanate

Otmani

Kandoussi

et al. 2021

Journal of Building Physics

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Phase change materials (PCMs) show a good capability in absorbing massive heat when undergoing phase change, which have great potential to be incorporated into building envelopes to enhance indoor thermal comfort by preventing heat penetration into buildings and reducing energy requirements. In this work, a deep analysis of PCM enhanced-walls model has been conducted in six representative climate regions of Morocco: El Jadida, Fez, Marrakesh, Ifrane, and Errachidia. More in detail, numerical simulations were carried out to assess the thermal behavior and energy performance of a residential building integrated with four different PCMs. The results showed that the effectiveness and selection of PCMs strongly depend on local weather where they are applied, characteristics of HVAC systems, PCM layer thickness, and position. Furthermore, with reference to each climate zone, the appropriate PCM leading to the lowest annual energy consumption was identified. The findings show that PCMs are particularly suitable for Mediterranean climates, which a promising annual energy saving of about 41% was obtained. While, the lowest value was recorded in Errachidia city reveals that the integration of PCM has little effect in desert climate zone. As for the other climates considered, values of about 28% to 31% were achieved in the studied house model.

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Non-isothermal crystallization kinetics of paraffin wax as a phase changing energy storage material

Cited by 16 publications

References 44 publications

Nanofibrous Membranes in Multilayer Fabrics to Avoid PCM Leakages

Nanofibrous Membranes in Multilayer Fabrics to Avoid PCM Leakages

Cooling-rate computer simulations for the description of crystallization of organic phase-change materials

Energy saving potential of phase change materials-enhanced building envelope considering the six Moroccan climate zones

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