Form-stable Composite Research Articles

Form stable phase change material supported by sensible and thermal controllable thermistor

A negative temperature coefficient (NTC) thermistor with thermal sensing and control capabilities was manufactured by adopting form stable phase change materials (PCMs). The incorporation of PCMs expanded their potential uses by providing a stable and continuous circuit. The PCMs underwent a nearly isothermal phase transition process, which lasted for a long time without significant temperature fluctuations. To hold the pure PCM and prevent leakage during melting and cooling processes, a graphene aerogel was employed as a supporting material. Compared with microsphere PCM composite, the graphene aerogel had a high porosity. The PCM composite retained over 98 wt% of the working material for thermal energy. The NTC thermistor probe was inserted into the PCM composite to construct a thermal sensible device. The PCM surrounded NTC thermistor exhibited an excellent thermal stability and could maintain the output current in the circuit. These findings suggest that the form stable PCM composite can be utilized in thermal controllable systems to prevent overcurrent and safeguard electronic devices.

Modified Supporting Materials to Fabricate Form Stable Phase Change Material with High Thermal Energy Storage.

Thermal energy storage (TES) is vital to the absorption and release of plenty of external heat for various applications. For such storage, phase change material (PCM) has been considered as a sustainable energy material that can be integrated into a power generator. However, pure PCM has a leakage problem during the phase transition process, and we should fabricate a form stable PCM composite using some supporting materials. To prevent the leakage problem during the phase transition process, two different methods, microencapsulation and 3D porous infiltration, were used to fabricate PCM composites in this work. It was found that both microsphere and 3D porous aerogel supported PCM composites maintained their initial solid state without any leakage during the melting process. Compared with the microencapsulated PCM composite, the 3D porous aerogel supported PCM exhibited a relatively high weight fraction of working material due to its high porosity. In addition, the cross-linked graphene aerogel (GCA) could reduce volume shrinkage effectively during the infiltration process, and the GCA supported PCM composite kept a high latent heat (∆H) and form stability.

Development and characterization a novel leakage-proof form stable composite of graphitic carbon nitride and fatty alcohol for thermal energy storage

The form-stabilization ability of the produced graphitic carbon nitride (g-C3N4) for preventing the leakage of stearyl alcohol (SAOH) as promising organic phase change material (O-PCM) was investigated comprehensively. The SEM analysis showed that the g-C3N4 had well defined pores which is capable to confine the molten SAOH in them. The FTIR and XRD confirm the chemical compatibility of g-C3N4 and SAOH. The differential scanning calorimetry thermogram showed that the melting and freezing temperature of the FS-OPCMs including 70 wt% SAOH were 54.57 °C and 55.25 °C with respective high latent heats as 191 kJ/kg and 187 kJ/kg respectively. The thermal aging test for 1000 melt/freeze cycles confirmed that structure and thermal degradation durability are excellent. The thermal conductivity of developed FS-OPCM is enhanced by 122 %, which were resulted in about 50–54 % reduction in the charging/discharging time of FS-OPCM relative to the SAOH. The results exposed that the developed g-C3N4/SAOH (70 wt%) composite can be considered as potential solar energy storage material in different implementations such thermal cooling of photovoltaic panels, automotive and electronic units as well as solar residential water heating and passive solar space heating.

Thermal and mechanical properties of cement based-composite phase change material of butyl stearate/isopropyl palmitate/expanded graphite for low temperature solar thermal applications

The thermal storage composite produced in this research was fabricated by integrating a novel eutectic phase change material of 80% butyl stearate (BS) and 20% isopropyl palmitate (ISOP) into supporting material of expanded graphite (EG) without leakage. 10% of eutectic mixture (EM) formed in the form-stable composite EM_EG is incorporated into the cemented test room's south wall in a laboratory-scale. The mass ratio of EM_EG is characterized by leakage test using a filter paper. The EM of BS and ISOP is successfully absorbed into the porous structure of EG, according to scanning electron microscopy (SEM) results. The differential scanning calorimeter (DSC) test demonstrates that the produced form-stable composite has proper phase change temperature of 15–19 °C and latent heat fusion of 119 J/g for thermal management in the buildings. The thermal conductivity is improved with the addition of EG. The thermogravimetric analysis (TGA) test reveals that the prepared novel eutectic and form-stable composite in the low temperature range are thermally stable. Furthermore, the flexural strength and density decreased with the integration of EM_EG. Cone calorimetry is used to investigate the flammability properties of the form-stable composite. In addition, cement containing EM_EG illustrates appreciated thermal performance in reducing the peak indoor temperature. The findings proved that the produced EM_EG composite might be evaluated as a potential material for reducing energy consumption and improving indoor thermal temperature particularly in building envelope.

Development and characterization of form‐stable porous TiO 2 /tetradecanoic acid based composite PCM with long‐term stability as solar thermal energy storage material

The present study focused on the preparation of form-stable composites of 1-tetradecanoic acid (TDA)/titanium dioxide (TiO2) powder via a facile impregnation method. The use of powdered TiO2 as porous material and thermal conductivity enhancer for TDA is a novel attempt. The morphological, chemical, and crystalline properties of form-stable composite PCMs (Fs-CPCMs), containing different amounts of TiO2, were characterized using field emission scanning electron microscope, Fourier transform infrared spectroscopy, and X-ray diffraction techniques. The finding supports that the produced composites were chemically and structurally stable. The latent heat storage (LHS) properties of composites were obtained from differential scanning calorimeter instrument, and the findings revealed that the Fs-CPCM with 50 mass% TDA has a melting temperature of 52.04°C and a considerably good LHS capacity of 97.75 J/g. The thermal conductivity of TDA was increased remarkably by the addition of TiO2 micro particles. The results obtained from thermogravimetric analysis and thermal cycling test exhibited that the Fs-CPCM, containing 50 mass% TiO2, possesses great thermal degradation durability, cycling chemical stability, and thermal reliability. This composite PCM can be very well used for passive thermal management of electronic devices, automotive components, photovoltaic thermal hybrid designs, solar air/water heating systems, etc.

Thermal and mechanical properties of mortar incorporated with paraffin/palm oil fuel ash composite

The aim of this research was to develop a form-stable phase change material by incorporating paraffin (PA) into palm oil fuel ash (POFA) through direct impregnation. The developed composite was characterized using Scanning electron microscope (SEM) and Fourier transform infrared spectroscopy (FTIR) to determine the microstructure and chemical property. The thermal properties of the composite was determined using Differential scanning calorimetry (DSC). The thermal reliability and thermal stability were assessed using Thermogravimetric analyser (TGA) and thermal cycling tests. Then, the developed form-stable composite was incorporated into cement mortar to evaluate their effects on compressive strength and thermal energy storage ability. From SEM results, PA was absorbed into pores of POFA. FTIR results showed there was no chemical interaction between PA and POFA. Latent heat of the composite was 13.34 J/g and 13.19 J/g for melting and solidification respectively. TGA and thermal cycling tests have validated that the composite was thermally stable and reliable. Incorporation of PA-POFA composite into cement mortar reduced compressive strength significantly. Incorporation of sufficient quantity of PA-POFA composite into cement mortar could increase thermal inertia and minimize temperature fluctuations of the mortar and model test room.

Preparation, Characterization and Thermal Properties of Paraffin Wax – Expanded Perlite Form-Stable Composites for Latent Heat Storage

In this study, form-stable composite phase change materials (PCM) for latent heat storage were prepared by impregnating paraffin wax into the pores of the expanded perlite (EP). The characterization of the composite PCMs was performed by FTIR, TGA, SEM and DSC analysis. The melting point and heat of fusion were determined for 25 % paraffin included composite, as 54.3 °C and 94.71 J/g and for 45 % paraffin included composite as 53.6 °C and 106.69 J/g, respectively. The FTIR results showed that there were no chemical reaction between the perlite and paraffin. TGA analysis indicated that both composite PCMs had good thermal stability. SEM images showed that the paraffin was dispersed uniformly into the pores and on the EP surface. There was no leakage and degradation at the composite PCMs after heating and cooling cycles. According to the results, both prepared composites showed good thermal energy storage properties, reliability and stability. All results suggested that the presented form- stable composite PCMs has great potential for thermal energy storage applications. DOI: http://dx.doi.org/10.5755/j01.ms.23.1.13661

Research on the preparation and properties of lauric acid/expanded perlite phase change materials

In this study, a form-stable lauric acid/expanded perlite (LA/EP) composite was prepared by absorbing paraffin into porous networks of expanded perlite. The form-stable composite was characterized by using Differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FT-IR), Scanning electron microscope (SEM) techniques, durability and leakage test. Leakage test results showed that optimum and maximum mass fraction of LA contained in the composite without leakage is 70wt.%. The FT-IR results revealed that there were physical interactions between the expanded perlite and the lauric acid. In addition, SEM images showed that LA can be quite evenly dispersed in the porous skeleton of EP. The melting temperature and latent heat of the form-stable EP/PA composite containing 70wt.% lauric acid were determined as 43.2°C and 105.58J/g, presenting its suitable phase transition temperature, sufficient latent heat, good thermal stability for application as composite phase change materials (PCMs). The durability test showed that the leakage problems of PCMs composite can be greatly prevented because of the interaction between the expanded perlite and the LA. All the results suggested that the form-stable EP/PA composite has great potential in building applications for thermal energy storage.

Wollastonite hybridizing stearic acid as thermal energy storage material

This paper reported on the preparation of a novel stearic acid (SA)/wollastonite (W) composite as a form-stable phase change material (PCM) for thermal energy-storage (TES) by vacuum impregnation, and especially investigated the effect of the size grade of W on the thermal properties of the SA/W composite. Samples were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), laser particle-size analysis, and differential scanning calorimetry (DSC). Natural W (Wr) was classified into four size grades by wet screening. The results indicate that no chemical reaction took place between SA and W, and the SA load in the SA/W composite increased with an increase in the length/diameter (L/D) ratio of the W. The SA/W composite with a W L/D ratio of 22.5 exhibited latent heats of melting and freezing of 58.64 J/g and 56.95 J/g, respectively, which was higher than those of the composite incorporating natural W. We believe that the as-prepared form-stable PCM composite could provide a potential means of TES for the concentrated solar power.

Preparation and characterization of expanded perlite/paraffin composite as form-stable phase change material

In this study, a form-stable expanded perlite/paraffin (EP/PA) composite was prepared by absorbing paraffin into porous networks of expanded perlite. The form-stable composite was characterized by using Differential scanning calorimetry (DSC), Thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FT-IR), Scanning electron microscope (SEM) techniques and leakage test. The melting temperature and latent heat of the form-stable EP/PA composite containing 60wt.% paraffin were determined as 27.56°C and 80.9J/g, which showed good thermal energy storage property, thermal stability and thermal reliability. In addition, the FT-IR results revealed that there was no chemical interaction between the expanded perlite and the paraffin. By means of the direct impregnation method, the paraffin was distributed uniformly in the EP/PA composite without liquid leakage. All the results suggested that the form-stable EP/PA composite has great potential in building applications for thermal energy storage.

Preparation, characterization and thermal properties of dodecanol/cement as novel form-stable composite phase change material

This research was aimed at preparing novel form-stable composite phase change material (PCM) for thermal heat storage application in buildings. Dodecanol was incorporated into cement through vacuum impregnation technique. The microstructure, chemical compatibility, thermal properties, thermal stability and reliability were determined by environmental scanning electron microcope (ESEM), Fourier transformation infrared spectrum analysis (FT-IR), differential scanning calorimetry (DSC), thermal gravimetric analyzer (TGA) and thermal cycling test. Test results showed that the maximum mass fraction of dodecanol retained in cement without seepage was 9%. This composite was characterized as form-stable composite. FT-IR results indicated that the form-stable composite is chemically stable. The melting temperature and latent heat of the form-stable composite were found to be 21.06°C and 18.39J/g. TGA and thermal cycling test results revealed that the form-stable composite is thermally stable and reliable. It can therefore be concluded that the prepared form-stable composite is a potential candidate for thermal energy storage application in buildings. With the help of an example it is shown that the 2 storey residential building has the capacity to store 2448MJ of thermal energy. This, in turn, will have significant impact in reducing the energy consumption of buildings.

Preparation and properties of highly conductive palmitic acid/graphene oxide composites as thermal energy storage materials

PA/GO (palmitic acid/graphene oxide) as PCMs (phase change materials) prepared by vacuum impregnation method, have high thermal conductivity. The GO (graphene oxide) composite was used as supporting material to improve thermal conductivity and shape stabilization of composite PCM (phase change material). SEM (Scanning electronic microscope), FT-IR (Fourier transformation infrared spectroscope) and XRD (X-ray diffractometer) were applied to determine microstructure, chemical structure and crystalloid phase of palmitic acid/GO composites, respectively. DSC (Differential scanning calorimeter) test was done to investigate thermal properties which include melting and solidifying temperatures and latent heat. FT-IR analysis represented that the composite instruction of porous palmitic acid and GO were physical. The temperatures of melting, freezing and latent heats of the composite measured through DSC analysis were 60.45, 60.05 °C, 101.23 and 101.49 kJ/kg, respectively. Thermal cycling test showed that the form-stable composite PCM has good thermal reliability and chemical stability. Thermal conductivity of the composite PCM was improved by more than three times from 0.21 to 1.02. As a result, due to their acceptable thermal properties, good thermal reliability, chemical stability and great thermal conductivities, we can consider the prepared form-stable composites as highly conductive PCMs for thermal energy storage applications.

Development of form-stable composite phase change material by incorporation of dodecyl alcohol into ground granulated blast furnace slag

This research was aimed at developing form-stable composite phase change material (PCM) by incorporating dodecyl alcohol (DA) into Ground granulated blast furnace slag (GGBS) through vacuum impregnation. The composite PCM were characterized by using Scanning electron microscope (SEM) and Fourier transformation infrared spectrum analysis (FT-IR). The thermal properties, thermal stability and reliability of the composite were determined by using Differential scanning calorimetry (DSC), Thermal gravimetric analyzer (TGA) and thermal cycling test.Test results showed that the maximum percentage of DA retained in GGBS without seepage was 11%. This composite was therefore called as form-stable composite PCM. FT-IR results validate that the components of the form-stable composite are chemically stable. The melting and freezing temperatures of the composite PCM were found to be 21.16°C and 19.1°C while the latent heat of melting and freezing were 22.51J/g and 21.62J/g. The results of TGA and thermal cycling test confirmed that the form-stable composite is thermally stable and reliable. It can therefore be concluded that the prepared form-stable composite is a potential candidate for thermal energy storage in buildings.

Preparation, thermal properties and thermal reliability of eutectic mixtures of fatty acids/expanded vermiculite as novel form-stable composites for energy storage

This paper deals with the preparation, characterization, thermal properties and thermal reliability of novel form-stable composite phase change materials (PCMs) composed of eutectic mixtures of fatty acids and expanded vermiculite for thermal energy storage. The form-stable composite PCMs were prepared by incorporation of eutectic mixtures of fatty acids (capric–lauric, capric–palmitic and capric–stearic acids) within the expanded vermiculite by vacuum impregnation method. The composite PCMs were characterized by SEM and FTIR techniques. Thermal properties of the composite PCMs were determined by differential scanning calorimeter (DSC) method. DSC results showed that the melting temperatures and latent heats of the prepared composite PCMs are in the range of 19.09–25.64 °C and 61.03–72.05 J/g, respectively. The thermal cycling test including 5000 heating and cooling process was conducted to determine the thermal reliability of the composite PCMs. The test results showed that the composite PCMs have good thermal reliability and chemical stability. Furthermore, thermal conductivities of the composite PCMs were increased by adding 10 wt% expanded graphite. Based on all results, the prepared form-stable composites can be considered as promising PCMs for low temperature thermal energy storage applications due to their satisfactory thermal properties, good thermal reliability, chemical stability and thermal conductivities.

Preparation, thermal properties and thermal reliability of palmitic acid/expanded graphite composite as form-stable PCM for thermal energy storage

This study is focused on the preparation and characterization of thermal properties and thermal reliability of palmitic acid (PA)/expanded graphite (EG) composite as form-stable phase change material (PCM). The maximum mass fraction of PA retained in EG was found as 80 wt% without the leakage of PA in melted state even when it is heated over the melting point of PA. Therefore, the PA/EG (80/20 w/w%) composite was characterized as form-stable PCM. From differential scanning calorimetry (DSC) analysis, the melting and freezing temperatures and latent heats of the form-stable PCM were measured as 60.88 and 60.81 °C and 148.36 and 149.66 J/g, respectively. Thermal cycling test showed that the composite PCM has good thermal reliability although it was subjected to 3000 melting/freezing cycles. Fourier transformation infrared (FT-IR) spectroscopic investigation indicated that it has good chemical stability after thermal cycling. Thermal conductivities of PA/EG composites including different mass fractions of EG (5%, 10%, 15% and 20%) were also measured. Thermal conductivity of form-stable PA/EG (80/20 w/w%) composite (0.60 W/mK) was found to be 2.5 times higher than that of pure PA (0.17 W/mK). Moreover, the increase in thermal conductivity of PA was confirmed by comparison of the melting and freezing times of pure PA with that of form-stable composite. Based on all results, it was concluded that the form-stable PA/EG (80/20 w/w%) has considerable latent heat energy storage potential because of its good thermal properties, thermal and chemical reliability and thermal conductivity.

Capric–myristic acid/expanded perlite composite as form-stable phase change material for latent heat thermal energy storage

The aim of this study is to prepare a novel form-stable phase change material (PCM) for latent heat thermal energy storage (LHTES) in buildings. A eutectic mixture of capric acid (CA) and myristic acid (MA) is incorporated with expanded perlite (EP). Thermal properties, thermal reliability, and thermal conductivity of the form-stable composite PCM are determined. The maximum CA–MA absorption of EP was found to be 55 wt% without melted PCM seepage from the composite, and therefore this mixture was described as a form-stable composite. The form-stable composite PCM was characterized using the FT-IR spectroscopy method. The melting and freezing temperatures and latent heats of form-stable composite PCM were measured using DSC analysis. Thermal cycling test of the form-stable composite PCM indicated good thermal reliability in terms of changes in thermal properties after 5000 thermal cycling. The thermal conductivity of the form-stable CA–MA/EP composite PCM was increased about 58% by adding 10 wt% expanded graphite (EG). The form-stable CA–MA/EP/EG composite PCM was considered as an effective LHTES material in the building energy conservation due to suitable phase change temperatures, high latent capacities, good thermal reliability, and good thermal conductivity.