Stable Composite Phase Change Materials Research Articles

Insights into effect of lignocellulosic biomass framework types on bio-based shape stable composite phase change materials

The utilization of biomass waste as framework materials to inhibit the leakage of phase change material (PCMs) has gained widespread attention. In this work, three new kinds of shape stable composite phase change materials (sscPCMs) were prepared which combined with stearic acid (SA) and peanut shell powders (PSP), poplar wood powders (PWP), and corn straw powders (CSP), respectively. The influence of lignocellulosic biomass types on the thermal energy storage performance of sscPCMs was studied by comparing three types of sscPCMs. The research results indicated that SA/CSP exhibited superior properties in terms of load capacity and thermal energy storage performance. According to leakage experiments the load capacity of SA/PSP, SA/PWP and SA/CSP was 31.67 %, 44.69 %, and 50.09 %, respectively. The phase change latent heat of SA/PSP, SA/PWP, and SA/CSP was 55.78, 84.27 and 98.47 J/g, respectively. In addition, the relationship between biomass component content and load rates was studied. The results showed that there was a positive correlation between the loading rates of SA and the ratio of holocellulose (cellulose + hemicellulose) to lignin. The results provided a promising approach for the selection of lignocellulosic biomass framework materials.

High value utilization of waste peanut shell: Prepared novel shape stable composite phase change materials with high thermal conductivity

To address the leakage and low thermal conductivity issues of phase change materials (PCMs), this study aims to prepare high thermal conductivity shape stable composite phase change materials (sscPCMs) using waste peanut shell. Employing pyrolysis technology, waste peanut shell has been successfully converted into high-performance framework materials. In addition, it also compared the thermal energy storage performance of shape stable composite stearic acid/peanut shell biochar (ss-cSA/PSC) with that of shape stable composite stearic acid/peanut shell (ss-cSA/PS). Excitingly, the thermal energy storage performance of ss-cSA/PSC has been significantly improved. Specifically, the thermal conductivity of ss-cSA/PSC reached 0.527 W/(m·K), which is 3.2 times higher than that of pure SA and 2.4 times higher than that of ss-cSA/PS. In addition, the phase change latent heat of ss-cSA/PSC can reach 70.59 J/g, which is 27.2% higher than that of ss-cSA/PS. The high thermal conductivity and phase change latent heat highlighted its significant superiority in the field of thermal energy storage. Furthermore, ss-cSA/PS and ss-cSA/PSC have been characterized by SEM, FTIR, XRD, and TGA. The results indicated that both two kinds of sscPCMs have excellent chemical compatibility, thermal reliability, and thermal stability. In summary, PSC is an economical, environmentally friendly, and sustainable framework material which used to prevent the leakage of PCMs and improve the thermal performance.

An experimental investigation on kinetic analysis of thermal degradation of shape stable composite phase change materials and adaptive neuro fuzzy inference system modeling for predicting mass loss

An experimental investigation on kinetic analysis of thermal degradation of shape stable composite phase change materials and adaptive neuro fuzzy inference system modeling for predicting mass loss

Synthesis and characterization of form-stable carbonate/steel slag composite materials for thermal energy storage

It is of practical importance to develop form stable composite phase change materials (FSPCMs) for high temperature thermal energy storage. Carbonates are promising candidates as the phase change material and steel slag is a promising economical skeleton material. However, the molten carbonates (Na2CO3 and K2CO3) react with steel slag (SS) at high temperature. Here, a two-step process was developed to overcome this problem. Firstly, the modified steel slag (MSS) was obtained by activation of the two carbonates, and secondly, FSPCMs were synthesized by mix-sintering method. The obtained K2CO3/KMSS FSPCMs kept better shape than that of Na2CO3/NMSS FSPCMs after the thermal cycles. Further test showed that K2CO3 had good chemical compatibility with KMSS and was uniformly distributed. With the increased K2CO3 content, the latent heat of K2CO3/KMSS FSPCMs gradually increases, and the measured latent heat was consistent with the calculated values. With mass ratio 4:6 (40K2CO3/60KMSS), the developed FSPCM showed the best thermal stability, the latent heat attenuation was 7.08%, and the mass loss was 6.56% after 200 thermal cycles.

Fabrication of temperature-regulating functional fabric based on n-octadecane/SWCNTs composite phase change material

PurposeFabrics with photothermal conversion functions were developed based on the introduction of shape stable composite phase change materials (CPCMs).Design/methodology/approachAcidified single-walled carbon nanotubes (SWCNTs) were selected as support material to prepare CPCMs with n-octadecane to improve the thermal conductivity and shape stability. The CPCMs were finished onto the surface of cotton fabric through the coating and screen-printing method. The chemical properties of CPCMs were characterized by Fourier transform infrared spectrometer, XRD and differential scanning calorimetry (DSC). The shape stability and thermal conductivity were also evaluated. In addition, the photothermal conversion and temperature-regulating performance of the finished fabrics were analyzed.FindingsWhen the addition amount of acidified SWCNTs are 14% to the mass of n-octadecane, the best shape stability of CPCMs is obtained. DSC analysis shows that the latent heat energy storage of CPCMs is as high as 183.1 J/g. The thermal conductivity is increased by 84.4% compared with that of n-octadecane. The temperature-regulating fabrics coated with CPCMs have good photothermal conversion properties.Research limitations/implicationsCPCMs with high latent heat properties are applied to the fabric surface through screen printing technology, which not only gives the fabric the photothermal conversion performance but also reflects the design of personalized patterns.Practical implicationsCPCMs and polydimethylsiloxane (PDMS) are mixed to make printing paste and printed cotton fabric with temperature-regulating functional is developed.Originality/valueSWCNTs and n-octadecane are composited to prepare CPCMs with excellent thermal properties, which can be mixed with PDMS to make printing paste without adding other pastes. The fabric is screen-printed to obtain a personalized pattern and can be given a thermoregulatory function.

Mechanical and thermal performance assessment of paraffin/expanded vermiculite-diatomite composite phase change materials integrated mortar: Experimental and numerical approach

In this paper, the influence of paraffin/expanded vermiculite-diatomite form stable composite phase change materials (paraffin/EVC-D FSCPCM) on the strength and thermal properties of the mortar was studied through experiments and numerical simulations. The mechanical properties, thermal conductivity and thermoregulation performance of the paraffin/EVC-D FSCPCM integrated mortar were studied in detail. Meanwhile, the energy-saving effect of the paraffin/EVC-D FSCPCM integrated mortar in building was studied by numerical simulation. Thermal-cycling test results indicated a 10.9% leakage reduction of form stable composite phase change material with a diatomite coating. Strength test results showed the addition of diatomite increased the compressive strength of paraffin/EVC-D FSCPCM integrated mortar. The thermoregulation performance test showed the paraffin/EVC-D FSCPCM integrated mortar displayed good thermoregulation performance regardless of the testing conditions (lab-scale or actual environment). During laboratory-scale thermal regulation performance testing, when the volume replacement rate of paraffin/EVC-D FSCPCM to sand reaches 70%, the paraffin/EVC-D FSCPCM integrated mortar reduced the maximum temperature of the testing room by 3.1 °C; in an actual environment, it reduced the maximum temperature of the wall board by 2.68 °C. The simulation results showed that in summer, compared with cement mortar, the use of paraffin/EVC-D FSCPCM integrated mortar in the building could save 17.03% of energy consumption.

Fabrication of form stable composite phase change materials for thermal energy storage by direct powder incorporation with a preheating process

This work concerns with form stable composite phase change materials (FSCPCMs) for thermal energy storage applications. A vast knowledge base has been established in formulation design, material selection and characterisation. However, research efforts on manufacturing technologies are insufficient, leading to limited information on the relationship between manufacture processes and product properties - the main motivation for this work. A commonly used fabrication method is the so-called direct powder incorporation method. We have modified the direct incorporation method by the integration of a preheating process and used the modified method to fabricate a KNO3-diatomite based FSCPCM. The characterisation of the fabricated FSCPCMs showed that the preheating method not only densified the microstructure, but also gave a significant increase in the thermal conductivity (by 54.91%). The improvements were found to be associated with wettability of the PCM on the matrix surface, whereas porous structure of the matrix material has a small effect.

Surface modification effects in phase change material-infiltrated attapulgite

Attapulgite has nanoporous structure and is an excellent supporting material for the preparation of form stable composite phase change materials (FSCPCMs). However, the effects of surface characteristics of attapulgite on the attapulgite based FSCPCMs were unclear. In this work, the effect of surface modification on the properties of different kinds of attapulgite-based FSCPCMs was investigated. First, N-(2-aminoethyl)-3-aminopropyltrimethoxysilane (KH792) was used to modify attapulgite. Then, a series of FSCPCMs were prepared by adsorbing three kinds of phase change materials (PCM) with modified attapulgite (M-ATP). The crystallization and thermal properties of these FSCPCPMs were investigated. The results showed that, the surface modification improves the crystallinity and the latent heat of the FSCPCMs when paraffin or polyethylene glycol are used as the PCM. When the mass fraction of the PCM is 40%, the surface modification increases the latent heat of the paraffin/attapulgite FSCPCM and the polyethylene glycol/attapulgite FSCPCM by 31.5% and 27.8%, respectively. After 800 cooling and heating cycles, the thermal properties of paraffin/M-ATP and polyethylene glycol/M-ATP are still stable. The results were explained by analyzing the interaction between the PCM and the attapulgite. This study provides new ideas to improve the thermal properties of FSCPCMs through surface modification.

Polyethylene Glycol Based Form Stable Composite Phase Change Material: A Review

In the present study polyethylene glycol based form stable composite phase change materials have been reviewed. Due to different molecular weight of polyethylene glycol, it contains different melting temperature. So, it can be used at various engineering applications. But, less thermal conductivity and leakage during phase transformation hampers the utilization of polyethylene glycol. To overcome these huddles various researchers develops form stable composite kind of phase change material with the incorporation of porous material and thermal conductivity enhancing material. Thermal, physical and mechanical properties of the composite phase change materials were investigated by the different authors. A number of results indicated that with addition of different form stabilized material the thermal, chemical and mechanical properties have been improved.

Novel Bio-Based Pomelo Peel Flour/Polyethylene Glycol Composite Phase Change Material for Thermal Energy Storage.

A series of novel bio-based form stable composite phase-change materials (fs-CPCMs) for solar thermal energy storage and management applications were prepared, using the pomelo peel flour (PPF) as the supporting matrix and poly (ethylene glycol) (PEG) or isocyanate-terminated PEG to induce a phase change. The microscopic structure, crystalline structures and morphologies, phase change properties, thermal stability, light-to-thermal conversion behavior, and thermal management characteristics of the obtained fs-CPCMs were studied. The results indicate that the obtained fs-CPCM-2 presented remarkable phase-change performance and high thermal stability. The melting latent heat and crystallization heat for fs-CPCM-2 are 143.2 J/g and 141.8 J/g, respectively, and its relative enthalpy efficiency () is 87.4%, which are higher than most reported values in the related literature. The obtained novel bio-based fs-CPCM-2 demonstrated good potential for applications in solar thermal energy storage and waste heat recovery.

Enhancement of ceramic foam modified hierarchical Al2O3@expanded graphite on thermal properties of 1-octadecanol phase change materials

Abstract The porous Al2O3 ceramic foam was composited with expanded graphite (EG) by calcination method to obtain Al2O3@EG composite with hierarchical pores. The specific surface area of Al2O3@EG composite was 2.3 times that of EG, which can better enhance the thermal conductivity and heat transfer performance of phase change materials (PCMs). The stable composite PCMs with high thermal conductivity and energy storage density were prepared via vacuum adsorbing 1-octadecanol (OD) in Al2O3@EG. The thermal conductivity of the modified OD containing 10 wt% Al2O3@EG was 4.5 times that of pure OD, while maintaining a high phase change enthalpy, approximately 200 kJ/kg. The results of SEM and EDS indicated that Al2O3 foam particles dispersed equably on the surface of EG without obvious agglomeration. The XRD and FTIR results revealed that OD, Al2O3 and EG were physically combined. The prepared OD/Al2O3@EG composite PCMs with high thermal conductivity and large energy storage density can be promising for low temperature heat storage, such as industrial heat recovery system, comfort applications in buildings and textiles, solar energy system, etc. This study provides an innovative idea for the application of porous ceramic foams in the field of solar energy storage PCMs modification.

Preparation of novel form–stable composite phase change materials with porous silica nanofibrous mats for thermal storage/retrieval

Electrospun SiO2 nanofibrous mats have been widely utilized as substrate of form-stable phase change materials due to large specific surface area and high convection coefficient. In order to overcome the brittleness and enhance the absorption capacity of SiO2 nanofibrous mats as substrate, flexible and hollow SiO2 nanofibrous mats were prepared by single-spinneret electrospinning which eliminated complicated spinneret and unstable structure compared with coaxial electrospinning. Quinary fatty acid eutectics were chosen as representative fatty acid which were adsorbed in SiO2 nanofibrous mats to form form-stable phase change materials. The results showed that hollow structure can be observed as the content of paraffin oil decreased from 1.67 to 0.70 g, and as-prepared hollow nanofibrous mats displayed favorable flexibility. DSC results demonstrated that the largest melting/crystallization enthalpy supported by hollow SiO2 nanofibrous mats was approximately 123.80/120.50 J g−1, which was much higher than solid SiO2 nanofibers. More importantly, after 30 cycles, there was no obvious change for phase change temperature and enthalpy. The thermal conductivity of representative form-stable phase change materials was over three times than that of quinary fatty acid eutectics. Hence, flexible and hollow SiO2 nanofibrous mats were excellent substrate in form-stable phase change materials and would have wide application prospects.

Composite phase change materials for thermal energy storage: From molecular modelling based formulation to innovative manufacture

Thermal energy storage (TES) has a crucial role to play in conserving and efficiently utilising energy, dealing with mismatch between demand and supply, and enhancing the performance and reliability of our current energy systems. A competitive TES technology requires a number of scientific and technological challenges to be addressed including TES materials, TES components and devices, and integration of TES devices with energy networks and associated dynamic optimization. This paper concerns mainly about TES materials challenges with a specific focus on using shape stable composite phase change materials (CPCMs) for medium and high temperature application. The paper first briefly reviews the state-of-the-art development of materials research for thermal energy storage. The focus is then on CPCMs for medium to high temperatures applications, covering materials screening, formulation based on molecular modelling validated at a different length scale through experiments, formulation based on chemical and physical compatibility, and manufacture of material modules via innovative use of conventional powder technology. The properties of the materials and materials modules are characterised and analysed with an aim to establish property-structure relationships. This includes a particularly interesting aspect of the motion of PCM and nanoscale objects with the PCMs for heat transfer enhancement during thermal cycling, which explains the mechanisms of the encapsulation of PCMs in the composite.

Experimental investigation on n–octadecane/polystyrene/expanded graphite composites as form–stable thermal energy storage materials

In this work, polystyrene–based form–stable composite phase change materials (CPCMs) were fabricated by a solution and reflux method. In the composites, the n–octadecane (ODE) was used as thermal energy storage material, the polystyrene (PS) acted as the supporting material, and expanded graphite (EG) was employed as thermal conductive filler to improve the thermal conductivity of the composites. The toluene was adopted as solvent. Both polystyrene and n–octadecane smoothly dissolve in toluene. EG was also easily dispersed into the matrix. CPCMs were obtained after distillation of the toluene. The differential scanning calorimeter (DSC) and a thermogravimetry analyzer (TGA) were adopted to assess the thermal properties and thermal stability of the CPCMs, respectively. Fourier transformation infrared (FT–IR) spectroscope and scanning electronic microscope (SEM) were utilized to determine the chemical structure and microstructure of the ODE/PS/EG composites. The thermal conductivity of the CPCM with 5 wt% content of EG can reach up to 1.01 W/m·K, which is nearly 7 times higher than that of the CPCM without the EG. The latent heat value of CPCM with the highest ODE content (48.5 wt%) is 98.05 J/g, the melting temperature is 27.5 °C, which is close to room temperature. Therefore, the form–stable CPCMs are promising thermal energy storage materials in solar thermal energy storage systems, such as solar heating system in buildings.

Form stable composite phase change materials from palmitic-lauric acid eutectic mixture and carbonized abandoned rice: Preparation, characterization, and thermal conductivity enhancement

In this study, novel form stable composite phase change materials (FS-CPCMs) from palmitic-lauric acid (PA-LA) eutectic mixture and carbonized abandoned rice (CAR) were prepared via vacuum impregnation. The CAR served as a good supporting material to prevent PA-LA from leaking and enhanced the thermal conductivity of PA-LA. SEM results showed that the CAR has a highly porous structure consisting of rough micro-pores and PA-LA did not leak from the CAR during the solid-liquid phase transition. DSC indicated that the latent heat and temperature of PA-LA/CAR FS-CPCMs during melt were 135.4J/g and 34.3°C, respectively, whereas, these values were 124.8J/g and 28.6°C during freezing, respectively. The thermal conductivity of PA-LA/CAR FS-CPCMs was 1.83 times that of PA-LA. The heat storage/release rate of the PA-LA/CAR FS-CPCMs is significantly more than that of PA-LA for practical applications. The results obtained from FTIR demonstrated that no new chemical bonds were formed between PA-LA and CAR. TGA and 200-cycle experiments showed that the PA-LA/CAR FS-CPCMs exhibit excellent thermal stability and form-stable performance. The PA-LA/CAR FS-CPCMs thus prepared were safe, environmentally friendly, and cost-effective; hence, they can be used as potential building materials for the applications of thermal energy storage.

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

Polyethylene glycol/Cu/SiO2 form stable composite phase change materials: preparation, characterization, and thermal conductivity enhancement

Novel form-stable composite phase change materials (FS-CPCMs) of polyethylene glycol (PEG)/Cu/SiO2 were prepared by adding Cu powder to PEG and SiO2via the ultrasound-assisted sol–gel method.

Polyethyl Methacrylate (PEMA)/Fatty Acids Blends as Novel Phase Change Materials for Thermal Energy Storage

This study deals with the preparation and characterization of polyethyl methacrylate/fatty acid blends as a novel form-stable phase change material for latent heat thermal energy storage applications. In the blends, fatty acids act as a phase change material when polyethyl methacrylate is operated as a supporting material. The fatty acids could be retained by 50 wt% into polyethyl methacrylate without melted phase change material seepage from the blends. Therefore, these blends are called form stable composite phase change materials and they have utility advantage without encapsulation in passive latent heat thermal energy storage applications. The prepared fatty acid/polyethyl methacrylate blends (50/50 w/w%) as form-stable phase change material was characterized using optic microscopy and Fourier transform infrared spectroscopy methods and the results showed that the polyethyl methacrylate was physically and chemically compatible with the fatty acids. Thermal properties and thermal stabilities of the form-stable phase change materials were measured using differential scanning calorimetry. Differential scanning calorimetry results indicated that the melting temperatures and latent heats of the prepared phase change materials are in the range of 30.67–61.09°C and 86.93–107.75 J/g, respectively. The thermal cycling test, including 5,000 cycling processes, was conducted to determine the thermal reliability of the synthesized form-stable phase change materials, and it is found that phase change materials were thermally and chemically stable after thermal cycling. On the basis of all the results, it was concluded that form stable polyethyl methacrylate/fatty acids composite phase change materials had important potential for practical latent heat thermal energy storage applications, such as under floor space heating of buildings and passive solar space heating of buildings by using wallboard, plasterboard, or floors impregnated with a form stable phase change material.

Preparation and Characterization of Diatomite Loaded Composite Phase Change Materials

Organic phase change materials like paraffin as phase change material, modified diatomite as carrier, composite phase change material with proper phase change temperature and larger phase change enthalpy is prepared by melt blending. The structure and performance of composite phase material are characterized using SEM, FI-IR and synthesized thermal analyzer DSC. The results show that the phase change temperature of composite phase change material is 30, and phase change enthalpy is 89.54J/g. With every part preserved, phase change particles are distributed in the diatomite/melted paraffin matrix evenly. Stable composite phase change materials are prepared with diatomite as carrier and paraffin as PCM, which are bonded with Vander Waals forces in the form of physical adsorption.