Potential For Use In Applications Research Articles

Thermally Insulating, Thermal Shock Resistant Calcium Aluminate Phosphate Cement Composites for Reservoir Thermal Energy Storage.

This paper presents the use of hydrophobic silica aerogel (HSA) and hydrophilic fly ash cenosphere (FCS) aggregates for improvements in the thermal insulating and mechanical properties of 100- and 250 °C-autoclaved calcium aluminate phosphate (CaP) cement composites reinforced with micro-glass (MGF) and micro-carbon (MCF) fibers for deployment in medium- (100 °C) and high-temperature (250 °C) reservoir thermal energy storage systems. The following six factors were assessed: (1) Hydrothermal stability of HSA; (2) Pozzolanic activity of the two aggregates and MGF in an alkali cement environment; (3) CaP cement slurry heat release during hydration and chemical reactions; (4) Composite phase compositions and phase transitions; (5) Mechanical behavior; (6) Thermal shock (TS) resistance at temperature gradients of 150 and 225 °C. The results showed that hydrophobic trimethylsilyl groups in trimethylsiloxy-linked silica aerogel structure were susceptible to hydrothermal degradation at 250 °C. This degradation was followed by pozzolanic reactions (PR) of HSA, its dissolution, and the formation of a porous microstructure that caused a major loss in the compressive strength of the composites at 250 °C. The pozzolanic activities of FCS and MGF were moderate, and they offered improved interfacial bonding at cement-FCS and cement-MGF joints through a bridging effect by PR products. Despite the PR of MGF, both MGF and MCF played an essential role in minimizing the considerable losses in compressive strength, particularly in toughness, engendered by incorporating weak HSA. As a result, a FCS/HSA ratio of 90/10 in the CaP composite system was identified as the most effective hybrid insulating aggregate composition, with a persistent compressive strength of more than 7 MPa after three TS tests at a 150 °C temperature gradient. This composite displayed thermal conductivity of 0.28 and 0.35 W/mK after TS with 225 and 150 °C thermal gradients, respectively. These values, below the TC of water (TC water = 0.6 W/mK), were measured under water-saturated conditions for applications in underground reservoirs. However, considering the hydrothermal disintegration of HSA at 250 °C, these CaP composites have potential applications for use in thermally insulating, thermal shock-resistant well cement in a mid-temperature range (100 to 175 °C) reservoir thermal energy storage system.

Development of non-equiatomic Bio-HEAs based on TiZrNbTa-(Mo and Mn)

This study produced non-equiatomic TiNbZrTaMn and TiNbZrTaMo high entropy alloy (HEAs) by argon arc-melting and heat-treated for microstructural homogenization. The phase composition, microstructure, and selected mechanical properties were measured and compared with theoretical predictions. Additionally, electrochemical and cytotoxicity tests evaluated their potential applicability for use as biomaterials. X-ray diffraction measurements patterns showed a single BCC phase for the TiNbZrTaMn and a secondary HCP phase for the TiNbZrTaMo sample. The microstructural analysis revealed the formation of irregular grain boundaries and some lamellae formation, with chemical segregation of the alloying elements at the sub-micro-scale. The samples exhibited elastic modulus (80–110 GPa) closer to CP-Ti grade 2 (100 GPa) and higher Vickers microhardness (450–550 HV) than Ti–6Al–4V alloy (400 HV). The electrochemical and biological tests indicated a superior corrosion resistance against 0.9% NaCl solution compared with commercial metallic biomaterials, with proper cell adhesion and viability of pre-osteoblastic cells and hydrophilic behavior. Altogether, the data indicate that TiNbZrTaMn depicts better applicability potential for being used as a biomaterial in biomedical applications than some commercial materials (SS 316L, CP-Ti grade 2, and Ti–6Al–4V), mainly considering load-bearing orthopedical implants.

Aluminium surface impregnated with nano constituents for enhanced mechanical performance

Aluminium alloys are widely used structural materials in automotive, aerospace, and transportation, among several other notable industries. However, aluminium alloys' low hardness and poor tribological performance prevent potential use in applications requiring high contact pressures and wear resistance. This paper presents a novel two-step technique for enhancing the mechanical properties of the aluminium alloy by impregnating the surface with Ni-coating containing hard TiO2 nanoparticles using a high-intensity electric arc generated during tungsten inert gas welding. The results show that the process significantly changes the Microstructure and mechanical properties. The surface hardness increased from 0.48 GPa to 0.65 GPa with a corresponding change of Young's modulus from 15 GPa to 24 GPa of the treated surface.

Performance of green roof installed on highly insulated roof deck and the plants’ effect: An experimental study

Extensive green roof system is widely used due to its lightweight, thin growing media, limited or no maintenance, low cost, and high potential application for use over the new or existing lightweight structures. This study is focused on the energy performance and rainwater retention performance of extensive green roofs when coupled with highly insulated roof deck. In this experimental study, three roof systems: conventional roof (CR) and two extensive green roofs with plants (GR) and with no plants (GM) are constructed, instrumented and their responses to real environmental conditions are monitored for over a year and analyzed. The experimental results suggest that during wet period, the rainwater retention potential of green roof is only about 21%, while in the summer the rainwater retention capacity increases as high as 100%. Plants play an important role in rainwater interception, growing media wetness, rain runoff and the green roof's thermal performance by modifying short- and long-wave radiation and as well as convective heat exchanges. Installation of green roofs on highly insulated roof decks yields a mixed performance in a mild and wet climate. The heat loss through the green roof during the heating months is about 2% higher than a similar roof without green roof. Whereas during the cooling months the green roof is able to reduce the heat gain by 66%. This substantial heat gain reduction can help to reduce overheating problems in highly insulated buildings.

Porous Elastomer Based Wide Range Flexible Pressure Sensor for Autonomous Underwater Vehicles

This work presents the design and implementation of a porous polydimethylsiloxane (PDMS)-based wide-range flexible pressure sensor for autonomous underwater vehicles. The capacitive sensor, with porous PDMS as dielectric, is encapsulated in bulk PDMS polymer. The fabricated sensor was evaluated over a wide pressure range (0-230 kPa), which is similar to pressures experienced up to approx. 23 m below the sea level. The sensors showed linear response when tested in air and near-linear response (98%) when submerged in water. The sensor showed much higher sensitivity (0.375 kPa <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">−1</sup> ) in water than in the air environment. However, the sensor exhibited the performance and sensitivity similar to the air condition (0.005 kPa <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">−1</sup> ) when the readout electronics (encapsulated inside a watertight enclosure) was also submerged inside the water along with the sensor. The fabricated sensor also exhibited fast response and recovery time (190 ms), as well as excellent repeatability and stability (no drift) over tested range of 50 loading and unloading cycles. These results demonstrate the suitability of presented sensors for potential use in applications requiring a wide range of pressure, particularly the underwater robotics where real-time pressure monitoring is critical for autonomous operation.

Increasing the composition range of a novel τ11-Al4Fe1.7Si alloy with additions of Mn

Automotive applications need low-cost, lightweight, high-temperature alloys to increase vehicle efficiency. The Al–Fe–Si system provides an opportunity to develop such a material, as it consists of three low-cost elements that are all abundant in nature. Specifically, the τ11-Al4Fe1.7Si ternary intermetallic phase is a high-temperature, lightweight phase with high strength and good corrosion resistance. However, this phase exhibits a narrow compositional range of stability, resulting in undesirable microstructures forming during solidification and processing, limiting its use in potential applications. Density functional theory (DFT) calculations and a thermodynamically-driven experimental approach utilizing diffusion couples were employed to study the effect of Mn on the stability and composition range of τ11-Al4Fe1.7Si. The DFT calculations showed a decrease in the energy of the structure when alloying with Mn. Experimental results confirmed the predictions from the DFT calculations, indicating that alloying with Mn increases the compositional range, and thus the processability of this phase. New phase diagrams and equilibria are proposed by exploring and determining phase boundaries for the τ11-Al4Fe1.7Si phase with Mn.

Decoupling Technique Using Ferrite-Film Loading for 5G MIMO Applications

Decreasing the mutual coupling between multiple-input-multiple-output (MIMO) antenna elements requires the selection of an appropriate decoupling technique without changing the geometry or operating frequency of the antenna. In this paper, a simple and flexible approach that involves loading a small ferrite film on the radiation patch of an MIMO antenna pair has been proposed to mitigate the unwanted mutual coupling. Through a thorough investigation, the two IFA elements with an element distance of only 1.4 mm can be decoupled adequately by properly controlling the ferrite-film loading area and the thickness of the ferrite film, along with maintaining the desired operating frequencies and acceptable radiation characteristics at the LTE Band 42 (3.4–3.6 GHz). The optimum ferrite-film loading on the grounding branch of the IFA element can increase the isolation from −6.64 dB to −10.43 dB and enhance the bandwidth from 3.20–3.88 GHz to 2.83–3.65 GHz, and its efficiency can reach to 45.5%, as well as a 2 dB gain. A physical model has also been established to interpret the operating mechanism of ferrite-film loading on the IFAs. The proposed simulated procedure is validated via measurements. This technique of ferrite loading on MIMO antennas can effectively decouple the mutual coupling at a low cost and with low design complexity, indicating its potential applicability for use in MIMO antennas in mobile handsets.

Simultaneous doping of sulfur and chloride ions into ZnO nanorods for improved photocatalytic properties towards degradation of methylene blue

In this study, we have successfully doped sulfide (S−2) and chloride (Cl−1) simultaneously into ZnO by hydrothermal method. The structure, morphology, composition, and optical properties of the prepared S–Cl doped ZnO nanostructures were investigated by x-ray diffraction (XRD), scanning electron microscopy (SEM), scanning transmission electron microcopy (STEM), energy dispersive spectroscopy (EDX) and UV–visible (UV–Vis) spectroscopy techniques. After, doping of both S and Cl into ZnO no significant alteration in the nanorod morphology was noticed. The wurtzite crystal structure of ZnO was retained with a red shift in the 2Ɵ towards high angle. The XRD results are supported by the high-resolution transmission electron microscopy. The elemental analysis revealed a successful doping of S and Cl into ZnO structure. Importantly, the optical band gap of ZnO was decreased 2.9 eV upon doping of S and Cl ions. Thus, the nonmetal doping via S and Cl has significantly enhanced the photocatalytic properties of ZnO towards methylene blue (MB) due to high density of active sites and decreased charge recombination rate of electron-hole pairs. The photo-degradation efficiency towards MB reached 99.64% upon using S and Cl doped ZnO photocatalyst using optimum dose of 15 mg and initial dye concentration of 1.87 × 10−6 M. The use of simultaneous nonmetal doping concept could of great importance for the preparation of other nanostructured materials and their use in potential applications like solar cells, and photoelectrochemical water splitting.

Cucurbit[8]uril-Assisted Nucleophilic Reaction: A Unique Supramolecular Approach for Cyanide Detection and Removal from Aqueous Solution.

A unique supramolecular approach of preparing and using a cucurbit[8]uril (Q[8])-based dynamic host-guest assembly for cyanide sensing in and removal from water has been successfully developed. The dicyanovinyl-attached cationic guest (1) was designed as the fluorescent response moiety for the detection of the cyanide anion via a nucleophilic addition reaction in the assist of the Q[8]-based 2:2 quaternary complexes. Furthermore, the reaction of cyanide with 1 further switched the Q[8]-based host-guest assemblies from the 2:2 complexes to the 1:1 supramolecular polymers that precipitate in water. Thus, the macrocyclic-based dynamic host-guest assembly has potential use in applications for solving the problem of toxic anion pollutants present in aqueous environments.

Modulation of the optical properties of soluble N-alkylated 4-pyridyl diketopyrrolopyrrole derivatives

The absorption and fluorescence properties of N-alkylated 3,6-di (pyridin-4-yl)-2,5-dihydropyrrolo [3,4-c]pyrrole-1,4-dione (PyrDPP NH) derivatives in solution and the solid state are reported, along with the modulation of these properties under varying acidity or basicity. The compounds with hexyl (PyrDPP N-Hex) and methoxy ethoxy ethyl (PyrDPP N-MEE) chains were synthesised from PyrDPP NH giving highly soluble dyes. In addition, the mono-substituted derivatives were also isolated. A range of solvents was explored to provide understanding regarding their potential use in applications ranging from organic electronics to sensors. Optically the dyes are highly fluorescent and, as a result of N-alkylation breaking the hydrogen bond network, emissive in the solid state with large Stokes shifts. The nature of the chain dictates the π interactions and packing of the materials, resulting in modulation of the solid-state absorption spectra and theoretical mobility predicted from the crystal structures. The methoxy ethoxy ethyl chain twists out of the plane and bends to allow considerable molecular overlap and small interchromophore displacement with strikingly similar π interactions to the parent PyrDPP NH, resulting in a contribution of H-type aggregation to the absorption band and an order of magnitude improvement in theoretical mobility compared with the hexyl analogue. In contrast, PyrDPP N-Hex possesses a distorted CH-π interaction between pyridyl and lactam units, with greater molecular displacement manifesting in dominant J -aggregation contribution to absorption band and moderate mobility. The results emphasise the potential for sidechain modification and show structural evidence for the potential benefits of the flexible polar chains. The nitrogen lone pair of the pyridyl ring can be protonated in acidic environment to produce a photometric response suggesting potential as a proton sensor. The mono-substituted compounds are responsive to both base and acid, making them interesting for molecular logic applications.

An 8768-year Yamal Tree-ring Chronology as a Tool for Paleoecological Reconstructions

Abstract—In recent years, the supra-long Yamal tree-ring chronology has been significantly extended and became much more reliable. This article characterizes the sample wood used to build the longest absolutely dated Siberian Larch tree-ring chronology of the Subarctic area, i.e. from 6748 BC to 2019 AD, for a total continuous period of 8768 years. The ecological value of the temporal and spatial distribution of the dated trees are presented, and their potential use for application in various field of natural sciences and humanities are discussed.

Triboelectric nanogenerator-based anodic bonding of silicon to glass with an intermediate aluminum layer

The application of anodic bonding with metal or alloy films as the intermediate layer in micro electromechanical systems (MEMS) is becoming more widespread. Simultaneously, the realization of lower bonding voltage and current is an urgent problem to be solved in anodic bonding, cause large voltages and currents can cause damage and failure to tiny devices of MEMS. Sputtering aluminum as an intermediate layer, well-bonded silicon to glass wafers can be obtained with lower bonding current by applying triboelectric nanogenerator (TENG) instead of traditional direct-current (DC) power supply for the first time. Meanwhile, the tensile strength of the bonded wafers with an intermediate aluminum layer is up to 20 MPa, which is comparable with the DC driven bonded strength and is also 50 % higher than that without the aluminum layer. The TENG-based anodic bonding of silicon to glass with an aluminum layer has good bonding quality, which exhibits potential usefulness for application in MEMS packing.

Effect of emulsifiers on the discoloration of chlorophyll and their potential for use in green beverages.

The discoloration of chlorophyll (Chl) by light is an ongoing issue for green beverages in the food industry. To suppress the discoloration of Chl in aqueous solution, the effects of different emulsifiers were investigated on the discoloration of Chl under ultraviolet (UV) irradiation to determine their potential application for use as food additives. Sucrose fatty acid ester (SE), sorbitan fatty acid ester (TW), and quillaja saponin (QS) were used as emulsifiers, while Triton X-100 (TX) was used for reference. The discoloration of Chl was measured using a color difference meter. The species of Chl in solution were determined using ultraviolet-visible (UV-Vis), fluorescence, and circular dichroism (CD) spectroscopy, and the particle size of Chl in solution was determined using dynamic light scattering. The Chl aggregates were observed by the observation of increased peak areas at longer wavelengths in the UV spectra of Chl, in addition to a reduced fluorescence intensity. The CD spectra showed that the Chl aggregates were arranged in a random structure. Furthermore, the average particle size of the Chl aggregates was determined to be approximately 100nm. SE and QS were found to significantly enhance the formation of self-aggregates due to their high hydrophilicities compared to those of TW and TX. As a result, SE and QS protect themselves from light to suppress the discoloration of Chl. The present results therefore suggest that SE and QS are suitable emulsifiers to address the problem of Chl discoloration in beverages, such as green tea and vegetable juices. PRACTICAL APPLICATION: Chlorophyll (Chl), a green pigment present in vegetables and green tea, is discolored by light. In this study, it was found that emulsifiers (sucrose fatty acid ester and quillaja saponin) suppress the discoloration of Chl. The implementation of these emulsifiers as food additives would enable green tea or green vegetable juices to maintain their colors for long periods and could contribute significantly to the beverage industry.

Highly efficient and selective removal of anionic dyes from water using a cellulose nanofibril/chitosan sponge prepared by dehydrothermal treatment

To obtain cost-effective and environmentally friendly adsorbents that can selectively remove anionic dyes from wastewater, a physically cross-linked cellulose nanofibril/chitosan (CNF/CS) sponge was developed by dehydrothermal treatment (DHT). The physicochemical properties of the prepared sponge were determined by various techniques, and its adsorption performance was evaluated using reactive blue 221 (RB) as the model dye. Batch adsorption experiments reveal that the capacity of RB adsorption on the sponge increases up to 778.5 mg/g with increasing temperature. This value is greater than the maximum adsorption capacities of all other non-conventional adsorbents reported in the literature. Based on kinetic and thermodynamic assessments, the RB adsorption process is best described by pseudo-second-order kinetics and the Langmuir model, which suggests that it is actually an endothermic monolayer chemisorption process. The RB removal efficiency reaches 99.64% after five repeated continuous separations and the CNF/CS sponge can be efficiently used in five adsorption-desorption cycles. Overall, the results reported in this study indicate that the novel CNF/CS sponge developed in this study has great potential for use in applications of dye removal from wastewater.

Magnesium Zirconate Titanate Thin Films Used as an NO2 Sensing Layer for Gas Sensor Applications Developed Using a Sol-Gel Method.

Magnesium zirconate titanate (MZT) thin films, used as a sensing layer on Al interdigitated electrodes prepared using a sol–gel spin-coating method, are demonstrated in this study. The p-type MZT/Al/SiO2/Si structure for sensing NO2 is also discussed. The results indicated that the best sensitivity of the gas sensor occurred when it was operating at a temperature ranging from 100 to 150 °C. The detection limit of the sensor was as low as 250 ppb. The sensitivity of the MZT thin film was 8.64% and 34.22% for 0.25 ppm and 5 ppm of NO2 gas molecules at a working temperature of 150 °C, respectively. The gas sensor also exhibited high repeatability and selectivity for NO2. The response values to 250, 500, 1000, 1500, 2000, 2500, and 5000 ppb NO2 at 150 °C were 8.64, 9.52, 12, 16.63, 20.3, 23, and 34.22%, respectively. Additionally, we observed a high sensing linearity in NO2 gas molecules. These results indicate that MZT-based materials have potential applications for use as gas sensors.

&lt;p class="Body"&gt;&lt;strong&gt;Acute toxicity and sublethal effects of metal oxide nanoparticles against the bulb mite&lt;/strong&gt;&lt;/p&gt;

Crocus sativus L. (Iridaceae) known as saffron is the most commercially important medicinal food product in Iran and worldwide because of its significance for exporting commercial. However, the health of this plant is adversely threatened by abiotic and biotic stress. Bulb mite Rhizoglyphus robini Claparede (Acari: Acaridae) as abiotic stress is oligophagous and the main pest of tuber plants, commonly found in all the cultivated saffron producing areas could decrease saffron economic value. The mites tunnel through corms allowing the entry of fungal and bacterial pathogens. The widespread use of commercial pesticides in modern agriculture to protect crops from pests has caused significant public concern because of their side impacts on the environment and non-target species. Nanotechnology has been used in the production, processing, storage, packaging, and transport of agricultural products. Newly, oxide nanoparticles have been introduced as novel pesticides against pests and fertilizer. This study was conducted as an effective and environmentally-friendly method to control the growth of Rhizoglyphus robini. The lethal and sublethal effects of metal oxide nanoparticles (MNPs) including nano copper oxides (nano-CuO), nano magnesium oxide (nano-MgO), nano zinc oxide (nano-ZnO), nano titanium dioxide (nano-TiO2), and nano iron oxide (nano-Fe2O3) which their lethal concentrations ranged between 159.2 and 1036.4 mg L-1 were studied on Rhizoglyphus robini adult females. The contact effect of the tested MNPs was evaluated using the corm dip bioassay method. Assays showed that the contact toxicity of the nano-CuO treatment (229.1 mg L-1) was higher than other MNPs. To assess the sublethal effects of the MNPs, adult females were exposed to the LC25 concentration of MNPs, and life history and life-table parameters of the surviving Rhizoglyphus robini were investigated. The exposure to sublethal concentrations of the tested MNPs prolonged the egg incubation, larval period, and nymphal period significantly when compared to the control mites. Compared to other MNPs or control mite, nano-MgO and nano-TiO2 led to the longest duration of the total immature stages (11.32 and 11.32, respectively). The net reproductive rate (R0), the intrinsic rate of increase (rm), the finite rate of increase (λ), and the generation time (T) were significantly different between control and MNP treatments. The population exposed to ZnO-, MgO-, and TiO2-nanoformulations had a much lower rm value (0.164, 0.164, and 0.171 d-1, respectively) compared to the control population (0.231 d-1) and those exposed to Fe3O4- and CuO-nanoformulations (1.19 and 1.19 d-1, respectively). According to our findings, all tested MNPs, especially CuO-, ZnO-, and MgO-nano formulations, have a potential application for use in the management of Rhizoglyphus robini.

Preparation of a porous bulk copper ferrite spinel with high performance in the electrolysis of water

Copper ferrite spinels (CFOs) show potential application for use in the field of water electrolysis. However, CFOs are prepared using traditional fabrication methods and as a result always exist in powder form, making them difficult to utilise in applications. In this work, a porous bulk CFO material was fabricated via the milling and sintering of metal oxides, which can be used directly as an electrode. This CFO shows excellent oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) activities. The results show that preparing the CFO under an argon (Ar) atmosphere, at high temperature and with a milling pretreatment improves the density of oxygen vacancies (OVs) in the material, thereby enhancing its ability to electrolyse water. The CFO shows high OER and HER performance when sintered at 1000°C under an Ar atmosphere and milled. In 6 M KOH solution at 10 mA cm−2, the OER and HER overpotentials of CFO are as low as 290 and 241 mV, with OER and HER Tafel slopes of 75.5 and 114 mV dec−1. The synthesis route developed in this study is versatile, with the CFO electrode produced exhibiting high performance in water electrolysis.

Multi-wavelength Er–Yb-doped fibre ring laser using a double-pass Mach–Zehnder interferometer with a Sagnac interferometer

In this paper, the performance of a switchable multi-wavelength Er–Yb-doped fibre ring laser incorporating a comb filter is described. The comb filter was developed by using the double-pass Mach–Zehnder interferometer with a Sagnac interferometer (DMZI–SI) arranged in series, a 10-m-long PANDA-type polarisation-maintaining optical fibre, and polarisation controllers (PCs). The laser output can be switched from 1536 to 1548 nm (C-band) via careful adjustment of the PCs. A side-mode separation ratio, greater than 28 dB, was obtained to facilitate stable single-, double-, quadruple-, and quintuple-wavelength emissions, with spectral power and wavelength fluctuations of 0.47–1.06 dB and 0.01–0.06 nm, respectively. The measurements were performed for 60 min at 25 °C. The proposed comb-filter configuration facilitates the double-clad fibre ring laser to realise switchable multi-wavelength emission. Experimental results reveal that the proposed laser demonstrates high stability and significantly improved performance compared to the existing DMZI–SI filter-based systems. This indicates their potential for use in applications involving optical sensing, communication systems, and microwave generation.

Facile in situ growth of ZIF-8 films onto aluminum for applications requiring fast thermal response

In this work, we report a simple approach for the synthesis of highly crystalline films of ZIF-8 directly grown onto non-functionalized common aluminum substrates through an easy, short in situ solvothermal methodology. Through several techniques such as XRD, SEM, EDS, AFM and XPS, it is shown that a simple, short pretreatment of the substrate with a dilute hydrochloric acid solution promotes the subsequent solvothermal nucleation and growth of continuous, homogeneous micrometer thickness and very adherent ZIF-8 films. The robustness and usefulness of ZIF-8/aluminum are shown by testing it in the highly exothermic catalytic reaction of carbon monoxide oxidation, in which it presented a high performance and durability, preserving the metal–organic framework integrity during reaction time. This behavior demonstrates that the novel ZIF-8/aluminum systems have a high potential for use in applications at moderate temperatures demanding a fast heat exchange rate between the metal–organic framework (MOF) film and the substrate.

Heat Storage of Paraffin-Based Composite Phase Change Materials and Their Temperature Regulation of Underground Power Cable Systems.

Excessive heat accumulation in backfill materials causes thermal fatigue damage in underground power cable systems that significantly affects the cable carrying capacity. To improve the thermal conditions of the system, two types of composite phase change materials (CPCMs) were prepared by incorporating paraffin into porous ceramsite (CS)/expanded graphite (EG) in this study. EG and CS can carry 90 and 40 wt.% paraffin, respectively. The phase change temperature of paraffin/CS and paraffin/EG CPCMs was approximately 65 °C, and the corresponding latent heats were 63.38 J/g and 156.4 J/g, respectively. Furthermore, the temperature regulation by CPCMs was evaluated experimentally by designing a setup to simulate the underground power cable system. The reduction in the maximum temperature of the backfill materials with paraffin/CS CPCM and paraffin/EG CPCM was approximately 7.1 °C and 17.1 °C, respectively, compared to reference samples. A similar conclusion was drawn from the heat flux curves. Therefore, the prepared CPCMs could significantly alleviate temperature fluctuations, where the paraffin/EG CPCM provided better temperature regulation than paraffin/CS CPCM. Both materials have potential applications for use in backfill materials for underground power cable systems.