Inorganic Salt Hydrates Research Articles

Preparation of Thermal Controlled Deoxygenation Inhibitor and Its Inhibition of Coal Spontaneous Combustion

ABSTRACT The purpose of this study was to prepare a new type of thermal controlled deoxygenation inhibitor successfully. By adding a particular inorganic salt hydrate, this new deoxidizing inhibitor effectively slows down the oxidative-exothermic reaction that may occur during the action of the original deoxidizing inhibitor, improving the efficiency of preventing coal from spontaneous combustion. The heat shielding approach was employed, using the inorganic salt hydrate’s high heat capacity to absorb and decelerate heat transport during the phase change process. To assess the heat shielding effect of inorganic salt hydrates like Na2CO3·10 H2O, MgSO4·7 H2O, Na2SO4·10 H2O, MgCl2·6 H2O, and CaCl2·6 H2O, we conducted tests using thermogravimetric analysis (TG) and differential scanning calorimetry (DSC). With a heat shielding effect of 171.2 J/g, which is much superior to that of other hydrates, the testing results demonstrate that Na2CO3·10 H2O has the best thermal control performance. In addition, we verified the effective inhibition of coal spontaneous combustion by the thermal controlled deoxygenation inhibitor, especially under the condition of increasing temperature, and the blocking effect of the inhibitor was enhanced with the increase of temperature. The findings of this study provide a new strategy for spontaneous combustion prevention during coal mining and storage and provide a scientific basis for further industrial application and optimization.

Evolving Thermal Energy Storage Using Hybrid Nanoparticle: An Experimental Investigation on Salt Hydrate Phase Change Materials for Greener Future

Thermal energy storage (TES) assisted with phase change materials (PCM)s seeks greater attention to bridge the gap between energy demand and supply. PCM has its footprint toward efficient storage of solar energy. Inorganic salt hydrate PCMs are propitious over organic PCMs in terms of energy storage ability, thermal conductivity, and fireproof, however the major issue of supercooling and poor optical absorbance remains. This research investigates commercialized inorganic salt hydrate PCM with phase transition temperature of 50 °C, thermal conductivity of 0.593 W m−1 K which is favoured with melting enthalpy of 190 J g−1, and 2–3 °C of supercooling. Mixture of graphene: silver at a proportion of (1:1) is used as the hybrid nanomaterial to further enhance the thermal conductivity, optical absorbance, and thermal stability. Hybrid nanocomposites are developed via two‐step process involving direct mixing and ultrasonication. Morphological behaviour, chemical stability, optical property, thermal property, thermal reliability, and stability of the developed nanocomposite samples are experimentally analysed. As a result, sustainable TES materials with thermal conductivity of 0.937 W m−1 K, optical absorbance of 0.8, increased energy storage potential is formulated. Subsequently a numerical simulation is conducted to illustrate the potential of the developed nanocomposite in transfer of heat energy.

Experimental investigation on nucleating agent for low temperature binary eutectic salt hydrate phase change material

The melting enthalpy and melting temperature have a significant impact on the latent heat that results from phase change materials (PCMs) used for thermal energy storage. Among the PCMs that are currently on the market, inorganic salt hydrates have greater thermal conductivity and latent heat than organic PCMs. However, the problem of salt hydrates' degree of supercooling limits their use in energy storage devices. Using sodium carbonate decahydrate (SCD) and sodium phosphate dibasic dodecahydrate (SPDD), a low temperature inorganic-inorganic eutectic salt hydrate PCM with a higher melting enthalpy and intended phase transition temperature is developed in this research study. The eutectic SCD/SPDD salt hydrate PCM eutectic point and the eutectic composition of salt hydrate PCMs to operate at low temperature range is numerically determined using Schrader equation. By numerical methods we obtain the 68 wt% of SCD with 32 wt% of SPDD to exhibit eutectic SCD/SPDD composite with eutectic melting temperature of 26.2 °C and melting enthalpy of 210.6 J/g. The synthesised eutectic PCM are characterised to explore their chemical stability, latent heat, melting point and their shortcoming due to degree of supercooling. A good way to get around the problem of the supercooling degree is to disperse the nucleating agents. In order to assess the type and degree of supercooling, the produced eutectic PCM composition is experimentally evaluated at 1–10% utilising borax, alumina, and sodium sulphate dodecahydrate as nucleating agents. However, for building cooling applications PCM with minimal degree of supercooling, with the ability to release low enthalpy during discharging is an advantage.

Energizing eutectic salt hydrate phase change material using 2D carbon based graphene nanoparticle

Energy being the strongly depended source for development and industrialization, their storage in any form tends to bridge the gap between demand and supply. Renewable energy technology systems now include energy storage as a crucial component. Thermal energy storage is a technique that stores thermal energy by heating or cooling a storage medium. This allows the energy to be used for heating and cooling purposes later on. The present study develops ternary inorganic salt hydrate eutectic phase change material (EPCM) that is intended for cooling buildings. Melting temperature, melting enthalpy and eutectic composition proportion of inorganic salt hydrate of sodium carbonate decahydrate (SCD), sodium phosphate dibasic dodecahydrate (SPDD), and sodium sulphate decahydrate (SSD) are determined using the eutectic melting point theory. Ternary EPCM is synthesised experimentally in accordance with the percentage of salt hydrates. Graphene nanoplatelets are distributed at different weight concentrations of 0.3%, 0.6%, and 0.9% in order to further improve the thermal performance; at higher concentration above 0.9% the graphene nanoplatelets tends to agglomerate. In order to assess the chemical stability and thermal properties of prepared nanoparticle dispersed PCMs, are experimentally assessed. Findings confirm the ternary EPCM's chemical stability and raise its latent heat with graphene nanoplatelets.

Hybrid Polymer Salogels for Reversible Entrapment of Salt-Hydrate-Based Thermal Energy Storage Materials.

One of the challenges preventing wide use of inorganic salt hydrate phase change materials (PCMs) is their low viscosity above their melting point, leading to leakage, phase segregation, and separation from heat exchanger surfaces in thermal management applications. The development of a broad strategy for using polymers that provide tunable, temperature-reversible shape stabilization of a variety of salt hydrates by using the lowest possible polymer concentrations is hindered by differences in solubility and gelation behavior of polymers with change in the type of ion. This work addressed the challenge of creating robust, temperature-responsive shape-stabilizing polymer gels (i.e., salogels) using a low cost PCM, calcium chloride hexahydrate (CaCl2·6H2O, CCH). Due to the extremely high (9 M) concentration of chloride ions and the tendency to salting-out polymer chains, the previous strategy of using single-polymer salogels was not successful. Thus, this work introduced a strategy of using two polymers, poly(vinyl alcohol) and ultrahigh molecular weight polyacrylamide (PVA and PAAm, respectively), along with borax as a cross-linker to achieve temperature-reversible, shape-stable salogels. This system resulted in robust salogels whose gel-to-sol transition temperature (Tgel) was tunable within an application-relevant range of gelation temperature (30-80 °C). This behavior was enabled by a synergistic combination of dynamic covalent cross-links between PVA units and entanglements of PAAm chains which were combined into a single hybrid network. The hybrid salogels had <5 wt % polymer content, maintaining ∼95% of the heat of fusion of the pure PCM. Importantly, the noncovalent nature of gelation supported thermo-reversibility of gelation, shape stability, and retention of thermal properties over 50 melting/crystallization cycles.

Optical performance and chemical stability evaluation of new era phase change material: Activated by hybrid nanoparticle

Inorganic salt hydrate phase change materials (PCMs) are ahead of organic PCMs in terms of energy storage ability and safety as they are non-flammable. However the major hindrance with inorganic PCM are degree of supercooling and low thermal conductivity though better than organic PCM. The common technique to enhance the thermal conductivity is via dispersion of metal and carbon nanoparticle. Though they enhance the thermal conductivity of the nanocomposite, with continuous operation the nanoparticle agglomerate and settles down owing to their density. Henceforth, in the current research work we conduct an experimental investigation to enhance the optical and thermal performance of commercialised inorganic salt hydrate PCM using metal-carbon hybrid nanoparticle. We disperse graphene silver nanoparticle at different weight ratio adopting a two-step method followed by probe sonication to ensure uniform dispersion. We achieve a highly stable nanocomposite with 584% increase in optical absorbance of electromagnetic waves and 86% decrease in transmittance. Thermal management of electronic gadgets has evolved to be a major consideration of research as overuse of gadgets lead to rapid temperature rise and is in need of passive cooling system. Henceforth the newly developed nanocomposite phase change materials (PCMs) not only acts as thermal batteries but can also be opted as energy materials for thermal regulation and heat mitigation.

Expanded graphite intersperse reliable binary eutectic phase change material for low temperature thermal regulation systems

Inorganic phase change materials (PCMs) frequently stuck by ineffaceable thermal conductivity and degree of supercooling for thermal energy storage (TES) accomplishment. The present research work is dedicated to resolve this problem by developing a unique inorganic salt hydrate based binary eutectic PCM employing sodium sulphate decahydrate (SSD) and sodium phosphate dibasic dodecahydrate (SPDD) in eutectic mixture ratio 62:38 mass percentage. The peculiar eutectic composition of SSD/SPDD developed with melting and bath sonication technique manifests eutectic latent heat of 207.4 J/g and eutectic melting point of 27.8 °C. Furthermore, to elevate thermal performance and to descent degree of supercooling three dimension expanded graphite (EG) is interspersed as nanoparticle. Optical absorbance of composite PCM elevated from 0.16 for SSD/SPDD to 0.92 with SSD/SPDD + EG nanoparticles; inversely transmissibility of the composite reduced by 82.13 %. Heat flow curves ensures the melting temperature (26.9 °C–28.7 °C) of EG dispersed composite to be within the operating condition with latent heat of 220.4 J/g at 2.0 % of EG owing to the intermolecular binding force of attraction increases as nano-sized sheets effectively disperse with the base PCM. Subsequently, thermal conductance of nano composite eutectic PCM upraised from 0.453 to 0.855 W/m⋅K. After 200 thermal cycle's chemical optical and thermal stability of the PCM composite was degraded insubstantially due to the presence of impurities with longer service; this affirmed the stability thermal perks of nanocomposite PCM. Numerical analysis on heat transfer propagation of heat source within SSD/SPDD PCM layer with and without EG nanoparticle provides inference on the importance of thermal conductivity.

Experimental evaluation of binary and ternary eutectic phase change material for sustainable thermal energy storage

Phase change materials (PCMs) are the active source for storing thermal energy in the form of latent heat. Inorganic salt hydrate based PCMs are regarded as high energy storage materials with high thermal conductivity and low flammability compared to organic PCM, whereas the major hindrances are supercooling and corrosivity which reduces service life. This encourages examining and developing new forms for inorganic-inorganic eutectic PCM with a focus on melting point and enthalpy. In this article we design, develop, and characterize, low temperature inorganic salt hydrate eutectic PCMs, using calcium chloride hexahydrate, sodium carbonate decahydrate, sodium sulphate decahydrate and sodium phosphate dibasic dodecahydrate. Schrader equations along with the thermophysical property of salt hydrates were adopted to determine eutectic phase transition temperature and eutectic mixtures proportions. Twenty-one different combination of PCMs mixture were numerically evaluated, out of which seven eutectic mixtures with a melting temperature between 21 and 28 °C (four binary and three ternary), were experimentally synthesised and characterized. Melting point, heating enthalpy, specific heat capacity and degree of supercooling of the pure salt hydrates and their eutectic mixtures were analysed using differential scanning calorimeter. The melting enthalpy of eutectic PCMs, were 200–215 J/g; furthermore, the degree of supercooling reduces by 10–13 °C for eutectic PCMs when compared to pure PCMs. The numerical values were supplemented with experimental results and ensured the suitability of the developed eutectic PCM for low temperature energy storage application with a focus towards building cooling.

Sodium acetate trihydrate/melamine foam composite PCM encapsulated by CuS/rGO modified epoxy resin and endowed with light-to-heat conversion properties

In this work, we proposed a novel strategy for the conversion and storage of photothermal energy. This strategy combined hydrothermally prepared CuS/rGO with commercial epoxy resin adhesives. The light-capturing capability of CuS and fast electron transfer rate of rGO was harnessed to endow the modified resin with photothermal conversion capability. Using an inorganic PCM as the energy-storage medium and melamine foam as its support carrier, a form-stabilized composite phase-change material with a latent heat of phase change of 233.7 J/g and a phase-change temperature of 48.7 °C was obtained. In addition, the pre-prepared MER was coated onto the surface of the CPCM. Its purpose was to utilize the photothermal conversion and waterproof properties of modified resins to store solar energy in the internal phase-change materials, while alleviating the leakage problem during the phase-change process of inorganic salt hydrate phase-change materials in the past. The leakage tests showed that the 1.0 mm thick MER provided excellent protection against leakage, significantly reducing leakage of the liquid phase and moisture escape. The composite phase-change material CPCM/MER demonstrated satisfactory results in photothermal conversion experiments. 2% CuS/rGO addition to CPCM/MER can complete the phase change. The samples also showed good stability in the cycling tests. After 100 cycles of testing, the latent heat of the CPCM only decreased by 5.13%. According to the FT-IR results, the CPCM also possessed chemical stability. In this study, a CPCM/MER was successfully prepared, extending the practical application of traditional inorganic phase-change materials in the field of solar energy storage.

Evaluating the effect of magnesium oxide nanoparticles on the thermal energy storage characteristics of the inorganic PCM

Thermal storage with phase changing materials (PCM) has got the attention of the researchers in recent days. Among the PCMs, inorganic salt hydrates are having high potential to act as thermal storing medium due to their large latent content. However, they lack large-degree supercooling and have issues with phase segregation. In the present study, the thermal characteristics of sodium acetate trihydrate (SAT) have been studied under the influence of different weight fractions (0.0%, 0.25%, 0.5%, 0.75%, and 1.0%) of MgO nanoparticles (nano-MgO). Carboxymethyl cellulose (CMC) has been used as the thickener, and nano-MgO has been tested as the nucleating medium. The results demonstrated that the use of 0.75% nano-MgO with SAT is suggested as the best composition to augment the thermal characteristics of SAT PCM. With 0.75% nano-MgO, the supercooling of the SAT was reduced to 0.32 °C, and the thermal conductivity of the SAT was enhanced by 40.94%. Nonetheless, the latent heat of the SAT PCM had not been significantly affected by the addition of nano-MgO until its fraction of 0.75%.

Selective Fragmentation of Lignocellulosic Biomass with ZnCl2·4H2O Using a Dissolution/Precipitation Method

Lignocellulosic biomass dissolution in an inorganic salt hydrate (ZnCl2·4H2O) and its subsequent precipitation with water for the separation of its main compounds were investigated. For this purpose, different dissolution times and temperatures were studied, where 24 h and 70 °C were found to be the optimal choice. Three solids were obtained, which were analyzed and identified by XRD, SEM, NMR, and FTIR spectroscopy. Solid I is the undissolved part of the starting material, and it consists of lignin, which does not react with the inorganic salt hydrate and the unreacted cellulose. Solid II is a cellulose-rich solid with a low portion of hemicellulose and lignin, and Solid III is mainly pure lignin as the characterization results showed. Hemicellulose is mainly dissolved and hydrolyzed in the dissolution treatment and the amount present in all solids was very small. The reactivity of Solid I and Solid II in a hydrolysis reaction was tested (0.2 M/L H2SO4, 5 h, and 140 °C), where a significant improvement in the conversion and the yield of sugars was obtained with respect to the untreated samples in both cases. Solid II yields a large amount of total reducing sugars, with a % selectivity of 78–88%, depending on the starting biomass.

Experimental Investigation of Graphene Nanoplatelets Enhanced Low Temperature Ternary Eutectic Salt Hydrate Phase Change Material

A sustainable approach to ensuring the thermal regulation of space is reliable with phase change materials (PCMs) operating at 15–25 °C. Henceforth, there is a need of a search of binary and ternary eutectic PCMs operating at desirable phase transition temperatures of 15–25 °C, high energy storage enthalpy (180–220 J/g), improved thermal conductivity and better absorptivity of solar energy. In this current research, we developed a ternary eutectic inorganic salt hydrate PCM intended for a low-temperature thermal regulation system. Based on the eutectic melting point theory, the phase transition temperature and proportion of sodium carbonate decahydrate (SCD), sodium phosphate dibasic dodecahydrate (SPDD) and sodium sulphate decahydrate (SSD) were determined. As per the calculated proportion, ternary eutectic PCM was experimentally prepared. Furthermore, to enhance the thermal property, graphene nanoplatelets (GNP) were dispersed at weight concentrations of 0.4%, 0.7% and 1.0%. The prepared nanoparticle-dispersed PCMs were characterized using an optical microscope, Fourier transform infrared (FT-IR) spectroscopy and a thermal conductivity meter, and a differential scanning calorimeter (DSC) was used to evaluate the morphology, chemical stability and thermal properties. The results showed increases in thermal conductivity and optical absorbance by 71.5% and 106.5%, respectively, with GNP at 1.0% weight concentration. Similarly, the degree of supercooling and transmissibility was reduced by 43.5% and 76.2% correspondingly. The prepared composite PCM is expected to contribute towards cooling, with an intention to contribute towards sustainable development.

The Potential Environmental and Social Influence of the Inorganic Salt Hydrates Used as a Phase Change Material for Thermal Energy Storage in Solar Installations.

The aim of this article is to assess the potential impact of inorganic salt hydrates used as PCM material in solar installations on the environment and human health and to assess the society's approach to this technology. The properties of salt are discussed in two ways: first, by analyzing the environmental and health problems caused by chemical hazards on the basis of the available material safety data sheets. Secondly, by analyzing the potential disadvantages of salt hydrates in terms of environmental hazards based on the results of experimental studies available in the literature. Then, using questionnaires, the public approach to solar installations with a built-in converter containing salt hydrates is assessed. Disodium hydrogen phosphate dodecahydrate turned out to be the most prospective salt in terms of environmental, thermophysical, and economic properties for use in solar installations. Understanding the attitudes of the local community toward technologies using inorganic salt hydrates will enable appropriate action to be taken in the future to promote their development. Surveys have shown great public concern about their impact on the environment and human health. In this regard, it is necessary to implement information and promotion activities.

INORGANIC SALT HYDRATES AS PHASE CHANGE MATERIALS (PCM) FOR THERMAL ENERGY STORAGE IN SOLAR INSTALLATIONS

The authors present a general idea of using inorganic salt hydrates in solar installations. A key role in this selection is played by thermophysical parameters, so the authors review their test methods and in turn characterize them for the most promising salt hydrates. Next, the authors describe the advantages and disadvantages of inorganic salt hydrates and indicate possibilities for their improvement. The use of salt hydrate converters in PV installations significantly improves the efficiency of photovoltaic modules. We show that at least 18 salt hydrates are promising for solar applications with the best ones being Sodium Hydrogen Phosphate Dodecahydrate, Sodium Carbonate Decahydrate and Calcium Chloride Hexahydrate. The selection of a test method for determining the thermophysical parameters of salt hydrates should be individual depending on the research objective. Comparing the methods presented, we believe that it is the DSC and DTA methods that provide the most accurate and repeatable results.

Mitigation of lithium-ion battery thermal runaway and inhibition of thermal runaway propagation using inorganic salt hydrate with integrated latent heat and thermochemical storage

Thermal runaway and its propagation in lithium-ion batteries is a severe problem that can result in fire or explosion. In this study, we propose an innovative thermal storage material that integrates latent heat and thermochemical storage to protect the battery during thermal runaway. Sodium acetate trihydrate-urea/expanded graphite—an inorganic salt hydrate—undergoes a solid-liquid phase change at 50.3 °C, with a corresponding latent heat storage density of 181 kJ/kg, and thermal decomposition at 114.0 °C, with a corresponding thermochemical storage density of 567.3 kJ/kg. The latent heat storage density ensures that the battery remains cool during minor accidents, such as an external short circuit, and the dual-stage thermal storage effectively suppresses thermal runaway propagation due to severe accidents involving the thermal or mechanical abuse of the battery. We also establish a mathematical model to describe the multistage latent heat and thermochemical storage processes and predict their impacts on battery temperature. The numerical results were in good agreement with the experimental data, with a maximum error of less than 5%. Compared to conventional phase change materials, the thermochemical storage of the inorganic salt hydrate provides a high thermal storage density at a safe temperature. Thus, the proposed thermal storage material can effectively prevent the incidence and propagation of battery thermal runaway.

Effect of surfactant on functionalized multi-walled carbon nano tubes enhanced salt hydrate phase change material

Phase change materials (PCMs) are effective thermal energy storage materials; however, their low thermal conductivity nature tends to affect heat storage performance. Salt hydrate being inexpensive, incombustible and ensuring high phase change enthalpy, are highly attractive for energy storage. The potential of multi-walled carbon nanotubes (MWCNTs) in improving the thermophysical properties of salt hydrate PCMs makes it a hotspot of current research. Therefore, in this research article, MWCNTs and functionalized multi-walled carbon nanotubes (FMWCNTs) nanoparticles were dispersed with inorganic salt hydrate at different concentrations (0.3, 0.5, and 1.0 wt%), in the presence and absence of surfactant. The role of surfactant with salt hydrate PCM has been discussed extensively. The results obtained have ensured an enhancement in melting enthalpy of prepared composites by 4.92 %, and 28.5 % for 0.5 wt% MWCNT dispersed PCM (SHM0.5), and 0.5 wt% FMWCNT dispersed PCM (SHF0.5), respectively. Furthermore, the maximum thermal conductivity was enhanced by 50.0 % and 84.78 % for 0.5 wt% MWCNT dispersed PCM with surfactant (SHMS0.5), and SHF0.5 respectively, compared to salt hydrate PCM. From the improvement in thermal conductivity, light absorptance, thermal stability, latent heat, and chemical stability, it is evident that the prepared nanocomposite is a potential candidate for solar thermal energy storage applications.

Organic Salt Hydrate as a Novel Paradigm for Thermal Energy Storage

The use of inorganic salt hydrates for thermochemical energy storage (TCS) applications is widely investigated. One of the drawbacks that researchers face when studying this class of materials is their tendency to undergo deliquescence phenomena. We here proposed and investigated, for the first time, the possibility of using organic salt hydrates as a paradigm for novel TCS materials with low water solubility, that is, more resistance to deliquescence, a tendency to coordinate a high number of water molecules and stability under operating conditions. The organic model compound chosen in this study was calcium; 7-[[2-(2-amino-1,3-thiazol-4-yl)-2-methoxyiminoacetyl]amino]-3-[(2-methyl-5,6-dioxo-1H-1,2,4-triazin-3-yl)sulfanylmethyl]-8-oxo-5-thia-1-azabicyclo[4.2.0]oct-2-ene-2-carboxylate, known as calcium ceftriaxone, hereafter named CaHS (calcium hydrated salt), a water-insoluble organic salt, which can combine up to seven water molecules. The CaHS was prepared by precipitation from the water-soluble disodium triaxone. The thermal behavior of CaHS, in terms of stability and dehydration–hydration cyclability, was assessed. The material can operate in the temperature range of 30–150 °C, suitable for TCS. No deliquescence phenomena occurred upon exposure to a relative humidity (RH) between 10 and 100%. Its heat storage capacity, so far unknown, was measured to be ~595.2 kJ/kg (or ~278.6 kWh/m3). The observed heat storage capacity, thermal stability, and good reversibility after dehydration–hydration cycles highlight the potential of this class of materials, thus opening new research paths for the development and investigation of innovative organic salt hydrates.

Effect of expanded graphite on the thermal conductivity of sodium sulfate decahydrate (Na2SO4·10H2O) phase change composites

Inorganic salt hydrate phase change materials (PCMs) are of interest for near-room temperature thermal energy storage (TES) systems, but their low thermal conductivity, ~ 0.5 W/m-K, limits their performance. In this work, we report the thermal conductivity and bulk density of composites containing sodium sulfate decahydrate (SSD) Na2SO4·10H2O with three types of graphite: expanded graphite (EG), milled EG (MG), and graphite nanoplatelets (GnP). The effect of these thermophysical properties on TES performance is presented. The composites were made using a readily scalable one-pot synthesis procedure with graphite received as-is. A 583% increase in thermal conductivity (4.1 W/m-K) was achieved with 25 wt% EG. However, as EG fraction increases, bulk density decreases and thermal conductivity plateaus. This ultimately resulted in lower thermal performance at higher EG fractions despite higher thermal conductivity. This highlights the tradeoff between PCM composite properties and performance, and why thermal conductivity is insufficient to describe PCM thermal performance. GnP is added to EG-SSD to increase bulk density and energy storage density, but these density improvements do not offset lower thermal conductivity and thus thermal performance declined. Similarly, MG-SSD composites had a higher bulk density and energy storage density, but lower thermal conductivity and thermal performance than EG-SSD composites at similar compositions. Atomistic molecular dynamics simulations were performed to understand the structure-property relationship of graphite-SSD interfaces. The simulations support the hypothesis that atomic level contact resistance between graphite and SSD increases thermal resistance at the interfaces resulting in effectively lower bulk thermal conductivity in MG-SSD compared to EG-SSD.

Cellulose pretreatment with inorganic salt hydrate: Dissolution, regeneration, structure and morphology

The special molecular structure and properties of cellulose restrict its resource utilization. In this work, two kinds of common inorganic salt hydrates (ZnBr2·RH2O and FeCl3·RH2O) were used to pretreat microcrystalline cellulose (MCC) by magnetic stirring method at temperatures below 80 °C. It was found that while high temperatures could shorten the dissolution time of MCC, while inorganic salt hydrates with either low water (ZnBr2·3.5H2O and FeCl3·5H2O) or high water (ZnBr2·5H2O and FeCl3·8H2O) content can prolong the dissolution time of MCC. The reactivity of regenerated cellulose (RC) after dissolution was evaluated by enzyme hydrolysis reaction. Moreover, ZnBr2·4H2O and FeCl3·6H2O have better pretreatment effect. The structure and surface morphology of MCC before and after pretreatment were investigated by XRD, FT-IR, SEM, AFM and TGA. The MCC was converted from cellulose Ⅰ to cellulose II through the pretreatment. With the extension of dissolution time, the strength of hydrogen bond and thermal stability of RC were both slightly weakened, Moreover, the crystallinity and degree of polymerization (DP) of RC decreased, and the surface morphology of RC was more rougher, more uneven and dispersed compared with the smooth and compact MCC. The adsorption rate curves showed that RC-ZnBr2·4H2O was more conducive to the adsorption of cellulase, thereby accelerating the rate of RC hydrolysis. Furthermore, ZnBr2·4H2O is a well reusable pretreatment solvent that can maintain a good pretreatment effect on cellulose after five cycles.

Experimental investigation of the simultaneous effect of using phase change material/plate-fin heat sink on thermal performance of a power supply unit

In this paper, a thermal management system of a personal computer power supply unit (PSU) is experimentally investigated. The simultaneous use of a passive cooling system such as PCM with a fan that is an active cooling system can improve performance and increase the lifetime of the PSU. Three cases with different volume fractions of fins have been fabricated. To investigate the effect of the fan on the thermal performance of the PSU, the experiments carried out at a minimum and maximum fan speed. The chosen PCM for this study, CaCl2.6H2O , is an inorganic salt-hydrate. According to the different operating conditions of the PSU, the input heat fluxes to the heat sink are variable. The results show that with simultaneous of fan/PCM, the average reduction in the steady temperature of the PSU circuit at the minimum and the maximum fan speeds are 12.8 (°C) and 12.4 (°C), respectively. The results indicate that increasing the number of fins does not have a favorable effect on the thermal performance of the PSU. On the other hand, using of a passive cooling system like PCM can be effective in reduction the dimensions and energy consumption of the fan.