Melting Temperature Range Research Articles

Effect of scanning speed on laser joining of carbon fiber reinforced PEEK to titanium alloy

Laser lap joining of carbon fiber reinforced plastics (CFRP) to titanium (Ti) alloy using various scanning speed was performed and the influence of scanning speed on joining process was investigated. The high speed camera was adopted to visualize the joining process and defects. The tensile-shear force was tested and the fracture surface was observed by optical microscope. Besides, the numerical simulation of temperature field was conducted to reveal the joining mechanism. The results indicated that fewer defects on titanium alloy surface and less bubbles inside CFRP were obtained with the experimental condition of higher scanning speed. Both mechanical interlocking and chemical bonding occurred at the interface. The compound layer was generated and was confirmed as CTi0.42V1.58 phase because of the carburization of titanium alloy. The thickness of compound layer increased with the decrease of scanning speed. Tensile-shear force first increased and then decreased as the travelling speed increased. When the travelling speed was 0.8 m/min, maximum tensile-shear force of 1024 N was obtained. The bonding width of the resin, and bonding ratio of the mixture of carbon fibers and resin also reached the maximum value at this experimental condition. This behavior was verified by results of temperature field simulation that the melting temperature range of CFRP first increased and then declined as the scanning speed increased. The fluctuation of the tensile-shear force of the CFRP/Ti joint was also explained by the developed simulation model.

Carbamoylethyl locust bean gum: Synthesis, characterization and evaluation of its film forming potential

The synthesis of carbamoylethyl locust bean gum (CLBG) was optimized using Plackett-Burman design. The generated model showed high significance (p < 0.05) to all the response variables which justifies the authenticity of the designed model. The optimal conditions i.e. acrylamide (5.12 mM), sodium hydroxide (3.00 mM), reaction temperature (50.97 °C) and reaction time (2.00 h) supported maximum -CONH2 content (5.44%), –COOH content (3.04%), degree of substitution (0.85) and product yield (7.25%, w/w). Carbamoylethylation of locust bean gum (LBG) involved substitution of its hydroxyl (-OH) moieties with amide group (-CH2CH2CONH2). FTIR and NMR spectroscopy confirmed the addition of amide group to CLBG. Scanning electron microscopy assured the slight rough surface of CLBG particles. Differential scanning calorimetry showed that carbamoylethylation of LBG lowered its melting temperature range (205.60–272.45 °C). However, the amorphous nature, non-Newtonian flow and shear-thinning behaviour of pure LBG were retained in CLBG. Further, CLBG films prepared with glycerol (1%, w/w, plasticizer) showed partially smooth surface and have clear transversal cross-sections. CLBG-glycerol films were highly water resistant and almost transparent. Further, CLBG-glycerol films showed good tensile strength (18.55 ± 0.02 MPa) and higher percentage elongation (6.11 ± 0.01%). Water vapor transmission rate of CLBG-glycerol film was quite lower (0.211 ± 0.001 g.mm/h.m2.kPa) which verified its higher resistance towards water.

ZnCl2 salt facilitated preparation of FeNC: Enhancing the content of active species and their exposure for highly-efficient oxygen reduction reaction

Introducing catalytically-active Fe and N into carbon materials results in promising FeNC catalysts for oxygen reduction reaction. However, the doped Fe and N species are frequently subject to heavy loss in a traditional carbonization process owing to Fe agglomeration and evaporation of N-contained small molecules. Besides, pyrolysis may make materials sintering which embeds a large number of active sites in the bulk phase and impedes direct exposure of reactive centers to the reactants. We here report that when calcinations, the addition of ZnCl 2 , an ordinary salt with very wide melting temperature range well covering the carbonization process of the precursor iron porphyrin, can significantly enhance the doping level of the active species and simultaneously create highly porous structures for FeNC catalysts. The obtained FeNC demonstrates ultrahigh catalytic activities even significantly better than Pt/C in oxygen reduction reaction. ZnCl 2 facilitated calcination functionalizes well in boosting the doping content of highly active species and constructing porous microstructures for FeNC catalysts.

Heat transfer study of phase change material incorporated into a cavity of a hollow brick during melting

The use of Phase Change Materials (PCMs) in the building sector is an attractive solution contributing to the reduction of energy consumption as well as the improvement of the thermal comfort. To achieve this objective, it is required to study the complex phenomena of phase changes when PCM incorporated in different types of building materials. In this study, PCM is incorporating in a cavity of hollow brick and check the effect of natural convection during melting process by compared between two cases, the first the case when there is only a pure conduction and for the second case is when natural convection is not neglected in the upper part of this cavity. For the numerical model, the finite element method is using with modification in the specific heat of PCM accounting for the increase amount of energy, in the form of latent heat, needed to melt the PCM over its melting temperature range. The result showed that the effect of natural convection is limited and can represented by using un equivalent thermal conductivity.

In Ukrainian

There were highly-filled composites, based on (polypropylene) PP and containing 5 – 50 % mass. of calcite concentrate (CC), consisting in highly-dispersed calite powder, modified with organic compounds. It is established, that value for organic part content in CC was 24 % mass. CC and highly-flowing PP was used for process of concentrate granulation process. It is shown, that, when at increase of CC’s contents values, those ones of viscosity for compositions melts decreases simultaneously, dissonating with traditional laws for polymer melt flows, when those are intrisically and typically increasing. It is established, that melt flow index values, when at increase of CC contents for those ones, increasing also – from 3.1 g/10 min for pure PP, to 6,6 g/10 min for composition of 50 % mass. CC. It is discovered, that CC is having influence on melt and crystallization processes of PP. When at low (5 % mass.) and middle (10 – 20 % mass.) of CC contents values, there are meling and crystallization temperatures increasing – from 168 °C to 169 – 170 °C and from 115 °C to 117 – 118 °C, accordingly, and melting temperature range is narrowing – from 42 °C pure PP) to 38 – 34 °C, for composites of CC contents values of 30 – 50 % mass., accordingly, and crystallization temperature range – from 18 °C (pure PP, 0 % CC), to 16 – 15 °C, for composites of high CC contents values, accordingly also. There are increasing of phase transitions temperatures exists, pointing on formation of more large and perfect crystallites, however, narrowing in those ones range points on creation of more dimensionally uniform such of supermolecular structures. Such influence for CC on rheological behavior and temperature characteristics of phase transitons phenomena links with plastyfying effect of modifier‘s chains on CC surfaces of particles, and, simultaneously, at presence of highly-flowing PP as base polymer in. CC injection making some decrease here, namely for activation energy values for oxidative thermodestruction, this phenomen is expaining with more decrease of bounding degree in system, causing with presence of modifier additions in system, and one have influence on.

Influence of defocus distance on laser joining of CFRP to titanium alloy

Laser joining of carbon fiber reinforced polyether ether ketone (CFRP-PEEK) to titanium alloy (TC4) was performed. The influence of defocus distance, also described as irradiance diameter of laser beam on interfacial joining was investigated. The appearance of welded joint and the microstructure at joint interface was observed. The fracture load was thereafter obtained. In addition, temperature field simulation at the joint interface during laser joining process was carried out to clarify the joining mechanism. The results indicated that good appearances were obtained with low defocused distance. The interfacial observation showed that mechanical bonding was generated at the joint interface since the melted resin was embedded in the rough surface of the TC4. Besides, a new phase formed at the interface between CFRP-PEEK and TC4, which was identified as CTi0.42V1.58. The content of the phase increased as the defocus distance increased. Shear force decreased when the defocus distance increased from −4 mm (irradiance diameter 0.84 mm) to 0 mm (irradiance diameter 0.6 mm), and then increased when the defocus distance increased from 0 mm to +8 mm (irradiance diameter 1.06 mm). This phenomenon was explained by simulation result of temperature field that the width of the range of melting temperature of the resin increased as the laser beam diameter increased. The simulation results were consistent with the changes of the width of resin adhesion in actual joint.

Study on the energy charging process of a plate-type latent heat thermal energy storage unit and optimization using Taguchi method

To understand the energy charging process of a plate-type thermal energy storage unit using phase change materials (PCMs) under various conditions, an experimental system was fabricated to identify the impact of heat transfer fluid (HTF) temperature, HTF velocity and plate inclination. The energy charging cycles were studied using liquid fraction and accumulated energy storage density with detailed temperature profiles. After the Taguchi optimization, a maximum energy charging rate of 759 W with a 23% increment was obtained with the HTF temperature of 55 °C, the HTF velocity of 5 m/s and the plate inclination of 75°. The melting process was influenced the most by the HTF temperature, followed by the HTF velocity and the plate inclination based on the standardized melting time. However, the influence of inclination angle was larger than the HTF velocity according to the actual melting time. Optimizing inclination angle was an effective way to improve the melting process without consuming additional materials and energy. Because of the PCM natural convection, the melting temperature range varied under different conditions. It was critical to identify the actual melting temperature range to predict the melting performance accurately.

Influence of multiple freezing/thawing cycles on a structural, rheological, and textural profile of fermented and unfermented corn dough.

In the current study, the impact of fermentation and freezing/thawing treatment on corn flour was studied. Fermentation revealed an increase (12%) in amylose content, while freezing reflected a loss of amylose. The results of scanning electron microscope (SEM) revealed more grooves, indentations, and the irregular shape of particles. Rapid Visco Analyzer (RVA) exhibited different pasting behavior on the dough. The molecular structure had similar profiles but showed several discernible absorbance at the different wavelengths. Differential scanning calorimetry (DSC) showed an increase in melting temperature range due to fermentation and freezing/thawing treatment attributed to more heterogeneous morphology. Overall, the results of this research showed the insight alterations that induce the changes in corn flour leading to improvement in some properties and it may enhance the acquaintance about the upright revolution in the profile of corn dough and its potential usage in industry and homes.

Tailoring Binder Melting Temperature to Study the Binder Melt Layer Flow in Ammonium Perchlorate Composite Propellants

ABSTRACT Understanding the melt layer of composite solid propellants is crucial to theoretically model the combustion mechanism. Numerous studies on the melt layer flow have determined that the melting temperatures of the binder govern the burning rate dependence on pressure. Previous investigations discovered that using curatives and using different binders alter the binder melting temperature. The authors have developed a process to tailor the melting temperature through a functionalization process on the hydroxyl-terminated polybutadiene (HTPB) polymer. This study presents the analysis on the impacts of the melt layer dynamics of an ammonium perchlorate (AP)/HTPB-based propellant with tailorable melting temperatures. Pyrolysis measurements observed increased binder melt layer flow, resulting in lower pyrolysis rates. Propellants made with similar melting temperatures to the traditional R45M had similar burning rates but introduced more scatter due to the hardness of the propellant. Additional propellant samples containing 17 wt% aluminum (Al) and 70 wt% AP were made with a range of melting temperatures to study the impact of melting temperature on the melt layer. A rheological study on the cured propellant mixtures with tailored melting properties identified the melting temperatures for the level of HTPB functionalization. Those mixtures were burned, and the burning rates varied based on the melting temperature. The results suggested that a lower melting temperature produces a plateau propellant.

Ore Forming Fluid of Epithermal Quartz Veins at Cisuru Prospect, Papandayan District, West Java, Indonesia

The Cisuru area is located in Talegong Sub-district, Garut Regency, West Java, Indonesia which is belongs to the central part of Southern Mountain Slope. The aim of this research is to understand the nature and characteristic of fluid inclusion from quartz veins (especially drill core samples) in the study area. Rock units in the area are characterized by Tertiary volcanic rocks and volcaniclastic sequence which is mainly composed of andesite, andesitic breccia, volcanic breccia, lapilli tuff, dacite and related to the intrusion of diorite. The Cisuru epithermal mineralization is dominantly hosted by andesite, dacite, breccia and lapilli tuff, and would probably be controlled by both permeable rocks and NS and NE-SW trending strike-slip faults. The mineralization is shown as void filling and replacement within the silica zone, veinlets along with the open space/fractures and dissemination. Fluid inclusion from quartz veins was studied to know nature, characteristics and origin of hydrothermal fluids. Microthermometric measurements of fluid inclusions were realized by using a Linkam THMSG 600 combined freezing and heating stages. Homogenization temperature and final ice melting temperature were measured for primary two-phase inclusion from quartz veins. Base on the study of the fluid inclusion, the value of homogenization temperature (Th) range from 200 ºC to 395 °C and ice melting temperature range from -0.1 to - 4.5 where salinity range from 0.2 to 7.2 wt. % NaCl equivalent. Fluid inclusion petrography and microthermometric measurement data exhibit that fluid mixing, dilution and boiling were main processes during the hydrothermal evolution. The formation temperature of each quartz vein is 260 ºC to 290 ºC and also their formation depth is estimated between 560m to 925m respectively. Combination of fluid inclusions petrography, microthermometric measurement, and estimate paleo depth from Cisuru area were suggested under the epithermal environment.

Investigation of phase change materials for efficient thermal management of electronic modules

Abstract Power electronics is a key technology for the advancement and spreading of electromobility applications and compact power supply devices on the market. The use of new WBG semiconductors (e.g. SiC, GaN) as well as highly integrated silicon-based power electronics enables a significant increase in power density with increasing integration. At the same time, however, this development requires costly thermal management solutions, since the power semiconductors generate considerable heat loss during operation. To ensure the robustness of the systems, the components must be protected from critical temperatures. Nowadays, a considerable effort for active and passive cooling by fans, microfluidic systems or heat pipes is operated. Compared with that, the usage of phase change materials (PCM) is a novel approach for sophisticated thermal management [1], [2]. In this paper some selected results of research project SWE-eT (Heat-retaining coatings for next-generation, efficient, compact power electronics) funded as part of KomroL program (Compact and robust power electronics of the next generation) of German Federal Ministry of Education and Research are presented. Main goal of this project is development, investigation and testing of efficient thermal management solutions based on heat-storing layer systems through phase transition processes. The research project was focused on investigation of sugar alcohols as PCM because of its wide range of melting temperature, high enthalpy of fusion and low cost.

Effect of the fabrication process on the thermophysical properties of Ca(NO3)2–NaNO3/expanded graphite phase change material composites

Studying the influence of various fabrication steps on the thermophysical properties of the shape-stable phase change materials (SSPCMs) is pivotal to adjust the thermophysical properties of the PCM/expanded graphite (EG) SSPCMs. In light of this, three kinds of PCM samples involving different fabrication steps (impregnation, cold-compression and sintering) were fabricated and characterized, to investigate the effects of the different fabrication steps and molar ratios of the Ca(NO3)2–NaNO3 binary salts on the microstructure and some thermal properties of the SSPCMs. The results show that the cold-compression and sintering led to a quite compact arrangement of EG regions separated by salt particles, which constrained the Ca(NO3)2 crystal arrangement and orientation of nitrate molecular chains within the mesopores of EG. As a result, two overlapped or convoluted DSC peaks, instead of one peak, and a wider melting temperature range appeared during the melting process of the SSPCMs when the Ca(NO3)2 M ratio was no less than that of the eutectic binary salt. The cold-compression and sintering also caused evident increases of the melting temperature range, reductions of the phase change enthalpy by 21–23%, and significant increases of the thermal conductivities of the SSPCMs by over 2.5 times from 1.56 to 1.9 to 5.02–6.27 W/(m⋅K). The cold-compression and sintering are suggested to be employed in the fabrications of the SSPCMs to establish a better conductive passageway and surge the energy storage density.

Transient melting of paraffin waxes embedded in aluminum foams: Experimental results and modeling

An energy saving way for electronics cooling during peak demand is represented by phase change materials (PCMs), which could maintain the temperature of the electronic equipment at low values by using the latent heat of melting without requiring any power input. Among the organic PCMs, paraffins are widely available in a large range of melting temperatures. This paper explores the possible use of three paraffins with different melting temperatures. Each paraffin is embedded in three different aluminum foams, having approximately the same volumetric porosity (92–93%), but different linear porosity (5, 10 and 40 pores per linear inch). The system made of foam and paraffin is electrically heated from one side by applying three different heat fluxes (10, 15 and 20 kW m−2). Results are given in terms of temperature distribution both of the heated side of the foams and of the paraffin inside the foams, and the effects of the melting temperature of the paraffins and of the linear porosity of the foams are highlighted. In addition, an empirical correlation is proposed to model the paraffin melting phenomenon.

Strongly Peraluminous Granites across the Archean–Proterozoic Transition

AbstractStrongly peraluminous granites (SPGs) form through the partial melting of metasedimentary rocks and therefore represent archives of the influence of assimilation of sedimentary rocks on the petrology and chemistry of igneous rocks. With the aim of understanding how variations in sedimentary rock characteristics across the Archean–Proterozoic transition might have influenced the igneous rock record, we compiled and compared whole-rock chemistry, mineral chemistry, and isotope data from Archean and Paleo- to Mesoproterozoic SPGs. This time period was chosen as the Archean–Proterozoic transition broadly coincides with the stabilization of continents, the rise of subaerial weathering, and the Great Oxidation Event (GOE), all of which left an imprint on the sedimentary rock record. Our compilation of SPGs is founded on a detailed literature review of the regional geology, geochronology, and inferred origins of the SPGs, which suggest derivation from metasedimentary source material. Although Archean and Proterozoic SPGs are similar in terms of mineralogy or major-element composition owing to their compositions as near-minimum melts in the peraluminous haplogranite system, we discuss several features of their mineral and whole-rock chemistry. First, we review a previous analysis of Archean and Proterozoic SPGs biotite and whole-rock compositions indicating that Archean SPGs, on average, are more reduced than Proterozoic SPGs. This observation suggests that Proterozoic SPGs were derived from metasedimentary sources that on average had more oxidized bulk redox states relative to their Archean counterparts, which could reflect an increase in atmospheric O2 levels and more oxidized sedimentary source rocks after the GOE. Second, based on an analysis of Al2O3/TiO2 whole-rock ratios and zircon saturation temperatures, we conclude that Archean and Proterozoic SPGs formed through partial melting of metasedimentary rocks over a similar range of melting temperatures, with both ‘high-’ and ‘low-’temperature SPGs being observed across all ages. This observation suggests that the thermo-tectonic processes resulting in the heating and melting of metasedimentary rocks (e.g. crustal thickening or underplating of mafic magmas) occurred during generation of both the Archean and Proterozoic SPGs. Third, bulk-rock CaO/Na2O, Rb/Sr, and Rb/Ba ratios indicate that Archean and Proterozoic SPGs were derived from partial melting of both clay-rich (i.e. pelites) and clay-poor (i.e. greywackes) source regions that are locality specific, but not defined by age. This observation, although based on a relatively limited dataset, indicates that the source regions of Archean and Proterozoic SPGs were similar in terms of sediment maturity (i.e. clay component). Last, existing oxygen isotope data for quartz, zircon, and whole-rocks from Proterozoic SPGs show higher values than those of Archean SPGs, suggesting that bulk sedimentary 18O/16O ratios increased across the Archean–Proterozoic boundary. The existing geochemical datasets for Archean and Proterozoic SPGs, however, are limited in size and further work on these rocks is required. Future work must include detailed field studies, petrology, geochronology, and constraints on sedimentary source ages to fully interpret the chemistry of this uniquely useful suite of granites.

Microthermometric evidence for the formation of Permian VHMS deposits in Tasik Chini area, Central Belt of Peninsular Malaysia

The VHMS deposits of Tasik Chini area are located in the Pahang State of Central Belt, Peninsular Malaysia. The deposits occur in a package of Permian volcanics within mixed volcano-sedimentary sequence, and have been exploited from the Bukit Botol and Bukit Ketaya deposits. They have many similarities with Kuroko-style massive sulfide deposits. The host rocks at both deposits are felsic volcanic rocks of rhyolitic to rhyodacitic composition. Mineralization occurs as distinct ore zonation forming a stringer to massive sulfide zone at the footwall followed by barite lenses and exhalite layers (Fe + Mn ± Si ore) at the stratigraphic top. The sulfide phases are characterized by pyrite as the major sulfide mineral, with subordinate chalcopyrite, sphalerite and rare galena; traces of gold, silver- and Sn-bearing minerals occur in the massive sulfide and barite ores. Primary fluid inclusions within quartz and barite occur as two types: (1) type I: two phase, liquid-vapour inclusions without daughter minerals, and (2) type II: three phase, liquid CO2-bearing carbonic inclusions. These three phase inclusions include liquid H2O, liquid CO2 and vapour CO2, with variable CO2 content, and often decrepitate before complete homogenization. Microthermometric measurements of the type I inclusions show that the temperature of homogenization (Th) varies between 180 °C and 310 °C with salinities ranging from 1.0 to 15.0 wt% NaCl equivalent in the quartz samples. Homogenization temperatures (Th) of 190 °C to 300 °C and salinities between 1.0 and 13.0 wt% NaCl equivalent are recorded from the barite samples. Type II inclusions have an initial melting temperature range of −57.1 °C to −57.5 °C, clathrate melting temperature (Tmclathrate) of 7.4 °C to 8.0 °C and CO2 homogenization temperature (ThCO2) between 30.1 °C and 30.3 °C, and salinity ranging from 4.0 to 5.1 wt% NaCl equivalent. Densities, pressure and depth of ore forming fluids range from 0.711 to 0.970 g/cm3, 12 to 93 bars, and ∼1500 m depth of seawater. Laser Raman spectroscopic analysis shows the presence of CO2 in the carbonic inclusions. The fluid inclusion results suggest that the main ore fluid during the formation of the Tasik Chini VHMS deposit is a seawater-dominated fluid, but contribution from a modified seawater or possibly magmatic origin is also indicated by higher salinities relative to seawater (3.2 wt% NaCl) and the presence of CO2. Taking into account the regional geodynamic evolution, it is also concluded that the formation of VHMS deposits in the Tasik Chini area occurred in a back-arc geotectonic setting.

Effect of Melt Temperature on Weld Line Strength

This article deals with the influence of the melt temperature on weld line strength in injection-molded plastic parts. A special mold was created for this investigation to make specimens with a central weld line. The experimental material was polypropylene Sabic PP 90910. Its stress at break is around 16 MPa and its melting temperature is between 200°C and 260°C. In general, the presence of weld lines has a negative impact on mechanical properties. This investigation showed that the strength depends on the melt temperature (160–260°C in this case). Strength was measured using mechanical testing. It was found to increase with the melt temperature, up to 210°C. Above 210°C, degradation of the plastic led to decreasing strengths. A melt temperature range of 190–210°C is therefore optimal for this application. Shear forces and friction were found to play a great role, as they raise the melt temperature during molding. This was confirmed by mold-flow analysis. The melt temperature during molding was up to 18% higher than the initial melt temperature. This investigation has important consequences for the plastic industry. It is relevant to evaluations of the polymer matrix strength in composite materials and the strength of 3D printed parts with multiple weld lines.

PCR effects of melting temperature adjustment of individual primers in degenerate primer pools.

Deep sequencing of small subunit ribosomal RNA (SSU rRNA) gene amplicons continues to be the most common approach for characterization of complex microbial communities. PCR amplifications of conserved regions of SSU rRNA genes often employ degenerate pools of primers to enable targeting of a broad spectrum of organisms. One little noticed feature of such degenerate primer sets is the potential for a wide range of melting temperatures between the primer variants. The melting temperature variation of primers in a degenerate pool could lead to variable amplification efficiencies and PCR bias. Thus, we sought to adjust the melting temperature of each primer variant individually. Individual primer modifications were used to reduce theoretical melting temperature variation between primers, as well as to introduce inter-cluster nucleotide diversity during Illumina sequencing of primer regions. We demonstrate here the suitability of such primers for microbial community analysis. However, no substantial differences in microbial community structure were revealed when using primers with adjusted melting temperatures, though the optimal annealing temperature decreased.

Thermodynamic and experimental study of cobalt-based alloys designed to contain TiC carbides

Two alloy compositions, {Co(bal.)-25Cr-0.25C-1Ti} and {Co(bal.)-25Cr- 0.50C-2Ti}, were studied using Thermo-Calc. In parallel the corresponding real alloys were elaborated by foundry and their microstructures, in their as-cast state or after a long stage at 1000 or 1200 °C, were characterized. Thermodynamic calculations and real experiments were globally in good agreement. They both demonstrate that the two alloys are highly refractory, that solidification starts by the crystallization of the alloy matrix in all cases and that all titanium carbides precipitate at the end of solidification and belong to a {matrix + TiC} eutectic compound. The TiC carbides remain stable during long exposure at elevated temperature, for both temperatures for the {0.50C-2Ti}-alloy but only at 1000 °C for the {0.25C-1Ti}-alloy. This observation suggests potential high mechanical properties of the {0.50C-2Ti}-alloy at elevated temperature. Many of the collected experimental data – temperature range of melting or solidification, microstructures stabilized at high temperature (natures, fractions and chemical compositions of the phases) – will be of interest for testing and improving databases.

Nano-encapsulation of phase change materials: From design to thermal performance, simulations and toxicological assessment

The paper presents the results of an experimental activity aimed at producing and characterizing a nano-encapsulated PEG600 (PCMs) into a silica shell. The nano-encapsulation was meant to be useful to improve the material's suitability to integration in building components. The (300 ± 15) nm nanoparticles that were produced underwent a full characterization of their thermal performances. An enthalpy of fusion as high as 66.24 kJ/kg, in a tight melting temperature range (20–21 °C) was obtained, making the material suitable for thermal energy storage in buildings. In order to demonstrate the benefits of such as this technology on the reduction of heating and cooling demand of buildings, a concentration of 50% in weight of nanoparticles was, then, embedded into a gypsum plasterboard and used for all indoor plastered surfaces of a reference residential buildings. A saving of respectively up to 4.3% and up to 1.1% of heating and cooling energy demand was predicted in comparison to the ones of a building without PCM. Finally, the material underwent a full toxicological characterization exposing human alveolar basal epithelial cells to nanoparticles. The results showed that there were no toxic effects on cell morphology.

Characterisation and evaluation of a new phase change enhanced working solution for liquid desiccant cooling systems

Desiccant solutions play an essential role in desiccant cooling systems to absorb moisture from the process air. This paper presents the characterisation of a new working solution for liquid desiccant cooling systems. The new working solution was prepared through dispersion of micro-encapsulated phase change materials (MPCMs) into lithium chloride (LiCl) desiccant solutions to ensure that the dehumidification process was achieved under a low temperature condition and to improve thermal capacity and moisture removal efficiency of the mixture. The properties of the new solution, including density, enthalpy-temperature relationship, particle size distribution, thermal conductivity, and vapour pressure were characterised through either experimental tests or theoretical analysis. It was shown that the density and thermal conductivity of the new working solution slightly decreased with the increase of the mass fraction of the MPCMs in the mixture. The thermal capacity of the new working solution substantially increased in the melting temperature range of the MPCMs used. The vapour pressure of the new working solution decreased due to the existence of the MPCM particles. It is expected that the dehumidification efficiency of adiabatic dehumidifiers can be potentially improved when using this new working solution due to the decreased vapour pressure and increased thermal capacity of the phase change enhanced desiccant solution.