Lindemann developed the melting temperature theory over 100 years ago, known as the Lindemann criterion. Its main assumption is that melting occurs when the root-mean-square vibration amplitude of ...ions and atoms in crystals exceeds a critical fraction, η of the inter-atomic spacing in crystals. The Lindemann coefficient η is undefined and scientific papers report different η values for different elements. Here we present previously unobserved data trends pointing to the fact that the Lindemann coefficient could be linked to the periodic groups of the periodic table, having an exact value for each element belonging to a given periodic group. We report 12 distinctive Lindemann coefficient values corresponding to 12 groups of the periodic table containing solid elements with identifiable melting temperature. Using these vales, the recalculation of the melting temperatures indicates a good match to the experimental values for 39 elements, corresponding to 12 out of 15 periodic groups. This newly observed result opens up the possibility of further refining the Lindemann melting criterion by stimulating analytical studies of the Lindemann coefficient in the light of this newly discovered result.
•Generalized Lindemann melting coefficient.•Melting temperature link to the Periodic Table of Elements.•Redefinition of the Lindemann melting criterion.
The objective of this work was to computationally predict the melting temperature and melt properties of thermosetting monomers used in aerospace applications. In this study, we applied an existing ...voids method by Solca. to examine four cyanate ester monomers with a wide range of melting temperatures. Voids were introduced into some simulations by removal of molecules from lattice positions to lower the free-energy barrier to melting to directly simulate the transition from a stable crystal to amorphous solid and capture the melting temperature. We validated model predictions by comparing melting temperature against previously reported literature values. Additionally, the torsion and orientational order parameters were used to examine the monomers’ freedom of motion to investigate structure–property relationships. Ultimately, the voids method provided reasonable estimates of melting temperature while the torsion and order parameter analysis provided insight into sources of the differing melt properties between the thermosetting monomers. As a whole, the results shed light on how freedom of molecular motions in the monomer melt state may affect melting temperature and can be utilized to inspire the development of thermosetting monomers with optimal monomer melt properties for demanding applications.
The main objective of this research was to investigate the effect on thermal properties of the addition of two different compatibilizing agents, maleic anhydride (MA)-grafted polypropylene (MAPP) and ...MA-grafted polyethylene (MAPE), to bio-flour-filled, Polypropylene (PP) and low-density polyethylene (LDPE) composites. The effect of two different types of MAPE polymer, MA-grafted high-density polyethylene (HDPE-MA) and MA-grafted linear LDPE (LLDPE-MA), was also examined. With increasing MAPP and MAPE content, the thermal stability, storage modulus (
E′), tan
δ
max peak temperature (glass transition temperature:
T
g) and loss modulus (
E
″
max
) peak temperature (
β relaxation) were slightly increased. The thermal stability,
E′ and
E″ of MAPE-treated composites were not significantly affected by the two different MAPE polymers. The melting temperature (
T
m) of the composites was not significantly changed but the crystallinity (
X
c) of MAPP- and MAPE-treated composites was slightly increased with increasing MAPP and MAPE content. This enhancement of thermal stability and properties could be attributed to an improvement in the interfacial adhesion and compatibility between the rice husk flour (RHF) and matrix due to the treatment of compatibilizing agent. Attenuated total reflectance (FTIR-ATR) analysis confirmed this result by demonstrating the changed chemical structures of the composites following MAPP and MAPE addition.
•Thermal behaviors of single and multi PCM thermocline storage are presented.•Temperature response and phase change process within capsules are revealed.•Energy analysis of thermocline latent heat ...thermal storage systems is presented.•Multi-stage PCM is a promising solution to store thermal energy for CSP plants.
This paper is aimed at analyzing the behavior of a packed bed latent heat thermal energy storage system in concentrating solar power (CSP). One way of improving the performance of a latent thermal energy storage system is by implementing the multiple phase change materials (PCMs) design. The behavior of a packed bed latent heat thermal energy storage system at different cases is numerically analyzed. The molten salt is considered for the heat transfer fluid (HTF) with phase change material (PCM) capsules as the filler. In this design, spherical capsules filled with PCMs of different thermo-physical properties are used. The capsules are packed in the bed at different sections based on the PCM melting temperature. The model developed using the Concentric-Dispersion (C-D) equations. The governing equations are solved in MATLAB, and the results obtained are validated against experimental data from the literature. The performance of the systems is calculated. The results show that the three-stage PCMs system with different melting point exhibited the highest energy and exergy efficiency during a charging discharging cycle. Moreover, results show that the three-stage PCMs unit can improve the heat transfer rate greatly and shorten the heat storage time effectively.
In this study, we establish an efficient enzymatic approach for producing novel inotodiyl-oleates (IOs) from pure inotodiol and oleic acid to improve the properties of inotodiol. For the ...esterification between inotodiol and oleic acid, CALA and n-hexane were the optimal biocatalyst and solvents for forming IOs with 80.17% conversion yield. These IOs comprised two distinct monoesters, the C3 or C22 ester forms of inotodiol. Intriguingly, no diesters were detected. The IOs had a melting point of 53.48 °C, much lower than that of inotodiol (192.06 °C). The in vitro digestion rate of IOs (25-28%) was significantly (p < 0.05) lower than that of cholesteryl-oleate (60%). Additionally, IOs exhibited much lower in vivo absorption than inotodiol when orally administered using different formulations (p < 0.05). The results indicated that IOs were resistant to enzymatic digestion in the small intestine, which could be advantageous in targeting the large intestine for disease treatments.
•Development of a low-melting temperature molten salt based on Sr(NO3)2/NaNO3/KNO3/LiNO3.•Application of a new low melting point quaternary salt for energy storage in district heating and cooling for ...the WEDISTRICT project.•Sizing and engineering description of a thermocline molten salt operating between 150 and 235 °C.•Steady state nominal design and dynamic model to evaluate the expected performance of the molten salt storage.
Thermal Energy storage is one of the critical components in district heating and cooling (DHC) facilities when based on intermittent energy sources (as solar). Currently, DHC energy storage is based on water tanks. Nevertheless, water storage cannot be used with medium temperature processes as double effect absorption chillers or other services requiring temperatures well above 100 °C. Current thermal storage at higher temperature may be based on a variety of technologies. Among then, molten nitrate salts are widely used for heat storage in concentrated solar plants (CSP), limited by the melting temperature of available commercial solar salts and their solidification risk. Such commercially available salts are not applicable to district heating and cooling as they are solid in the expected operational temperature range. Other storage media may be solid materials, either by the use of packed-bed materials, concrete or phase change materials.
In this paper, an innovative molten salt mixture with a melting temperature below 150 °C is used. The availability of a storage medium in a temperature range from 150 up to 250 °C might increase the solar share in DHC installations, integrating concentrated solar technologies. Such storage allows to apply solar technologies to supply heat to services for DHC that now can be only provided by boilers. In this communication, a molten salt storage tank operating in thermocline mode will be proposed in the framework of the WEDISTRICT project 1. The project seeks to deliver the highest possible share of renewable sources for the energy needs of a district demand, maximizing performance by the application of advanced absorption chillers, that requires temperature feeds well above 100 °C.
Meat product adulteration caused by temptation of economic benefit among different meats has always been a serious global problem. It is necessary to carry out a reliable and convenient method to ...identify meat species in foodstuff. In this paper, we developed a hexaplex real-time PCR (RT-PCR) assay using melting curve analysis to identify eleven meat species simultaneously. A total of six pairs of specific primers were designed based on mitochondrial genes, including CO I, CO II, ND4, 12S rRNA and 16S rRNA. The amplicons uniquely corresponded to six distinct melting peaks at 71.69 ± 0.60 °C (Sheep/Goat), 74.47 ± 0.34 °C (Horse), 78.87 ± 0.33 °C (Cattle), 80.75 ± 0.15 °C (Pig), 83.36 ± 0.08 °C (Donkey) and 85.10–87.16 °C (Poultry: chicken, duck, goose, wild goose and quail), respectively. This study presented a validation including specificity, detection limit and practicability. The results showed that this method has good specificity of primers and the detection limits were 0.01–0.1 ng DNA of absolute detection limit and 0.1–1% meat mixture of relative detection limit. Validated by amplification ability and commercial products, this method can simultaneously and accurately identify eleven common meat species, indicating a good application foreground.
•A hexaplex real-time PCR for simultaneous detection of eleven species was developed.•The amplicons with different Tm values were analyzed by melting curve analysis.•Two of six pairs of primers based on mitochondrial DNA were degenerated primers.•This method had good sensitivity which satisfied the actual detection situation.
In applications of solar energy, thermal ratcheting is a crucial topic connected to the periodic performance of dual-phase thermocline storage tank. In order to investigate this phenomenon, a ...detailed simulation of a thermocline reservoir that includes both the hybrid tank wall and the varied filling zone is necessary. The thermo-mechanical characteristic of the cascaded layers storage tank for parabolic trough power plants is examined in the current work using one parametric study (dimensionless temperature difference) to determine the impact of changing the melting temperature of the phase change material (PCMs) layers. Experimental work from earlier studies is utilized to validate the numerical outcomes currently being presented. The results showed that structures-VIII and XIV have acceptable thermal performance, but ineffective mechanical performance since the normalized stress values were greater than one. The structure-XIII has the best overall efficiency of 79.58%, followed by structures-II, III, and XI, with performance levels of 70.82%, 67.83%, and 66.85%, respectively. The lowest overall efficiency attains by structure-XII, which equals 22.21%. The energy retrieved, overall efficiency, capacity ratio, and utilization ratio for the best scenario “structures- XIII ″ are 188.2 MWh, 79.58%, 44.34%, and 40.5%, respectively, based on the charging/discharging duration.
•A numerical model of cascaded layers storage tank for PTP plants is addressed.•Thermo-mechanical analysis of varying the melting temperature of each PCM layer.•The normalized stress values for structures-VIII and XIV are greater than one.•Based on the charging/discharging period, structures-XIII is recommended due to its 188.2 MWh energy recovery.
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