Confined‐Volume Effect on the Thermal Properties of Encapsulated Phase Change Materials for Thermal Energy Storage

We have encapsulated the heat exchange material, n‐docosane, into polyurethane capsules of different sizes. Decreasing the size of the capsules leads to changes of the crystallinity of phase‐change material as well as melting/crystallization temperature. The novelty of the paper includes 1) protection of the nanostructured energy‐enriched materials against environment during storage and controlled release of the encapsulated energy on demand and 2) study of the structure and surface‐to‐volume properties of the energy‐enriched materials dispersed in capsules of different sizes. The stability of energy nanomaterials, influence of capsule diameter on their energy capacity, homogeneity and operation lifetime are investigated.     

Estimation of the Thermophysical Properties of Pentaalkylguanidinium-Based Magnetic Ionic Liquids with Unusual Thermal Expansion Coefficient

The thermal expansion coefficient (α_exp.), the molecular volume (V_m), the entropy of surface formation (S_a), and the Gibbs energy of surface formation (E_a) of four pentaalkylguanidinium-based MILs [C_nTMG][FeCl₃Br] (n=2, 4, 6, 8) were calculated based on the density and surface tension data determined from 278.15 to 323.15 K. In terms of classical semiempirical methods, the standard molar entropy (S⁰), the lattice energy (U_POT), the molar enthalpy of evaporation ( , (298 K)), and the thermal expansion coefficient (α_est.) of the MILs were further estimated. The estimation results indicate that the classical semiempirical methods are suitable for estimating the thermophysical properties of the MILs, except the unusual α_exp., which were extremely larger than those of representative non-magnetic ionic liquids (ILs). We further optimized the estimation methods and discussed the potential reasons for the unusual thermal expansion coefficient of the MILs.     

Thermal Charging Optimization of a Wavy-Shaped Nano-Enhanced Thermal Storage Unit

A wavy shape was used to enhance the thermal heat transfer in a shell-tube latent heat thermal energy storage (LHTES) unit. The thermal storage unit was filled with CuO–coconut oil nano-enhanced phase change material (NePCM). The enthalpy-porosity approach was employed to model the phase change heat transfer in the presence of natural convection effects in the molten NePCM. The finite element method was applied to integrate the governing equations for fluid motion and phase change heat transfer. The impact of wave amplitude and wave number of the heated tube, as well as the volume concertation of nanoparticles on the full-charging time of the LHTES unit, was addressed. The Taguchi optimization method was used to find an optimum design of the LHTES unit. The results showed that an increase in the volume fraction of nanoparticles reduces the charging time. Moreover, the waviness of the tube resists the natural convection flow circulation in the phase change domain and could increase the charging time.     

混合高级醇固-液相变储热材料的研究

相变储热材料研究与开发是国内外的一个新兴领域[1-6]。为了解决一些仪器的内部散热问题,本文研究了混合高级醇固-液相变储热材料的凝固和熔化特性、相变焓值、固液相体积以及石墨粉对材料的导热性能。1实验部分1·1试剂与仪器CDR-1型差动热分析仪-配微机处理系统,上海天平仪器     

Thermal Analysis in Studies of Technological Waste Materials to Be Subjected to Thermal Treatment

Attempt was made to evaluate the usefulness of thermoanalytical methods, combined with X-ray phase analysis and chemical analyses, for the study of thermal decomposition of waste materials to be subjected to thermal treatment. The object of the studies were petrochemical waste materials intended to be decomposed in a rotary furnace. Results are given of the studies of five selected waste materials. This revised version was published online in August 2006 with corrections to the Cover Date.     

Development of Novel Polypropylene Syntactic Foams Containing Paraffin Microcapsules for Thermal Energy Storage Applications

polypropylene (PP) syntactic foams (SFs) containing hollow glass microspheres (HGMs) possess low density and elevated mechanical properties, which can be tuned according to the specific application. A possible way to improve their multifunctionality could be the incorporation of organic Phase Change Materials (PCMs), widely used for thermal energy storage (TES) applications. In the present work, a PCM constituted by encapsulated paraffin, having a melting temperature of 57 °C, was embedded in a compatibilized polypropylene SF by melt compounding and hot pressing at different relative amounts. The rheological, morphological, thermal, and mechanical properties of the prepared materials were systematically investigated. Rheological properties in the molten state were strongly affected by the introduction of both PCMs and HGMs. As expected, the introduction of HGMs reduced both the foam density and thermal conductivity, while the enthalpy of fusion (representing the TES capability) was proportional to the PCM concentration. The mechanical properties of these foams were improved by the incorporation of HGMs, while they were reduced by addition of PCMs. Therefore, the combination of PCMs and HGMs in a PP matrix generated multifunctional materials with tunable thermo-mechanical properties, with a wide range of applications in the automotive, oil, textile, electronics, and aerospace fields.     

三环己基锡取代间苯二甲酸酯的合成、表征及热稳定性分析

以三环己基氢氧化锡为原料,与取代的间苯二甲酸反应,得到了含有萘二甲酰亚胺结构的有机锡羧酸酯,化合物经元素分析、红外光谱及核磁共振波谱表征确认。晶体结构由X-射线单晶衍射法测定,它属于三斜晶系,空间群为P-1,晶胞参数:a=11.7829(7),b=12.9965(8),c=19.2944(12),α=92.6570(10)°,β=99.7970(10)°,γ=115.5100(10)°,V=2603.9(3)3,Z=2,Dc=1.397mg/m3,R1=0.0362,wR2=0.0761。热重分析表明化合物具有良好的热稳定性。     

热分析动力学数据处理方法的研究进展

综述了最近几年来用热分析法研究固相反应动力学的数据处理方法的新进展,指出了现有方法的成功与局限性,介绍了几种新的动力学处理方法及一种新的热分析技术。     

Thermal Expansion Coefficients of the Axes of the Unit Cell of Syndiotactic 1,2-Poly(1,3-Butadiene)

Samples of syndiotactic 1,2-poly(1,3-butadiene) subjected to different thermal and mechanical treatments have been characterized by DSC and X-ray. The treatments induce changes in the crystallinity, crystal size and size of the unit cell, but do not evidence polymorphism. Values of the thermal expansion coefficients of the axes of the unit cell have been determined by X-ray measurements at various temperatures.     

学科大概念统领下基于真实情境的“合成高分子”单元教学

通过新旧课标与教材的对比分析,在大概念的统领下,确定“合成高分子”的教学目标以及认识方式。以“结构决定性质,性质决定用途”大概念统领单元教学,围绕教学目标选择新冠疫情下的“防病毒口罩”为情境,在真实问题的解决过程中发展学生认识合成高分子的基本思路,促进学生化学学科核心素养的发展。     

Use of Thermoanalytical Methods in Prediction of Thermal Endurance of Insulating Impregnating Varnishes

The results of testing the thermal properties of insulating impregnated varnishes obtained by thermoanalytical methods and based on the IEC 216 standard are presented. It was found that the temperature index determined by means of thermoanalytical testing is quite close to that derived by a conventional standardized procedure. It was also established that thermoanalytical methods could be used in the recipe selection for the development of a new varnish. The results obtained confirmed the possibility of using thermoanalytical methods for a quick, prognostic estimation of the thermal endurance of insulating impregnating varnishes. This revised version was published online in August 2006 with corrections to the Cover Date.     

A Kinetic Study of the Dehydration of VOPO4.2H2O by Thermal Methods

The dehydration of VOPO₄.2H₂O hasbeen studied by thermogravimetric analysis (TGA),differential thermal analysis (DTA) and differentialscanning calorimetry (DSC). From the shift of the DTA,DTG, and DSC peaks, activation energies of thedehydration processes have been calculated based onKissinger's method. The most suitable kinetic modelsfor two-step dehydration have been found.     

Phase-Transition Thermal Charging of a Channel-Shape Thermal Energy Storage Unit: Taguchi Optimization Approach and Copper Foam Inserts

Thermal energy storage is a technique that has the potential to contribute to future energy grids to reduce fluctuations in supply from renewable energy sources. The principle of energy storage is to drive an endothermic phase change when excess energy is available and to allow the phase change to reverse and release heat when energy demand exceeds supply. Unwanted charge leakage and low heat transfer rates can limit the effectiveness of the units, but both of these problems can be mitigated by incorporating a metal foam into the design of the storage unit. This study demonstrates the benefits of adding copper foam into a thermal energy storage unit based on capric acid enhanced by copper nanoparticles. The volume fraction of nanoparticles and the location and porosity of the foam were optimized using the Taguchi approach to minimize the charge leakage expected from simulations. Placing the foam layer at the bottom of the unit with the maximum possible height and minimum porosity led to the lowest charge time. The optimum concentration of nanoparticles was found to be 4 vol.%, while the maximu possible concentration was 6 vol.%. The use of an optimized design of the enclosure and the optimum fraction of nanoparticles led to a predicted charging time for the unit that was approximately 58% shorter than that of the worst design. A sensitivity analysis shows that the height of the foam layer and its porosity are the dominant variables, and the location of the porous layer and volume fraction of nanoparticles are of secondary importance. Therefore, a well-designed location and size of a metal foam layer could be used to improve the charging speed of thermal energy storage units significantly. In such designs, the porosity and the placement-location of the foam should be considered more strongly than other factors.     

Thermal Methods of Organic Matter Maturation Monitoring During a Composting Process

The possibility to use thermal analysis for a quick characterisation of chemical changes in the organic matter of composted materials was tested. Nine samples were taken at progressive stages of maturation from the same trench of a fully automated composting plant. DSC and TG were simultaneously performed in static air conditions on whole ground composts. Progressive stages in the composting process yielded samples whose DSC traces revealed appreciable modifications in thermal patterns that agreed well with quantitative data obtained from TG measurements. The ratio between the mass losses associated with the two main exothermic reactions (R1) showed a good sensitivity in detecting the changes in the level of stabilisation during the composting process. Thermal methods seem to be a valid comparative method in evaluating the level of bio-transformation of materials during a composting process. This revised version was published online in July 2006 with corrections to the Cover Date.     

Study on Electric Double Layer of a Cylindrical Particle with Functional Theoretical Approach

A new method, i.e. the iterative method in functional theory, was introduced to solve analytically the nonlinear Poisson-Boltzmann （PB） equation under general potential ψ condition for the electric double layer of a charged cylindrical colloid particle in a symmetrical electrolyte solution. The iterative solutions of ψ are expressed as functions of the distance from the axis of the particle with solution parameters： the concentration of ions c, the aggregation number of ions in a unit length m, the dielectric constant e, the system temperature T and so on. The relative errors show that generally only the first and the second iterative solutions can give accuracy higher than 97%. From the second iterative solution the radius and the surface potential of a cylinder have been defined and the corresponding values have been estimated with the solution parameters, Furthermore, the charge density, the activity coefficient of ions and the osmotic coefficient of solvent were also discussed,     

Thermal Behaviour of Silica Waste from a Geothermal Power Station and Derived Silica Ceramics

The silica waste originating from a geothermal power plant in Mexico was investigated with the aim of finding its applicability as a raw secondary material for ceramics production. The thermal behaviour of the original silica waste (containing NaCl and KCl from marine brine) and of the purified silica was characterized by means of DTA/TG, emanation thermal analysis (ETA) and thermodilatometry (TD). The reactivity of the purified silica waste mixed with CaCO₃ (1.8 mass%) was characterized by means of ETA, DTA and TG. The microstructures and phase compositions of the final products prepared by heating in air were tested by means of X-ray diffraction and of scanning electron microscopy coupled with electron probe X-ray microanalysis. The thermal analysis methods allowed determination of the optimal conditions for thermal treatment of the silica waste in order to obtain partly sintered porous materials for use as refractory bricks. This revised version was published online in August 2006 with corrections to the Cover Date.     

Synthesis,Characterization and Thermophysical Properties of Three Neoteric Solvents-Ionic Liquids Based on Choline Chloride

The authors prepared,characterized and preliminary studied the properties of some neoteric solvents-ionic liquids based on choline chloride,i.e.,three ionic liquids based on the eutectics of choline chloride（2-hydroxyN,N,N-trimethylethanaminium chloride） with,respectively,urea,malonic acid and citric acid.The obtained mixtures were clear and colorless ionic liquids at room temperature.The thermophysical properties,namely,density,viscosity,and electrical conductivity of these mixtures were investigated as a function of temperature within a range of 298-353 K.Correlations for the temperature dependence of the measured properties were generated and discussed in terms of Arrhenius theory.Finally the electrochemical windows of the eutectic liquids were determined.     

Thermal Analysis Characterization of a Commercial Thermoplastic/Thermoset Adhesive

DSC, TGA and DMA thermal analysis techniques are used to characterize a complex adhesive blend. The chemical and thermomechanical property development shown to follow a two-stage process. Beneficial synergy between these analysis tools is demonstrated in this study.This revised version was published online in November 2005 with corrections to the Cover Date.     

用非等温DSC基于Harcourt-Esson方程估算含能材料热爆炸临界温度的一种简单方法

用合理假设,由Semenov热爆炸理论和基于Harcourt-Esson速率表达式非等温动力学方程 ,推导了估算含能材料热爆炸临界温度的一种简单方法。该计算式为 ,比较简单。从非等温DSC曲线上onset温度（ ）通过表达式 可得到 ,由方程 可求得 值,随后算出 。该方法计算结果与Zhang-Hu-Xie-Li方法结果相一致。