Research Of Phase Change Materials (C_nH_2n+1NH₃)₂MnCl₄ And Polyethylene Glycol Incorporating Energy Storage Materials

Energy as one of the three pillars of modern civilization, restricts the development of economy, science and technology. At present, the energy consume is increasing all over the world, but because of the low ratio of utilization and high expenditure, now energy is in short supply. The environment is polluted heavier and heavier because of the consuming of oil and coal. As a result, all nations in the world regard the developing sanity resource, the employing storing and recycling energy as the most important thing. All this helps to accelerate the studies about storing energies. Now to develop new highly efficient energy has become the hot issue of all nations in the world.Energy-storing material is a kind of storing material which alters solar energy, terrestrial heat energy and residuary energy, and releases it at proper conditions. It can be widely employed in the field like industry, agriculture, textile and engineering. The related research has begun in 1970s by European countries, in 1980s;our country has also begun some initial studies about it.Considering the principle of selecting energy storage materials, phase change materials (PCMs) have been widely studied. Particularly, the solid-solid phase materials are attached to increasing importance because of many advantages such as low temperature, high enthalpies, and low supercooling degree and so on during solid-solid phase transition. They also offer many other advantages of small change in volume and no phase separation, which make them suitable for heat storage. Alkylammonium teyrachlorometallates (II) (C_nH_2n+1NH₃)₂MX₄ (C_nMX) and their binary system have solid-solid phase transition and can be widely used in many heat storage areas. We chose those compounds and their binary system as the key substances, and have a detailed study of their energy storage ability which is aimed at giving the theoretical support;draw the binary system phase diagram which is aimed at providing the meaningful reference on choosing the proper substance at the practical application;and discuss the relationship of the structure of the compound and the Ea when the solid -solid phase change happeneduuauIn the first part, a series of CnMnCl (n=8, 10, 12, 14, 16, 18) and their binary system C,0MnCl/Ci4MnCl, Ci0MnCl/Ci6MnCl, Ci4MnCl/Ci6MnCl were synthesized, element analysis and IR spectra were used to characterize them. Then the structure and mechanism of solid to solid transition are analyzed in order to understand the different of the thermal parameter of CnMX deeply.In the second part, differential scanning calorimetric (DSC) method was used to study the energy storage properties of pure materials and their binary system. The calorimetric results show that CnMnCl and their binary system have good properties in heating storage such as high enthalpies, no volatility, and low extent of cooling and long-time usage. The results also show that their binary system have wide range of phase transition temperatures, that are lower than the pure materials and more suitable for low-temperature heating storage.In the third part, the experimental phase diagrams of binary system CioMnCl/CnMnCl and CnMnCl/CieMnCl were established at by three techniques: DSC method, X-ray diffraction, and IR spectra at various temperatures. DSC method is used to determine the relationship between the component and the transition temperature. X-ray diffraction patterns are convenient for phase analysis, because the interplanar spacing d and relative intensity I are intrinsic properties of substances, which can confirm the phase of different binary system. The infrared spectra in the range 4000-450cm'' were measured. In the temperature range corresponding to the solid-solid phase transition the characteristic absorption has a sudden change which can declare the mechanism of solid-solid phase transition.The results show that the phase diagrams of the above mentioned two systems are similar. In other words partial miscibility phase diagram has clearly shown that a stable compound is formed.This need think about the miscible degree of two compositions. For binary system phase diagram is determined by the different of two compositions. Their size and their structure influent the degree of dissolve each other and the form of phase diagram. The thermal informations provided by the phase diagram are instructive for the practical choose of the phase change materials (PCMs).The fourth part of the article chiefly dealt with the calculation of two kinetic parameters (activation energy, Ea;reaction order, n) of CnMnCl (n=8, 10, 12, 14, 16, 18) and CioMnCl / C^MnCl binary system by modeling the thermograms observed by DSC. The kinetic treatment methods—Kissinger and Ozawa were used and came to the same conclusion. The conclusion is drawn that the reaction order of their solid-solid phase transition is the first and the changes of Ea have a rule: with the increasing of n in Ci4MnCl^Ci6MnCl, activation energy Ea were decreased which is related to the intermolecular force.In the last part, two cross-linking agents—dimethylolethylene urea(DMEU) and dihydroxydimethylol-ethlene urea(DMDHEU) were synthesized, polyethylene glycol(av.molecular wt.1000) was incorporated into cotton fabric with these two crosslinkingers, and DSC methedwas used to study the thermodynamic properties of the energy storage materials. The results show that not only PEG 1000 can be incorporated into cotton fabric but also their circulating heat-storage properties is very good. The conclusion of kinetic study is drawn that not only PEG 1000 can be incorporated into cotton fabric but also the incorporation is not effective for solid-liquid phase transition.My work was done on the basis of other people, the research of solid-solid transition was studied from thermodynamics and kinetic aspects. The theory for the use of phase change materials was provided by the study, at the same time the blank and incompletion were revised and replenished. Many experimental methods were adopted, IR spectra at various temperature which is used to study the transition was a new testing method.