| Energy is the base of human's life and development and is one of the three pillars of modern civilization .It controls the development of the economy and science and technology. While on the usage of the energy, there exists a contradiction: as the science and technology develop greatly, the demands for energy increased sharply, the utilization ratio of the coal and petroleum is very low, twinned with the largest waste, all of these have made the shortage of energy more gravely day by day. Furthermore, during the course of using these energies our environment was polluted severely. Therefore, all countries have made the exploiting of the new, high efficiency, economic energy as the first problem to be dissolved.The solar energy, as the biggest, no pollution, regenerative energy, has become more and more important. Because of its low density and its diversity, such as varying with the seasons, climates, its regions, the solar energy has some defects. To overcome these defects, we need some apparatus as the media to store the energy. So the study on the storage of the solar energy in theoretical and experimental aspects has become the most important thesis in the usage of the solar energy.The phase change materials use its phase change patent heat to store the energy. We aim at finding the perfect phase change materials. The ideal phase change materials (PCMs) should have suitable phase change temperature; high enthalpies; good heat conductivity; favorable phase equilibrium; low evapor pressure; high density; little volume change; no supercooling; proper crystallizing velocity; chemical stabilization; no toxic; no pollution, easily get; low price. 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, lower 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) (CnH2n+12MCl4 (CnMX) and their binary system have solid-solid phase transition andcan be widely used in many heat storage areas. We chose the three compounds among (n-CnH2n+iNH3) 2ZnCl4 simplified as CnZnCl(n=8, 10, 14) 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 happened through the study of its kinetic.The article is divided into four parts to study and analyze CnMX and their binary system. In the first part, a series of CgMX (M=Mn,Cu,Zn,Co;X=Cl,Br) C|0ZnX and CuZnX were synthesized, element analysis and IR spectra were used to characterize themo Differential scanning calorimetric (DSC) method was used to study their thermodynamic properties which include the phase change temperatures and the enthalpies; we discuss the effects of different solutions to the thermodynamic properties of the pure compounds; from the aspect of IR we also discuss the effects of different metal atoms, different halogens to the structure of the compound. The study shows that when the solid -solid phase change happened the compound have lower transition temperature and higher enthalpy; different metal atoms, different halogens all have different effects on the shape of the IR and the thermodynamic properties of the compounds. Then the structure and mechanism of solid - solid transition are analyzed in order to understand the difference of the thermal parameter of CnMX deeply.In the second part, differential scanning calorimetric (DSC) method was used to study the thermodynamic properties of CnMX and their binary system. The calorimetric results show that CgZnCl as the phase change material (PCM) is not ideal. Although its high enthalpy, low supercooling, its properties of repetition is not very well. After several times recycles, there have an obvious falling of its enthalpies which short its life -span .But when it was used with others compounds their binary system have good properties in heat storage such as high enthalpies, no volatility, low supercooling degree and wide range of phase transition temperatures; and with the certain percentage the enthalpies are largely higher than the two pure samples which make candidate materials more suitable for thermal energy storage.In the third part, the experimental phase diagrams of binary system CgZnCl/ CioZnCl and... |
PDF Full Text Request