储氧材料制备过程中的结构及织构变化

Ce_0.65Zr_0.35O₂ solid solution was prepared by co-precipitation method and characterized by X-ray diffraction (XRD), Raman spectra, BET, oxygen storage capacity (OSC) and temperature-programmed reduction measurements (H₂-TPR) after calcination at 100 ℃, 300 ℃, 600 ℃, and 1 000 ℃. The results showed that the precipitation was a crystalline of fluorite structure, and in the process of the precipitation transformation into Ce_0.65Zr_0.35O₂ solid solution, the fluorite structure of the precipitation kept unchanged. The samples had different BET surface areas and OSC at different temperatures, but they held the performance of stable structure. After 1 000 ℃, there didn′t appear the other crystalline phase. So the samples prepared by co-precipitation method had excellent texture and higher thermal stability.     

Analyses of an air conditioning system with entropy generation minimization and entransy theory

In this paper,based on the generalized heat transfer law,an air conditioning system is analyzed with the entropy generation minimization and the entransy theory.Taking the coefficient of performance(denoted as COP) and heat flow rate Q~(out) which is released into the room as the optimization objectives,we discuss the applicabilities of the entropy generation minimization and entransy theory to the optimizations.Five numerical cases are presented.Combining the numerical results and theoretical analyses,we can conclude that the optimization applicabilities of the two theories are conditional.If Q~(out) is the optimization objective,larger entransy increase rate always leads to larger Q~(out),while smaller entropy generation rate does not.If we take COP as the optimization objective,neither the entropy generation minimization nor the concept of entransy increase is always applicable.Furthermore,we find that the concept of entransy dissipation is not applicable for the discussed cases.