Papers by Keyword: Thermodynamical Analysis

Abstract: This paper is aimed at the situation that the discharge amount of chemical industry wastes is raising rapidly and its treatment is extremely difficult. The advantages and disadvantages of common treatment methods are discussed, and the incineration method has obvious supremacy. The structure of cascade reciprocating incinerator is analyzed, and the burning process is thermodynamically analyzed and optimized by the parameter calculation of grate area, incinerator body height and heat preservation performance of incinerator brickwork. It is concluded that the optimization design of grate can intensify the burning process of wastes and the pollution can be controlled and even eliminated.

Abstract: We study thermodynamically the behaviour of PdSe2 while subjected to high pressure under isothermal conditions. The present paper continues the study started in [1]. Here we present the results of the axial calculations and analyses. Specific lengths, linear adjusted Gibbs free energy changes and linear adjusted entropy generations were studied along each spatial axis separately. We found that the first-order transition from PdS2 structure type to pyrite one at 20oC is accompanied by saltatory contraction of a and b specific lengths and respective saltatory expansion of c specific length. Under 300oC all specific lengths contract saltatory. In the transition point under 20oC PdSe2 gains saltatory stability along a and b axis and looses along c one, respectively. Besides, the loose along c axis is bigger than the gains along a and b ones. Under 300oC the transition is accompanied by slight gain of stability along all three spatial axes. Plateaux duration affects the stability of PdSe2 strongly under higher temperature.

Abstract: We study thermodynamically the behaviour of PdSe2 while subjected to high pressure under isothermal conditions. The present paper discusses the volumetric-level calculations and results. Experiments under two certain temperature levels are performed: 20oC and 300oC. Calculations and analyses are done according to the method for thermodynamical analysis developed by us in [1]. We detected the order of phase transition from PdS2 structure type to pyrite one to be first order notwithstanding the temperature level. Values of transition pressure were found to be 12.24 GPa and 9.785 GPa at 20oC and 300oC, respectively. Adjusted entropy generation during compression was calculated aiming to study stability of treated compound. Influence of compression temperature level was analysed, as well as duration of pressure plateaux.

Abstract: In the present paper we studied the thermodynamical behaviour under high pressure of two MTe2-type compounds (M = Pd, Pt) by applying the thermodynamical method, which we elaborated in previous studies [1,2]. The two discussed compounds are representatives of the CdI2 structure type, which is bi-dimensional and as such is atypical for the big family of lamellar MQ2- type dichalcogenides (Q=S, Se, Te). Specific of lamellar structure is the strong ionicity of the bonds. Its direct consequence is cleavage obtaining, lubrication properties, anisotropic physic properties. One of the most interesting points stands on the possibility for realising interactions between the layers of different types of ions. That could be done under high pressure by any of the following transformation processes: (i) a phase transition to the typical pyrite structure; (ii) a phase rearrangements changing the parameters of the crystal cell but keeping the 2D-type structure. The computation of the volumetric thermodynamical functions showed that both PdTe2 and PtTe2 do not undergo any classical phase transition [1]. But we observed a curious difference in their stability: PtTe2 loosed its stability quite fast and PdTe2 was quite stable. Aiming to clarify if the difference in the volumetric entropy generation was due to different phase rearrangements, we calculated the longitudinal thermodynamical functions. In such a way we detected that both PdTe2 and PtTe2 undergo a phase rearrangement. The change along one of the space axis in both compounds was compensated by the reverse change along the other space axis. Like this no changes at the volumetric level were observed. The longitudinal calculations gave an explanation for the differences in entropy generation at volumetric level: beyond the rearrangement point PdTe2 decreases its entropy generation, i.e. its new arrangement is somehow stable under increasing pressure. While, beyond its rearrangement point PtTe2 increases its entropy generation, i.e. even in the new arrangement it loses stability under increasing pressure. We conclude that both PdTe2 and PtTe2 do not undergo a classical phase transition at volumetric level. At longitudinal level both compounds undergo phase rearrangement. A difference between PdTe2 and PtTe2 is observed in their entropy generation beyond the rearrangement point.