计及污垢影响的换热器热优化

本文利用熵产生数方法研究了气体和液体传热介质的顺流、逆流换热器的热力学完善性，结果表明，如给定冷、热流体的入口温度，在综合考虑传热、流动阻力和污垢的情况下，可用优化方法确定其它参数。     

Opacity calculations for high-Z plasma in non-local thermodynamic equilibrium

Opacity of high-Z element plasma in non-local thermodynamic equilibrium (NLTE) is calculated. In the calculation, a collisional radiative model in detailed-configuration-accounting (DCA) is applied to population calculations for NLTE plasmas. Configuration-averaged rate coefficients that needed in the rate equations are obtained based on the first order perturbation theory. The Hatree-Fock-Slater self-consistent-field method is used to calculate the electron wave functions. The spin-orbit splitting is included in the spectrum calculations. The unresolved transition array method is used in the opacity calculations. The calculated frequency-dependent opacity of high-Z plasma Lu is presented. The comparison shows that the present spectrum agrees with another theoretical result well except that the present one shifts a little to the lower energy due to its lower mean ionization stage. The effects of highly doubly excited states on ionization balance and on the opacity are investigated. The mean ionization stage increases more than three stages when doubly excited states 5l6l′ and 5l5l′ are not included in the population calculations and the absorption spectrum also shifts to the higher energy.     

The influence of molecular conformation ofN-alkylsubstituted six-membered cyclic amines and alkylcyclohexanes on the thermodynamic characteristics of sorption in gas chromatography

The standard partial molar free energies, enthalpies, and entropies of sorption of the methylene units in the homologous series of alkylcyclohexanes andN-alkylsubstituted sixmembered heterocycles (piperidines, morpholines, and thiomorpholines) were determined on a capillary column with the methylsiloxane OV-101 stationary phase at 70–150°C. A characteristic feature of all series under study is an abnormally high increase in the values of thermodynamic parameters of sorption on going from the methyl to the ethyl homolog. This peculiarity is believed to be associated with the presence of thegauche butane orgauche methylethylamine fragments in the ethyl homolog. Thesegauche fragments have an increased sorption activity under conditions of gas chromatography in comparison with the correspondingtrans form. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 500–503, March, 1997.     

Nuclear Level Density and Thermodynamic Functions for Nuclei with Static Deformation

The level densities of even-odd and even-even isotopes^161,162Dy,^166Er and ^171,172Yb were calculated using microscopic theory of interacting fermions and compared with experiments.It is found that the data can be well reproduced with level density formalism for nuclei with static deformation.The nuclear temperature as well as the reproduced with level density formalism for nuclei with static deformation.The nuclear temperature as well as the entropy of nuclear system as a function of excitation energy has been extracted from the BCS theory.It is shown that the entropy exhibits an S-formed shape as a function of excitation energy.This is interpreted as a phase transition.Procedure of treating the even-odd and even-even nuclear systems has been presented and discussed.     

The equivalence of ensembles for lattice systems: Some examples and a counterexample

We describe the problem of the equivalence of ensembles at the level of states for classical lattice systems. We discuss circumstances where the vanishing of the specific information gain of a sequence of microcanonical measures with respect to a sequence of grand canonical measures implies the equivalence of ensembles. We give a simple derivation of a criterion for the vanishing of the specific information gain in terms of thermodynamic functions. The proof uses ideas from the theory of large deviations but is self-contained. We show how the criterion works in a simple model of a paramagnet and in the Ising model of a ferromagnet in any dimension but fails in the case of the Curie-Weiss mean-field model.     

Mössbauer Study of Thin Iron Film Beryllization

Beryllium coating of the iron foil is made by means of magnetron sputtering. Mössbauer studies are performed by means of two registration techniques: conversion electron Mössbauer spectroscopy (CEMS) and the γ-ray technique in absorption geometry. Performed investigations confirm the original thermodynamic approach to creation of thermally stable multi-layer materials.

     

Beiträge zu den Eigenschaften von Titanaten mit Ilmenitstruktur. II. Zur Thermodynamik und elektrischen Leitfähigkeit von NiTiO3 und anderen oxidischen Phasen mit Ilmenitstruktur

Contributions to the Properties of Titanates with Ilmenite Structure. II. Study on the Thermodynamics and the Electrical Conductivity of NiTiO₃ and Other Phases with Ilmenite Structure NiTiO₃ shows a phase transition at high temperatures (T_c = 1290°C). The standard enthalpy and entrop of the reaction NiO + TiO₂ = NiTiO₃ was estimated for temperatures above and below the transition temperature using emf-measurements based on the following solid state galvanic cell: Ni,TiO₂, NiTiO₃|ZrO₂(+CaO)|Ni,NiO. The transition enthalpy was found to be 18 ± 2 kJmol^?1, The transition entropy is 12 ± 1 JK^?1mol^?1. This is in good agreement with the calculated entropy change for an order-disorder transition (11.5 JK^?1mol^?1). The influence of other cations like Mg²⁺ and Co²⁺ on the transition temperature was investigated by measurements of the electrical conductivity as a function of composition. Ni_1?xMg_xTiO₃ shows a strong shift of the transition to higher temperatures if a small part of the Ni²⁺ was replaced by Mg²⁺. A linear correlation between the temperature shift and the amount of Co²⁺ was found for Ni_1?xCo_xTiO₃. Thermoanalytical investigations reveal an endothermic peak during the heating period some degrees below the melting point of CoTiO₃. The substitution of Ge⁴⁺ for Ti⁴⁺ is without any influence on the transition temperature. By doping the NiTiO₃ with Ga₂O₃, the anomalous increase of the electrical conductivity with temperature is shifted to lower temperatures.     

气液色谱法测定双-(4,6-二异丙基水杨酸)合铜(Ⅱ)与脂肪胺和醇加合反应的热力学性质

用气液色谱法,在不同的温度下,测定了以α-甲基萘作为固定液时,路易斯碱脂肪胺和醇的溶解平衡常数K_R~0,以及它们与作为路易斯酸的过渡金属配合物双-(4,6-二异丙基水杨酸)合铜(Ⅱ)相互作用的表观分配常数K_R和加合反应的平衡常数K_1。再根据热力学公式: 进一步求出了加合反应的焓变ΔH和熵变ΔS。     

Thermodynamics and phase transitions in the Overhauser model

We analyze the thermodynamics of the Overhauser model and demonstrate rigorously the existence of a phase transition. This is achieved by extending techniques previously developed to treat the BCS model in the quasi-spin formulation. Additionally, we compare the thermodynamics of the quasi-spin and full-trace BCS models. The results are identical up to a temperature rescaling.     

Evaluation of thermodynamic functions for complexation reactions involving bivalent metal ions and ethyl-2,3-dioxobutyrate-2 p -bromophenylhydrazone

Complexation reactions of bivalent metal ions and ethyl-2,3-dioxobutyrate-2p-bromophenylhydrazone (EDOB-2p-BPH) have been studied potentiometrically in 50% (v/v) ethanol/water medium at different ionic strengths with respect to NaClO₄ and at different temperatures and their stability constants determined. The method of Bjerrum and Calvin as modified by Irving and Rossotti has been used to determine then andpL values. S_min values which have the same significance as ‘T²’ have also been calculated. The thermodynamic stability constants and standard free energy change (ΔG) have also been calculated. ΔG values are negative in all cases indicating that the reactions are spontaneous. The ligand field stabilization energy (δH) has also been calculated for the 3d transition metals.