高师院校统计热力学教学实践与探索

统计热力学是物理化学的重要组成部分,包含许多抽象的概念和复杂的公式。笔者从统计热力学课程特点和自身教学实践出发,分析了统计热力学教学中存在的问题,对如何提高统计热力学教学质量提出了建议。     

Mechanism of ONB based on nonequilibrium thermodynamics of natural circulation in narrow channels

Based on the experiment of onset of nucleate boiling （ONB） in natural circulation and the nonequilibrium thermodynamics dissipative theory, the mechanism of ONB in narrow rectangle channels of natural circulation is proposed. It points out that the onset of nucleate boiling is influenced by the degree of superheat and the special conditions of narrow channels. Under the conditions of both density difference in natural circulation and narrow rectangle channels, the prediction model of ONB in natural circulation of narrow channels based on fluctuating is established. The experimental results show that the present model can be used to predict the heat flux of ONB in narrow rectangle channels. Features of ONB in natural circulation narrow rectangle channels are as follows： heating power is the incentive of the happen of ONB; the higher the heating power is, the higher the degree of superheat is, and the earlier the ONB will appear. With the pressurizing, the appearance of ONB will be delayed. The higher the degree of supercooling is, the later the ONB appears. The ONB will happen easier when there are noncondensable gases and roughness in the channels.     

HFETR裂变中子转换器设计

为提高高通量工程试验堆(HFETR)局部快中子注量率,裂变中子转换器采用以含7%Mo的高裂变密度UMo合金作为燃料芯体的十字形燃料棒。转换器内62根燃料棒以三角点阵布置于63 mm外套管和24 mm内套管间,中心区域为20 mm的辐照孔道。采用蒙特卡罗计算表明,该转换器内辐照样品的快中子（E>1 MeV）注量率可达3.34×10¹⁴cm^-2•s^-1,较堆芯相同位置不放置转换器时高约40%。在HFETR设计流速和压力下,利用ANSYS/CFX程序分析得到,转换器最大允许功率可达2.4 MW,燃料棒芯体最大功率密度为8.007 kW/cm³。此时,燃料棒包壳温度为193.6 ℃,能满足HFETR的热工要求,不会产生流动不稳定。     

铒二氢化物的氘、氚热力学同位素效应

在真空系统中对金属铒的氘活化特性进行了测试,测定了铒与氘、氚反应生成二氢化物及其可逆反应的压强-组成-温度（PCT）曲线。结果显示,铒的氘、氚化物α+β相平台区较宽且十分平坦,其二氘化物和二氚化物分解反应均未见明显滞后效应。基于PCT曲线获得了H/Er原子比在0.6～1.6区间的标准焓（ΔH°）和标准熵（ΔS°）,其数值均随H/Er比的增大而减小,相同原子比下氚化物的ΔH°和ΔS°较氘化物的小,具有轻微的同位素效应。其中,ErD₁的ΔH°和ΔS°分别为（-199.7±7.3）kJ/mol和（-143.4±7.2） J/(mol•K),ErT₁的ΔH°和ΔS°分别为（-209.3±3.3） kJ/mol和（-152.9±3.2）J/(mol•K)。     

Leaching test of gamma-emitting Cs,Ru, Zr,and U from neutron-irradiated UO2/ZrO2 solid solutions in non-filtered surface seawater

The leaching behaviors of gamma-ray radionuclides, Cs-137, Ru-103, and Zr-95, produced by neutron irradiation of UO₂/ZrO₂ solid solutions, in real surface seawater were investigated under atmospheric conditions. The fraction of radionuclide inventory leached in the seawater was in the order of Cs > Ru (～U) ? Zr, indicating that the fraction was significantly affected by the chemical state of the radionuclides. However, the amount of soluble nuclides was proportional to that of uranium regardless of whether the solid solutions were prepared under an oxidative or reductive environment. A tiny fraction of Ru was filtered out by a 3 kDa nominal molecular weight cut-off filter after the 160 d leaching test, suggesting a different behavior from its ionic form, but Cs and U did not form a colloid-like species in seawater.     

Studies on the Characteristic of Titanium–Tritium Reaction

The p–c–T curves of tritium absorption and desorption of titanium were measured using the method of step equilibrium by stepping up the tritium quantity on an experimental apparatus of metal hydride. The p–c–T curves for tritium have one plateau at temperature below 300°C and two plateaus at temperature above 300°C. The thermodynamic parameters of the different phases were determined according to the van’t Hoff equation. The hysteresis effect was not observed in reversible process of tritium absorption and desorption of titanium on our experimental condition. The tritium absorption behavior of titanium in the temperature ranging from 550°C to 750°C and desorption behavior of titanium in the temperature ranging from 350°C to 550°C have been investigated in a constant volume system. A method of the reaction rate analysis was proposed and examined for determining the rate constant. The apparent activation energy obtained by this analysis for the absorption and the desorption were 155.5 ± 3.2 kJ mol⁻¹ and 62.1 ± 1.6 kJ mol⁻¹ respectively.     

三峡水库安坪库岸段斜坡破坏机制及稳定性评价

基于斜坡的工程地质测绘和实验室分析,总结了研究地段区域滑坡规律,引入粘弹性基础板的弯曲破坏原理,对该地段斜坡破坏机制进行分析。从岩体本身的质量和岩体在地球内外营力作用下所表现的自稳性两方面考虑,采用两级模糊综合评判理论对测区进行斜坡稳定性工程地质单元划分,并利用刚体平衡理论验证模糊评判结果。     

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压井是试油中经常采用的一项工艺技术，多年来对于压井暂闭通常是采用重泥浆压井，有时还在井内加注一个水泥塞。对于压井酸化、通常是在井底压降较大的情况下进行。过去的这种压井方法不仅对地层造成了较严重的污染，而且在些井还造成了严重的工程事故，耗费了大量的人力和财力。为了防止这些问题的发生，着重针对四川碳酸盐地层高压高产气井的压井暂闭、常规压井酸化增产措施中防止地层污染、防止工程事故的问题进行了研究。从实际     

初步设计阶段的监理工作初探

初步设计阶段的监理工作,主要包括确定监理人员,编制监理大纲,拟定设计要求等。