Model of a total momentum filtered energy selective electron heat pump affected by heat leakage and its performance characteristics

A total momentum filtered energy selective electron (ESE) heat pump model with heat leakage is established in this paper. The analytical expressions of heating load and coefficient of performance (COP) for both the total momentum filtered (k_r-filtered) ESE heat pump and the conventionally filtered (k_x-filtered) ESE heat pump in which the electrons are transmitted according to the momentum in the direction of transport only are derived, respectively. The optimal performance of the k_r-filtered ESE heat pump is analyzed by using the theory of finite time thermodynamics (FTT). The optimal regions of COP and heating load for the k_r-filtered heat pump are obtained. By comparing the performance of the k_r-filtered device with that of the k_x-filtered device, it is found that the heating load performance and the COP versus heating load characteristic curves of the k_r-filtered heat pump are totally different from those of the k_x-filtered device; and the maximum COP and maximum heating load of the k_r-filtered device are generally higher than those of the k_x-filtered device. The influences of heat leakage, resonance width, hot reservoir temperature and chemical potential on the performance of the total momentum filtered ESE heat pump are further analyzed by numerical calculations. The obtained results can provide some theoretical guidelines for the design of practical electron systems such as solid-state thermionic heat pump devices.     

磷酸一铵链条炉改换热器效果分析

对云南天安化工220kt/a磷酸一铵产品烘干工艺进行了描述,对链条炉存在的问题及改进效果进行了分析评价,得出链条炉改翅片换热器工艺可行、设备可靠、效果明显的观点。     

齿轮减速器的热功率试验及提高热功率的措施

在分析影响齿轮减速器热功率因素基础上,提出采用散热装置来提高热功率的方法,对不同散热装置的热效应进行对比试验结果表明,新型板块式和列管式冷油器比其他散热装置具有更好的散热效应,在此基础上提出提高大功率齿轮减速器热功率的措施。     

换热器制造过程中的质量标准

对换热器制造过程中的质量标准进行分析,并对主要控制方法提出了看法.     

AN IMPROVED GENERALIZED WATSON EQUATION FOR PREDICTION OF LATENT HEAT OF VAPORIZATION

In this paper, an improved generalized Watson equation for the prediction of latent heats of vaporization at any temperature in the two-phase region for any substance has been proposed. Generalized relations for exponents n ₁, and n _2, have also been established, respectively.

In the current work, the latent heats of vaporization calculated with the proposed equation are compared with corresponding experimental values presented in the literature for 108 substances involving a total of 3361 points. These comparisons are further examined using the results of the original Watson equation and three other well-known equations available in the literature. The results of these comparisons indicate that the proposed equation is more accurate than the other four equations.     

DYNAMIC SIMULATION OF A NON-ISOTHERMAL MSMPR CRYSTALLIZER

The effect of including temperature variations in the dynamic simulation of an MSMPR cooling crystallizer is investigated. Power law nucleation and growth kinetic models incorporating an Arrhenius temperature dependence are used. The effects of changes in the input variables feed temperature, feed flowrate and feed concentration on the output variables operating temperature and concentration and moments of the size distribution are investigated and compared with corresponding responses obtained under isothermal conditions. Significant differences are found.     

离心压缩式热泵装置的(火用)传递分析

依据(火用)传递原理,建立在线运行大功率离心压缩式热泵机组及装置的(火用)传递模型。提出并定义装置和设备(火用)转换率、(火用)功率下降率、(火用)流密度下降率和(火用)阻系数等评价分析准则及其计算式。在此基础上,对热泵在能量转换及传递过程中之能质行为做了(火用)传递分析,得出节流阀、压缩机的(火用)功率下降率最高。原因是节流过程流速、流态在瞬间发生剧烈变化,导致过程(火用)损很大,压缩机的机械性能与冷媒的热物理性能均存在某些不足;蒸发器的(火用)阻系数最高,说明其结构设计有明显缺陷;节流阀的(火用)功率下降率和(火用)流密度下降率相同,表明设备的结构因素与时间条件对节流阀的影响相同。分析结果揭示出机组主要设备的结构设计、热工性能及冷媒热物性对装置用能过程的影响度,得出压缩机在结构设计上仍有改进余地,节流降压因其严重影响装置的合理用能而不宜取,蒸发器的主要问题是在冷媒侧而非结构设计缺陷的结论。对装置同时做的能量分析和(火用)分析计算表明,前者仅给出能的数量利用分析,后者也只是对能量行为的静态分析,而(火用)传递分析由于是对过程能量行为的动态分析,可直接提供机组和设备的结构参数及随机运行工况对用能过程影响的新信息,从而为改进机组设计及指导装置运行提供具体意见。     

纵流壳程换热器性能研究

本文对纵流壳程换热器的流体力学和传热机理分别进行了理论探讨和实验研究，并编制了相应的计算机程序。研究结果表明，纵流壳程换热器较折流板换热器具有优异的流体力学和传热性能。     

基于热度曲线分类建模的微博热门话题预测

及时掌握大众关心的热点话题是企业进行商业创新和商务营销的重要前提。现有方法大都依赖于非结构化数据的处理或反复遍历样本集,使算法复杂性较高。文中从话题的统计特性出发,提出建立在结构化数据上的非参数方法。首先对单个话题构建表征话题传播扩散程度和关注聚焦程度的热度曲线;然后对这些形态丰富的热度曲线进行分类建模,得到不同类别曲线的共性特征及发展规律;最后使用分类模型上的加权投票规则预测新话题是否会发展成为热门话题。基于新浪微博平台进行数据收集和实验,结果表明该方法数据结构简单、效果良好、复杂度低且易于控制。     

Modeling a non-equilibrium distillation stage using irreversible thermodynamics

We compare transport equations derived from non-equilibrium thermodynamics to a classical rate model developed over the last 20 years, in terms of their ability to calculate the heat and mass fluxes by modeling a segment of a packed distillation column. We show, using water and ethanol separation as an example, that there is a significant coupling between heat and mass transfer. Neglect of this transport coefficient leads to variations in the magnitude, even the sign of the calculated heat flux, while the mass flux is less affected.