Uniformity principle of temperature difference field in heat transfer optimization

The uniformity principle of temperature difference field is very useful in heat exchanger analyses and optimizations.In this paper, we analyze some other heat transfer optimization problems in the thermal management system of spacecrafts,including the cooling of thermal components, the one-stream series-wound heat exchanger network, the volume-to-point heat conduction problem, and the radiative heat transfer optimization problem, and have found that the uniformity principle of temperature difference field also holds. When the design objectives under the given constraints are achieved, the distributions of the temperature difference fields are uniform. The principle reflects the characteristic of the distribution of potential in the heat transfer optimization problems. It is also shown that the principle is consistent with the entransy theory. Therefore, although the principle is intuitive and phenomenological, the entransy theory can be the physical basis of the principle.

Dynamical Model to Optimize Student’s Academic Performance

Excellent student’s academic performance is the uppermost priority and goal of educators and facilitators.The dubious marginal rate between admission and graduation rates unveils the rates of dropout and withdrawal from school.To improve the academic performance of students,we optimize the performance indices to the dynamics describing the academic performance in the form of nonlinear system ODE.We established the uniform boundedness of the model and the existence and uniqueness result.The independence and interdependence equilibria were found to be locally and globally asymptotically stable.The optimal control analysis was carried out,and lastly,numerical simulation was run to visualize the impact of the performance index in optimizing academic performance.

多股流换热器设计的量纲1温差场均匀性优化因子

The concept of dimensionless temperature-difference uniformity optimization factor was proposed.The application of this factor to path arrangement was studied.The study showed that dimensionless temperature-difference uniformity optimization factor was an effective evaluation criterion of path arrangement of multi-stream heat exchangers and the design of multi-stream heat exchangers could be guided by this factor.

一种基于属性分布的非均匀油藏数值模拟网格优化算法

油藏数值模拟是油气田勘探开发的基础,三维地质网格模型是数值模拟的基础数据之一,网格的数量和大小决定了数值模型的精细程度,同时也影响了数值模拟的效率。为了有效保证地质模型的准确性,又可以提高数值模拟的效率,借鉴自适应网格法的思想,提出了一种改进的不均匀网格优化方法。该方法在储层物性非均质性强烈或重点研究区域采用细网格,而在储层物性均质性相对较好的区域采用粗网格,相邻粗、细网格间均匀渐变过渡。首先,设计了网格优化的基本原则;随后,在网格优化基本原则的基础之上,设计并实现了一种改进的不均匀网格优化算法;最后,以陕西省X区油田实例数据对算法的有效性和准确进行了验证。结果表明:该算法可以实现网格的均匀渐变过度,既有效减少了网格数量,又很好的保证了模型的精确度。

关于企业标准化的工作原则的研究

古往今来,标准化伴随着人类的发展史而成长从未间断,秦始皇统一度量衡更是在中国古代为科技文化的迅速传播发展提供了良好的基础。当下,伴随着科学技术的高度发达、生产的社会化全球化程度越来越高和生产规模越来愈大的大环境下,企业的标准化程度几乎可以代表着一个企业的成熟与否。企业标准化在企业的生产、经营和管理等活动中都具有极其重要的作用,是企业现代化管理的重要组成部分和技术基础。那么,在企业标准化工作中,如何合理的选择和利用简化、统一化、通用化和系列化等标准化常用的几种形式,最终形成属于企业自己的标准化工作基本准则,就是本文所要研究的对象。

最小热阻原理在组合式相变材料蓄热过程优化中的应用

最小热阻原理为近年来火积理论中所提出的传热过程优化的新方法.本文基于最小热阻原理对组合式相变材料蓄热过程进行了优化.通过变分原理,获得了组合式相变材料最佳融化温度的通用表达式.在此基础上,进一步研究了相变材料数对火积耗散热阻和蓄热性能的影响,探讨了最小热阻原理用于组合式相变材料蓄热过程优化的可行性.定义了组合效率,考察了传热单元数和热容流率对火积耗散热阻的影响.结果表明,组合效率随相变材料数的增加逐渐提高,火积耗散热阻随传热单元数和热容流率的增加逐渐降低其提高与降低的幅度均逐渐减弱,该研究为组合式相变材料的遴选以及流动和结构参数的设计提供了理论指导.此外,基于最小热阻原理的优化分析,提出了相变蓄热过程的温差场均匀性原则,为组合式相变材料的优化提供了一种新的优化标准.

直接接触式换热器传热性能多目标优化

直接接触式换热器传热性能研究对中低温余热的高效利用起着决定性作用.本研究通过控制分散相和连续相初始温差和流率比,研究了不同初始温差和流率比对连续相和分散相出口温度、温差场均匀性因子、(火积)耗散、容积换热系数的影响,建立了(火积)耗散、温差场均匀性、容积换热系数的多指标评价模型.研究发现:蒸发器在恒温状态下,初始温差增加,容积换热系数和系统的(火积)耗散也随之增加.研究表明:当初始温差为100℃,流率比为6∶1时,系统的(火积)耗散最小,传热不可逆性较小,容积换热系数最大.多目标评价为蒸发器优化提供了指导意义.