丙烯酸缩水甘油酯的合成工艺改进

采用充分干燥的丙烯酸钠盐为原料和减压抽滤的后处理方法,对传统丙烯酸缩水甘油酯合成工艺进行改进。探讨了丙烯酸钠纯度、含水量、催化剂及阻聚剂品种、反应条件、减压抽滤时蒸馏压力等因素对丙烯酸缩水甘油酯收率的影响。结果表明,当丙烯酸钠纯度99％以上,含水量小于0．5％,十六烷基三甲基溴化铵为催化剂,对苯二酚为阻聚剂,环氧氯丙烷与丙烯酸钠摩尔比为4．5：1,反应温度100～105℃,反应时间2．5h,减压蒸馏压力0．097MPa时,丙烯酸缩水甘油酯收率达92％以上。     

Constructal optimization for an organic fluid shell-and-tube condenser based on entransy theory

A complex function composed of linear weighted sum of the entransy dissipation rate (EDR) caused by heat transfer and total pumping power is established in this paper. Under the conditions of fixed total condensation rate and heat transfer area, constructal optimization of a shell-and-tube condenser (STC) with organic fluid is carried out by taking minimum complex function as optimization objective. The minimum complex function and the optimal external diameter of the condensation tube are obtained. The results show that compared with the initial design construct, the optimal construct of the STC increases the total EDR caused by heat transfer by 10.70%, and reduces the total pumping power and complex function by 54.94% and 6.46%, respectively. This illustrates that the complex function sacrifices a certain heat transfer performance, and improves the fluid flow performance evidently, which leads to the overall performance improvement of the STC. The twice minimization of the complex function can be realized by choosing an appropriate number of the condensation tubes. New guidelines for the optimal structure designs of the STCs are provided by introducing entransy theory into constructal optimizations of the organic fluid STCs, and this method can be further extended to the optimal designs of the cycle systems with organic fluids.     

浅谈虚拟样机建造过程中零部件的二次加工问题

在建造虚拟样机的工程实践中,提出了研究零部件二次加工问题的必要性,并分析了二次加工的常见形式、信息来源、检验手段、实施环境以及模型保存等一系列实用问题,对虚拟样机建造有一定指导或参考价值。     

人为粗糙度强化换热技术研究概述

人为粗糙度强化换热技术的研究既具有重要的理论意义又具有广阔的应用前景,经过长期的研究和探索,人们对它的认识不断加深,研究范围不断扩大。对人为粗糙度强化换热技术的机理进行了分析,对其研究和应用现状进行了综述。     

基于子结构阻抗匹配与优化拟合的高精度磨床整机动力学建模研究

基于分布质量 Riccati传递矩阵法和有限元法 ,分析了高精度内圆磨床的自由转子和由床身、工作台等部件所组成的基础的动态性能。根据阻抗匹配原理 ,建立了由转子—轴承—基础所组成的整机动力学模型。通过整台机床的试验模态分析 ,采用参数优化拟合修正动力学模型 ,并计算出滚动轴承刚度 ,为整机动态性能分析优化奠定基础。     

齿轮啮合沿齿面油膜厚度的分布

总结了齿轮啮合时油膜厚度分析计算的方法,并对一般机械工业中重合度ε＞1,即存在两齿啮合的普遍情况的油膜厚度进行了分析计算,得到了齿轮传动沿啮合线的油膜压力、油膜形状,为齿轮传动的失效分析和摩擦学设计提供分析计算基础.     

Efficient approach for dynamic simulation of complex fluid networks in frequency domain

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含H_2O气氛下Cu液中Ti的氧化SCIEI

本文研究了1500℃H_2O气氛下液态Cu合金中Ti的氧化。     

Theoretical model of a drying system including turbulence aspects

Biological products contain high moisture content in the harvest period. Such moisture could cause their deterioration in storage. Drying is an interesting solution to keep the quality of these products. Generally, drying process is based on contact of a dry air phase with a wet solid. A theoretical model was developed to describe the dynamic behavior of a forced convection drying process. This model takes into account the entire dynamic phenomenon including turbulence, diffusivity and tortuosity effects. Only the mass transfer of water molecules during vaporization was referred to as an empirical expression. The model thus strongly build, was compared to Thompson’s empirical model. Corn grain was used in the validating process. Transient temperature and water content results are presented.