Thermal and rheological effects in a classical Graetz problem using a nonlinear Robertson-Stiff fluid model

The present article elaborates the Graetz problem for the Robertson-Stiff fluid model with imposed iso-thermal conditions. The closed-form expression of Robertson-Stiff fluid velocity is obtained. Employing the classical separation of variables approach, the energy equation of the said problem is reduced into an eigenvalue problem. The solution of the eigenvalue problem is developed numerically via the MATLAB built-in algorithm BVP4C. The constants appearing in series solutions are computed by Simpson's rule. The special case of this analysis with appropriate scaling is also applicable for the Bingham, power-law, and Newtonian fluid models. The impact of the dissipation function on Nusselt numbers and mean temperature is also considered. The pictorial representation of average temp7erature and Nusselt number are discussed in the presence of the plug radius, power-law index, and Brinkman number. It is observed that the presence of the plug radius and power-law index delay the prevalence of fully developed conditions for the Nusselt number. Moreover, the local Nusselt number for channel confinement attains higher values as compared with tube confinement. The present investigation has numerous applications in the field of engineering, nanotechnology, biomedical sciences, and development of several thermal types of equipment or microfluidic devices.     

浅谈军用空调制冷系统管路抗振动、抗冲击工艺措施

本文介绍了军用空调制冷系统管路存在的常见管路断裂问题,并对系统管路出现的断裂缺陷进行了详细的原因分析,由此提出解决该问题的相应工艺措施。将该工艺措施用于实际生产,并生产出多品种、大批量的产品。     

复建超高层建筑的混凝土运输研究

以广州城际中心工程为例,介绍了已局部建成运营的超高层建筑在后期复建过程中,混凝土输送方式的选择以及在已建成运营楼层区域内混凝土输送管道的布置。实践证明,所述的混凝土运输方案有较好的可行性,可为同类型工程提供参考和经验借鉴。     

A 3E,hydrogen production,irrigation, and employment potential assessment of a hybrid energy system for tropical weather conditions – Combination of HOMER software,shannon entropy,and TOPSIS

The increasing threat to environmental sustainability as a result of greenhouse gas (GHG) emissions from fossil fuel base power plants has necessitated the need to find sustainable energy sources to meet the world's energy demands. This study focuses on assessing the potential of a hybrid power plant for the production of electricity, hydrogen for the production of fertilizer for agricultural activities, farmland irrigation, environmental impact as well as its employment potential in northern Ghana. The Shannon entropy weight and TOPSIS multi-criteria decision-making approach were adopted to rank and identify the optimal configuration out of five possible options for the study area. Results from the simulation show that the winning system, i.e., Hydro + Battery system would generate a total electricity of 1,095,679 kWh/year. A cost of electricity of 0.06 $/kWh with an operating cost (OC) of $18,318 was recorded for the winning system. The total produced hydrogen by the optimum configuration is 8816 kg/year at a levelized cost of hydrogen (LCOH) of 4.47 $/kg. The quantity of low-carbon fertilizer that can be produced from the produced hydrogen is also assessed. The optimum configuration also recorded an employment potential of 4 persons in 25 years. A total GHG equivalence of 383.49 metric tons of CO₂ equivalent indicating the level of emissions that will be avoided should the optimum system be used to meet the demands specified in this study was obtained.     

乙烯-乙酸乙烯酯共聚物Levapren 800硫化胶溶度参数的测定及应用

采用溶胀实验及计算机HSPiP软件对牌号为Levapren 800的乙烯-乙酸乙烯酯硫化胶的溶度参数进行了研究。结果表明,单一溶剂与混合溶剂都可用于Levapren 800硫化胶溶度参数的测定,用溶胀法测得其一维溶度参数(δt)为18.90~19.25(J/cm3)1/2。通过HSPiP软件测得Levapren 800硫化胶的δt为19.97(J/cm3)1/2;三维溶度参数的色散力、极性力和氢键力溶度参数分别为18.20,5.50,6.10(J/cm3)1/2。利用三维溶度参数可以预测Levapren 800硫化胶在标准实验油中的溶胀行为;相对能量差对预测聚合物在溶剂中的溶胀性能方面具有一定的应用价值。     

乙苯负压脱氢制苯乙烯大型实验装置自动控制系统设计

随着我国高等学校各项建设工作的大力推进,实验设备的需求也逐渐丰富起来。传统的化学工程专业实验设备的控制简单,与现今的大工业生产的装置自动化程度相比,有一定的脱节。这对于高校培养具有创新能力的"技术型"和"应用型"人才是不利的。华东理工大学化工学院的化学工程与工艺专业实验中心自主设计具有计算机控制的,能适应本专业学生的大型化工流程实验装置——乙苯负压脱氢制苯乙烯装置,运用MCGS工控组态软件对乙苯负压脱氢制苯乙烯装置进行自动控制系统的设计,实现了对脱氢装置的实验过程的监控,从而达到了实验的要求。     

离心泵与滑片泵流量脉动特性及串联实验研究

对离心泵和滑片泵的流量脉动特性进行研究,探讨两泵串联运行的可行性。然后建立以离心泵为前级泵、滑片泵为后级泵的串联实验平台,通过改变串联中间管路阻力和滑片泵的出口管路阻力对滑片泵的运行特性进行实验研究,实验结果表明:泵与管路所构成的系统流量小于或接近滑片泵的理论流量时,系统才能正常工作,否则会造成整个系统的流量和压力脉动;不可改变串联中间管路阻力,以免滑片泵偏离正常工作状态;可通过改变滑片泵的出口管路阻力调整泵和系统运行参数。     

浅谈油品减阻剂的发展现状及趋势

油品减阻剂具有用量小、效果显著、对油品性质影响小等优势,因此对减阻剂的研究显得尤为重要,文章主要介绍了油品减阻剂的分类、减阻机理及其影响因素,同时对其发展趋势进行了展望。     

天然气管道带压开孔施工技术

介绍了天然气管道带压开孔施工的原理,阐述了天然气管道带压开孔的工艺与施工过程,对类似工程的施工提供一定的参考作用。     

基于ASPEN PLUS的磷酸二铵装置尾气洗涤及余热回收研究

利用脱盐水间接冷凝尾气中的水蒸气以减少白雾的排放和回收尾气的低温位余热,同时使用ASPEN PLUS软件对尾气洗涤塔及余热回收过程进行模拟。结果表明,该软件模拟结果与现场测量参数较为吻合,可用于指导生产,并为装置改造提供依据。