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1.
Ruixiang Yi Chao Chen Chen Shi Yuxiang Li Haijun Li Yibo Ma 《Ceramics International》2021,47(15):20807-20820
Brazing, as a common method of bonding ceramic and metal, has been applied in microelectronics, aerospace, machinery and other domains extensively. The residual thermal stress in the brazed joint has direct effects on the mechanical properties of the joint, so how to control the generation of residual thermal stress has become the vital point. In this paper, the methods of reducing residual thermal stress in the brazing process in recent years are reviewed. The generation and effects of residual thermal stress in the brazed joint are introduced. Besides, the methods of detecting residual thermal stress are discussed, and different methods of reducing residual thermal stress in brazed joints are also analyzed. Finally, the future development directions of reducing residual thermal stress in the brazed joint are proposed. 相似文献
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3.
《International Journal of Hydrogen Energy》2022,47(10):6508-6518
Municipal solid waste steam gasification and direct melting system is proposed in this study for H2 production and ash melting simultaneously. Part of the H2 generated in gasification is extracted for combustion with pure oxygen in the melting zone to provide the energy necessary for auto-thermal operation. A simulation model is developed with Aspen Plus to investigate the performance and optimum conditions of the system. For the feedstock with a lower heating value of 18.91 MJ/kg used in this study, 39.8% of the generated H2 needs to be extracted to maintain the heat balance of the system at the gasification temperature of 900 °C, melting temperature of 1400 °C, and S/M of 1. The net H2 yield is ~77.3 kg/t-MSW with a net cold gas efficiency of 49.1% under the same operating condition. An optimum operation condition for T (850–1000 °C) and S/M (0.6–1.0) is determined considering the balance between H2 production ability and the auto-thermal energy balance. 相似文献
4.
In process industry, predictive control approaches have been widely used for nonlinear production processes. Practically, the predictor in a predictive controller is extremely important since it provides future states for the optimization problem of controllers. The conventional predictive controller with precise mathematical predictors approximating the state space of physical systems is difficult and time-consuming for nonlinear production processes, and it performs poorly over a wide range of working conditions and with significant disturbances. To address the challenges, the trend of applying artificial intelligence emerges. However, the industrial process-specific knowledge is ignored in most cases. In this study, a predictive controller with a control process knowledge-based random forest (RF) model is proposed. Specifically, working data are clustered at first to handle diverse working conditions. Then, a process knowledge-based forest predictor, namely MIW-RF model with a redesigned cascading RF structure, is proposed to incorporate control process knowledge into modeling. Thus, future states of controlled variables could be more accurately acquired for the optimizer. A simplified version of the predictive model is also developed with quick model training and updating. The proposed predictive methods are finally introduced into the controller design. According to the empirical results, the proposed methods deliver a better control performance against benchmarks, including more accurate anticipated controlled-variable responses, better set-point tracking and disturbance rejection capability. 相似文献
5.
《International Journal of Hydrogen Energy》2022,47(18):10137-10155
In this work, hydrate based separation technique was combined with membrane separation and amine-absorption separation technologies to design hybrid processes for separation of CO2/H2 mixture. Hybrid processes are designed in the presence of different types of hydrate promoters. The conceptual processes have been developed using Aspen HYSYS. Proposed processes were simulated at different flow rates for the feed stream. A comprehensive cost model was developed for economic analysis of novel processes proposed in this study. Based on the results from process simulation and equipment sizing, the amount of total energy consumption, fixed cost, variable cost, and total cost were calculated per unit weight of captured CO2 for various flow rates of feed stream and in the presence of different hydrate promoters. Results showed that combination of hydrate formation separation technique with membrane separation technology results in a CO2 capture process with lowest energy consumption and total cost per unit weight of captured CO2. As split fraction and heat of hydrate formation increases, the share of hydrate formation section in total energy consumption increases. When TBAB is applied as hydrate promoter, due to its higher hydrate separation efficiency, more amount of CO2 is captured in hydrate formation section and consequently the total cost for process decreases considerably. Hybrid hydrate-membrane process in the presence of TBAB as hydrate promoter with 29.47 US$/ton CO2 total cost is the best scheme for hybrid hydrate CO2 capture process. Total cost for this process is lower than total cost for single MDEA-based absorption process as the mature technology for CO2 capture. 相似文献
6.
Increasing the reaction temperature of the living cationic polymerization of isobutylene is crucial for industrial production due to the cost of refrigeration. The reaction temperature increase was achieved with an accelerated reaction rate using a flow reaction system. The polymerization conditions, including the flow reactor design, were based on the results of kinetic studies. Utilizing a milli‐scale flow reactor, polyisobutylene, which has a narrow molecular weight distribution, was obtained within a considerably short residence time at a high temperature. Furthermore, it was confirmed that the value of Mw/Mn correlates with the product of the Reynolds number and the angle of collision. 相似文献
7.
The performance of the Taylor‐Couette flow apparatus as a heat sterilizer is numerically investigated. The destruction of Clostridium botulinum and thiamine (vitamin B1) was selected as model reaction. When Taylor vortices were formed in the annular space, the heat transfer significantly enhanced as compared to the case without vortex flow. As a result, the equivalent lethality calculated from the temperature field increased, which is regarded as a quantum leap. Conversely, the improvement of heat transfer induced destruction of thiamine. These results suggest that there is a trade‐off relationship between the enhancement of heat transfer and the avoidance of thermal destruction of nutritional components. In conclusion, the Taylor‐Couette flow sterilizer has the potential for process intensification in heat sterilization processes. 相似文献
8.
The concept of process intensification(PI) has absorbed diverse definitions and stays true to the mission—"do more with less", which is an approach purposed by chemical engineers to solve the global energy environment problems. To date, the focus of PI has been on processes mainly involving vapor/liquid systems. Based on the fundamental principles of vapor–liquid mass transfer process like distillation and absorption, there are three strategies to intensify interphase mass transfer: enhancing the overall driving force, improving the mass transfer coefficient and enlarging the vapor–liquid interfacial area. More specifically, this article herein provides an overview of various technologies to strengthen the vapor–liquid mass transfer, including application of external fields, addition of third substances, micro-chemical technology and usage of solid foam, with the objective to contribute to the future developments and potential applications of PI in scientific research and industrial sectors. 相似文献
9.
Yumeng Zhang Yudan Zhu Anran Wang Qingwei Gao Yao Qin Yaojia Chen Xiaohua Lu 《中国化学工程学报》2019,27(6):1403-1415
In modern chemical engineering processes, solid interface involvement is the most important component of process intensification techniques, such as nanoporous membrane separation and heterogeneous catalysis. The fundamental mechanism underlying interfacial transport remains incompletely understood given the complexity of heterogeneous interfacial molecular interactions and the high nonideality of the fluid involved. Thus, understanding the effects of interface-induced fluid microstructures on flow resistance is the first step in further understanding interfacial transport. Molecular simulation has become an indispensable method for the investigation of fluid microstructure and flow resistance. Here, we reviewed the recent research progress of our group and the latest relevant works to elucidate the contribution of interface-induced fluid microstructures to flow resistance.We specifically focused on water, ionic aqueous solutions, and alcohol–water mixtures given the ubiquity of these fluid systems in modern chemical engineering processes. We discussed the effects of the interfaceinduced hydrogen bond networks of water molecules, the ionic hydration of ionic aqueous solutions, and the spatial distributions of alcohol and alcohol–water mixtures on flow resistance on the basis of the distinctive characteristics of different fluid systems. 相似文献
10.
《Journal of the European Ceramic Society》2019,39(11):3364-3372
This research addresses the residual stresses phenomenon taking place during the manufacture of porcelain tiles. Residual stresses were quantified by the strain relaxation slotting method. The method is based on the fact that stresses are released when a slot is made leading to a curvature change.Once the method was validated, the impact of process variables such as starting body composition, temperature and cooling rate of firing cycle was investigated. Findings showed that cooling rate was the most influencing variable whereas Young’s modulus of fired specimens also play a significant role. Symmetry of the parabolic residual stress profile denoted homogenous cooling on upper and lower tile surfaces during the cooling step. In addition, it was observed that polishing of a stressed tile gives rise to a decreasing of deformation as a consequence of stress release by mechanical grinding. 相似文献