A thermal design method for the performance optimization of multi-stream plate-fin heat exchangers

Zhe Wang,Fenghui Han,Bengt Sundén,Yanzhong Li 대한기계학회 2017 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.31 No.6

An optimization design method based on field synergy principle is developed for Multi-stream plate-fin heat exchangers (MPHEs)with a segmented differential model. The heat exchanger is divided into a number of sub-exchangers along the main stream, and eachsub-exchanger consists of N passages along the height of the exchanger. Compared with the traditional heat exchanger design, this methodallows temperature and pressure fields to be obtained via coupling calculation with consideration of variable physical properties andthe axial heat loss of the heat exchanger. Finally, the heat exchanger is optimally designed using a temperature-difference uniformityoptimization factor based on field synergy principle. This design model can provide an accurate temperature field and pressure field,because the stream properties are determined by the mean temperature and pressure of each local sub-exchanger. Optimum results indicatethat the temperature distribution on the cross section of the heat exchanger is relatively uniform and that the temperature differenceof heat transfer for each stream is always a small value. These characteristics prove the feasibility and effectiveness of this design model. In this paper, a case of five stream plate-fin heat exchangers for an ethylene plant is designed under a practical cold box operating conditionwith the proposed model, the structure and heat transfer of which are optimally determined. The design model and optimizationmethod proposed in this work can provide theoretical and technical support to the optimization design of MPHEs.

The Complete Oxidation of Ethanol at Low Temperature over a Novel Pd-Ce/γ-Al₂O₃-TiO₂ Catalyst

Wang, Yanping,Zhao, Jinshuang,Wang, Xiaoli,Li, Zhe,Liu, Pengfei Korean Chemical Society 2013 Bulletin of the Korean Chemical Society Vol.34 No.8

Pd-$Ce/{\gamma}-Al_2O_3-TiO_2$ catalysts were prepared by combined sol-gel and impregnation methods. Transmission electron microscopy, X-ray diffraction, $H_2$-temperature-programmed reduction, $O_2$-temperature-programmed desorption, and ethanol oxidation experiments were conducted to determine the properties of the catalysts. Addition of an optimal amount of Ce improved the performance of the $Pd/{\gamma}-Al_2O_3-TiO_2$ catalyst in promoting the complete oxidation of ethanol. The catalyst with 1% Ce exhibited the highest activity, and catalyzed complete oxidation of ethanol at $175^{\circ}C$; its selectivity to $CO_2$ reached 87%. Characterization results show that addition of appropriate amount of Ce could enrich the PdO species, and weaken the Pd-O bonds, thus enhancing oxidation ability of the catalyst. Meanwhile, the introduction of $CeO_2$ could make PdO better dispersed on ${\gamma}-Al_2O_3-TiO_2$, which is beneficial for the improvement of the catalytic oxidation activity.

Microstructure-modified proton exchange membranes for high-performance direct methanol fuel cells

Wang, Manxiang,Liu, Guicheng,Tian, Zhe,Shao, Yingna,Wang, Lei,Ye, Feng,Tran, Minh Xuan,Yun, Yanbin,Lee, Joong Kee Elsevier 2017 Energy conversion and management Vol.148 No.-

<P><B>Abstract</B></P> <P>To lower methanol crossover and volume swelling degree, and to improve proton conductivity, a simple hot-mould-modifying method has been introduced to modify Nafion membrane for the direct methanol fuel cell application. To evaluate effect of the modification on properties of the Nafion membrane and fuel cell performance, a series of measurements of membranes and fuel cells have been carried out. The results show that, compared with the normal membrane, the modified Nafion membrane with regular spindle-type groove array possesses higher proton conductivity and methanol diffusion resistance, and 31.9% better dimensional stability, owing to its larger electrical double-layer capacitance come from the higher contact area between electron-electrode and ion electrolyte, and its more compact internal structure. And also, the direct methanol fuel cell based on the modified Nafion membrane shows 13.3% higher discharge power density and better long-time running performance than the normal one. Furthermore, this hot-mould-modifying method could be introduced into doping/coating-modified membranes reported in the current literature to further modify Nafion membranes, because this method is compatible with the current modifications.</P> <P><B>Highlights</B></P> <P> <UL> <LI> A simple hot-mould-modified Nafion membrane is used for direct methanol fuel cells. </LI> <LI> Regular spindle-type groove array is uniformly distributed on the membrane surface. </LI> <LI> Modification lowers methanol crossover, swelling, and improves proton conductivity. </LI> <LI> Power density and long-time running performance of fuel cells are improved visibly. </LI> <LI> This method provides a practicable way for direct methanol fuel cell applications. </LI> </UL> </P>

APPLICATIONS OF CALCIUM PHOSPHATE NANOPARTICLES IN POROUS HARD TISSUE ENGINEERING SCAFFOLDS

ZHE WANG,ZHURONG TANG,FANGZHU QING,YOULIANG HONG,XINGDONG ZHANG 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2012 NANO Vol.7 No.4

To repair bone defects, an important approach is to fabricate tissue engineering sca®olds as substitutions to replace auto-/allologous bones. Currently, processing a biomaterial into threedimensional porous sca®olds and incorporating the calcium phosphate (Ca?P) nanoparticles into sca®olds pro¯le two main characteristics of bone tissue engineering sca®olds. Based on this fact, in this paper we describe the design principles of the Ca?P nanoparticle-based and porous bone tissue engineering sca®olds. Then we summarize a variety of the Ca?P nanoparticle-based sca®olds, including discussion of the integration of the Ca?P nanoparticles with ceramics and polymers, followed by introduction of safety of the Ca?P nanoparticles in scaffolds.

Anti-androgen receptor signaling and prostate cancer inhibitory effects of sucrose- and benzophenone-compounds.

Wang, Zhe,Lee, Hyo-Jeong,Wang, Lei,Jiang, Cheng,Baek, Nam-In,Kim, Sung-Hoon,L?, Junxuan Kluwer Academic/Plenum Publishers 2009 Pharmaceutical research Vol.26 No.5

<P>Novel agents that target multiple aspects of androgen receptor (AR) signaling are desirable for chemoprevention and treatment of prostate cancer (PCa). We aimed to identify compounds isolated from medicinal herbs as such drug candidates.</P>

Analysis and Optimization of Fault Tolerant Permanent Magnet Vernier Rim Driven Machine Based on the Continuous Variable Magnetic Network Model

Wang Zhe,Zhu Jingwei,He Wangsong,Yue Jiubo,Zhao Tianrui 대한전기학회 2024 Journal of Electrical Engineering & Technology Vol.19 No.5

Aiming at the time-consuming issue of traditional fi nite element analysis (FEA) method machine design and optimization, and the infl exibility of machine parameter verifi cation, an analysis and optimization method for the design of a fault tolerant permanent magnet vernier rim driven machine (FTPMV-RDM) based on the continuous variable magnetic network model (CVMNM) is proposed. The machine is modeled by the method using a combination of fl ux path and cross-shaped mesh, with full consideration of the eff ects of permanent magnet leakage and machine core saturation. Meanwhile, the connection relationship between the stator and rotor models can be continuously varied to simulate the rotation of the machine. The continuous variable magnetic network model is further combined with the Non-dominated Sorting Genetic Algorithm II (NSGA-II) for the optimal design of the machine. Compared to the conventional FEA method, the proposed model reduces the computation time without sacrifi cing accuracy in both no-load and loaded magnetic fi eld calculations. Finally, the experimental results verify the accuracy and eff ectiveness of the method proposed in this paper.

On Lateral Buckling of Subsea Pipe-in-pipe Systems

Zhe Wang,Zhi-Hua Chen,Hongbo Liu 한국강구조학회 2015 International Journal of Steel Structures Vol.15 No.4

Lateral buckling is a common phenomenon in unburied high temperature and high pressure (HT/HP) subsea pipe-in-pipe systems. An effective finite element model based on beam element and tube-to-tube contact element is proposed to study lateral buckling in pipe-in-pipe systems, in which the initial imperfection (out-of-straightness), nonlinear pipe-soil interaction and nonlinear material properties are considered. The results show that it is the resultant axil force of the inner and outer pipe that governs the lateral buckling phenomenon in pipe-in-pipe systems. The initial imperfection and pipe-soil interaction are the most important factors which influence evolution of the displacement and stress in pipe-in-pipe systems. Nonlinear material properties are necessary when plastic strain may occur in post-buckling stage. At last, a simplified model is proposed which can easily calculate the critical buckling temperature of the corresponding pipe-in-pipe system.

Leader-following Non-fragile Consensus Control of Fuzzy Multi-agent Fractional Order Interval Systems

Zhe Wang,Dingyu Xue,Xuefeng Zhang,Qing-Guo Wang 제어·로봇·시스템학회 2024 International Journal of Control, Automation, and Vol.22 No.2

The consensus control of fuzzy multi-agent fractional order interval systems (MA-FOISs) is proposed in this brief. Firstly, a new model of fuzzy MA-FOISs based on the non-fragile observer is presented. Then, by using the technologies of generalised matrix singular value decomposition (SVD) and linear matrix inequalities (LMIs), the sufficient conditions for determining the consensus of fuzzy MA-FOISs are given through the equivalence of the stability and the consensus of multi-agent systems (MASs). Moreover, when the actual system does not need to be described by the fuzzy set, the consensus conditions for the MA-FOISs are given. Finally, the validity of the results given are illustrated by the numerical example.

Studies on Purification of 1,3-propanediol by Molecular Distillation

Zhe Wang,Zhe Wu,Tianwei Tan 한국생물공학회 2013 Biotechnology and Bioprocess Engineering Vol.18 No.4

The separation of 1,3-propanediol using molecular distillation has been studied. The effects of operating temperature and feed flow rate through a sequential distillation strategy were investigated. The optimal experimental temperature was at 70oC for separating 1,3-propanediol and the by-product 2,3-butanediol. Meanwhile, the volume flow rate was 10 mL/min. As a result, the recovery of 1,3-propanediol and 2,3-butanediol were 87.6 and 87.5%,respectively. Furthermore, the integrated separation characteristic of 1,3-propanediol was evaluated through macrolevel and micro-level models. The separation factors of 1,3-propanediol versus 2,3-butanediol and glycerol were 0.11 and 1.07, respectively, affirming that the separation of 1,3-propanediol by molecular distillation was feasible.

Leaching characteristics and curing mechanism of magnesium phosphate cement solidified zinc-contaminated soil in an acid rain environment

Zhe Wang,Hangjun Zhu,Xuehui Wu,Binpin Wei,Hongli Zhou,Sifa Xu 대한환경공학회 2021 Environmental Engineering Research Vol.26 No.4

A semi-dynamic leaching test was used to simulate the erosion effect of acid rain on magnesium phosphate cement (MPC)-stabilized/solidified zinc-contaminated soil. The leaching characteristics and curing mechanism were studied with a combination of X-ray diffraction (XRD) and scanning electron microscopy (SEM). Influences of the initial pH value of the simulated acid rain, the ratio of the curing agent (MgO/KH₂PO₄, abbreviated M/P), and the mass of water glass on the leaching characteristics of Zn<SUP>2+</SUP> and conductivity in the leachate of the sample were studied. It is shown that the curing effect of the cement component on Zn<SUP>2+</SUP> is better for M/P = 6 when compared to M/P = 4 in a strong acid environment. While in a weak acid environment, it is observed that the curing effect is superior when M/P = 4. Also it is observed that 4% water glass content can effectively improve the cement curing effect of heavy metal Zn in an acid rain environment. These results indicate that water glass can be effectively applied to MPC solidified heavy metal Zn.