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Thermally developing forced convection and the corresponding thermal stresses in a porous plate channel

YANG Xiao, LIU Xuemei

《机械工程前沿(英文)》 2007年 第2卷 第1期   页码 57-61 doi: 10.1007/s11465-007-0009-7

摘要: Based on the Darcy fluid model, by considering the effects of viscous dissipation due to the interaction between solid skeleton and pore fluid flow and thermal conduction in the direction of the fluid flow, the thermally developing forced convection of the local thermal equilibrium and the corresponding thermal stresses in a semi-infinite saturated porous plate channel are investigated in this paper. The expressions of temperature, local Nusselt number and corresponding thermal stresses are obtained by means of the Fourier series, and the distributions of the same are also shown. Furthermore, influences of the P晱let number () and Brinkman number () on temperature, Nusselt number () and thermal stress are revealed numerically.

关键词: semi-infinite saturated     direction     interaction     skeleton     thermal equilibrium    

Thermodynamic analysis of reaction pathways and equilibrium yields for catalytic pyrolysis of naphtha

《化学科学与工程前沿(英文)》 2022年 第16卷 第12期   页码 1700-1712 doi: 10.1007/s11705-022-2207-6

摘要: The chain length and hydrocarbon type significantly affect the production of light olefins during the catalytic pyrolysis of naphtha. Herein, for a better catalyst design and operation parameters optimization, the reaction pathways and equilibrium yields for the catalytic pyrolysis of C5–8 n/iso/cyclo-paraffins were analyzed thermodynamically. The results revealed that the thermodynamically favorable reaction pathways for n/iso-paraffins and cyclo-paraffins were the protolytic and hydrogen transfer cracking pathways, respectively. However, the formation of light paraffin severely limits the maximum selectivity toward light olefins. The dehydrogenation cracking pathway of n/iso-paraffins and the protolytic cracking pathway of cyclo-paraffins demonstrated significantly improved selectivity for light olefins. The results are thus useful as a direction for future catalyst improvements, facilitating superior reaction pathways to enhance light olefins. In addition, the equilibrium yield of light olefins increased with increasing the chain length, and the introduction of cyclo-paraffin inhibits the formation of light olefins. High temperatures and low pressures favor the formation of ethylene, and moderate temperatures and low pressures favor the formation of propylene. n-Hexane and cyclohexane mixtures gave maximum ethylene and propylene yield of approximately 49.90% and 55.77%, respectively. This work provides theoretical guidance for the development of superior catalysts and the selection of proper operation parameters for the catalytic pyrolysis of C5–8 n/iso/cyclo-paraffins from a thermodynamic point of view.

关键词: naphtha     catalytic pyrolysis     reaction pathway     equilibrium yield    

Measurement and correlation of the solid-liquid equilibrium of 2-(

Yanhong SUN, Zhiyong LI, Chuang XIE, Wei CHEN, Cui ZHANG

《化学科学与工程前沿(英文)》 2013年 第7卷 第1期   页码 110-115 doi: 10.1007/s11705-013-1316-7

摘要: In this work, the enthalpy of fusion and melting points of 2-( -butyl)-5-methylphenol (2B5MP) and 2-( -butyl)-4-methylphenol (2B4MP) were measured by differential scanning calorimetry (DSC). The binary solid-liquid equilibrium (SLE) of both compounds were predicted by integrated computer aided system (ICAS) and measured by DSC. The corresponding eutectic molar composition is 0.6998 and the eutectic temperature is 281.96 K. The quasi-static heat capacities of 2B5MP and 2B4MP were evaluated by stochastic temperature modulation DSC technique (TOPEM). The SLE experimental data were correlated using the Margules, Wilson, and non-random two liquid (NRTL) equations and a good agreement between measurement and calculation could be obtained.

关键词: solid-liquid equilibrium (SLE)     eutectic     integrated computer aided system (ICAS)     TOPEM     correlation    

Brown marine algae turbinaria conoides as biosorbent for Malachite green removal: Equilibrium and kinetic

R. RAJESH KANNAN, M. RAJASIMMAN, N. RAJAMOHAN, B. SIVAPRAKASH,

《环境科学与工程前沿(英文)》 2010年 第4卷 第1期   页码 116-122 doi: 10.1007/s11783-010-0006-7

摘要: In this study, the biosorption of Malachite green (MG) onto Turbinaria conoides, brown marine algae, was studied with respect to initial pH, temperature, initial dye concentration, and sorbent dosage. The optimum initial pH and temperature values for MG removal were found to be 8.0 and 30°C, respectively. Sorbent dosage was found to strongly influence the removal of MG. Equilibrium studies were carried out to test the validity of the Langmuir ( = 66.6 mg/g and = 0.526 mL mol/L) and the Freundlich ( = 1.826 and = 3.751 mg/g) isotherms. The kinetic studies indicated the validity of the pseudo first-order and second-order equation.

关键词: Malachite green (MG)     Turbinaria conoides     marine algae     equilibrium studies     biosorption    

Non-equilibrium model for catalytic distillation process

WANG Feng, ZHAO Ning, LI Junping, XIAO Fukui, WEI Wei, SUN Yuhan

《化学科学与工程前沿(英文)》 2008年 第2卷 第4期   页码 379-384 doi: 10.1007/s11705-008-0071-7

摘要: A new improved tri-diagonal method was developed for the non-equilibrium stage model of the catalytic distillation by coupling consumptive reaction coefficient. The reactions in the distillation column were divided into generative reaction and consumptive reaction. The non-equilibrium stage model was introduced for the catalytic distillation process of the dimethyl carbonate (DMC) synthesis by urea methanolysis over solid based catalyst, and the improved tri-diagonal method was used to solve the model equations. Comparison of predicted results with experiment data shows that the mean relative error of the yield of DMC was 3.78% under different conditions such as different operating pressures and reaction temperatures. The improved tri-diagonal matrix method could avoid the negative values of the liquid compositions during the calculations and restrain the fluctuation of compositions by slowing down the variations of the values in the iteration. The modeling results show that the improved tri-diagonal method was appropriate for system containing a wide range of boiling point components and a different rate of reactions.

into nitrogen and sulfur co-doped carbon nanotubes for effective desulfurization of liquid phases: Equilibrium

《环境科学与工程前沿(英文)》 2021年 第15卷 第5期 doi: 10.1007/s11783-021-1397-3

摘要:

• Synthesis of NS-CNTS is used in a high desulfurization performance.

关键词: Dibenzothiophene (DBT)     Tertiary methyl mercaptan     Adsorption     Carbon nano tube (CNT)     Desulfurization     Doping    

Removal of Rhodamine B from aqueous solutions and wastewater by walnut shells: kinetics, equilibrium

Jasmin Shah, M. Rasul Jan, Attaul Haq, Younas Khan

《化学科学与工程前沿(英文)》 2013年 第7卷 第4期   页码 428-436 doi: 10.1007/s11705-013-1358-x

摘要: An adsorption study of Rhodamine B (RB) dye from aqueous solutions was carried out using walnut shells pretreated by different methods. In addition to the effects of the pretreatment, the effects of various parameters like pH, adsorbent dose, contact time, initial dye concentration and temperature on the adsorption of RB was studied. The adsorption process was highly pH dependent and a maximum adsorption was achieved at pH 3.0. The best fit for the rates of dye adsorption was a pseudo-second-order kinetic model with good correlation coefficients ( >0.99). Langmuir isotherms were used to determine that the maximum loading capacity of the different walnut shells and the RB capacities ranged from 1.451–2.292 mg·g . The dye adsorption was also evaluated thermodynamically. Positive standard enthalpy (? °) values were obtained indicating that the RB adsorption process is endothermic as well as ? ° and ? ° values showed that adsorption process is spontaneous with an increased randomness at the solid-liquid interface. Desorption studies were carried out to explore the feasibility of regenerating the used walnut shells and it was found that 97.71%–99.17% of the retained RB was recovered with 0.1 mol?L NaOH solution. The walnut shells were also successfully used to remove RB from industrial effluents.

关键词: Rhodamine B     walnut shell adsorption     kinetics     isotherms     regeneration    

Influence evaluation of loading conditions during pressurized thermal shock transients based on thermal-hydraulics

Jinya KATSUYAMA, Shumpei UNO, Tadashi WATANABE, Yinsheng LI

《机械工程前沿(英文)》 2018年 第13卷 第4期   页码 563-570 doi: 10.1007/s11465-018-0487-9

摘要:

The thermal hydraulic (TH) behavior of coo-lant water is a key factor in the structural integrity assessments on reactor pressure vessels (RPVs) of pressurized water reactors (PWRs) under pressurized thermal shock (PTS) events, because the TH behavior may affect the loading conditions in the assessment. From the viewpoint of TH behavior, configuration of plant equipment and their dimensions, and operator action time considerably influence various parameters, such as the temperature and flow rate of coolant water and inner pressure. In this study, to investigate the influence of the operator action time on TH behavior during a PTS event, we developed an analysis model for a typical Japanese PWR plant, including the RPV and the main components of both primary and secondary systems, and performed TH analyses by using a system analysis code called RELAP5. We applied two different operator action times based on the Japanese and the United States (US) rules: Operators may act after 10 min (Japanese rules) and 30 min (the US rules) after the occurrence of PTS events. Based on the results of TH analysis with different operator action times, we also performed structural analyses for evaluating thermal-stress distributions in the RPV during PTS events as loading conditions in the structural integrity assessment. From the analysis results, it was clarified that differences in operator action times significantly affect TH behavior and loading conditions, as the Japanese rule may lead to lower stresses than that under the US rule because an earlier operator action caused lower pressure in the RPV.

关键词: structural integrity     reactor pressure vessel     pressurized thermal shock     thermal hydraulic analysis     pressurized water reactor     weld residual stress    

Assessment indices for uniform and non-uniform thermal environments

ZHANG Yufeng, SUN Shufeng, ZHAO Rongyi

《能源前沿(英文)》 2008年 第2卷 第2期   页码 129-133 doi: 10.1007/s11708-008-0029-y

摘要: Different assessment indices for thermal environments were compared and selected for proper assessment of indoor thermal environments. 30 subjects reported their overall thermal sensation, thermal comfort, and thermal acceptability in uniform and non-uniform conditions. The results show that these three assessment indices provide equivalent evaluations in uniform environments. However, overall thermal sensation differs from the other two indices and cannot be used as a proper index for the evaluation of non-uniform environments. The relationship between the percentage and the mean vote for each index is established.

关键词: thermal sensation     proper assessment     relationship     equivalent     thermal acceptability    

地下水碳酸平衡检查系统

刘建刚,郑克勋,傅伟宁,吴顺华

《中国工程科学》 2003年 第5卷 第9期   页码 61-64

摘要:

文章主要研究地下水在不同温度和CO2分压条件下碳酸三种存在形式与pH值的关系,以便更有效地对地下水水质资料进行可靠性检查。分析认为HCO3-出现峰值的分界pH0值,纯水在CO2分压1~105Pa,温度0~30℃时的变化范围为7.92~8.60,碳酸盐岩地下水的变化范围为8.28~8.57。pH0值随温度的升高而降低。石灰岩和白云岩的pH0十分接近,碳酸盐岩地区的平衡特性将取决于方解石成分。

关键词: 碳酸盐岩     地下水     碳酸平衡     pH值    

Phase equilibrium of the ternary system of NH 4 Cl—CaCl 2 —H 2 O at 50°C

Xia LI, Junsheng YUAN, Zhiyong JI, Jianxin CHEN,

《化学科学与工程前沿(英文)》 2010年 第4卷 第1期   页码 75-77 doi: 10.1007/s11705-009-0296-0

摘要: The equilibrium data on the ternary system of NHCl—CaCl—HO at 50°C were investigated using the wet-residue method. The experimental results show that there are three pure phase crystal areas of NHCl, 2NHCl·CaCl·3HO and CaCl·2HO, two mixture phase crystal areas of NHCl and 2NHCl·CaCl·3HO, and 2NHCl·CaCl·3HO and CaCl·2HO in the system. A new hydration double salt (2NHCl·CaCl·3HO) was found in the ternary equilibrium system for the first time.

Liquid metal thermal hydraulics R&D at European scale: achievements and prospects

《能源前沿(英文)》 2021年 第15卷 第4期   页码 842-853 doi: 10.1007/s11708-021-0743-2

摘要: A significant role for a future nuclear carbon-free energy production is attributed to fast reactors, mostly employing a liquid metal as a coolant. This paper summarizes the efforts that have been undertaken in collaborative projects sponsored by the European Commission in the past 20 years in the fields of liquid-metal heat transfer modeling, fuel assembly and core thermal hydraulics, pool and system thermal hydraulics, and establishment of best practice guidelines and verification, validation, and uncertainty quantification (UQ). The achievements in these fields will be presented along with the prospects on topics which will be studied collaboratively in Europe in the years to come. These prospects include further development of heat transfer models for applied computational fluid dynamics (CFD), further analysis of the consequences of fuel assembly blockages on coolant flow and temperature, analysis of the thermal hydraulic effects in deformed fuel assemblies, extended validation of three-dimensional pool thermal hydraulic CFD models, and further development and validation of multi-scale system thermal hydraulic methods.

关键词: liquid metal     thermal hydraulics     Europe    

Statics of levitated vehicle model with hybrid magnets

Desheng LI, Zhiyuan LU, Tianwu DONG

《机械工程前沿(英文)》 2009年 第4卷 第1期   页码 35-39 doi: 10.1007/s11465-009-0002-4

摘要: By studying the special characteristics of permanent and electronic magnets, a levitated vehicle model with hybrid magnets is established. The mathematical model of the vehicle is built based on its dynamics equation by studying its machine structure and working principle. Based on the model, the basic characteristics and the effect between the excluding forces from permanent magnets in three different spatial directions are analyzed, statics characteristics of the interference forces in three different spatial directions are studied, and self-adjusting equilibrium characteristics and stabilization are analyzed. Based on the structure above, the vehicle can levitate steadily by control system adjustment.

关键词: magnetic levitation     permanent magnet     modeling     equilibrium    

Coupling evaluation for material removal and thermal control on precision milling machine tools

《机械工程前沿(英文)》 2022年 第17卷 第1期   页码 12-12 doi: 10.1007/s11465-021-0668-9

摘要: Machine tools are one of the most representative machining systems in manufacturing. The energy consumption of machine tools has been a research hotspot and frontier for green low-carbon manufacturing. However, previous research merely regarded the material removal (MR) energy as useful energy consumption and ignored the useful energy consumed by thermal control (TC) for maintaining internal thermal stability and machining accuracy. In pursuit of energy-efficient, high-precision machining, more attention should be paid to the energy consumption of TC and the coupling relationship between MR and TC. Hence, the cutting energy efficiency model considering the coupling relationship is established based on the law of conservation of energy. An index of energy consumption ratio of TC is proposed to characterize its effect on total energy usage. Furthermore, the heat characteristics are analyzed, which can be adopted to represent machining accuracy. Experimental study indicates that TC is the main energy-consuming process of the precision milling machine tool, which overwhelms the energy consumption of MR. The forced cooling mode of TC results in a 7% reduction in cutting energy efficiency. Regression analysis shows that heat dissipation positively contributes 54.1% to machining accuracy, whereas heat generation negatively contributes 45.9%. This paper reveals the coupling effect of MR and TC on energy efficiency and machining accuracy. It can provide a foundation for energy-efficient, high-precision machining of machine tools.

关键词: machine tools     cutting energy efficiency     thermal stability     machining accuracy     coupling evaluation    

An autonomous system for thermal convection of viscoelastic fluids in a porous layer using a thermal

Qi WEI, Xiaohui ZHANG

《能源前沿(英文)》 2010年 第4卷 第4期   页码 507-516 doi: 10.1007/s11708-010-0017-x

摘要: Thermal convection of viscoelastic fluids saturating a horizontal porous layer heated from below is analyzed using a thermal nonequilibrium model to take account of the interphase heat transfer between the fluid and the solid. The viscoelastic character of the flow is considered by a modified Darcy’s law. An autonomous system with five differential equations is deduced by applying the truncated Galerkin expansion to the momentum and heat transfer equations. The effects of interphase heat transfer on the thermal convection of viscoelastic fluids in a porous medium are analyzed and discussed. The results show that the weak interphase heat transfer tends to stabilize the steady convection.

关键词: thermal convection     porous media     viscoelastic fluid     thermal nonequilibrium model    

标题 作者 时间 类型 操作

Thermally developing forced convection and the corresponding thermal stresses in a porous plate channel

YANG Xiao, LIU Xuemei

期刊论文

Thermodynamic analysis of reaction pathways and equilibrium yields for catalytic pyrolysis of naphtha

期刊论文

Measurement and correlation of the solid-liquid equilibrium of 2-(

Yanhong SUN, Zhiyong LI, Chuang XIE, Wei CHEN, Cui ZHANG

期刊论文

Brown marine algae turbinaria conoides as biosorbent for Malachite green removal: Equilibrium and kinetic

R. RAJESH KANNAN, M. RAJASIMMAN, N. RAJAMOHAN, B. SIVAPRAKASH,

期刊论文

Non-equilibrium model for catalytic distillation process

WANG Feng, ZHAO Ning, LI Junping, XIAO Fukui, WEI Wei, SUN Yuhan

期刊论文

into nitrogen and sulfur co-doped carbon nanotubes for effective desulfurization of liquid phases: Equilibrium

期刊论文

Removal of Rhodamine B from aqueous solutions and wastewater by walnut shells: kinetics, equilibrium

Jasmin Shah, M. Rasul Jan, Attaul Haq, Younas Khan

期刊论文

Influence evaluation of loading conditions during pressurized thermal shock transients based on thermal-hydraulics

Jinya KATSUYAMA, Shumpei UNO, Tadashi WATANABE, Yinsheng LI

期刊论文

Assessment indices for uniform and non-uniform thermal environments

ZHANG Yufeng, SUN Shufeng, ZHAO Rongyi

期刊论文

地下水碳酸平衡检查系统

刘建刚,郑克勋,傅伟宁,吴顺华

期刊论文

Phase equilibrium of the ternary system of NH 4 Cl—CaCl 2 —H 2 O at 50°C

Xia LI, Junsheng YUAN, Zhiyong JI, Jianxin CHEN,

期刊论文

Liquid metal thermal hydraulics R&D at European scale: achievements and prospects

期刊论文

Statics of levitated vehicle model with hybrid magnets

Desheng LI, Zhiyuan LU, Tianwu DONG

期刊论文

Coupling evaluation for material removal and thermal control on precision milling machine tools

期刊论文

An autonomous system for thermal convection of viscoelastic fluids in a porous layer using a thermal

Qi WEI, Xiaohui ZHANG

期刊论文