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Optimal retrofit of a novel multi-component supercritical thermal fluid generation system via thermodynamic analysis

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APPLIED THERMAL engineering 2023年第PartB期219卷

作者： Xu, Jialing Peng, Zhiyong Rong, Siqi Zhao, Qiuyang Jin, Hui Guo, Liejin Zhou, Teng Zhang, Xiang Xi An Jiao Tong Univ State Key Lab Multiphase Flow Power Engn 28 Xianning West Rd Xian 710049 Peoples R China Hong Kong Univ Sci & Technol Guangzhou Sustainable Energy & Environm Thrust Guangzhou Peoples R China Hong Kong Univ Sci & Technol Dept Chem & Biol Engn Hong Kong Peoples R China Max Planck Inst Dynam Complex Tech Syst Proc Syst Engn Sandtor str 1 D-39106 Magdeburg Germany

Multi-component supercritical thermal fluid (mcSCTF) has been recently recognized as a promising media for enhancing heavy oil recovery. For its economic application, an efficient mcSCTF generation should be studied. In this work, a novel experimental system with various units is being first introduced for mcSCTF generation and theoretically modelled for the energy and exergy analysis as the two contributions of this work. Based on the results, optimal retrofit strategy is proposed as the coming improvement. Starting with a specific experimental setup, theoretical modeling methods including Gibbs free energy minimization and mass balances are employed to predict the output of the core unit of reactor. The models are validated using measured experimental data. Then, energy and exergy analysis are conducted to quantify the energy and exergy losses in each unit. The reactor, heat exchanger and compressor are found to contribute for the major exergy losses accounting for 40.1%, 39.4% and 12.3%, respectively. With this, sensitivity analysis of three key factors (i.e., reactor heat dissipation rate, heat exchanger efficiency, and compressor isentropic efficiency) as well as their combinations are performed to identify potential solutions for improving efficiency. Finally, a retrofit design with around 10% efficiency enhancement is proposed.

关键词： Supercritical water gasification Thermodynamic analysis Multi-component supercritical thermal fluid Optimal retrofit

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Optimal design of non-isothermal supercritical water gasification reactor: From biomass to hydrogen

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ENERGY 2022年第PartB期244卷 123163-123163页

作者： Xu, Jialing Rong, Siqi Sun, Jingli Peng, Zhiyong Jin, Hui Guo, Liejin Zhang, Xiang Zhou, Teng Xi An Jiao Tong Univ State Key Lab Multiphase Flow Power Engn 28 Xianning West Rd Xian 710049 Peoples R China Otto von Guericke Univ Proc Syst Engn Univ Pl 2 D-39106 Magdeburg Germany Max Planck Inst Dynam Complex Tech Syst Proc Syst Engn Sandtorstr 1 D-39106 Magdeburg Germany

Supercritical water gasification (SCWG) of biomass is a promising technology for large-scale hydrogen production and its success is greatly affected by the performance of SCWG reactor. In this work, a novel mathematical modeling and optimization approach is applied to design optimal tubular reactor for the SCWG of biomass. The tubular reactor is first discretized into cells. Then, detailed mathematical models are developed to represent the reactions occurring in each cell and the mass balances among the cells. By integrating all the models along the reactor, the reactor design problem is formulated as a nonlinear optimization problem. The objective is to maximize the hydrogen yield and multiple constraints have to be fulfilled. After solving the problem, the optimal reactor design (e.g., reactor length, diameter, and axial fluid temperature profile) can be obtained. To demonstrate the applicability of our approach, two design scenarios are studied. The results show that non-isothermal reactors with three-stage zigzag-like temperature profiles are preferred for hydrogen production, instead of traditional isothermal reactors. Compared with isothermal reactors, the optimal non-isothermal ones can increase hydrogen yield up to 25.06% (i.e., 16.67 vs 13.33 mol/kg glycerol). The results provide useful insights on industrial SCWG reactor design for achieving efficient hydrogen production. (c) 2022 Elsevier Ltd. All rights reserved.

关键词： Supercritical water gasification Biomass Hydrogen production Optimal reactor design Mathematical optimization

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Coupled combustion and hydrodynamics simulation of a 1000MW double-reheat boiler with different FGR positions

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FUEL 2020年 261卷 116427-000页

作者： Liu, Hu Zhang, Wei Wang, Huan Zhang, Yuanhang Deng, Lei Che, Defu Xi An Jiao Tong Univ Sch Energy & Power Engn State Key Lab Multiphase Flow Power Engn Xian 710049 Shaanxi Peoples R China Beijing Univ Civil Engn & Architecture Sch Environm & Energy Engn 1 Zhanlanguan Rd Beijing 100044 Peoples R China Xian Univ Architecture & Technol Sch Environm & Municipal Engn Xian 710055 Shaanxi Peoples R China

Flue gas recirculation (FGR) has been widely adopted as the steam temperature regulation method of choice for double-reheat boilers. In this work, the effect of the FGR position on the hydrodynamic characteristics of a double-reheat boiler is studied. Heat flux distributions of the water-cooled wall are determined through combustion simulation, then hydrodynamic characteristics of the boiler are calculated by user-defined program. The hydrodynamic characteristics including working fluid temperature, average tube temperature, fin-tip temperature, and temperature deviation between adjacent loops under 100% boiler maximum continuous rating (BMCR) and 75% turbine heat acceptance (THA) loads were numerically analyzed. The calculation results show that, under 100% BMCR and 75% THA loads, compared with the case that FGR introduced from the nozzle above the burner, the average tube and fin-tip temperatures at the outlet of water-cooled wall are higher, and the temperature deviation between adjacent loops is more significant, when the FGR is introduced from the nozzle below the burner. Therefore, it is suggested in this work that introducing FGR from the nozzle above the burner is safer for water-cooled walls of the 1000 MW double-reheat boiler.

关键词： Coupled simulation Double-reheat boiler FGR position Mass flux distribution Metal temperature distribution

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Investigation of pool boiling heat transfer on hydrophilic-hydrophobic mixed surface with micro-pillars using LBM

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INTERNATIONAL JOURNAL OF THERMAL SCIENCES 2021年 163卷 106814-106814页

作者： Feng, Yuan Chang, Fucheng Hu, Zitu Li, Huixiong Zhao, Jianfu Xi An Jiao Tong Univ State Key Lab Multiphase Flow Power Engn Xian 710049 Peoples R China Chinese Acad Sci Inst Mech CAS Key Lab Micrograv Beijing 100190 Peoples R China Univ Chinese Acad Sci Sch Engn Sci Beijing 100049 Peoples R China

Surface modification technology by controlling the surface wettability or applying micro/nano-structures to enhance the boiling heat transfer performance has attracted a great deal of interest in recent years. Abundant experiments were performed to investigate the boiling processes on the modified surfaces, and lots of experimental data as well as reliable conclusions were obtained. With the advantages of saving costs and time, the numerical method has been a new reliable way to investigate the bubble dynamics and heat transfer during pool boiling processes on the modified heated surfaces. Pseudopotential LB model is capable of simulating the entire boiling processes including the bubble nucleation, and this model has been successfully applied to simulate the pool boiling processes on both the smooth surfaces and the hydrophilic-hydrophobic mixed surfaces with micro-pillars. However, the numerical simulations of the boiling processes on the mixed surfaces were still rare, and the influence of geometrical parameters of pillar structures of the mixed surface on boiling heat transfer performance was still unclear yet. Moreover, some of the conclusions in existing literature were inconsistent with those in others. Thus it's necessary to carry out more numerical and experimental researches to solve these problems. In this study, the MRT pseudopotential model coupled with phase-change model was applied to simulate the pool boiling processes on the hydrophilic-hydrophobic mixed surface textured with micro-pillars. Under different wall superheats, the bubble dynamics and heat transfer during boiling processes on the mixed surface with micro-pillars were compared to those on the smooth hydrophilic surface and the hydrophilic-hydrophobic mixed surface without micro-pillars. The heat transfer enhancement mechanism of the mixed surfaces was revealed and the influence of geometrical parameters of pillars, including pillar width and pillar number, on bubble dynamics and heat tran

关键词： Boiling heat transfer Surface modification technology Lattice Boltzmann method

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Experimental investigation of gasoline spray vaporization behaviors under various ambient conditions 12

Experimental investigation of gasoline spray vaporization be...

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12th Asia-Pacific Conference on Combustion, ASPACC 2019

作者： Zhan, Cheng Yang, Rui Tong, Shangqing Huang, Zuohua State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an710049 China

In terms of spray vaporization visualization, effects of ambient temperature (394-516 K) and ambient pressure (0.1-3.8 MPa) on multi-hole gasoline spray macroscopic characteristics has been investigated separately via optical diagnostics. Schlieren method was adopted to visualize vapor phase fuel at high ambient temperature. Laser sheet optical patternation provided us with cross-section perspective to verify results in schlieren images and acquire additional information like plume distribution. The results show that vaporization process will be promoted by high ambient temperature due to enhanced heat transfer between spray body and surrounding gas. The effects of ambient pressure on spray evolution possess different inner mechanisms with ambient temperature variation. In low ambient temperature, axial evolution indicated by vapor tip penetration will be restricted by high ambient pressure, whereas radial expansion indicated by spray angle will be facilitated. For atmospheric ambient pressure in high ambient temperature, spray collapse will appear due to enhanced vaporization of single plume and intensified jet-to-jet interaction. Moreover, because of inhibited vaporization of light component in high ambient pressure, vaporization model will transfer from distilled-like vaporization to co-vaporization, indicated by homogeneous vapor phase distribution. © Asia-Pacific Conference on Combustion, ASPACC *** right reserved.

关键词： Vaporization

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Classical and alternative disinfection strategies to control the COVID-19 virus in healthcare facilities: a review

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ENVIRONMENTAL CHEMISTRY LETTERS 2021年第3期19卷 1945-1951页

作者： Choi, Hosoon Chatterjee, Piyali Lichtfouse, Eric Martel, Julie A. Hwang, Munok Jinadatha, Chetan Sharma, Virender K. Cent Texas Vet Hlth Care Syst 1901 Vet Mem Dr Temple TX 76504 USA Aix Marseille Univ CNRS IRD INRAECEREGEColl France F-13100 Aix En Provence France Xi An Jiao Tong Univ State Key Lab Multiphase Flow Power Engn Xian 710049 Shaanxi Peoples R China Texas A&M Univ Sch Publ Hlth Dept Environm & Occupat Hlth Program Environm & Sustainabil College Stn TX 77843 USA

The coronavirus disease COVID-19 has spread throughout the world and has been declared as a pandemic by the World Health Organization on March 11th, 2020. The COVID-19 is caused by the severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2). One possible mode of virus transmission is through surfaces in the healthcare settings. This paper reviews currently used disinfection strategies to control SARS-CoV-2 at the healthcare facilities. Chemical disinfectants include hypochlorite, peroxymonosulfate, alcohols, quaternary ammonium compounds, and hydrogen peroxide. Advanced strategies include no-touch techniques such as engineered antimicrobial surfaces and automated room disinfection systems using hydrogen peroxide vapor or ultraviolet light.

关键词： COVID-19 Chemical disinfectants Virus inactivation Ultraviolet light irradiation Reactive oxygen species

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Prediction and New Insight for the Drag Reduction of Turbulent flow with Polymers and Its Degradation Mechanism

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JOURNAL OF PHYSICAL CHEMISTRY LETTERS 2021年第30期12卷 7201-7206页

作者： Zhang, Xin Dai, Xiaodong Han, Qiaorong Zhao, Jishi Jing, Dengwei Liu, Fei Li, Lei Xin, Yanping Liu, Kun Shandong Inst Petr & Chem Technol Coll Petr Engn Dongying 257061 Shandong Peoples R China Changqing Oilfield Co Oil & Gas Technol Res Inst Xian 710018 Shaanxi Peoples R China Yunfu Foshan R&D Ctr Hydrogen Energy Standardizat Yunfu 527326 Guangdong Peoples R China Xi An Jiao Tong Univ State Key Lab Multiphase Flow Power Engn Xian 710049 Shaanxi Peoples R China Xi An Jiao Tong Univ Int Res Ctr Renewable Energy Xian 710049 Shaanxi Peoples R China

A physicochemical understanding of the mechanism of turbulent flow drag reduction with polymer and its degradation is of great interest from both science and industry perspectives. Although the correlation based on the Fourier series has been proposed to predict the drag reduction and its degradation, its physical meaning was not clear until now. This letter aims to clarify this issue. We develop a comprehensive model to predict the drag reduction and degradation of polymers in turbulent flow from a chemical thermodynamics and kinetics viewpoint. We demonstrate that the Fourier series employed to predict the drag reduction and its degradation is due to the viscoelastic property of drag-reducing polymer solution, and the phase angle in the model, in physical nature, represents the hysteresis of the polymer in turbulent flow. Besides, our new insight of drag reduction with flexible polymers can also explain why a maximum drag reduction in rotational flow appears before degradation happens.

关键词： Turbulent flow

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Facile synthesis of eggshell biochar beads for superior aqueous phosphate adsorption with potential urine P-recovery

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COLLOIDS AND SURFACES A-PHYSICOCHEMICAL AND engineering ASPECTS 2021年 622卷 126589-126589页

作者： Wang, Li Wang, Jingyi Wei, Yifei Xi An Jiao Tong Univ Sch Energy & Power Engn Dept Environm Sci & Engn State Key Lab Multiphase Flow Power Engn Xian 710049 Peoples R China UCL Ctr Nat Inspired Engn Dept Chem Engn London WC1E 7JE England

Phosphorus (P) uptake from wastewater is a widespread concern due to the concurrent issues of P contamination and deficiency. A corn straw biochar-based eggshell bead composite (CS-E0.25-Ca(b)) was innovatively synthesized via a facile gelation-calcination method for efficient P recovery from urine solutions. Batch adsorption experiments showed that CS-E0.25-Ca(b) fabricated under optimal conditions exhibited a superior adsorption capacity (136.83 mg/g), which was 29.93 and 6.77 times that of pristine biochar (CSBC) and bead without the addition of eggshell respectively. CS-E0.25-Ca(b) exhibited favorable adsorption performance at pH 6.0-9.0 and in the presence of coexisting anion conditions, and showed good mass transfer performance in urine environment. Characterization results indicated that corn straw biochar matrix can lead to porous internal structure, which could facilitate better dispersion of CaO/Ca(OH)2 in eggshell to adhere on CS-E0.25-Ca(b). The comparison of FTIR and XPS analyses revealed that the surface precipitation with Ca-P products of hydroxyapatite (HAP) and amorphous calcium phosphate (ACP) was the predominant mechanism of phosphorus adsorption on CS-E0.25-Ca (b). In the slow-releasing experiment, the urine P-saturated CS-E0.25-Ca(b) displayed controllable and long-term slow-releasing property in neutral solution. Besides, CS-E0.25-Ca(b) after P release displayed favorable adsorption performance for common heavy metals, showing potential extra benefit for remediating heavy metal contaminated soils. All the results suggested that CS-E0.25-Ca(b) can realize superior P uptake from urine, also be potentially qualified as a promising slow-releasing fertilizer for soil P supply.

关键词： Phosphate recovery Eggshell Biochar Beads Urine Slow-release

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Effects of operational parameters on liquid nitrogen spray cooling

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APPLIED THERMAL engineering 2019年 146卷 85-91页

作者： Ruan, Yixiao Hou, Yu Xue, Rong Luo, Gaoqiao Zhu, Kuizhang Liu, Xiufang Chen, Liang Xi An Jiao Tong Univ State Key Lab Multiphase Flow Power Engn Xian 710049 Shaanxi Peoples R China Anhui Prov Key Lab Cryogen Technol Hefei 230088 Anhui Peoples R China

To determine the influence of design parameters on droplet evaporation and distribution of liquid nitrogen (LN2) spray cooling, experimental and numerical studies are performed by varying the mass flow rate, flow velocity, droplet diameter, injection orientation, and droplet velocity. The results demonstrate that backward injection yields the highest droplet evaporation ratio, which is 40% and 10% higher than the evaporation ratios obtained through forward and transverse injections, respectively. Counter-rotating vortex pairs are observed in the transverse injection, which improves the temperature distribution via convective mixing. Reducing the droplet diameter provides a more effective means of enhancing the evaporation than increasing the droplet velocity, and a linear increase in the droplet evaporation is observed by reducing the droplet diameter from 0.6 to 0.2 mm. The results and findings provide guidelines for the design of LN2 spray cooling systems for cryogenic wind tunnels.

关键词： Spray cooling Liquid nitrogen Wind tunnel Computational fluid dynamics

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Film levitation and central jet of droplet impact on nanotube surface at superheated conditions

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Physical Review E 2020年第4期102卷 043108-043108页

作者： Dongdong Zhou Yuhui Zhang Yu Hou Xin Zhong Jian Jin Lidong Sun State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Shaanxi 710049 China State Key Laboratory of Mechanical Transmission School of Materials Science and Engineering Chongqing University Chongqing 400044 China

Influences of surface nanotubes at high temperatures are investigated on droplet impact dynamics and Leidenfrost effect. Five distinct regimes of impact droplets are found on the nanotube surface, including contact boiling, film levitation, central jet levitation, central jet, and Leidenfrost phenomenon. The regimes of film levitation, central jet levitation, and central jet are characterized by either film levitation and/or liquid central jet. The regime of Leidenfrost phenomenon is characterized by droplet bounce-off behavior free of any liquid jets. Film levitation is driven by the vaporization of two parts of the droplet, with one as the droplet bottom layer over the contact area above the nanotube structure, and the other as the hemiwicking liquid in nanotubes. Both the vaporization is impaired by increasing the surface temperature, which is attributed to the reduced contact time and less extent of spread of the droplet at a higher surface temperature. The central jet phenomenon is driven by the vapor stream produced by hemiwicking liquid in the central area upon impact. It is enhanced and then suppressed by elevating the surface temperature, resulting from the collective effects of the vapor pressure in nanotubes which increases with the surface temperature, and the cross-sectional area of the vapor stream, which increases and then decreases with the surface temperature. At a high Weber number, the Leidenfrost temperature can be increased by 125∘C on the nanotube surface, implying a great potential in heat transfer enhancement for droplet-based applications.

关键词： Drop & bubble phenomena Drop breakup multiphase flows

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