检索结果-内蒙古大学图书馆

Hierarchical Heterojunctions of Metal Sulfide Nanosheets/ Metal Oxide Nanofibers for an Efficient Detection of Formaldehyde

学校读者我要写书评

暂无评论

SSRN 2024年

作者： Zhu, Lei Zhang, Jiaxin Wang, Jianan Liu, Jianwei Wang, Ze Yan, Wei Xi’an Key Laboratory of Solid Waste Resource Regeneration and Recycling State Key Laboratory of Multiphase Flow Engineering School of Energy and Power Engineering Xi’an Jiaotong University Xi’an710049 China School of Physics and Electrical Engineering Weinan Normal University Chaoyang Street Weinan714099 China School of Chemistry and Chemical Engineering Xi’an University of Science & Technology Xi’an710054 China

The construction of transition metal dichalcogenides (TMDs) heterojunctions for high performance gas sensors has garnered significant attention due to their capacity to operate at low temperature. Herein, we realize two-dimensional (2D) WS2 nanosheets in situ grown on one-dimensional (1D) In2O3 nanofibers to form heterostructures for formaldehyde (HCHO) gas sensors. Capitalizing on the p-n heterojunctions formed between WS2 and In2O3, coupled with the high surface-to-volume ratio characteristic of 1D nanostructures, the WS2/In2O3 NFs sensor demonstrated a high gas response value of 12.6 toward 100 ppm HCHO at operating temperature of 140 ℃, two times greater than that of the pristine In2O3 sensor. Meanwhile, the sensor presents remarkable repeatability, rapid response/ recovery time, and good long-term stability. The superior sensing capabilities of WS2/In2O3 NFs heterojunction are attributed to the combined impact of the increased charge transfer and the presence of more sites for gas adsorption. The research endows a potent approach for fabricating TMDs heterojunctions to significantly improve the performance of gas sensors. © 2024, The Authors. All rights reserved.

关键词： Tungsten compounds

Transient Analysis of Cryogenic Cooling Performance for High-power Semiconductor Lasers Using Flash-Evaporation Spray

学校读者我要写书评

暂无评论

SSRN 2022年

作者： Tian, Jiameng Li, Bufa Wang, Junfeng Chen, Bin Zhou, Zhifu Wang, Hai School of Energy and Power Engineering Jiangsu University Zhenjiang212013 China State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Shaanxi Xi’an710049 China

Focusing on the cryogenic cooling for the high-power semiconductor lasers to improve their output performance, this work conducted an experimental investigation on analyzing the transient cooling performance using a pulsed two-phase flash-evaporation spray with the environmental cryogen R32. A heat flux estimation methodology that considers an imposed heat flux as a boundary condition, was first developed to assist the transient heat transfer analysis. The results provided further insight into phase-change heat transfer on the hot surface from high-temperature to cryogenic regimes through coupling the heat transfer measurements with observations of hydrodynamic liquid film formation and development. The moderate spurt duration (Δ t = 30 s) that produced a large temperature drop (109.5 °C) and high time-averaged cooling rate (24.1 W/cm2) was preferable. The significant losses in droplets’ momentum and mass contributed to the fast decrease in cooling effect as spray distance (Z) increased. Specifically, shortening Z from 50 to 10 mm not only increased the maximum surface heat flux from 19.6 to 73.6 W/cm2, but also broadened the temperature region with high heat flux. The nozzle with a smaller orifice diameter (0.5 mm) produced a lower cooling rate. Whereas surprisingly, its lower flow rate resulted in the lesser coolant accumulation and splashing on the hot surface, which elevated its thermal efficiency. Spurt duration that can produce a specific temperature drop almost remained unchanged or slightly raised as the input heating power increased, implying that the fluid supply is excess and the liquid flow rate could be reduced to save liquids. © 2022, The Authors. All rights reserved.

关键词： Heat flux

Analysis on the Thermal Behaviour of the Latent Heat Storage System Using S-Co2 and H-Pcm

学校读者我要写书评

暂无评论

SSRN 2022年

作者： Nan, Wenguang Ming, Zhu Wang, Yueshe School of Mechanical and Power Engineering Nanjing Tech University Nanjing211816 China State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Xi’an710049 China

Energy storage and utilization of CO2 have attracted increasing attention due to international zero carbon plan. Here, the latent heat storage system using high-temperature phase change material (H-PCM) and supercritical CO2 (S-CO2) is analysed by using CFD simulation, in which the tube containing S-CO2 is submerged in a tank containing the salt with high melting temperature. A new and combined phase transition model is developed to describe the dynamics of PCM in different phase state, and it is validated against experimental data in literature. The dynamics of natural convection is focused, and its effects on the heat storage system are analysed, including maximum natural convection velocity, phase interface, and melting pattern. The results show that natural convection has a great influence on the melting process of the H-PCM in the charging process. The melting pattern of H-PCM could be contrary between the cases with and without considering natural convection. During the discharging process, natural convection has little effect on the heat transfer of energy release due to its short duration. With the increase of ratio between the S-CO2 tube and H-PCM tank, the strength of the natural convection of melting H-PCM is enhanced, especially the duration of natural convection. © 2022, The Authors. All rights reserved.

关键词： Natural convection

Catalytic Conversion of Toluene by Biochar Modified with Kmno4

学校读者我要写书评

暂无评论

SSRN 2022年

作者： Jin, Xiaoling Zhang, Kai Jiang, Jiahao Zhu, Zhengrong Deng, Lei Che, Defu State Key Laboratory of Multiphase Flow in Power Engineering School of Energy and Power Engineering Xi’an Jiaotong University Xi’an710049 China Kunming Institute of Physics Kunming650223 China

This study aims to investigate the effects of biomass species, modification treatment, experimental time and atmosphere on the catalytic conversion of toluene (model tar compound) by the biochar from gasification of oak, wheat straw and Enteromorpha. The gas and liquid phase products are detected by GC and GC-MS, respectively. The physical and chemical characteristics of biochar samples are analyzed by SEM-EDS, XRD and XPS. The results show that the activity of oak char modified by KMnO 4 (Mn-OC) is higher than that of other biochar samples. The KMnO 4 modification improves the pore structure, increases oxygen-containing groups and enhances the activity of biochar. The relatively high toluene conversion rate (53.96%) and low carbon deposition rate (3.41%) of Mn-OC indicates that KMnO 4 is more suitable for the modification of oak char. H 2 and aromatic hydrocarbons (especially biphenyl and their derivatives) are the main components of gas and liquid products, respectively. The proportion of H 2 in the total volume of H 2 , CO, CH 4 and CO 2 of Mn-OC reaches 56.94%. The addition of water vapor is helpful to the formation of oxygen-containing groups, more uniform distribution of inorganic salt particles and the improvement of biochar surface structure. Thus, adding moderate water vapor is beneficial to promote the catalytic activity of biochar. The toluene conversion rate and the total volume fraction of four main gases decrease with the increase of experimental time. They reduce significantly when the experimental time is longer than 120 min, from 44.51% (120 min) to 24.86% (180 min), which might be due to the damage of pore structure and the consumption of oxygen-containing functional groups. © 2022, The Authors. All rights reserved.

关键词： Toluene

An Investigation on the Formation and flow Characteristics of Nature Gas Hydrates at Different Loop Inclination Angles

学校读者我要写书评

暂无评论

SSRN 2022年

作者： Liu, Ni Wang, Cheng Meng, Fei Yang, Liang Liu, Daoping School of Energy and Power Engineering The University of Shanghai for Science and Technology Shanghai200093 China Shanghai Key Laboratory of Multiphase Flow and Heat Transfer in Power Engineering Shanghai200093 China

One of the major issues in flow assurance includes pipeline plugging due to gas hydrate formation and deposition,which makes it imperative to look for appropriate hydrate control strategies. In this study, a high-pressure visual flow loop was used to analyze the influence of different inclination angles (0°–4°) on the formation, flow, morphology evolution, deposition process, and mechanism of hydrates. The macro-parametric data, including pressure, temperature, velocity, hydrate induction time and hydrate volume fraction, were compared and analyzed. Results showed that the hydration reaction rate of downslope section is slightly faster than that of upslope section in inclined section. Although the amount of hydrate finally formed is the same, the hydrate in the downslope section is more dense. While the loop inclination angle had little effect on the amount of hydrate formation, with the increase of inclination angle, the induction time tends to decrease and the hydration reaction time will be longer overall. At 1° inclination angle, the induction time was the shortest and the hydration reaction time was the longest. The deposition process of the horizontal pipe is divided into four stages, in which large hydrate particles in the liquid phase are evenly distributed throughout the pipeline, forming a hydrate moving bed. The hydrate deposition process of the inclined pipe is also divided into four stages. Among them, the large hydrate particles in the liquid phase are concentrated on the upper wall of the pipeline, which causes the density of the upper part of the pipeline to be much higher than that of the lower part, forming a hydrate-fixed *** results of this study can deliver theoretical support to ensure the safe transportation of gas hydrate slurries. © 2022, The Authors. All rights reserved.

关键词： Gas hydrates

Numerical simulation of condensation of supercritical water gasification products in a supersonic nozzle

学校读者我要写书评

暂无评论

International Journal of Fluid Engineering

International Journal of Fluid engineering 2024年第4期1卷 76-88页

作者： Hongtu Wu Miso Jurcevic Henrik Ström Muhammad Shahzad Khurram Hui Jin State Key Laboratory of Multiphase Flow in Power Engineering(SKLMF) Xi’an Jiaotong University28 Xianning West RoadXi’an 710049ShaanxiChina LTEF—Laboratory for Thermodynamics and Energy Efficiency Faculty of Electrical EngineeringMechanical Engineering and Naval Architecture(FESB)University of SplitRudjera Boskovica 3221000 SplitCroatia Chalmers University of Technology GöteborgSweden COMSATS LahorePakistan

The clean and efficient separation of supercritical water gasification products(SCWGP)has emerged as a significant challenge in supercritical water gasification *** paper proposes the use of a supersonic nozzle for the condensation and separation of H2and CO_(2)from SCWGP,leveraging the high-pressure characteristics of these *** establishing a flow model and a condensation model for the supersonic nozzle,the effects of inlet pressure and inlet temperature on the condensation process are *** analysis reveals that the latent heat released during condensation causes an abnormal distribution of pressure and temperature within the *** the inlet pressure of the nozzle is increased from 7.0 to 9.0 MPa,the liquid phase mass fraction at the outlet rises from 5.3×10^(-3)to ***,when the inlet temperature is lowered from 300.0 to 290.0 K,the liquid phase mass fraction at the outlet also rises from 5.3×10^(-3)to *** increase in inlet pressure leads to the condensation location shifting toward the throat by~8.5×10^(-3)m·MPa^(-1),while the impact of inlet temperature is approximately-2.3×10^(-3)m·K^(-1).The nucleation rate in the nozzle is always concentrated in a small region.

关键词： condensation separation outlet

Experimental Study on Supported MnO2-Based Catalysts for No Oxidation

学校读者我要写书评

暂无评论

SSRN 2022年

作者： Wang, Denghui Li, Hui Wu, Feng Hui, Shien State Key Laboratory of Multiphase Flow in Power Engineering School of Energy and Power Engineering Xi’an Jiaotong University No. 28 Xianning West Rd. Xi’an710049 China

The selective catalytic oxidation (SCO) of NO in the flue gas to easily soluble NO2 has received extensive attention. In this paper, a single-phase supported MnO2/Al2O3 catalyst and Ce-doped MnCe/Al catalyst system were used for the NO-SCO experiment with MnO2 as the main active component. Combined with XRD, BET, XPS, SEM, O2-TPD, and H2-TPR characterization methods, the physicochemical state of the catalyst surface was analyzed. Furthermore, the effect of loading and Ce doping on active oxygen species and the important factors related to catalyst activity was revealed. The MnO2 catalyst obtained the best activity at 300 °C, corresponding to a NO conversion rate of 79.4%. After MnO2 was loaded on the γ-Al2O3, the activity of the Mn/Al catalysts was not as good as that of the MnO2 catalyst, and the temperature window of Mn/Al shifted to the high-temperature region with the increase of the loading ratio. The relative content of adsorbed oxygen Oα of Mn/Al catalysts was lower than that of MnO2, resulting in poor activity. Ce-doped Mn0.23Ce0.023/Al catalysts exhibited good low-temperature activity. The introduction of the Ce element enhanced the dispersion of Mn species on the catalyst surface, the relative content of surface adsorbed oxygen Oα increased, and the low-temperature activity and mobility of surface oxygen species were enhanced. The Mn0.23Ce0.023/Al catalyst was endowed with both a high specific surface area and good pore structure, as well as a large oxygen storage capacity and excellent surface oxygen species. © 2022, The Authors. All rights reserved.

关键词： Manganese oxide

Prediction of Pressure Drop in Heavy Oil-Water Ring Two-Phase flow Based on Modified Two-Fluid Model

学校读者我要写书评

暂无评论

SSRN 2024年

作者： Fu, Jiqiang Du, Mingjun Jing, Jiaqiang Sun, Jie Liu, Huichao Chen, Yongjiu State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Xi’an710049 China China Petroleum Engineering & Construction Corp North Company Heibei Renqiu062552 China School of Oil & Natural Gas Engineering Southwest Petroleum University Sichuan Chengdu610500 China

Accurate prediction of pressure drop of the heavy oil-water ring flow in pipeline is of great significance for establishing an optimal drag reduction model and ensuring safe production. The effects of different factors on the flow pattern and pressure drop of heavy oil-water annular two-phase flow were systematically analyzed, and a standard two-fluid pressure drop prediction model for annular flow was established. By modifying the shear stress equation of oil-water interface and introducing the wave-flow theory to modify the shear stress equation of water wall, a pressure drop prediction model for the generalized concentric water ring was obtained to calculate the periodic fluctuations of oil phase. Furthermore, by introducing the comprehensive Reynolds number expression of eccentric water ring, the pressure drop prediction model for the generalized eccentric water ring was obtained to calculate the periodic fluctuations of oil phase. The results show that the pressure drop prediction accuracy of the concentric water ring for ultra-heavy oil is improved by 80 % by using the modified pressure drop prediction model. The comprehensive Reynolds number expression of eccentric water ring can effectively reflect the influence of eccentric effect on shear stress of water wall and the calculation error is less than 20 % by predicting the pressure drop of the generalized eccentric water ring with different density differences. © 2024, The Authors. All rights reserved.

关键词： Two phase flow

Thermodynamics analyses on a novel CHP system integrated with multi-grade thermal energy storage

学校读者我要写书评

暂无评论

Journal of Energy Storage 2025年 106卷

作者： Liu, Rongtang Zhang, Kezhen Qin, Yuanzhi Wan, Kaidi Xu, Can Liu, Ming Ningbo Institute of Technology Beihang University Ningbo315800 China Xi'an Thermal Power Research Institute Co. Ltd. Xi'an710054 China State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an710049 China Dongfang Boiler Co. Ltd. of Dongfang Electric Group Chengdu611731 China

The high penetration level of intermittent renewable power necessitates the crucial requirement for combined heat and power systems to possess both high efficiency and flexibility. However, the heat-controlled operation modes of traditional combined heat and power systems impose limitations on their efficiency and flexibility. Therefore, it is of great significance to develop a heat-power decoupling technology that exhibits exceptional efficiency and flexibility. A novel combined heat and power system integrated with multi-grade thermal energy storage is proposed in this study. Thermodynamic analysis models of all operational conditions are developed, and the comprehensive characteristics of efficiency and operational flexibility for the proposed system are assessed by taking a 330 MW system as an example. Results show that the proposed system can decrease/increase 16.05 MW/30.96 MW power loads comparing with the reference system during the charging/discharging periods under the design condition. Energy efficiency of the proposed system can reach 49.40 %, which is improved by 1.66 percentage points. Exergy analysis reveals the exergy destruction order for the proposed system, and shows that the combustion and heat transfer in the boiler are the major process of exergy dissipation. Moreover, operation strategies of the proposed system during charging-discharging cycle are explored and formulated under off-design condition, suggesting that thermodynamic performances of the novel system under various conditions even extreme conditions exhibits exceptional properties. The maximum heat load of the proposed system can be improved by 46.78 % comparing with the reference system, and the maximum improvement of power load capacity during charging-discharging cycle is 14.58 percentage points. This study provides a promising approach for multi-grade thermal energy storage to improve the comprehensive characteristics of combined heat and power systems. © 2024

关键词： Charge storage