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

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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

Simulation Study on Heat Exchangers Characteristics of Solar Thermal Steam System Based on Aspen Plus

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Simulation Study on Heat Exchangers Characteristics of Solar...

Algorithms, High Performance Computing and Artificial Intelligence (AHPCAI), International Conference on

作者： Pengfei Chen Kang Chen Huaiwu Peng Yanlong Zhang Baercheng Bawaa Qiuyang Zhao Institute of Solar Engineering Technology Northwest Engineering Corporation Limited Power China Xi'an China State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an China

In the thermal recovery project of thick oil, there are high standards for steam temperature and flow rate. The solar thermal steam supply system can convert unstable solar energy into stable and efficient carrier heat, which can be used to transfer heat to low-temperature water to produce high-temperature steam and achieve a clean and low-carbon steam supply. The rated pressure of steam and the split ratio of molten salt in the heating system have a great influence on the demand area and heat load of solar panels. In this paper, a simulation is made on the solar thermal steam supply system based on Aspen Plus. The simulation result shows that the increase in pressure will cause a growth in the area of the photothermal concentrator field but will reduce the area used for photovoltaic panels. At the same time, it reduces the heat load of the evaporator and extends its service life. The split ratio affects the molten salt temperature at the outlet of the superheater and the reheater. When the split ratio increases, the heat transfer temperature difference between the two ends of the superheater heat flow decreases, and the heat transfer temperature difference of the reheater grows bigger. Therefore, the molten salt temperature flowing out of the reheater rises.

关键词： Water Temperature Costs Oils Simulation Water heating Solar heating

Experimental Study on Electrocatalytic Reduction of CO2 to Methanol over Cu2O and Cu2O/ZnO films

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Experimental Study on Electrocatalytic Reduction of CO2 to M...

International Conference on power engineering 2021, ICOPE 2021

作者： Zhang, Wenfei Zhou, Qulan Qi, Ji Li, Na State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an710049 China China Mobile System Integration Co. Ltd Beijing100052 China

The Cu2O film electrodes were prepared by solution immersion method, the ZnO/Cu2O film electrodes were prepared by electrodeposition method. Then the pure Cu2O film electrodes and ZnO/Cu2O film electrodes were used to reduce CO2 to CH3OH. The crystal structure, morphology, particle size and specific surface area of pure Cu2O films prepared under different immersion time and ZnO/Cu2O films prepared under different deposition time and Zn2+ concentration were analyzed by XRD, SEM, and BET. The electrolytic activity of the pure Cu2O film electrodes and ZnO/Cu2O film electrodes were studied. Under the same reaction conditions, the Cu2O film electrode with 2 h preparation time has the best electrolysis effect in the three groups of pure Cu2O electrode. The increase of reaction temperature can significantly promote the reduction of CO2 to CH3OH on Cu2O film electrodes. the ZnO/Cu2O film electrode with the Zn2+ concentration of 0.05 M and the deposition time of 30 min had the highest total CH3OH yields. This study highlights that the ZnO have a very good promotion of electrolytic CO2 reduction on Cu2O film. © 2021 The Japan Society of Mechanical Engineers.

关键词： Carbon dioxide

Analysis of Different Control Strategies Considering Individual Regulation of Heat User

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Analysis of Different Control Strategies Considering Individ...

Electrical engineering and Mechatronics Technology (ICEEMT), IEEE International Conference on

作者： Zhiwei Xun Huijie Wang Liyuan Wang Long Yang Yunfang Gao Ming Liu Guoneng Jinjie Energy Co. Ltd Yulin China Xi’an Jiaotong University Xi’an China State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Xi’an China

In the process of outdoor temperature change, it is beneficial to improve the comfort of thermal users to formulate adjustment and control strategies according to the actual needs of each user. In this paper, different adjustment modes are established according to the thermal comfort of users, and the control strategies of rising and cooling within 0, 30 and 60 minutes are proposed, and the indoor temperature control effect and heating energy consumption of each adjustment mode under different control strategies are analyzed. The results show that: in different modes, when the rise and cooling time increase, compared with the design room temperature, the indoor temperature difference under the control mode is smaller, but the time needed to reach stability is longer. At the same time, the total heat load is unchanged, but the total pump work decreases.

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

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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

Corrosion Effect Analysis on Thermal-Hydraulics of Lbe/Water Spiral Tube Steam Generator Under Oxygen-Controlled Environment

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SSRN 2023年

作者： Lu, Dingsheng Yang, Yupeng Wang, Chenglong Zhang, Dalin Qiao, Pengrui Tian, Wenxi Qiu, Suizheng Su, Guanghui H. School of Nuclear Science and Technology Shanxi Key Laboratory of Advanced Nuclear Energy and Technology Xi'an Jiaotong University Xi'An710049 China China Institute of Atomic Energy Beijing102413 China State Key Laboratory of Multiphase Flow in Power Engineering China

In order to explore the flow and heat transfer characteristics of spiral tube steam generators under Lead-Bismuth Eutectic (LBE) corrosion, the accelerated removal effect of LBE corrosion flow was perfected, and a bidirectional coupling model of LBE corrosion and flow heat transfer was established. Computational fluid dynamics (CFD) method was used to simulate the corrosion and flow heat transfer of helical tube steam generator under saturated oxygen concentration and oxygen-controlled environment. The results indicate that the corrosion of liquid LBE forms an oxidation layer, which hinders the heat transfer in the spiral tube steam generator. This leads to a significant increase in the wall friction coefficient and a decrease in the surface Nusselt number. However, it does not have a significant effect on the water side evaporation process of the spiral tube steam generator. The implementation of an oxygen-controlled environment can effectively reduce the influence of LBE corrosion on the flow heat transfer of the spiral tube steam generator. Especially under high temperature conditions, it can reduce the near wall temperature of LBE change by up to 57.5% and the outlet temperature change by up to 61.5%. The oxygen-controlled environment results in prolonged local hypoxia time, with a more pronounced effect at higher temperatures. © 2023, The Authors. All rights reserved.

关键词： Oxygen

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

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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

Catalytic Conversion of Toluene by Biochar Modified with Kmno4

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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

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

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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