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Waste heat recovery in the coal-fired power generation integrated with post-combustion

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Waste heat recovery in the coal-fired power generation integ...

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

作者： Yali Yang Guiwen Wang Yan Li Yongping Liu Yue Fu Ming Liu Guoneng Jinjie Energy Co. Ltd Yulin China State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Xi’an China

Post combustion systems (PCS) are a viable technology option to reduce carbon dioxide in the electricity production. However, the energy-intensive of PCC precludes its wide scale application. As for the optimization of the post combustion system, there is an optimal inlet temperature of the stripper. By optimizing the parameter of the post combustion system, the energy consumption rate of the post combustion system decreased by 1.4 GJ/t CO 2 under 100% THA compared to the original post combustion system. The needed heat by the stripper shows a fall with the decrease of the unit load ratio. However, the heat changes of the post combustion system decrease with the decrease of the unit load ratio under 90% absorption rate. The efficiency penalty can be as low as 4.1% through waste heat recovery.

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Effects of Inherent Aaems on Catalytic Gasification of Biomass with Large Particle Size Under Oxygen-Steam Atmosphere

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SSRN 2023年

作者： Ren, Jiyun Li, Yuhang Jin, Xiaoling Huang, Xiaole Li, Yang 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 Xi’an Thermal Power Research Institue Co. Ltd. Xi’an710032 China

Oxygen-steam gasification of biomass is a promising technology because of its ability to improve syngas quality and reduce energy consumption. In this study, a fixed-bed reactor is employed to assess the effects of inherent alkali and alkaline earth metals (AAEMs) on the catalytic gasification of candlenut wood with large particle size under oxygen-stream atmosphere. The results show that the acid-washing would remarkably remove the inherent AAEMs in biomass, which is affected by the grain direction. In terms of the gasified chars derived from acid-washed biomass, AAEMs content gradually decreases along the end surface and radial direction, which could also be observed from the 3D reconstruction of X-ray CT images. In all biomass samples and gasified chars, micropores (0-10 μm) dominate and are distributed along the grain direction. In general, pores of 20-30 μm and above 30 μm comprise a minor proportion. Inherent AAEMs facilitate an augmentation in char yield as well as BET and total pore volume of gasified char. AAEMs and grain direction have a slight effect on functional groups of gasified chars. The tar component is remarkably affected by the grain direction. Acid-washing pretreatment augments the content and organic species of M2-M4 compounds (containing 2-4 benzene rings) in the tar. It also leads to a decrement in concentrations of H2, CH4, and CO2 by 14.49% and 13.35%, 0.51% and 0.89%, 2.32% and 1.37% in syngas for two-grain direction, respectively. But it raises the CO concentration by 17.1% and 15.18%, resulting in a reduction of 4.09% and 1.53% in syngas calorific value. A decrement in the volume fraction of CnHx induced from AAEMs is significantly affected by the grain direction. © 2023, The Authors. All rights reserved.

关键词： Biomass

Effects of Inherent Aaems on Catalytic Gasification of Biomass with Large Particle Size Under Oxygen-Steam Atmosphere

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SSRN 2023年

作者： Ren, Jiyun Li, Yuhang Li, Yang Huang, Xiaole Jin, Xiaoling Yang, Chenglong Zhao, Hanchen 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 Xi’an Thermal Power Research Institue Co. Ltd. Xi’an710032 China

Oxygen-steam gasification of biomass is a promising technology because of its ability to improve syngas quality and reduce energy consumption. In this study, a fixed-bed reactor is employed to assess the effects of inherent alkali and alkaline earth metals (AAEMs) on the catalytic gasification of candlenut wood with large particle size under oxygen-stream atmosphere. The results show that the acid-washing would remarkably remove the inherent AAEMs in biomass, which is affected by the grain direction. In terms of the gasified chars derived from acid-washed biomass, AAEMs content gradually decreases along the end surface and radial direction, which could also be observed from the 3D reconstruction of X-ray CT images. A large number of mesopores (20-30 μm) align along the grain direction in the biomass sample. Numerous micropores (10-20 μm), mesopores (20-30 μm), and macropores (30-50 μm) are present in the gasified char derived from the biomass sample. Micropores (10-20 μm) prevail in the gasified char from the acid-washed biomass sample. Inherent AAEMs facilitate an augmentation in char yield as well as BET and total pore volume of gasified char. AAEMs and grain direction have a slight effect on functional groups of gasified char. The tar component is remarkably affected by the grain direction. Acid-washing pretreatment augments the content and organic species of M2-M4 compounds (containing 2-4 benzene rings) in the tar. It also leads to a decrement in concentrations of H2, CH4, and CO2 by 14.49% and 13.35%, 0.51% and 0.89%, 2.32% and 1.37% in syngas for two-grain direction, respectively. But it raises the CO concentration by 17.1% and 15.18%, resulting in a reduction of 4.09% and 1.53% in syngas calorific value. A decrement in the volume fraction of CnHx induced from AAEMs is significantly affected by the grain direction. © 2023, The Authors. All rights reserved.

关键词： Biomass

Comprehensive Parameter Analyses on Steam-Air Condensation at Equal- Height-Difference Natural Circulation Loop Under Large Air Mass Fraction

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SSRN 2024年

作者： Chen, Weixiong Wang, Han Li, Sinian Kai, Hui Zhao, Quanbin Li, Shaodan Wang, Jinshi State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Xi’an710049 China Missile Engineering College Rocket Force University of Engineering 710025 China Science and Technology on Thermal Energy and Power Laboratory Wuhan 2nd Ship Design and Research Institute Wuhan430205 China

With the development of small-sized reactors, a passive containment cooling system (PCCS) named equal-height difference natural circulation loop (EHDNCS) has been developed. Experiments were conducted at higher air mass fractions to evaluate the condensation heat transfer coefficient (HTC) as a function of steam-air mixture pressure, air mass fraction, and wall subcooling. The results indicate that the condensation HTC decreases with increasing air mass fraction and increases with increasing steam-air mixture pressure in the containment. The relationship between condensation HTC and air mass fraction gradually transitions from non-linear to linear as the steam-air mixture pressure increases. The condensation HTC increases with increasing wall subcooling;However, for air mass fractions greater than 75%, the condensation HTC remains nearly constant with changes in wall subcooling. A quantitative relationship between the condensation HTC and the height of the PCCS (sum of riser height and 0.5 times heat exchanger height) has been derived by calculating the cooling water flow driving force and resistance in the natural circulation loop. The applicable conditions for optimizing the riser height and the initial ratio of the riser to heat exchanger height to enhance the heat transfer power of the PCCS were proposed. Based on the experimental results, an empirical correlation equation for predicting the condensation HTC for PCCS with EHDNCS is established, with a prediction deviation within ±31%. © 2024, The Authors. All rights reserved.

关键词： Heat exchangers

Experimental Study on Non-Isothermal Mixing Characteristics of Water in T-Junction

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Experimental Study on Non-Isothermal Mixing Characteristics ...

China Instrument and Control Society (ACCIS), Academic Conference of

作者： Shuhan Liu Wencang Guo Xianliang Lei Zhaojun Yuan Shuqi Meng Desheng Jin State Key Laboratory of Multiphase Flow Engineering Xi'an Jiaotong University Xian China China Nuclear Power Technology Research Institute Co. Ltd. Shen Zhen Guangdong China

ISBN: (数字)9798350350326

ISBN: (纸本)9798350350333

T-junction is an essential component in piping system of various thermal systems. When hot and cold fluid mixing in the T-junction, several compound mechanisms (like turbulent mixing, turbulent penetration, fluid stratification) make the mixing characteristics more complex. To clearly reveal such mixing mechanism with non-isothermal fluids, an experimental study was conducted with Ultrasound Doppler Velocimetry (UDV) and fast-response thermocouples bundle. The results show that the local velocity uncertainty of the UDV is within 10%, the uncertainty of the thermocouple bundle is 0.5°C, and the response time is 66.7 ms. After verification, the mixing characteristics between the main and branch pipe under different momentum ratios and temperature differences were discussed. It is shown that as the momentum ratio decreases, the location of the most intense radial temperature fluctuations and velocity fluctuations shifts towards the lower wall. At the same time, the peak flow rate in the cross-section increases by 35.7% and the main branch fluid mixing is more homogeneous. As the temperature difference increases, the thermal stratification is more pronounced and the velocity fluctuation peak moves towards the upper wall of the pipe.

关键词： Temperature measurement Temperature distribution Fluctuations Fluids Uncertainty Measurement uncertainty Thermocouples Distance measurement Velocity measurement Voltage control

A Gpu-Accelerated Multi-Resolution Lsmps Method for Multiphase flows Simulation with Gas-Liquid Phase Transition

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SSRN 2024年

作者： Cao, Sheng Ren, Qianyong Wang, Wenpeng Zhang, Bin Shan, Jianqiang School of Nuclear Science and Technology Xi’an Jiaotong University Shaanxi Xi’an710049 China State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Shaanxi Xi’an710049 China

The meshless Lagrangian method (particle method) demonstrates significant advantages in simulating multiphase flows with highly dynamic phase interfaces and has been widely applied in research areas such as ocean engineering, nuclear engineering, and aerospace engineering. The least squares moving particle semi-implicit (LSMPS) method theoretically attains high-order accuracy, significantly enhancing the precision and stability of simulations. However, compared to traditional Eulerian methods, its numerical discretization is more complex and computationally intensive, which limits its applicability in large-scale simulations. To mitigate these challenges, a multi-resolution particle model is implemented to reduce computational costs, and algorithmic improvements and optimizations enable GPU-based parallel processing, significantly boosting computational efficiency. Building on this foundation, a high-precision surface particle detection algorithm and a stable gas-liquid phase transition model are developed. The phase transition model integrates the volume change resulting from phase transition as a source term in the pressure Poisson equation. Benchmark tests of single bubble rising in liquid, Rayleigh-Taylor instability, and two-dimensional horizontal film boiling were conducted to validate the accuracy and efficiency of the GPU- accelerated multi-resolution LSMPS method for simulating multiphase flows, thereby promoting the application of the LSMPS method in both scientific research and practical engineering. © 2024, The Authors. All rights reserved.

关键词： Poisson equation

Uncertainty and Sensitivity Analysis of Containment Aerosol Removal Under Severe Accident

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SSRN 2025年

作者： Ou, Pingwen Chen, Yongzheng Chen, Peng Ouyang, Yong Guo, Chao Su, Guanghui China Nuclear Power Technology Research Institute Co. Ltd. Shenzhen518000 China State Key Laboratory of Nuclear Power Safety Technology and Equipment China Nuclear Power Technology Research Institute Co. Ltd. Shenzhen518000 China School of Nuclear Science and Technology Xi'an Jiaotong University Shaanxi Xi’an710049 China State Key Laboratory of Multiphase Flow in Power Engineering China

This study focuses on the uncertainty and sensitivity analysis of containment aerosol removal under severe accident conditions using the severe accident integral code ASTEC, validated by experiments carried by CNPRI, and the coupled uncertainty and sensitivity tool SUNSET. A "separated" methodology is introduced, which distinguishes between thermal-hydraulic and aerosol boundary conditions to highlight the impact of containment aerosol mechanisms. Eleven uncertainty input parameters related are selected for uncertainty propagation and the Spearman correlation coefficient is utilized to describe sensitivity. The removal factor exhibits significant variation, with peaks due to temporary enhancement of diffusiophoresis deposition caused by corium relocation and subsequent steam generation. Uncertainty in the removal factor is substantial before aerosol release termination and narrows afterward. The gravitational settling and the diffusiophoresis deposition are the most important contributors with approximately 70% and 20% deposited aerosol mass, respectively. The initial mass medium diameter, the gravitational shape factor and the agglomeration shape factor are the most influential input parameters in aerosol removal, including in-containment deposition and environmental release, and they should be considered discreetly with conservatism in source term estimation and radioactive consequence evaluation in nuclear engineering. © 2025, The Authors. All rights reserved.

关键词： Sensitivity analysis

Numerical and Experimental Investigation of Proton Exchange Membrane Fuel Cell with Perpendicular Gas Supply Through the Ridge

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SSRN 2023年

作者： Zhang, Yan Lu, Xinyu Su, Jinzhan School of International Trade and Economics China International Research Center for Renewable Energy State Key Laboratory of Multiphase Flow in Power Engineering School of Energy & Power Engineering Xi’an Jiaotong University Xi’an710049 China

The structural design of the cathode flow field in proton exchange membrane fuel cell (PEMFC) is essential for efficient gas supply and effective water removal. For investigating the mechanism behind the effect of gas flow direction on improving the performance of PEMFC, a novel modified serpentine flow channel with vertical inlets through the ridge for PEMFC was proposed and investigated by numerical and experimental methods. Under the operating voltage of 0.4 V, the vertical air supply mode exhibits a 7% higher current density compared to the parallel air supply mode. Compared with conventional air supply mode through the serpentine flow channel, vertical air supply mode modified serpentine through a tunnel inside the ridge exhibited higher oxygen uniformity and higher current density. Furthermore, we conducted research on the impact of physical parameters, including the porosity and thickness of the GDL, as well as the vertical gas supply pore density, on the performance of the PEMFC within the vertical gas supply mode. At an operating voltage of 0.4 V, the current density of PEMFC with a GDL thickness of 0.28 mm is 1.0009 A/cm2, which is 3.02% and 6.13% higher than that of PEMFC with vertical inlets with GDL thickness of 0.38 and 0.48 mm, respectively. With a porosity of 0.6, the current density of PEMFC reaches 1.0395 A/cm2, surpassing that of PEMFCs with porosities of 0.2 and 0.4 by approximately 24.8% and 6.6%, respectively. Moreover, higher vertical inlet densities lead to improved PEMFC performance. Simulation and experimental results demonstrate that this modified flow field effectively addresses uneven current density distribution and enhances power output at low voltage. © 2023, The Authors. All rights reserved.

关键词： Porosity

Load Forecasting of District Heating System Based on Improved Fb-Prophet Model

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SSRN 2022年

作者： Shakeel, Asim Chong, Daotong Wang, Jinshi State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Shaanxi Xi'An710049 China

Accurate load forecasting of district heating networks (DHN) is an essential guide to guaranteeing effective energy production, distribution, and rational utilization. Artificial neural networks have been extensively applied to heating energy prediction in DHN. An improved FB-Prophet model with additional positional encoding layers has been developed to forecast the DHN heat consumption. The accuracy of univariate and multivariate FB-prophet models is evaluated;this paper also investigates how training data affects the accuracy and robustness of improved FB-prophet model. Results revealed that the accuracy of the improved FB-Prophet model increases as the amount of training data increases;it is also observed that there exists a turning point after which robustness starts to decrease. To explore the performance of the improved FB-Prophet model in heating load forecasting tasks, another seven machine learning models, namely FB-Prophet, DeepVAR, long-short term memory (LSTM), extreme gradient boosting (XGBoost), multilayer perceptron (MLP), recurrent neural network (RNN), and support vector regression (SVR) are used for comparison. The historical heating load, outside temperature, relative humidity, speed of wind, direction of wind, and weather type (sunny, overcast, rainy) of a DHN in Serbia are utilized as the key parameters to extensively investigate the effectiveness of the improved FB-Prophet model. The prediction outcomes of all the models were analyzed thoroughly. The results indicated that the improved FB-Prophet model can generate the most precise and consistent predictions and it showed better results for sparse and noisy data of DHN. The prediction curve is fitted to the trend of hourly DHN consumption change, which can play an effective guiding function in the distribution of heat. © 2022, The Authors. All rights reserved.

关键词： Forecasting