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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

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

Experimental Study on Non-Isothermal Mixing Characteristics ...

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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

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Enhanced catalytic activity for simultaneous removal of PCDD/Fs and NO over carbon nanotubes modified MnO_(x)-CeO_(2)/TiO_(2)catalyst at low temperatu

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Waste Disposal and Sustainable Energy 2021年第1期3卷 63-71页

作者： Qiulin Wang Zhuping Jiang Jianjian Zhou Jin Jing School of Energy and Power Engineering University of Shanghai for Science and TechnologyShanghai 200093China Shanghai Key Laboratory of Multiphase Flow and Heat Transfer in Power Engineering University of Shanghai for Science and TechnologyShanghai 200093China Henan Diesel Engine Industry Co LtdLuoyang 471000China

Simultaneous catalytic removal of polychlorinated dibenzo-p-dioxins and dibenzofurans(PCDD/Fs)and nitrogen oxides(NO_(x))emission at low temperature is of great significance to solve the multiple air pollution problem caused during waste incineration.A novel catalyst with excellent low-temperature activity towards PCDD/Fs catalytic decomposition,as well as selective catalytic reduction(SCR)of NO with NH_(3)is urgently needed to simultaneously control PCDD/Fs and NO ***-cerium composite oxides supported on titanium dioxide(MnO_(x)-CeO_(2)/TiO_(2))or TiO_(2)and carbon nano-tubes(CNTs)composite carrier(MnO_(x)-CeO_(2)/TiO_(2)-CNTs)were prepared using sol-gel method,and their catalytic activity towards simultaneous abatement of ortho-dichlorobenzene(o-DCBz,model molecular to simulate PCDD/Fs)and NO was *** comparison with their removal,the simultaneous removal efficiencies of o-DCBz and NO over MnO_(x)-CeO_(2)/TiO_(2)catalyst are lowered to 27.9%and 51.3%at 150℃under the gas hourly space velocity(GHSV)of 15,000 h−1,due to the competition between the reactants for the limited surface acid sites and surface reactive oxygen *** addition improves the catalytic activity for their simultaneous *** optimum condition occurs on MnO_(x)-CeO_(2)/TiO_(2)combined with 20 wt.%CNTs that above 70%of o-DCBz and NO are removed *** results reveal that MnO_(x)-CeO_(2)/TiO_(2)-CNTs catalyst with proper CNTs content has larger Brunauer-Emmet-Teller surface area and greatly improved surface acidity property,which are beneficial to both o-DCBz and NO ***,the relatively higher surface atomic concentration of Mn^(4+)as well as the existence of abundant surface Ce^(3+)atom accelerates the redox cycle of the catalyst and enriches the surface reactive oxygen *** the above factors alleviate the competition effect between o-DCBz catalytic oxidation and NH_(3)-SCR reaction and are conducive to the simulta

关键词： o-DCBz catalytic oxidation Simultaneous removal MnO_(x)-CeO_(2)catalyst Composite carrier Carbon nanotube

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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

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Fluidized bed combustion of high water content alcohol extracted herb residue and the impacts of blending wasted activated coke

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Carbon Resources Conversion 2023年第1期6卷 11-19页

作者： Xuan Liu Xinyu Zhu Wenyan Wang Bowen Shi Guangyi Zhang Jianling Zhang Jiancheng Yang Yanming Shen School of Chemical Engineering Shenyang University of Chemical TechnologyShenyang 110142LiaoningChina School of Ecology and Environment Beijing Technology and Business UniversityBeijing 100048China State Key Laboratory of Multiphase Complex Systems Institute of Process EngineeringChinese Academy of SciencesBeijing 100190China China Power Engineering Consulting Group Co. LtdBeijing 100120China

Combustion of herb residues(HRs)for heat recovery is a good way for their utilization,but there exists such a problem as high concentration NOx emission in flue *** alcohol extracted herb residue(AEHR),one special type of HRs,was chosen as the object and was subjected to immediate combustion in a fluidized bed reactor to investigate the characteristics of its resulting NOx *** results showed that,most of the NOx in the flue gas was produced from the char nitrogen(C-N);as the fuel water content increased,the NOx emission concentration exhibited a trend of first decreasing and then increasing;and a properly low combustion temperature inhibited the NOx emission upon the premise of ensuring full *** staging combustion was adopted to effectively control NOx:the NOx emission concentration in the flue gas was reduced to 296 mg⋅m􀀀3 and the NOx emission reduction rate reached 46.51%compared to conventional ***-combustion by blending wasted activated coke(WAC)into the AEHR helped both stabilize the combustion state and reduce further the NOx *** the blending ratio of WAC fell within a proper range of 20-30%,the NOx emission concentration in the flue gas was as low as 231.4 mg⋅m􀀀*** addition to the dilution effect of the combustion flue gas of the blended WAC,the local reducing atmosphere caused by its incomplete combustion as well as its strong absorbability and catalytical effect was accountable for the further decrease of the NOx emission concentration.

关键词： Alcohol extracted herb residue Wasted activated coke Fluidized bed combustion NOx Air staging combustion

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Experimental Study on Slagging and Fouling Behaviors During Oxy-Fuel Combustion of Zhundong Coal Using a Drop Tube Furnace 9th

Experimental Study on Slagging and Fouling Behaviors During ...

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9th International Symposium on Coal Combustion, ISCC 2019

作者： Zhao, Lei Wang, Chang’an Hu, Yueyi Sun, Ruijin Tang, Guantao Guo, Jin Jiang, Zhiming Du, Yongbo Che, Defu State Key Laboratory of Multiphase Flow in Power Engineering School of Energy and Power Engineering Xi’an Jiaotong University Xi’an710049 China Guangdong Institute of Special Equipment Inspection and Research Foshan528251 China Shunde Institute of Inspection Guangdong Institute of Special Equipment Inspection and Research Foshan528251 China

ISBN: (纸本)9789811616563

Zhundong coal featuring high content of alkali metals induces severe slagging and fouling problems during its utilization in utility boilers. Oxy-fuel combustion technology can achieve a large amount of CO2 capture and reduce the NOx emission. Unfortunately, in-depth investigation has been seldom carried out on the process of ash deposition and slagging of high-alkali coal during oxy-fuel combustion. In the present study, the oxy-fuel combustion of high-alkali coals were experimentally studied using a non-cooled sampling probe in a drop tube furnace. The fouling and slagging mechanisms were investigated in various atmospheres, temperatures and different O2 concentrations. In addition, the slag samples were characterized by X-ray diffraction (XRD) and Scanning Electron Microscopy (SEM) coupled with Energy Dispersive X-ray Spectrometer (EDS). Experimental results indicated that under air and oxy-fuel conditions with the same O2 content, the types of elements and minerals were almost the same. With the temperature increased, the adhesion between the slag samples was strengthened and the pore structure slag was increased. The degree of slag melting and sintering was aggravated at the temperature of 1200 °C and the slag structure was complicated. As the oxygen concentration was increased, some of the spherical particles had completely melted on the surface of the massive ash, resulting in an uneven surface. The present work can provide new insights into the slagging and ash deposition of Zhundong high-alkali coal during oxy-fuel combustion. © 2022, Tsinghua University Press.

关键词： Coal

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An Experimental Study on Ash Deposition Problem of Low-Low Temperature Flue Gas System 9th

An Experimental Study on Ash Deposition Problem of Low-Low T...

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9th International Symposium on Coal Combustion, ISCC 2019

作者： Yan, Yu Jiang, Jiahao Guo, Jin Li, Yuesheng 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 Guangdong Institue of Special Equipment Inspection and Research Foshan528251 China Guangdong Institue of Special Equipment Inspection and Research Shunde Institue of Inspection Foshan528300 China

ISBN: (纸本)9789811616563

In order to achieve the ultra-clean emission standards, many power plants in China have completed the installation of low-low temperature flue gas system. However, during the operation of this system, many problems have emerged, such as the ash deposition problem in the heat exchanger and dry ESP (electrostatic precipitator). In this paper, the fixed adsorption system and entrained flow experimental system were built to study the ash deposition characteristics in low-low temperature flue gas system under different temperatures and particle sizes. The repose angle was measured to evaluate the flowability and adhesion capacity of ash particles. The results show that as the increase of adsorption time, the particle size increased gradually, and the agglomeration effect is attenuated after the particles have reached adsorption saturation. The time at which the ash particles began to agglomerate with each other was defined as the agglomeration threshold. As the adsorption temperature decreased, the particle size growth rate increased. The smaller the size of ash particles, the more significant the agglomeration effect. Large particles were easy to adsorb small particles, but the agglomeration effect between large particles was weak. In addition, in the initial stage of particle agglomeration, it was mainly included the adhesion between smaller particles and the adhesion of smaller particles on the surface of large particles. The followability of the ash particles was greatly reduced after the adsorption and agglomeration process. The repose angle of the ash particles increased as the temperature of the flue gas decreased. The smaller the particle size, the larger the repose angle changes, and the more pronounced the repose angle is influenced by the adsorption temperature. The flue gas temperature cannot be blindly dropped in pursuit of high sulfur oxide removal efficiency and dust removal efficiency. © 2022, Tsinghua University Press.

关键词： Particle size

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A Three-Dimensional Curve Interface Reconstruction Algorithm for Two-Phase Fluid flow

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SSRN 2024年

作者： Chen, Yujie Gong, Junhua Sun, Dongliang Han, Dongxu Wang, Peng Yu, Bo Tao, Wen-Quan School of Mechanical Engineering Beijing Institute of Petrochemical Technology Beijing102617 China State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Shaanxi Xi’an710049 China Key Laboratory of Thermo–Fluid Science and Engineering Ministry of Education School of Energy & Power Engineering Xi’an Jiaotong University Shaanxi 710049 China

The curve interface reconstruction algorithm has received significant attention in the context of two-dimensional two-phase flow. However, it remains absent in the three-dimensional scenario. This paper proposes a novel three-dimensional curve interface reconstruction (CIR) algorithm to address this challenge within structured meshes for the first time. Specifically, a portion of the spherical surface is employed to reconstruct the three-dimensional curve interface segment, with the radius and center coordinates determined by curvature and mass conservation constraints, respectively. To enhance curvature accuracy, a sphere-based iterative reconstruction (SIR) algorithm is proposed to calculate the reconstructed distance function (RDF) for the three-dimensional curve interface. Various tests involving the reconstruction and interface capture of spherical, ellipsoidal, and cubic objects demonstrate that the coupled SIR and CIR (SIR-CIR, simplified by SCIR) method achieves high accuracy, particularly with coarse mesh resolutions. Additionally, the SCIR method offers the advantages of straightforward implementation and coding for interface reconstruction in two-phase flow research. This advantage results in reduced computational costs compared to the coupled volume-of-fluid and level set (VOSET) method, which also utilizes an iterative method to solve RDF. © 2024, The Authors. All rights reserved.

关键词： Spheres

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Research on Artificial Neural Network for Geometric Design and Optimization of Three-Stage Segmented Thermoelectric Generators

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SSRN 2024年

作者： Zhang, Yin Guo, Kailun Wang, Chenglong Zhang, Jing Wang, Yulu Tian, Wenxi Su, Guanghui Qiu, Suizheng School of Nuclear Science and Technology Shanxi Key Laboratory of Advanced Nuclear Energy and Technology State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi’an710049 China School of Mechatronic Engineering Xianyang Vocational Technical College Xi’an712000 China

More green and environmentally friendly electricity production is the driving force for the development of thermoelectric generators. In addition to high-performance thermoelectric materials, optimizing the geometric shape of thermoelectric generators can also maximize thermoelectric efficiency. This work applies artificial neural networks to the design and optimization of a three-stage segmented thermoelectric generator. After verifying the thermoelectric numerical model of COMSOL, this work generated 3000 sets of simulation data for neural network training. After hyperparameter and particle swarm optimization, the trained neural network can exhibit extremely high prediction accuracy. By coupling the genetic algorithm and artificial fish swarm algorithm, the trained artificial neural network can optimize eight geometric parameters of a three-stage segmented thermoelectric generator under different temperature differences. Compared with COMSOL optimization results, the conversion efficiency optimized by GA has increased by 1.42% and 2.48% in cases 1 and 2, respectively;The conversion efficiency optimized by AFSA has increased by 3.61% and 2.86% in cases 1 and 2, respectively. By obtaining almost identical optimization values, the neural network can achieve geometric design optimization within 5 minutes under different temperature differences. This method provides a new and economical avenue for rapid prediction and design of thermoelectric generators. © 2024, The Authors. All rights reserved.

关键词： Genetic algorithms

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The blow-off and transient characteristics of co-firing ammonia/methane fuels in a swirl combustor 38th

The blow-off and transient characteristics of co-firing ammo...

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38th International Symposium on Combustion, 2021

作者： Zhang, Meng Wei, Xutao Wang, Jinhua Huang, Zuohua Tan, Houzhang State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an 710049 China MOE Key Laboratory of Thermo-Fluid Science and Engineering Xi'an Jiaotong University Xi'an 710049 China

Recent studies have demonstrated that ammonia could be one of the most promising hydrogen carrier candidates which can be used in large-scale power plants. However, it is challenging to burn ammonia in gas turbines due to its narrow flame stabilization limits. In this study, the blow-off characteristics and flame macrostructure transition behavior of ammonia/air flame (NH₃ flame) and ammonia/methane/air flame (50%NH₃ flame) in a swirl combustor were investigated. Flame structures and flow fields near the blow-off limit were analyzed. Methane/air flame (CH₄ flame) was also examined for comparative purposes. The flow field and instantaneous OH profile were measured with PIV and OH-PLIF technique, respectively. Large eddy simulation (LES) was conducted to extend the understanding of the experimental findings. Results revealed that the NH₃ flame possesses a poor lean flame stability limit which can be largely extended by adding CH₄ in the fuel. Changing swirl number (S) had no apparent effect on the lean blow-off limit (Φ_b) for the NH₃ flame. On the contrary, a clear extension on Φ_b was found for the 50%NH₃ flame when increasing S. Four flame macrostructure modes were identified when decreasing equivalence ratio (Φ). The transition from flame II to flame III ((Φ_tdescribes the transition equivalence ratio) can be considered as the early warning of blow-off for a swirl stabilized flame. For the NH₃ flame, there was no clear flame macrostructure transition at small inlet velocities (U < 3.8 m/sec), i.e., Φ_b ≈ Φt. The difference between Φ_b and (Φ_twas observed as the inlet velocity increased. However, for the 50%NH₃ and CH₄ flames, a clear flame macrostructure transition from flame II to flame III was observed even for a lower inlet velocity. The LES results demonstrated that the NH₃ flame h

关键词： Ammonia

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