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SSRN 2022年

作者： Zhang, Meng Xu, Wanying Wang, Ruixiang Wei, Xutao Wang, Jinhua Huang, Zuohua Tan, Houzhang State Key Laboratory of Multiphase Flow in Power Engineering Xian Jiaotong University Xian710049 China MOE Key Laboratory of Thermo-Fluid Science and Engineering Xian Jiaotong University Xian710049 China

Ammonia (NH 3 ) combustion is regarded as one of the most promising solutions to realize zero CO 2 emission. However, the low reactivity, low heat release result in a strong flame-wall interaction (FWI) which significantly affects the flame stabilization and the NOx emission characteristics. In this study, an air film cooling on the swirling combustion chamber was designed to investigate the thermal effect of the FWI on NOx emission. The flame structure and NO production are measured with the OH-/NO-PLIF techniques. The NOx emission is analyzed by the Gasmet DX4000 Fourier Transform Infrared (FTIR) gas analyzer. Large eddy simulation is also conducted to extend the understandings of experimental findings. For the current combustion chamber, the temperature difference is increasing as downstream location, resulting a larger convection heat loss. The heat loss shows no apparent effect on the flame structure and NO production at the symmetrical plane. The flame tends to be more fragmentized and the NO production is largely decreased at near wall region and the outer recirculation zone with increasing heat loss. This can be understood that NO production rate from the oxidation of NH i by O, H and OH radicals through HNO is largely decreasing in these regions. Therefore, a decreasing NO trend is found at the chamber outlet. NO emission shows a decreasing trend with heat loss at lean condition, which is mainly caused by the decreased NO production at near wall region resulting from the lower combustion efficiency. However, N 2 O, a more serious greenhouse gas, significantly increases as the heat loss increases. This is mainly because that the production of N 2 O from NO is promoted and N 2 O decomposition is suppressed within the thermal boundary. Thus, N 2 O might become a more serious emission component in NH 3 fuelled gas turbines. Moreover, a tradeoff behaviour between NO and N 2 O is observed as increasing heat loss. This study suggests the thermal effect of FWI on t

关键词： Heat losses

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Neutronic/Thermal-Hydraulic Coupling Analysis of Heat Pipe Reactor Nuster-100 Based on Comsol

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SSRN 2022年

作者： Zhang, Yin Nie, Jingyu Wang, Chenglong Guo, Kailun 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

Heat pipe cooled nuclear reactor plays an important role in future space and ocean exploration missions due to its advantages such as high inherent safety, removability, passive safety. Xi’an Jiatong University proposed a concept design of 100kWe nuclear reactor named NUclear Silent ThermoElectric heat pipe cooled Reactor (NUSTER-100). To explore NUSTER core’s performances, COMSOL are used for neutronic/thermal-hydraulic coupling calculation. Neutron diffusion equations are used to calculate NUSTER’s neutron flux distribution by partial differential equation (PDE) model. Dragon code is used to solve the group constants of neutron diffusion equations. The heat transfer module of COMSOL is used to calculate NUSTER’s temperature distribution. for NUSTER-100, the keff calculated by the neutron diffusion module of COMSOL is 1.0372. The calculation results of three-dimensional NUSTER show that the maximum temperature of heat pipe is 1226.2 K and that of fuel rod is 1447.1K. The calculated temperatures have not exceeded the limit. The unified calculation of neutron physics and temperature distribution is realized in COMSOL platform. This work provides a preliminary basis for neutronic/thermal-hydraulic coupling calculation for heat pipe reactor. © 2022, The Authors. All rights reserved.

关键词： Heat pipes

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Numerical Study on Transverse Mixing Characteristics of flow Sweeping in Helical Cruciform Rod Bundle

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SSRN 2022年

作者： Jiang, Dianqiang Zhang, Dalin Tian, Wenxi Qiu, Suizheng Su, Gguanhui State Key Laboratory of Multiphase Flow in Power Engineering Shaanxi Key Laboratory of Advanced Nuclear Energy and Technology School of Nuclear Science and Technology Xi’an Jiaotong University Xi'An710049 China

In the chemical industry, nuclear energy, electronics, and other industries, heat transfer enhancement has been the focus of significant attention. To enhance the flow heat transfer performance of coolant in the nuclear fuel assembly, helical cruciform fuel rods are designed as a foundation fuel element. The transverse mixing characteristics of flow sweeping of heat conduction oil in the present study using the numerical approach in helical cruciform rod bundle. The fluid in the helical cruciform rod bundle exhibits a substantial flow sweeping crossflow phenomena as a result of the impact of the helical structure. The transverse mixing velocity and temperature profiles are analyzed. The subchannel conservation equation is optimized, and the link between flow sweeping mixing parameters and dimensionless local gap width in various Reynolds number ranges is determined by fitting. Furthermore, the turbulent mixing parameters of the cylindrical rod bundle are analyzed. It can be concluded that the helical cruciform rod bundle has considerable transverse mixing, which enhances the flow heat transfer performance of the reactor core. This study provides a guide for the numerical study of flow heat transfer in helical structures, and a foundation for the development of the subchannel mixing model. © 2022, The Authors. All rights reserved.

关键词： Mixing

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Evaluation of droplet drag force model on spray and atomization behaviours of R134a flashing spray 14

Evaluation of droplet drag force model on spray and atomizat...

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14th International Conference on Liquid Atomization and Spray Systems, ICLASS 2018

作者： Zhou, Zhi-Fu Lu, Guan-Yu Zhang, Lu Chen, Bin State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an710049 China

Flashing spray is of great importance in a variety of engineering fields, which occurs as the pressurized liquid is released into a low-pressure environment below its saturation pressure. This paper conducts a systematically numerical study on the spray and thermal characteristics of R134a flashing spray with high volatility and low saturation temperature, using a modified sprayFoam solver in the open source tool OpenFOAM-2.4.0. key physics involved in the complex process, including droplet flash boiling, evaporation, droplet transport, breakup, heat transfer and interaction between droplet and gas phases are taken into consideration. The emphasis is put on the droplet drag force model and nozzle diameter on flashing spray including spray morphology, droplet diameter, velocity and temperature. The result indicates that most of the drag force models have little effect on droplet diameter, velocity and temperature distributions in flashing spray, except the Khan-Richardson (K-R) model. The K-R model predicts lower temperature, higher velocity and larger size of droplet, compared to other models. The nozzle diameter greatly affects R134a spray morphology and tip penetration, that smaller diameter contributes to a larger radial expansion at the near nozzle region while leading to a much smaller penetration distance. This research give a useful guidance that how people choose the appropriate drag force model for simulation of flashing spray. © 2018 Solar Turbines Incorporated.

关键词： Morphology

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Experimental investigation on flash evaporation related to pipe leakage

Experimental investigation on flash evaporation related to p...

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作者： Cai, Benan Zhang, Qi Weng, Yu Gu, Hongfang Wang, Haijun State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an710049 China

Pipelines such as the surge line and main pipe are easily subjected to thermal stratification and thermal fatigue as a result of the nonuniform temperature distribution in the nuclear power plants. When the surge line or main pipe subjected to thermal stratification and thermal fatigue keeps operating for long time, the pipe leakage may happen due to the existence of pipeline crack. When the fluids with high temperature and pressure leak in the crack, the water will evaporate quickly, which means this process belongs to spray flash evaporation process. The flash evaporation related to pipe leak was experimentally studied in the paper. The experiment was carried out under high temperature and high pressure with low spray rate. The temperature and relative humidity (T&H) variations over time were monitored in the experiment with installing T&H detectors. The T&H variations at different measurement positions and with different spray rates were analyzed, respectively. In addition, the effect of the dimensionless parameters including the Weber number and Jakob number was also investigated. Results indicated that the response speed increased with the increase of the spray flow rate. Higher Weber number and higher Jakob number led to higher evaporation rate. The slight pipe leakage can be predicted by using the (T&H) in the hazardous areas. Copyright © 2020 by ASME

关键词： Nuclear fuels

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Inverse Analysis of Radiative Properties of Internal Medium and Surface for Cylindrical System Using Csm-Cgm Approach

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SSRN 2023年

作者： Zhang, Chao Li, Ben-Wen Zhou, Rui-Rui Li, Pan-Xin Huang, Ling-Yun Key Laboratory of Ocean Energy Utilization and Energy Conservation Ministry of Education School of Energy and Power Engineering Dalian University of Technology Dalian116024 China Shanghai Key Laboratory of Multiphase Flow and Heat Transfer in Power Engineering School of Energy and Power Engineering University of Shanghai for Science and Technology Shanghai200093 China State Key Laboratory of Complex Nonferrous Metal Resources Clean Utilization Faculty of Land Resource Engineering Kunming University of Science and Technology Kunming650093 China

An inverse analysis is conducted to simultaneously estimate the radiative properties in a 2D cylindrical system including the extinction coefficient, scattering albedo, and the wall emissivity from the knowledge of the radiative heat flux over different boundaries. In which the collocation spectral method (CSM) is developed to solve the forward problem, the conjugate gradient method (CGM) is employed to solve the inverse problem, and the complex-variable-differentiation method is used to treat the sensitivity problem, separately. Meanwhile, the effects of measurement errors, initial values, and imaginary values of complex variables on the precision of the inverse analysis are investigated. Results show that the proposed inverse analysis can successfully retrieve the unknown radiative physical properties of 2D cylindrical system. Under the same physical properties, good inversion results can be obtained by using different wall (end walls and side wall) radiative heat fluxes, but the inversion efficiency from sidewall radiative heat flux is higher. Besides, it is found that, the inversion for the scattered participating medium is more efficient than that for the non-scattered participating medium;the true values and iterative convergence values have little effect on the inversion result;the influence of the initial values and the imaginary values of the complex variable on the inversion cannot be ignored. © 2023, The Authors. All rights reserved.

关键词： Conjugate gradient method

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Numerical study on drop-on-demand droplet formation dynamics 7

Numerical study on drop-on-demand droplet formation dynamics

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7th International Conference on power engineering, ICOPE 2019

作者： Zhu, Maoguo Chong, Daotong Zhao, Quanbin Chen, Weixiong Yan, Junjie State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an710049 China

Inkjet printing technology has been applied in many industrial fields for its significant usefulness. The drop-on-demand droplet formation dynamics was studied numerically based on the VOF and CSF method. Droplet formation was modeled by imposing a vertical velocity pulse waveform perturbation. The effects of printhead geometry and fluid properties on droplet ejection stability were analyzed. Simulation results make clear that choosing an appropriate printing fluid with relatively lower density and viscosity or higher surface tension can improve the droplet ejection stability. Designing the printhead with a larger inclination of outlet is also a key way to improve the droplet ejection stability. In addition, droplet ejection stability becomes better as Z increased or Ca decreased. © ICOPE 2019 - 7th International Conference on power engineering, Proceedings. All rights reserved.

关键词： Stability

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Heart, a Specific Code for Thermal-Electrical Analysis of Heat Pipe Cooled Nuclear Reactor

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SSRN 2022年

作者： Zhang, Zeqin Wang, Chenglong Guo, Kailun Huang, Jinlu Qiu, Suizheng Su, Guanghui H. Tian, Wenxi 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

Heat pipe cooled reactor (HPR) features high power density, compact structure, long operation life and high reliability, which is an excellent candidate for small nuclear power source for deep space or underwater missions. In this paper, a conceptual Nuclear Silent Thermal-Electrical Reactor (NUSTER) is preliminarily designed, using 109 sodium heat pipes for passive cooling. The thermoelectric generators (TEGs) are employed in the reactor to convert fission heat to electric power. Based on the design, a HEat pipe cooled Advanced Reactor Transient analysis code (HEART) is developed, including point reactor kinetics model, multi-channel model, core heat transfer model, heat pipe model, thermoelectric generator model and coolant model. The models proposed in HEART are preliminarily verified against the design value and experiment data, and the maximum deviation is less than 12.3%. Steady-state performance of the NUSTER are successfully predicted by HEART, and results indicate that the solid-state core has good temperature flattening ability. The surface temperature of the heat pipe is less than 1300K, and the average temperature drop of the TEG module in central channel is 724.1K, which can produce an electrical power of 301.94W. The models developed in HEART can also be applied to other heat pipe cooled reactors, providing valuable experience in design and thermal-hydraulic evaluation of HPRs. © 2022, The Authors. All rights reserved.

关键词： Transient analysis

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Design and Optimization of the Heat Transport and Passive Residual Heat Removal System for Fluoride-Salt-Cooled High-Temperature Advanced Reactor (FuSTAR)

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SSRN 2022年

作者： Li, Xinyu Zhang, Dalin Lv, Xindi Zhou, Xingguang Tian, Wenxi Qiu, Suizheng G.H. State Key Laboratory of Multiphase Flow in Power Engineering Shaanxi Key Laboratory of Advanced Nuclear Energy and Technology School of Nuclear Science and Technology Xi’an Jiaotong University Xi’an710049 China

The new generation of reactor technology: Fluoride-Salt-cooled high-Temperature Advanced Reactor (FuSTAR), mainly applied to the steady supply for stable electricity and high-temperature process heat for remote, underground, and arid areas, has an urgent need for a scheme of the heat transport system and Passive Residual Heat Removal System. Given the complexity and consistency of the design, a unified design and optimization method is required, which can directly obtain detailed configurations and dimensions. In this paper, a design and optimization method - Multi-Layer Nonlinear Programming was proposed to obtain the optimal parameters, including vital thermodynamic values, the dimensions of heat exchangers, the configurations of pipelines, and the optimal equivalent parameters in the transient simulation. Finally, based on Multi-Layer Nonlinear Programming, the effectiveness of the Passive Residual Heat Removal System was demonstrated by the deterministic safety analysis. The detailed parameters of the Passive Residual Heat Removal System in this paper can provide the references for subsequent experimental verification. Moreover, for any reactor relying on a heat transport system, researchers can directly obtain its excellent preliminary configurations by this method avoiding a lot of iteration and conflict design, which is conducive to the integrated modeling and simulation of a new generation of reactors. © 2022, The Authors. All rights reserved.

关键词： Nonlinear programming

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Dynamic modeling of an air-cooling supercritical power plant under temp oral variant ambient conditions 7

Dynamic modeling of an air-cooling supercritical power plant...

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7th International Conference on power engineering, ICOPE 2019

作者： Yan, Wenchen Han, Xiaoqu Chen, Nana Wu, Wenxiang Zhou, Yan State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an710049 China

Air-cooling systems are widely used in coal-fired power plants, especially in areas rich in coal resources and short of water. To prompt its economic and safe operation, dynamic modeling is urgently required to acquire the power plant's characteristics under complex working conditions. In particular, the condensing pressure of the air-cooling unit is significantly affected by the ambient temperature, and the thermal power plant is a complicated energy system with serious nonlinearity. In many cases, it is difficult to establish the mathematical model of the system by traditional analytical methods. In the present work, a 1000 MW supercritical power plant thermal system was modeled and simulated by GSE simulation software. The model was developed according to the structural characteristics, incorporating boiler system, steam turbine system and direct air-cooling system. The simulation results were compared with the actual operation data of the power plant to validate the model. The relative errors of the simulation models under steady-state conditions were less than 3%, which indicates that the models have high accuracy. On this basis, the influence of condensing pressure on the standard coal consumption rate was obtained. It was shown that when the condensing pressure ranged between 5 kPa and 20 kPa, the coal rate increased by 1.6 g/kW∙h with 1 kPa increase in the condensing pressure. Then the boundary conditions of the system were changed. When the parameters changed, the changes of condensing pressure and power were monitored, so as to study the dynamic characteristics of the system. © ICOPE 2019 - 7th International Conference on power engineering, Proceedings. All rights reserved.

关键词： Coal

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