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Experimental investigation of heat transfer characteristics of supercritical water in the entrance region of vertical upward tube 7

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Experimental investigation of heat transfer characteristics ...

7th International Conference on power engineering, ICOPE 2019

作者： Kong, Xiangfei Zhang, Qian Guo, Kaikai Feng, Yuan Lei, Xianliang Li, Huixiong State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an710049 China

In order to investigate the special heat transfer characteristics of supercritical water in the entrance region, series of experiments have been conducted in 3-m and 6-m long vertical upward tubes with 20.0-mm internal diameter. The experimental parameters cover the pressures from 22.5 to 27 MPa, the mass fluxes from 150 to 600 kg/(m2·s), and the heat fluxes from 50 to 500 kW/m2. Enhanced heat transfer (EHT) was observed at the inlet of the test sections which was different from the EHT occurred near the pseudo-critical point. Deteriorated heat transfer (DHT) was also observed at the inlet of the test sections under high q/G conditions. It was found that the inlet bulk fluid enthalpy could affect the occurrence and the degree of DHT at the inlet of the test section. DHT disappeared when the inlet bulk fluid enthalpy exceeded the pseudo-critical enthalpy. Finally, the mechanisms of the EHT and DHT occurred at the inlet of test section were analyzed. © ICOPE 2019 - 7th International Conference on power engineering, Proceedings. All rights reserved.

关键词： Heat transfer

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

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

Study on basic coal consumption characteristics in dynamic process of 660MW ultra-supercritical coal-fired unit

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Study on basic coal consumption characteristics in dynamic p...

2019 Canadian Society for Civil engineering Annual Conference, CSCE 2019

作者： Yin, Junjie Liu, Ming Yan, Junjie Zhao, Yongliang State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an Shaanxi China

ISBN: (纸本)9780791883747

With the spreading of intermittent renewable power, coalfired power units should cycle frequently to balance the load between power supply side and demand side. Coal consumption of coal-fired units operating in dynamic processes is influenced by many factors, including thermal system, control system, heat storage variation, etc. Therefore, it is very difficult to evaluate the energy efficiency of coal-fired units operating in dynamic processes. It is important to ascertain the basic coal consumption rate in dynamic processes, which is the basis to evaluate the operation performance of coal-fired units. In this study, an off-design calculation model of 660MW ultra-supercritical coal-fired unit is developed and validated with design parameters. The developed model can be used to predict the coal consumption rates under steady-state off-design conditions. The basic coal consumption means the coal consumption of coal-fired units with operating parameters the same as target values. To calculate the basic coal consumption rate, a load cycling process is differentiated into lots of short time periods and every period is regarded as a steady-state condition with constant load, therefore the coal consumption rates in every period are equal to that of the corresponding steady-state condition. The calculation formula of basic coal consumption rates in is derived for load cycling processes. On the basis of the off-design calculation model and assumption of idealized condition, average coal consumption rates during different processes with constant load cycling rates can be calculated and analyzed. Results show that if the initial and final loads are both settled, the basic coal consumption rate remains unchanged and is independent of load cycling rate. If the load cycling amplitude remains unchanged, the basic coal consumption rate increases as the initial load decrease. The study aims to provide benchmark values for the energy consumption analysis in actual dynamic processes,

关键词： Energy efficiency

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

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

Steam Entrainment and Heat Transfer Characteristic of Steam Submerged Jet Condensation within Steam-Water Mixture Layer

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SSRN 2022年

作者： Zhao, Quanbin Fu, Pengfei Chong, Daotong Chen, Weixiong Liu, Jiping Yan, Junjie State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Xi’an710049 China MOE Key Laboratory of Thermal Fluid Science and Engineering Xi'an Jiaotong University Xi'An710049 China

Steam-water interface and mixture layer are the key window for understanding the heat and mass transfer mechanism of steam submerged jet condensation. In this paper, the steam-water two-phase mixture layer is captured and the interfacial vortex is observed with a quasi-two-dimensional submerged steam jet visualization experimental platform. Then, the volume heat transfer capacity of steam-water mixture layer and heat transfer coefficient with steam-water inner interface are obtained. Furthermore, a new turbulent eddy entrainment model is developed to calculate the local entrainment mass rate and local condensation heat transfer coefficient. Both the local entrainment mass rate and local condensation heat transfer coefficient increases along steam jet direction, and reaches the maximum value at the tail of the mixture layer. The calculated condensation heat transfer coefficient ranges from 0.88 to 2.94 MW·m -2 ·K -1 , which is about the half of the value of hypothetical heat transfer coefficient with inner interfacial area. © 2022, The Authors. All rights reserved.

关键词： Condensation

The Thermal Effect of Flame-Wall Interaction on the Nox Emission Characteristics of Ammonia Swirling Flames in a Model Combustor

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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

Hydrothermal pretreatment of protein-rich substrate:Modified physicochemical properties and consequent responses in its anaerobic digestion

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Carbon Resources Conversion 2023年第1期6卷 1-10页

作者： Fa Qiao Guangyi Zhang Jie Fan Hang Zhang Bowen Shi Jiancheng Yang Jianling Zhang Zhennan Han Shenyang University of Chemical Technology Shenyang 110142Liaoning ProvinceChina 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 School of Urban Construction Wuhan University of Science and TechnologyWuhan 430081Hubei ProvinceChina China Power Engineering Consulting Group Co. LtdBeijing 100120China

Wasted tofu rich in protein was subject to hydrothermal pretreatment(HTPT)under different conditions(at 120,140,160 and 180℃;for 0,30,60 and 90 min)followed by biochemical methane potential(BMP)tests,and 140℃and 0 min were found to be respectively the best temperature and duration for HTPT of tofu in terms of its biogas *** the under the optimal conditions(140℃,0 min)the accumulative methane yield reached up to 510.9 mL⋅(gVS)-1,which was 26.98%higher than that without HTPT(402.3 mL⋅(gVS)-1).The start-up process of continuous anerobic digestion(AD)of the tofu before and after hydrothermal treated(HT)at the optimal HTPT conditions(140℃,0 min)was examined,to investigate and compare how their consequent AD responded to *** was found that,for start-up of continuous AD,the HT tofu delivered more balanced nutrients and thus led to more stable AD and quicker biogas ***,HTPT generated products refractory to biodegradation,to slightly decrease the total biogas *** AD of HT tofu some weak ammonia-tolerant microbes,such as methylotrophic methanogens,survived and played indispensable *** of living microbial community structure indicated that,some hydrolytic acidification bacteria intolerant to ammonia nitrogen(such as Proteobacteria)were always active and appeared at high *** viable methylotrophic methanogens,*** M2,took obvious responsibilities in start-up of the AD for HT tofu.

关键词： Hydrothermal pretreatment(HTPT) Protein-rich substrate Anaerobic digestion(AD) Biogas Microbial community structure