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Study on the thermal and geometrical parameters of helical coil once-through steam generator system

International Journal of Advanced Nuclear Reactor Design and Technology 2021年 3卷 80-96页

作者： Yao, Hao Chen, Guo Lu, Kailin Liao, Haoyu Wu, Yingwei Tian, Wenxi Su, Guanghui Qiu, Suizheng School of Nuclear Science and Technology State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an710049 China Nuclear Power Institute of China Chengdu610226 China

Due to the special structure, helical coil once-through steam generators (HCOTSGs) can withstand greater thermal expansion stress, have a larger heat exchange area, and cause the secondary flow phenomenon to improve the heat transfer capacity. Thus, it is inevitable to further study the thermal-hydraulic characteristics of the HCOTSG, a vital component of reactors. The optimal physical models were selected for different heat transfer areas by detailed investigation and comparison, to adopt in the TACS, a self-developed thermal-hydraulic analysis code that is accurate and widely-used in HCOTSG simulation. After verification with experiments of Santini, taking the IRIS reactor as the object, the TACS was employed to briefly study the thermal-hydraulic performances of the HCOTSG system at first, and then discuss the influences of thermal and geometric parameters on the HCOTSG. The analysis results showed that: the variation of the primary flow rate greatly affects the heat transfer coefficient of the primary side, while the maximum value of the heat transfer coefficient of the secondary side only changes drastically with the secondary flow rate;when the primary side flow drops to 70%, superheated steam is not generated on the secondary side;when the secondary mass flow rate decreases to a certain extent, the steam superheat degree increases by a small amplitude;the primary side inlet temperature has a little influence on the primary temperature difference, but significant influence on the two-phase zone length of the secondary side;the secondary inlet temperature has very little influence on the HCOTSG system;the inner diameter and the outer diameter of helical tubes have obvious influences, while the helical diameter has not. © 2021.Xi'an Jiaotong University

关键词： Heat transfer coefficients

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Investigation on the matching performance of a small cryogenic air turboexpander 24

Investigation on the matching performance of a small cryogen...

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24th IIR International Congress of Refrigeration, ICR 201.

作者： Yang, Shanju Li, Bowen Liu, Guoqing Hou, Yu Chen, Shuangtao State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an710049 China

ISBN: (纸本)9782362150128

The matching performance of a turboexpander is essential for a small reverse Brayton air refrigerator, especially when it works under varied operation parameters. Generally, an appropriate brake pressure is required when the turboexpander works under different operation parameters. In this paper, the matching performance of a turboexpander supported by a bump journal foil bearing and a pressurized thrust gas bearing is studied. A centrifugal blower is used as a brake. The performance curve is analyzed through a numerical simulation using CFX. The matching calculations were carried out with different brake blowers under both room temperature and low temperature. A brake pressure feedback control is applied in the experimental study. A thermal performance of the refrigerator is tested. The results indicated that the appropriate brake blower and brake pressure facilitate the system thermal performance under both room and low temperature. The simulation agrees well with the experimental results.

关键词： Temperature

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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 {1., ICOPE 201.

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 1.00 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 201. - 7th International Conference on power engineering, Proceedings. All rights reserved.

关键词： Coal

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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 {1., ICOPE 201.

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 201. - 7th International Conference on {1. engineering, Proceedings. All rights reserved.

关键词： Stability

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Theoretical Chemical Kinetic Study of the H-atom Abstraction from Ethanol by Hydroperoxyl Radical 12

Theoretical Chemical Kinetic Study of the H-atom Abstraction...

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1.th Asia-Pacific Conference on Combustion, ASPACC 201.

作者： Zhao, Qian Sun, Wuchuan Deng, Fuquan Yang, Feiyu Zhang, Yingjia Huang, Zuohua State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an710049 China

Reactions of ethanol + hydroperoxyl radical (H?2) are well known a crucial reaction class in oxidation mechanism of ethanol. However, the kinetic parameters of the reactions are basically extrapolated by analogy with n-butanol + H?2 system calculated by Zhou et al. [1.. The reliability of such the analogy remains to be seen, as no directly theoretical or experimental evidence is available in literature to date. In this study, thermal rate coefficients of H-atom abstraction reactions for ethanol + H?2 system were calculated at both CCSD(T)/cc-pVTZ//M06-2x/def-TZVP and CCSD(T)/CBS//M06-2x/def-TZVP levels of theory, with an uncertainty of a factor of 3, by means of using both conventional transition-state theory and canonical variational transition-state theory. Similar to n-butanol + H?2 system, the title reactions are dominated by alpha site H-abstraction, whereas the rate coefficients of all channels of ethanol are slightly slower than that of n-butanol + H?2 system. Generally, the new calculations show only limited effect on ethanol reactivity at low pressures and high temperatures (over 1.00 K) but it prevents the kinetic mechanisms to over-predict ignition delay times under engine relevant conditions. © Asia-Pacific Conference on Combustion, ASPACC *** right reserved.

关键词： Ethanol

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Experimental investigation on flow patterns and frictional pressure drop of downward air-water two-phase flow in vertical pipes

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ASME 201. Heat Transfer Summer Conference, HT 201. Collocated with the ASME 201. 7th International Conference on Energy Sustainability and the ASME 201. 1.th International Conference on Fuel Cell Science, engineering and Technology

作者： Xue, Yuqing Li, Huixiong Tianyou, Sheng Liao, Changjiang State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiao Tong University Xi'an China

ISBN: (纸本)9780791855485

A large amount of air need be transported into the reservoir in the deep stratum to supply oxygen to some microbes in Microbial Enhanced Oil Recovery (MEOR). Air-water twophase flows downward along vertical pipeline during the air transportation. Base on the experiment data described in this paper, the characteristics of air-water two phase flow patterns were investigated. The flow pattern map of air-water two phase flows in the pipe with inner diameter of 65 mm was drawn, criterions of flow pattern transition were discussed, and the dynamic signals of the pressure and the differential pressure of the two phase flow were recorded to characterize the three basic flow regimes indirectly. The frictional pressure drop of downward flow in vertical pipe must not be disregarded contrast with upward two phase flow in the vertical pipe because the buoyancy must be overcame when the gas flows downward along pipe, and there would be a maximum value of frictional when the flow pattern translated from slug flow to churn flow. Copyright © 201. by ASME.

关键词： Two phase flow

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DISTRIBUTED MULTI-ENERGY SYSTEMS CONSIDERING power-TO-X TECHNOLOGY: PLANNING, SCHEDULING, AND PERFORMANCE ASSESSMENT 37

DISTRIBUTED MULTI-ENERGY SYSTEMS CONSIDERING POWER-TO-X TECH...

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37th International Conference on Efficiency, Cost, Optimization, Simulation and Environmental Impact of Energy Systems, ECOS 2024

作者： Xue, Kai Wang, Jinshi Han, Xiaoqu Zhao, Quanbin Chong, Daotong Chen, Weixiong Yan, Junjie State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Shannxi Xi'an China

ISBN: (纸本)9798331307660

The distributed multi-energy systems place emphasis on the complementary and local application of heterogeneous energy sources, and power to methanol process can be coupled, reducing carbon emissions while increasing the *** providing an economical and low-carbon solution, a real community energy system integrated with solar energy and natural gas has been investigated in this *** at the minimization of the daily cost referring to the net expenditure after considering the offsetting benefits, the carbon capture, water electrolysis, and methanol synthesis are combined, with the methanol and oxygen exported as *** capacity planning and operation scheduling have been performed, and the results indicated that the daily cost can be reduced by 69.67% compared to the conventional energy supply after the scheduling *** the case scenario and typical day, the production of methanol and oxygen is 6.30 t and 1..49 t based on an electricity demand of 28.78 MWh and a heat demand of 1..85 *** to the contribution of carbon capture, the purchase of 5.90 t of carbon allowances is avoided and instead there are 3.86 t of allowances available for ***, the effect of device capacity and operating parameters on economics has been *** study could help to promote the application of power to methanol in distributed energy systems. © 2024 37th International Conference on Efficiency, Cost, Optimization, Simulation and Environmental Impact of Energy Systems, ECOS 2024. All rights reserved.

关键词： Carbon capture and utilization

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Experimental study of natural convection in horizontally-positioned open-celled metal foams

Experimental study of natural convection in horizontally-pos...

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International Conference on Materials for Renewable Energy and Environment

作者： Xu, Z.G. Qu, Z.G. Zhao, C.Y. State Key Laboratory of Multiphase Flow School of Energy and Power Engineering Xi'An Jiaotong University China

ISBN: (纸本)9781612847504

Experimental study of air natural convection in horizontally-positioned copper metallic foams with open cells was conducted. Temperature distributions on the heating surface were tested under different heating power for foam samples having different porosities and pore densities. The effects of porosity and pore density on the total thermal resistance of the foam sample were quantified. It is found that the porous surface can enhance the natural convection and reduce the thermal resistance by about 20% in comparison with a smooth surface. The surface area density and mass {1. rate in natural convection are affected by porosity and pore density simultaneously. When the porosity is relative small (Ε = 90%), there exits a critical value of the Gr number (turning point) for two pore densities (1.ppi and 40ppi). When the Gr number is less than this critical value, the foam with a higher pore density has the lower total thermal resistance, whereas when the Gr number exceeds the turning point value, the opposite holds. If the porosity is increased to Ε = 95%, the foam with a higher pore density has the lower thermal resistance in the whole experimental range. When the porosity and pore density is the same, the foam with smaller size has the higher thermal resistance in the whole experimental range. If the size is relatively small (1.01.050mm), for the two pore densities studied (20ppi and 80ppi), there exits a critical value of the Gr number (turning point). The foam with a lower porosity(Ε = 90%) has the lower thermal resistance and the decrease is more obvious for the case of *** the size is relatively big(1.01.080mm),there exists a critical value of the Gr number (turning point) only for the case of 1.ppi. When the Gr number is less than this critical value, the foam with a higher porosity (Ε = 95%) has the higher total thermal resistance, the opposite holds. While for the other two pore densities (20ppi and 40ppi), there is no turning point. The foam with a highe

关键词： Natural convection

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Burning velocity and flamelet structure of turbulent premixed CH4/H2/air flames with CO2 dilution 10

Burning velocity and flamelet structure of turbulent premixe...

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1.th Asia-Pacific Conference on Combustion, ASPACC 201.

作者： Wang, Jinhua Yu, Senbin Zhang, Meng Jin, Wu Huang, Zuohua State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an710049 China

Turbulent burning velocity and statistical flame front structure parameters of turbulent premixed CH4/H2/air flames diluted with CO2 were measured with OH-PLIF technique. Hydrogen fractions are up to 0.2 and CO2 dilution ratios are up to 0.1. The instantaneous flame front structure was detected using the OH-PLIF technique on a turbulent premixed Bunsen burner. Through image processing and statistic analysis, turbulent burning velocity ST and statistic quantitative parameters, i.e. flame surface density Σ and flame brush thickness δT were obtained. Results show that turbulent burning velocity ST normalized by laminar burning velocity SL decreases with CO2 dilution. Increased Markstein number LM and flame intrinsic instability li with CO2 dilution leads to the passive response of flame to turbulence wrinkling which resulting in less wrinkled flame front, smaller Σ, lower local burning velocity and ST/SL. Convex structure is more frequent than that of concave ones at normal pressure and the bias distribution is much weaker comparing to that of high pressure. The positive structure decreases while the negative structure increases slightly with CO2 dilution. This would be one of the mechanisms leading to the decrease of the effective contact surface between reaction zone and unburned mixture which resulting in the decrease of ST/SL with CO2 dilution.

关键词： Carbon dioxide

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Effect of water addition on auto-ignition of kerosene under afterburner relevant conditions 12

Effect of water addition on auto-ignition of kerosene under ...

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1.th Asia-Pacific Conference on Combustion, ASPACC 201.

作者： Sun, Wuchuan Huang, Wenlin Qin, Xiaokang Zhang, Yingjia Huang, Zuohua State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an710049 China

Ignition delay times were measured for stoichiometric kerosene/air mixtures with and without H2O addition behind reflected shock conditions: pressures of 0.45 - 7.5 atm and temperatures of 900 - 1.50 K. The effect of H2O addition on the reactivity of RP-3 was explored at various pressure and temperatures. The Arrhenius-type expressions were fitted by using the current ignition data. A four-component surrogate model of RP-3 was proposed based on similarity criterion of function group. The proposed model generally reproduces the tendency of pressure-dependence of ignition delay times but it over-predicts the experimental data at lower pressures. The addition of H2O presents different effects at elevated pressures. The kinetic analysis was performed to clarify the kinetic and thermodynamic effects. © Asia-Pacific Conference on Combustion, ASPACC *** right reserved.

关键词： Kerosene

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