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Study on the Dynamic Characteristics, Control Strategy and Load Variation Rate of the Concentrated Solar power Plant

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SSRN 2023年

作者： Li, Gen Du, Guanghan Liu, Guixiu School of Electric Power Engineering South China University of Technology Guangzhou510641 China State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Xi’an710049 China

With more and more wind power and photovoltaic power connected to the electric power system, it has brought great challenges to the stability of the power grid. Concentrated solar power (CSP) plant as one form of solar power generation can undertake the task of load regulation and frequency regulation in power grid to balance the electricity demand and generation. However, the maximum load variation rate of the CSP plant is not known, which limits sufficient utilization of its advantages. In this study, a dynamic simulation model of the CSP plant was built using the APROS, and the dynamic characteristics were investigated by applying the step disturbances to molten salt flowrate, molten salt temperature, and the opening of steam regulating valve. Based on the results of dynamic characteristics, the control strategies were developed with the consideration of thermal storage in system and the feedforward signal of set load and load variation rate. Then, the maximum load increase and reduction rates within different load ranges were studied. The results indicated that the steam regulating valve could be used to control turbine power, molten salt flowrate could be used to control steam pressure, and the molten salt temperature could be used to control steam temperature. The designed control system could effectively follow the load variation, with the load deviation less than 0.3 MW and the steam temperature deviation less than 1.2 ℃ in the condition of load variation rate at 3% Pe·min-1. The maximum load increase and reduction rates were 11.57% Pe·min-1 and 8.94% Pe·min-1 within the load range of 75%THA-100%THA, and they were 10.42% Pe·min-1 and 7.46% Pe·min-1 within the load range of 50%THA-75%THA, respectively. © 2023, The Authors. All rights reserved.

关键词： Concentrated solar power

Electromagnetic Effects and Accurate Wall-Temperature Measurement Method Under Directly Electric Heating Mode

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SSRN 2022年

作者： Lei, Xianliang Liu, Yunfan Liu, Shuhan Li, Debiao Gou, Lingtong Li, Yusheng State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Xi’an710049 China

By directly imposed electrical energy on metal materials with low voltage but high current to generate Joule heat is an effective energy conversion method. The corresponding temperature will quickly reach the predetermined value. It is also an effective way to achieve homogeneous heating or local non-uniform heating in the heterogeneous conductive elements, thus directly electric heating is widely used in scientific experiments and industrial practices. However, different direct Electrical heating method (i.e., Direct-Current or Alternating Current heating) will lead to different power losses and the interference on the sensor, results in inconsistent temperature distribution or inaccurate temperature, even under the condition with power frequency (f= 50 Hz or 60 Hz). In the present paper, the skin effect and eddy current in different metal materials with variable frequency and different section-shapes have been analyzed by electromagnetic coupling simulation. Meanwhile, two comparative experimental investigations on temperature measurement methods with DC and AC heating have been implemented. It is found that the measured temperature by AC heating is always lower than that of DC heating effected by skin effect and mutual inductance effect, the skin depth in four common used materials is: Iron © 2022, The Authors. All rights reserved.

关键词： Temperature measurement

Chromium Promoted the Efficient and Stable Catalytic Degradation of Propane Over Pt/Hzsm-5 Catalyst: Optimization and Reaction Mechanism

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SSRN 2025年

作者： Jian, Yanfei Xu, He Wang, Yao Wang, Jingjing Xia, Lianghui Liu, Yujie Yu, Yanke He, Chi State Key Laboratory of Multiphase Flow in Power Engineering School of Energy and Power Engineering Xi'an Jiaotong University Shaanxi Xi'An710049 China National Engineering Laboratory for VOCs Pollution Control Material and Technology University of Chinese Academy of Sciences Beijing101408 China Yunnan University China

Light alkanes are a class of ubiquitous volatile organic compounds (VOCs), which bring great environmental hazards and health risks. However, low-temperature degradation of light alkanes is still a great challenge. Herein, a series of Pt/HZSM-5 catalysts without/with additives of Cr were fabricated. Catalytic performance of the catalyst for C3H8 low temperature combustion was investigated. It was found that Cr element had a significant effect on the activity of Pt/HZSM-5. Pt/Cr1/HZSM-5 performed the best activity for C3H8, excellent high temperature stability and water resistance. Characterization results of catalysts indicated that the introduction of Cr element could fix Pt site to promote the dispersion of Pt on the support. Moreover, the interaction between Cr and Pt produced more active Pt species, surface active lattice oxygen and acidic sites, which could promote the activation of C-H bonds in C3H8. Theoretical calculations showed that the interface between Pt and Cr had stronger adsorption for O2 and C3H8, which could accelerate propane oxidation. In this study, the effect of transition metal elements on the promotion of noble metal catalysts in the low-temperature degradation of light alkanes was discussed in depth, and it provided a reference for the design of efficient noble metal molecular sieve catalysts. © 2025, The Authors. All rights reserved.

关键词： Molecular sieves

Enhancing Vertical-Axis Tidal Turbines with Strategic Superhydrophobic Surfaces for Optimized Aerodynamic and Self-Starting Performances

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SSRN 2024年

作者： Yin, Dawei Sun, Jinjing School of Energy and Power Engineering University of Shanghai for Science and Technology Shanghai200093 China Shanghai Key Laboratory of Power Energy in Multiphase Flow and Heat Transfer Shanghai200093 China

As observation and research on nature deepen, bionic and hydrophobic surface drag reduction are gaining increasing popularity among researchers. The application of bionic principles and hydrophobic surface technologies in the field of fluid dynamics has opened up new avenues for enhancing the performance of various engineering systems, including vertical-axis tidal turbines (VATTs). By mimicking the natural mechanisms observed in certain species, such as the lotus effect, researchers have been able to develop superhydrophobic surfaces (SHS) that significantly reduce drag in fluid ***, SHS have been applied uniformly across the entire surface of an airfoil. However, this study takes a more nuanced approach by investigating the impact of SHS application at different positions on the airfoil. Through numerical simulations, the study explores how varying the distribution of SHS can influence the power coefficient (Cp), a key performance metric for VATTs . The findings from the study are quite revealing. At a tip speed ratio (TSR) of 1.68, the study observes that applying SHS to 30% of the chord length near the leading edge of the airfoil yields the maximum relative power coefficient benefit, with an increase of up to 34.8%. This suggests that strategic placement of SHS can lead to significant performance improvements without the need for uniform application, which could potentially reduce material costs and maintenance requirements. Moreover, the study also finds that applying SHS only on the inner surface of the VATT can result in a 32% increase in the power coefficient. This indicates that the inner side of the airfoil, which experiences the higher pressure side of the fluid flow, is particularly sensitive to the drag reduction effects of SHS. The leading edge of the airfoil is another critical area where SHS application can have a substantial impact. The leading edge is the first point of contact between the airfoil and the fluid, and any reduc

关键词： Drag reduction

Effect of Mixer Structure on Liquid Film Formation and Nox Conversion Efficiency in Selective Catalytic Reduction System

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SSRN 2022年

作者： Fu, Hang Huang, Zuohua Tang, Chenglong State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Xi’an710049 China

Selective Catalytic Reduction as an efficient technology to reduce NOx emission has been widely applied in exhaust aftertreatment system. However, the reductant injection causes inevitable impingement on the exhaust pipe and mixer surface and the liquid film will be generated. In this paper, the simulation of a double-blade mixer (Mixer 1) is verified by a bench test and other three kinds of mixer structures (baffle mixer: Mixer 2, blade-baffle mixer: Mixer 3, and blade mixer: Mixer 4) are simulated. The effect of the mixer structures on the liquid film formation, the pressure drop, the flow and temperature distribution after the mixers and ultimately the NOx conversion efficiency are investigated. Results show that the liquid film is prone to form and accumulate at the connection region between the mixer and exhaust pipe, and liquid film tends to develop with the flow direction. Mixer 2 and Mixer 4 shows smaller liquid film area about 15 cm2. The temperature distribution in four types of mixers shows negligible difference (within 4 °C). NH3 mass fraction distribution uniformity and pressure drop shows a trade-off relationship. For the vertical injection system, it is found Mixer 3 gets the worst NOx conversion efficiency, 57%, and Mixer 2 shows better NOx conversion efficiency, 78%. The paper are supportive to the SCR mixer selection and design. © 2022, The Authors. All rights reserved.

关键词： Computational fluid dynamics

Experimental Study on Frost Crystal Morphologies and Frosting Characteristics Under Different Working Pressures

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SSRN 2022年

作者： Lai, Tianwei Liu, Xue Dong, Xiaojun Qiang, Mingchen Yan, Shaohang Hou, Yu State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Xi’an710049 China

Frost usually grows on the cooling surface of heat transfer equipment which often operates under different working pressures. In such conditions, one of the fundamental influencing factors of frosting, the diffusion coefficient of water vapor around the cooling surface is different from that in the normal atmosphere pressure. In order to investigate the pressure effect on frosting, a test rig for frosting visualization is designed. The role of working pressure around the cooling surface on the frost crystal morphologies and frost layer characteristics are evaluated under different air parameters and temperatures of cooling surface. The vertical growth and lateral distribution of frost crystals are related strongly to working pressure around the cooling surface. More frost crystal morphologies and faster growth rate of frost layer are presented at a lower pressure. The frost thickness, frost accumulation and density reduce with higher pressure. The dimensionless correlation of frost thickness is proposed considering working pressure around the cooling surface, humid air parameters, and temperature of cooling surface. © 2022, The Authors. All rights reserved.

关键词： Working pressure

Study on the Safety Characteristics of Fluoride-Salt-Cooled High-Temperature Advanced Reactor

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SSRN 2023年

作者： Lv, Xindi Zhang, Dalin Li, Xinyu Zhou, Xingguang Jiang, Dianqiang Su, Guanghui Tian, Wenxi Qiu, Suizheng 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

FuSTAR is a small, modular fluoride-salt-cooled high-temperature advanced reactor, proposed by Xi'an Jiaotong University (XJTU), aiming at fulfilling the requirements of Gen IV nuclear system and meanwhile ensuring the inherent safety and economics. In order to evaluate the safety performance of FuSTAR, five typical design basis accidents are selected for safety analysis with different initial events. The sensitivity analysis is also performed. The results of transient accidents indicate that safety of FuSTAR has been guaranteed in URIA and ULOF. Meanwhile, the maximum limit of external parameters causing ULOHS and UOC are obtained by sensitivity analysis. In the ULOF and ULOHS, the peak of fuel temperature, cladding surface temperature and core outlet temperature of coolant are below their safety limits. Therefore, FuSTAR exhibits acceptable safety under design basis accidents. This study will provide supports in verifying the rationality of the design and the subsequent optimization of FuSTAR. © 2023, The Authors. All rights reserved.

关键词： Sensitivity analysis

Numerical Investigation on the Radiation Performance of a Crisscross Liquid Droplet Radiator in Space Under Different Operating Conditions

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SSRN 2022年

作者： Zhu, Maoguo Sha, Zhaoyang Zhao, Quanbin Chong, Daotong Chen, Weixiong Yan, Junjie State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'An710049 China

Crisscross liquid droplet radiator (LDR) is a promising solution for the heat dissipation of large-power space structures. In this study, a three-dimensional steady numerical simulation of the radiation performance of crisscross LDR in space under different operating conditions was conducted. Significantly, the radiation interaction between adjacent droplet planes was introduced into the radiation model to accurately compute the energy radiated by the crisscross droplet sheet. Simulation results indicated the radiation performance of crisscross droplet sheet deteriorated with an increase in the nonuniformity of droplet planes arrangement and hence droplet planes uniformly arranged were required for a good crisscross LDR. Moreover, there existed a critical droplet sheet angle of 72° where the pressure disturbance frequency almost had no influence on the radiation performance of crisscross LDR. For certain pressure disturbance frequency, decreasing the droplet sheet angle can expand the available operational pressure difference range. The radiation performance of crisscross LDR with high initial droplet temperature was more sensitive to the changes in droplet sheet angle than that with low initial droplet temperature. Finally, the optimal working medium collocation scheme and droplet sheet configuration for crisscross liquid metal LDR were proposed. Given the lightweight and efficiency of crisscross liquid metal LDR, the collocation scheme of working medium including tin and lithium can be adopted and the droplet sheet angle should be designed as 15°. The present work can provide significant guidance for selecting suitable operating conditions for droplet generators to optimize the thermal design of a crisscross LDR. © 2022, The Authors. All rights reserved.

关键词： Drops

Improving sampling depth of laser speckle imaging by topical optical clearing:A theoretical and in vivo study

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Journal of Innovative Optical Health Sciences 2020年第2期13卷 33-43页

作者： D.Li Y.Zhang B.Chen State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an Shaanxi 710049P.R.China

The effect of optical cleaning method combined with laser speckle imaging(LSI)was discussed to improve the detection depth of LSI due to high scattering characteristics of skin,which limit its clinical application.A double-layer skin tissue model embedded with a single blood vessel was established,and the Monte Carlo method was used to simulate photon propagation under the action of light-permeating agent.808 nm semiconductor and 632.8 nm He–Ne lasers were selected to study the e®ect of optical clearing agents(OCAs)on photon deposition in *** show that the photon energy deposition density in the epidermis increases with the amount of tissue°uid replaced by *** with glucose solution,polyethylene glycol 400(PEG 400)and glycerol can considerably increase the average penetration depth of photons in the skin tissue,thereby raising the sampling depth of the *** the action of glycerol,PEG 400,and glucose,the average photon penetration depth is increased by 51.78%,51.06%,and 21.51%for 808nm,68.93%,67.94%,and 26.67%for 632.8 nm lasers,*** vivo experiment by dorsal skin chamber proves that glycerol can cause a substantial decrease in blood°ow rate,whereas PEG 400 can signicantly improve the capability of light penetration without a®ecting blood velocity,which exhibits considerable potential in the monitoring of blood°ow in skin tissues.

关键词： Laser speckle image topical optical clearing imaging depth Monte-Carlo simulation dorsal skin experiment