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Release and Transformation of Potassium during Combustion of Biomass

Energy Procedia 2017年 142卷 401-406页

作者： Lei Deng Jiaming Ye Xi Jin Tao Zhu Defu Che State Key Laboratory of Multiphase Flow in Power Engineering School of Energy and Power Engineering Xi’an Jiaotong University Xi’an 710049 China

To investigate the release and transformation of fuel K during combustion of biomass, wheat straw and corn stalk are burnt in a fixed-bed reactor system during 400−1000 °C, and weight measurement, elemental composition analysis, and chemical fractionation analysis are performed. The influences of fuel type, combustion temperature, and water washing pretreatment are discussed. The results show that wheat straw has a higher K release ratio than corn stalk, especially when combustion temperature is above 500 °C. For both biomass fuels, the released K is far less than the water-soluble K. For wheat straw, some of the other occurrence modes of K turn into the insoluble K gradually. For corn stalk, the water-soluble and ion-exchangeable K turn into HCl-soluble and insoluble K. Water washing removes all the water-soluble K of corn stalk and reduces the K release from 3.26 to 0.27 mg g -1 at 1000 °C.

关键词： Potassium release Transformation Biomass combustion Water washing

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A comprehensive model for uniform heat flux inside cavity receiver with air-carbon mixture

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Energy Procedia 2017年 142卷 177-183页

作者： Yabin Jin Jiabin Fang Jinjia Wei Xinhe Wang State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Xi’an Shaanxi 710049 China

Cavity receiver is one of the main components of efficient concentrating solar collector systems. It has the ability to operate at relatively higher temperature and efficiency. The safety and thermal efficiency of solar cavity receiver can affect the efficiency of the whole power system. However, the non-uniform distribution of heat flux and temperature inside the cavity tends to cause the operation instability and bring damage to the tube as well. In the present work, a comprehensive numerical model was developed by coupling Monte Carlo Ray Tracing (MCRT) and Finite Volume Method (FVM) to simulate the thermal performance of a 2D square solar cavity filled with air-carbon particle mixture. Firstly, the complicated photon transmission in the air-carbon particle mixture absorber is simplified as the transmission process in the statistically homogenous and isotropic turbid media. The solar heat flux distribution from the aperture to the wall is simulated by MCRT, and the photo-thermal convection process in the cavity receiver is modeled by FVM. Then the two parts are coupled in the cavity receiver by transferring the absorbed energy computed by MCRT to FVM, and this energy is applied as a source term of the energy equation in the FVM part. Based on this model, the temperature and heat flux characteristics of the cavity receiver were studied at various carbon densities. The result indicated that the air-carbon particle mixture can actively take part in the radiation and it appears that it has a remarkable effect on the temperature homogenization. It decreases the temperature of wall 3 dramatically and increases the temperature of wall 2 and wall 4. The relationships between the temperature unevenness and the number particle density were also analyzed. The temperature unevenness on the wall 3 drops most with the increase of number density of carbon particle, from 25.0K to 2.4K. The unevenness of temperature on the top and bottom walls also decreases slightly by 3K. In ad

关键词： solar cavity receiver non-uniform air-carbon particle mixture homogenization Monte Carlo ray tracing Finite volume method

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Flame brush thickness of premixed turbulent flames: Hydrodynamic theory versus experiments 9

Flame brush thickness of premixed turbulent flames: Hydrodyn...

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9th International Conference on Modeling and Diagnostics for Advanved Engine Systems, COMODIA 2017

作者： Zhang, M. Patyal, A. Fogla, N. Wang, J.H. Huang, Z.H. Matalon, M. State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an710049 China Department of Mechanical Science and Engineering University of Illinois at Urbana-Champaign UrbanaIL61801 United States

The effect of varying turbulence intensities on the flame brush thickness is investigated numerically using a hybrid Navier-Stokes/front-tracking methodology in the context of the hydrodynamic theory. Two configurations, namely planar and Bunsen, are chosen with the latter used for direct comparison with experimental OH-PLIF Bunsen flame images. The Darrieus-Landau influences are controlled through the mixture Markstein length and the flame brush is analyzed under two regimes, sub- and supercritical based on the absence/presence of the hydrodynamic instability. In the planar configuration at low intensities, the sub-critical flame brush retains its near flat shape, while the super-critical flame brush forms a highly corrugated structure reminiscent of the cusped-like flames that result in the laminar setting. With increasing turbulence levels, these effects start to gradually diminish as the flame becomes dominated by velocity fluctuations arising from the turbulent field, finally leading to nearly identical behavior in both regimes for very high intensities. Unlike the planar flame, the sub-critical Bunsen flame surface is dominated by large wrinkles with a more rounded shape while the super-critical flame highlights the formation of cusp-like structures on its surface. Numerical verification of the Bunsen flame brush thickness shows a good qualitative match with experimental tests for turbulent CH4/air flames. The good agreement indicates the qualitative prediction capabilities of the hydrodynamic model. Copyright © 2017 by the Japan Society of Mechanical Engineers.

关键词： Navier Stokes equations

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Optimal design of guide vane inthe cyclone vortex finder based on orthogonal analysis 12

Optimal design of guide vane inthe cyclone vortex finder bas...

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12th International Conference on Fluidized Bed Technology, CFB 2017

作者： Huang, Zhong Liu, Ming Liu, Guanjie Wang, Fengyang Che, Defu State Key Laboratory of Multiphase Flow in Power Engineering Xi 'an Jiaotong University Xi 'an710049 China State Key Laboratory of Hydroscience and Engineering Tsinghua University Beijing100084 China China Huaneng Clean Energy Research Institute Beiijing102209 China

A new structure of installing guide vane inside eccentric vortex finder of cyclone was proposed. Five parameters including eccentric ratio e, blade number Z, hub inlet installing angle p, middle coefficient of hub installing angle k, shroud inlet installing angle increment Ap were selected to design an orthogonal table of five elements and four levels. Based on RNG k-e model, separation efficiencies of the conventional cyclone and 16 cyclones installing guide vanes inside vortex finder were calculated. By means of orthogonal analysis, the influence of each element has been ranked, and the optimal level of each element has been combined as the optimal structure. The simulation result indicated that the separation efficiency of the optimal structure has increased up to 7.04% while the pressure drop decreased no more than 12.5%. The flow field analysis showed the velocity in the inner vortex of cyclone was lower, while it was higher in the outer vortex, which is of great help for particle separation.

关键词： Vortex flow

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Influence of Oxy-fuel Atmosphere on Microscopic Physical-Chemical Properties of High-alkali Ash at Softening Temperature

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Energy Procedia 2017年 142卷 3240-3243页

作者： Chang’an Wang Hanqing Li Chenzhao Zhu Tao Han Yinhe Liu Lei Deng Defu Che State Key Laboratory of Multiphase Flow in Power Engineering School of Energy and Power Engineering Xi’an Jiaotong University Xi’an 710049 China

The utilization of high-alkali coals in Zhundong coalfield with oxy-fuel combustion technology has a great potential, however, the ash fusion properties of high-alkali coals are still unclear. Here, we studied the influence of oxy-fuel atmosphere on the microscopic properties of high-sodium ash. The change from air to oxy-fuel condition has a negligible influence on ash fusion temperatures, but exhibits certain impact on physical-chemical properties of high-alkali ash. Oxygen content presents a primary effect on the microscopic morphology of ash at softening temperature.

关键词： high-alkali coal oxy-fuel combustion CO 2 capture microscopic properties SEM

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Investigation on Heat Transfer Characteristics of the H-type Finned Tube in Flue Gas with High Content of Ash

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Energy Procedia 2017年 105卷 4680-4684页

作者： Tao Han Chang’an Wang Qi Cao Wufeng Chen Defu Che State Key Laboratory of Multiphase Flow in Power Engineering School of Energy and Power Engineering Xi’an Jiaotong University Xi’an 710049 China

H-type finned tube is rarely used in waste heat recovery power generation stations, though it has an efficient heat transfer performance in large thermal power stations (WHRPGs, hereafter). To date, understanding of heat performance of H-type finned tube in WHRPGs is still lacked. The heat transfer characteristics of H-type finned tube in gas with high content of ash in WHRPGs was investigated in practical cement plant in present work. The actual ash deposition pattern was observed meanwhile. The characteristics of heat transfer process including heat transfer coefficient, heat effective coefficient, and flue resistance at gas velocity between 4.5 - 6.5 m·s –1 are obtained. Experimental results show that the heat transfer coefficient increases with gas velocity linearly, the heat effective coefficient nearly keep stable on the other hand, and serious ash-block problem occurs in flow area in the heat exchanger at the gas velocity of 4.5 - 6.5 m·s –1 . The max heat transfer coefficient remain below 10 w·m –2 ·k –1 , implying heat performance of H-type finned tube in WHRPGs is possibly inefficient.

关键词： H-type finned tube heat performance heat transfer

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Excess thermodynamic properties and FTIR studies of binary of 1, 3-dichlorobenzene with alkyl acetates (C1–C5) at different temperatures

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Chemical Data Collections 2020年 29卷

作者： R. Raju S. Ravikumar R. Gerald Arokiaraj S. Karlapudi K. Sivakumar V. Pandiyan Department of Physics Nehru Memorial College (Autonoums) Puthanampatti 621 007Tamil Nadu India. State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Shaanxi 710049 P. R. China. Department of Chemistry S.V.Arts Degree & P.G.College (T.T.D'S) Tirupati 517502 A.P India

Densities ( ρ ) and speed of sound ( u ) have been reported for the binary mixtures containing 1, 3- dichlorobenzene (1, 3-DCB) with methyl acetate, ethyl acetate, propyl acetate, butyl acetate and pentyl acetate at four different temperatures ( T = 303.15, 308.15, 313.15 and 318.15 K) and at atmospheric pressure. The experimental data of densities and speeds of sound has been further utilized to calculate excess molar volume ( V m E ) and excess isentropic compressibility ( κ S E ) the excess properties have been fitted to Redlich-Kister equation. Further, V m E results have also been discussed by using Prigogine–Flory–Patterson (PFP). The experimental speeds of sound data in the present investigated mixtures were compared with various theoretical models like collision factor theory (CFT) and free length theory (FLT) to check their relative merits of pure component properties. Moreover, the experimental excess functions were correlated in terms of FTIR spectral analysis.

关键词： Binary mixtures Densities Ester Halogenated benzene Speed of sound FTIR

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Investigation of exergy efficiency of organic Rankine cycle

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IOP Conference Series. Earth and Environmental Science 2019年第1期354卷 012050-012050页

作者： Liu, G L Xu, J L Cao, S Beijing Key Laboratory of Multiphase Flow and Heat Transfer for Low Grade Energy Utilization North China Electric Power University Beijing 102206 Beijing China School of Energy and Power Engineering Zhengzhou University of Light Industry Zhengzhou 450002 Henan Province China

Organic Rankine cycle (ORC) which recovers waste heat in the temperature range of 80°C-140°C was investigated. Exergy efficiencies of various components and ORC system were paid great attention. The working fluids of R245fa and R600a are used. It is found that, for saturated ORCs, the expander inlet temperature has the optimum value, so the system exergy efficiency is maximum. With the increase of heat source temperature, the optimal inlet temperature of the expander is also increased. And also for saturated ORCs, the exergy efficiencies of evaporator and expander are highest efficiency, when evaporator exergy efficiency is increased with increase of heat source temperatures, the expander exergy efficiency is unchanged. The condenser decreased exergy efficiencies by increasing the heat source temperatures.

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Laser-induced Morphology Change and Photo-thermolysis of Gold Nano Particles with Application in Laser Dermatology

Laser-induced Morphology Change and Photo-thermolysis of Gol...

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2017第六届国际新材料大会

作者： Bin Chen State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University China

Based on the principle of selective photothermolysis,laser photothermal therapy is regarded as the most effective treatment methodology for port-wine stain（PWS）,which is a congenital vascular malformation caused by the expansion of capillaries in the dermis.1064 nm Nd:YAG laser has great potential for the treatment of deeper and larger ***,the clinical effectiveness is limited because of the weak absorption of blood to Nd:YAG *** order to enhance the blood absorption,spherical gold nanoparticles were prepared by Sodium citrate reduction method with average size of 16.7 nm and absorbance peak at 522 *** nanorods were prepared by Seeded growth method and modified by PEG with average length and width of 79.1 nm and 13.5 *** this aspect ratio of 5.89,a strong absorption band at050 nm in the near-infrared range is *** can inject spherical gold particles into the bloodstream to enhance the light absorption of blood in visible range,while using gold nanorod to increase absorbance of blood to Nd:YAG Laser for improving the cure rate of laser treatment of vascular *** absorption was increased by 1.25 times for 581 nm（PDL laser） and 3.71 times for 1064 nm（Nd:YAG laser）.To investigate the morphology change and photothermolysis of gold NRs induced by Nd:YAG laser and obtain the optimal irradiation conditions for effectively destroying the vascular lesions,tissue-like phantoms were prepared and exposed to Nd:YAG laser with various laser parameters to investigate the photothermolysis of gold *** obtained the optimal photothermolysis of gold NRs for destroying the blood vessel as follows:When the concentration of gold NRs is 26.67 g/mL,the Nd:YAG laser energy density should be 40 J/cm2,with long laser pulse width of 0.3 ms for ten pulses.

关键词： Laser-induced Morphology Change and Photo-thermolysis of Gold Nano Particles with Application in Laser Dermatology

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Numerical Investigation on the Performance of Different Primary Nozzle Structures in the Supersonic Ejector

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Energy Procedia 2017年 105卷 4997-5004页

作者： Kangkang Xue Kaihua Li Weixiong Chen Daotong Chong Junjie Yan State Key Laboratory of Multiphase Flow in Power Engineering Xi’an JiaotongUniversity Xi’an Shaanxi 710049 P.R. China

Computational fluid dynamics (CFD) technique is employed to investigate the effect of primary nozzle structures on the supersonic ejector performance. The performance of the supersonic ejectors with three different nozzle structures, including conical nozzle, petalage nozzle and crenation nozzle, have been compared under the same conditions. Compared with the ejector equipped with the conical nozzle, the entrainment ratio of petalage nozzle is slightly smaller, while the critical back pressure increases by 5.2%. Just the opposite, the entrainment ratio of crenation nozzle is slightly higher, and the critical back pressure would decrease by 2.1%. In addition, the effects of primary/induced fluid pressure on the flow field (pressure and Mach number along the ejector centerline) are observed and analyzed to explain the mixing process occurring inside the ejector. It finds out that the shape of the mixing layer in the supersonic ejector with different nozzles is different.

关键词： Supersonic ejector CFD Primary nozzle Entrainment ratio Critical back pressure

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