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Influence of nozzle height to width ratio on ignition and NO

Liutao SUN, Yonghong YAN, Rui SUN, Zhengkang PENG, Chunli XING, Jiangquan WU

《能源前沿(英文)》 2021年 第15卷 第2期   页码 431-448 doi: 10.1007/s11708-021-0726-3

摘要: To improve the ignition behavior and to reduce the high NO emissions of blended pulverized fuels (PF) of semicoke (SC), large-scale experiments were conducted in a 300 kW fired furnace at various nozzle settings, i.e., ratios (denoted by / ) of the height of the rectangular burner nozzle to its width of 1.65, 2.32, and 3.22. The combustion tests indicate that the flame stability, ignition performance, and fuel burnout ratio were significantly improved at a nozzle setting of / = 2.32. The smaller / delayed ignition and caused the flame to concentrate excessively on the axis of the furnace, while the larger / easily caused the deflection of the pulverized coal flame, and a high-temperature flame zone emerged close to the furnace wall. NO emissions at the outlet of the primary zone decreased from 447 to 354 mg/m (O = 6%), and the ignition distance decreased from 420 to 246 mm when the / varied from 1.65 to 3.22. Furthermore, the ratio (denoted by / ) of the strong reduction zone area to the combustion reaction zone area was defined experimentally by the CO concentration to evaluate the reduction zone. The / rose monotonously, but its restraining effects on NO formation decreased as / increased. The results suggested that in a test furnace, regulating the nozzle / conditions sharply reduces NO emissions and improves the combustion efficiency of SC blends possessing an appropriate jet rigidity.

关键词: rectangular jet burner     nozzle height to width ratio     ignition characteristics     pyrolyzed semicoke (SC) and bituminous blend     NOx formation    

Stability of an annular viscous liquid jet in compressible gases with different properties inside andoutside of the jet

Chunji YAN, Maozhao XIE,

《能源前沿(英文)》 2010年 第4卷 第2期   页码 198-204 doi: 10.1007/s11708-009-0054-5

摘要: A spatial linear instability analysis is conducted on an annular viscous liquid jet injected into compressible gases and a three-dimensional model of the jet is developed. The model takes into account differences between the velocities, densities of the gases inside and outside of the liquid jet. Theoretical analysis reveals that there exist 9 dimensionless parameters controlling the instability of the liquid jet. Numerical computations reveal some basic characteristics in the breakup and atomization process of the liquid jet as well as influences of these relevant parameters. Major observations and findings of this study are as follows. The Mach number plays a destabilizing role and the inner Mach number has a greater effect on the jet instability than the outer Mach number. The Reynolds number always tends to promote the instabilities of the liquid jet, but its influence is very limited. The Weber number and the gas-to-liquid density ratio also have unstable effects and can improve the atomization of liquid jets. Furthermore, the effects of the Weber number and gas-to-liquid density ratio on the maximum growth rates of axisymmetric and non-axisymmetric disturbances and corresponding dominant wave numbers are manifested in a linear way, while that of the Mach number is non-linear. The effect of Reynolds on the maximum growth rates is non-linear, but the dominant wavenumber is almost not affected by the Reynolds number.

关键词: liquid jet     dominant wave number     compressibility     instability    

Combustion and emissions of RP-3 jet fuel and diesel fuel in a single-cylinder diesel engine

《能源前沿(英文)》 2023年 第17卷 第5期   页码 664-677 doi: 10.1007/s11708-021-0787-3

摘要: The combustion characteristics and emission behaviors of RP-3 jet fuel were studied and compared to commercial diesel fuel in a single-cylinder compression ignition (CI) engine. Engine operational parameters, including engine load (0.6, 0.7, and 0.8 MPa indicating the mean effective pressure (IMEP)), the exhaust gas recirculation (EGR) rate (0%, 10%, 20%, and 30%), and the fuel injection timing (−20, −15, −10, and −5 ° crank angle (CA) after top dead center (ATDC)) were adjusted to evaluate the engine performances of RP-3 jet fuel under changed operation conditions. In comparison to diesel fuel, RP-3 jet fuel shows a retarded heat release and lagged combustion phase, which is more obvious under heavy EGR rate conditions. In addition, the higher premixed combustion fraction of RP-3 jet fuel leads to a higher first-stage heat release peak than diesel fuel under all testing conditions. As a result, RP-3 jet fuel features a longer ignition delay (ID) time, a shorter combustion duration (CD), and an earlier CA50 than diesel fuel. The experimental results manifest that RP-3 jet fuel has a slightly lower indicated thermal efficiency (ITE) compared to diesel fuel, but the ITE difference becomes less noticeable under large EGR rate conditions. Compared with diesel fuel, the nitrogen oxides (NOx) emissions of RP-3 jet fuel are higher while its soot emissions are lower. The NOx emissions of RP-3 can be effectively reduced with the increased EGR rate and delayed injection timing.

关键词: RP-3 jet fuel     diesel     engine     combustion     emissions    

Influence of mass air flow ratio on gas-particle flow characteristics of a swirl burner in a 29 MW pulverized

Rong YAN, Zhichao CHEN, Shuo GUAN, Zhengqi LI

《能源前沿(英文)》 2021年 第15卷 第1期   页码 68-77 doi: 10.1007/s11708-020-0697-9

摘要: In a gas/particle two-phase test facility, a three-component particle-dynamics anemometer was used to measure the characteristics of gas/particle two-phase flows in a 29 megawatt (MW) pulverized coal industrial boiler equipped with a new type of swirling pulverized coal burner. The distributions of three-dimensional gas/particle velocity, particle volume flux, and particle size distribution were measured under different working conditions. The mean axial velocity and the particle volume flux in the central region of the burner outlet were found to be negative. This indicated that a central recirculation zone was formed in the center of the burner. In the central recirculation zone, the absolute value of the mean axial velocity and the particle volume flux increased when the external secondary air volume increased. The size of the central reflux zone remained stable when the air volume ratio changed. Along the direction of the jet, the peak value formed by the tertiary air gradually moved toward the center of the burner. This tertiary air was mixed with the peak value formed by the air in the adiabatic combustion chamber after the cross-section of / = 0.7. Large particles were concentrated near the wall area, and the particle size in the recirculation zone was small.

关键词: industrial pulverized coal boiler     swirl burner     air/particle flow     particle dynamic analyzer (PDA)    

Fabrication of micro/nano-structures by electrohydrodynamic jet technique

Dazhi WANG, Xiaojun ZHAO, Yigao LIN, Tongqun REN, Junsheng LIANG, Chong LIU, Liding WANG

《机械工程前沿(英文)》 2017年 第12卷 第4期   页码 477-489 doi: 10.1007/s11465-017-0461-y

摘要:

Electrohydrodynamic jet (E-Jet) is an approach to the fabrication of micro/nano-structures by the use of electrical forces. In this process, the liquid is subjected to electrical and mechanical forces to form a liquid jet, which is further disintegrated into droplets. The major advantage of the E-Jet technique is that the sizes of the jet formed can be at the nanoscale far smaller than the nozzle size, which can realize high printing resolution with less risk of nozzle blockage. The E-Jet technique, which mainly includes E-Jet deposition and E-Jet printing, has a wide range of applications in the fabrication of micro/nano-structures for micro/nano-electromechanical system devices. This technique is also considered a micro/nano-fabrication method with a great potential for commercial use. This study mainly reviews the E-Jet deposition/printing fundamentals, fabrication process, and applications.

关键词: electrohydrodynamic jet deposition     electrohydrodynamic jet printing     micro/nano-structures     film    

Numerical simulation of bituminous coal combustion in a full-scale tiny-oil ignition burner: influence

Zhengqi LI, Chunlong LIU, Xiang ZHANG, Lingyan ZENG, Zhichao CHEN

《能源前沿(英文)》 2012年 第6卷 第3期   页码 296-303 doi: 10.1007/s11708-012-0191-0

摘要: The progression of ignition was numerically simulated with the aim of realizing a full-scale tiny-oil ignition burner that is identical to the burner used in an 800 MWe utility boiler. The numerical simulations were conducted for four excess air ratios, 0.56, 0.75, 0.98 and 1.14 (corresponding to primary air velocities of 17, 23, 30 and 35 m/s, respectively), which were chosen because they had been used previously in practical experiments. The numerical simulations agreed well with the experimental results, which demonstrate the suitability of the model used in the calculations. The gas temperatures were high along the center line of the burner for the four excess air ratios. The flame spread to the burner wall and the high-temperature region was enlarged in the radial direction along the primary air flow direction. The O concentrations for the four excess air ratios were 0.5%, 1.1%, 0.9% and 3.0% at the exit of the second combustion chamber. The CO peak concentration was very high with values of 7.9%, 9.9%, 11.3% and 10.6% for the four excess air ratios at the exit of the second combustion chamber.

关键词: numerical simulation     tiny-oil ignition burner     pulverized coal     temperature field    

Effects of rotor and stator geometry on dissolution process and power consumption in jet-flow high shear

Lin Yang, Wenpeng Li, Junheng Guo, Wei Li, Baoguo Wang, Minqing Zhang, Jinli Zhang

《化学科学与工程前沿(英文)》 2021年 第15卷 第2期   页码 384-398 doi: 10.1007/s11705-020-1928-7

摘要: The jet-flow high shear mixer (JF-HSM) is a new type of intensified equipment with special configurations of the rotor and the stator. The mass transfer property and power consumption were studied in the solid-liquid system for a series of JF-HSMs involving different configuration parameters, such as rotor diameter, rotor blade inclination, rotor blade bending direction, stator diameter, and stator bottom opening diameter. The flow characteristics were examined by computational fluid dynamic simulations. Results indicate that the turbulent power consumption of the JF-HSM is affected by the change in rotor blade inclination and stator bottom opening. With the increase in the shear head size and the change in the rotor into a backward-curved blade, the solid-liquid mass transfer rate can be remarkably increased under the same input power. Dimensionless correlations for the mass transfer coefficient and power consumption were obtained to guide the scale-up design and selection of such a new type of equipment to intensify the overall mixing efficiency.

关键词: jet-flow high shear mixer     solid particle dissolution     power consumption characteristics     CFD Simulation    

Convective mass transfer from a horizontal rotating cylinder in a slot air jet flow

Hongting MA , Dandan MA , Na YANG ,

《能源前沿(英文)》 2009年 第3卷 第3期   页码 289-296 doi: 10.1007/s11708-009-0019-8

摘要: The effects of air jet impinging on the mass transfer characteristics from a rotating spinning cylinder surface were experimentally investigated. The effects of rotational Reynolds number

关键词: air jet impinging     rotating cylinder     critical point     mass transfer characteristics    

Simulation of steel beam under ceiling jet based on a wind–fire–structure coupling model

《结构与土木工程前沿(英文)》 2023年 第17卷 第1期   页码 78-98 doi: 10.1007/s11709-022-0936-8

摘要: For localized fires, it is necessary to consider the thermal and mechanical responses of building elements subject to uneven heating under the influence of wind. In this paper, the thermomechanical phenomena experienced by a ceiling jet and I-beam in a structural fire were simulated. Instead of applying the concept of adiabatic surface temperature (AST) to achieve fluid–structure coupling, this paper proposes a new computational fluid dynamics–finite element method numerical simulation that combines wind, fire, thermal, and structural analyses. First, to analyze the velocity and temperature distributions, the results of the numerical model and experiment were compared in windless conditions, showing good agreement. Vortices were found in the local area formed by the upper and lower flanges of the I-beam and the web, generating a local high-temperature zone and enhancing the heat transfer of convection. In an incoming-flow scenario, the flame was blown askew significantly; the wall temperature was bimodally distributed in the axial direction. The first temperature peak was mainly caused by radiative heat transfer, while the second resulted from convective heat transfer. In terms of mechanical response, the yield strength degradation in the highest-temperature region in windless conditions was found to be significant, thus explaining the stress distribution of steel beams in the fire field. The mechanical response of the overall elements considering the incoming flows was essentially elastic.

关键词: CFD–FEM coupling     steel beam     wind     ceiling jet     numerical heat transfer    

Numerical study on natural convection in a square enclosure containing a rectangular heated cylinder

Jianhua LU, Zhaoli GUO, Zhenhua CHAI, Baochang SHI,

《能源前沿(英文)》 2009年 第3卷 第4期   页码 373-380 doi: 10.1007/s11708-009-0078-x

摘要: In this paper, the natural convection in a square enclosure with a rectangular heated cylinder is investigated via the lattice Boltzmann method. A detailed study is conducted on the effect of the cylinder width and the Rayleigh number on the fluid flow and heat transfer. The flow structures and heat transfer patterns are classified into eight buoyant regimes, i.e., four steady regimes, two periodic regimes, one multiple periodic regime, and one chaos regime, two of which are reported for the first time.

关键词: natural convection     buoyant regime     heated cylinder     lattice Boltzmann    

Axial compression behavior of CFRP-confined rectangular concrete-filled stainless steel tube stub column

《结构与土木工程前沿(英文)》 2021年 第15卷 第5期   页码 1144-1159 doi: 10.1007/s11709-021-0762-4

摘要: The mechanical properties of CFRP-confined rectangular concrete-filled stainless steel tube (CFSST) stub columns under axial compression were experimentally studied. A total of 28 specimens (7 groups) were fabricated for the axial compression test to study the influences of length-to-width ratio, CFRP constraint coefficient, and the thickness of stainless steel tube on the axial compression behavior. The specimen failure modes, the stress development of stainless steel tube and CFRP wrap, and the load–strain ratio curves in the loading process were obtained. Meanwhile, the relationship between axial and transverse deformations of each specimen was analyzed through the typical relative load−strain ratio curves. A bearing capacity prediction method was proposed based on the twin-shear strength theory, combining the limit equilibrium state of the CFRP-confined CFSST stub column under axial compression. The prediction method was calibrated by the test data in this study and other literature. The results show that the prediction method is of high accuracy.

关键词: CFRP     rectangular CFSST stub column     bearing capacity     limit equilibrium state     twin-shear strength theory    

RETRACTED ARTICLE: Momentum exchange coefficient for two jet flows mixing in a tee junction

《化学科学与工程前沿(英文)》 2023年 第17卷 第12期   页码 2161-2161 doi: 10.1007/s11705-009-0143-3

摘要: RETRACTED ARTICLE: Momentum exchange coefficient for two jet flows mixing in a tee junction

关键词: tee junction     Momentum exchange coefficient     RETRACTED    

An experimental study on spray auto-ignition of RP-3 jet fuel and its surrogates

Yaozong DUAN, Wang LIU, Zhen HUANG, Dong HAN

《能源前沿(英文)》 2021年 第15卷 第2期   页码 396-404 doi: 10.1007/s11708-020-0715-y

摘要: Jet fuel is widely used in air transportation, and sometimes for special vehicles in ground transportation. In the latter case, fuel spray auto-ignition behavior is an important index for engine operation reliability. Surrogate fuel is usually used for fundamental combustion study due to the complex composition of practical fuels. As for jet fuels, two-component or three-component surrogate is usually selected to emulate practical fuels. The spray auto-ignition characteristics of RP-3 jet fuel and its three surrogates, the 70% mol -decane/30% mol 1,2,4-trimethylbenzene blend (Surrogate 1), the 51% mol -decane/49% mol 1, 2, 4-trimethylbenzene blend (Surrogate 2), and the 49.8% mol -dodecane/21.6% mol -cetane/28.6% mol toluene blend (Surrogate 3) were studied in a heated constant volume combustion chamber. Surrogate 1 and Surrogate 2 possess the same components, but their blending percentages are different, as the two surrogates were designed to capture the H/C ratio (Surrogate 1) and DCN (Surrogate 2) of RP-3 jet fuel, respectively. Surrogate 3 could emulate more physiochemical properties of RP-3 jet fuel, including molecular weight, H/C ratio and DCN. Experimental results indicate that Surrogate 1 overestimates the auto-ignition propensity of RP-3 jet fuel, whereas Surrogates 2 and 3 show quite similar auto-ignition propensity with RP-3 jet fuel. Therefore, to capture the spray auto-ignition behaviors, DCN is the most important parameter to match when designing the surrogate formulation. However, as the ambient temperature changes, the surrogates matching DCN may still show some differences from the RP-3 jet fuel, e.g., the first-stage heat release influenced by low-temperature chemistry.

关键词: RP-3 jet fuel     surrogate     spray auto-ignition     constant volume combustion chamber    

Formation of coke in thermal cracking of jet fuel under supercritical conditions

ZHU Yuhong, YU Caixiang, LI Zimu, MI Zhentao, ZHANG Xiangwen

《化学科学与工程前沿(英文)》 2008年 第2卷 第1期   页码 17-21 doi: 10.1007/s11705-008-0024-1

摘要: Continuous-flow reactor experiments were carried out to study coke formation from thermal cracking of home-made jet fuel RP-3 under supercritical conditions. The mechanism and precursor of coke forming were analyzed. The starting cracking temperature of RP-3 fuel was determined to be 471.8°C by differential scanning calorimetry (DSC). Temperature-programmed oxidation and scanning electron microscopy (SEM) characterizations of the stressed tubes showed that there are three different coke species including chemisorbed carbon, amorphous carbon and filamentous coke in the solid deposits. More than 90% of coke deposits are carried away by the supercritical fluid, which has strong capabilities of extraction for coke deposits and their precursors. There were 17.1 wt-% of iron and 11.1 wt-% of chromium found on the coke surface detected by energy dispersive spectroscopy (EDS) which suggests carburetion on alloy. RP-3 fuel and its cracking liquids were analyzed by GC-MS,which showed that the content of alkyl benzene and alkyl naphthalene increased evidently in cracking liquids.

关键词: dispersive spectroscopy     different     extraction     calorimetry     filamentous    

水射流技术在石油工程中的应用及前景展望

沈忠厚,李根生,王瑞和

《中国工程科学》 2002年 第4卷 第12期   页码 60-65

摘要:

论述了水射流技术在我国石油工程中的研究和应用情况。应用实验方法建立了淹没非自由射流压力及水功率衰减计算模型,建立了以井底获得最大水功率,优选水力参数设计的新方法和新模型。应用瞬态流理论及水声学原理建立了两种谐振腔的基本关系式和结构数学模型。建立了在钻井双向应力作用下,岩石裂纹发展方向模型。介绍了研制的3种新型高效钻头,即加长喷嘴牙轮钻头、自振射流钻头和射流及机械联合破岩钻头。展望了水射流技术在超高压射流钻井、稠油及低渗油藏开采、提高采收率等方面的应用前景。

关键词: 水射流技术     石油钻井     油气开采     高压和超高压射流    

标题 作者 时间 类型 操作

Influence of nozzle height to width ratio on ignition and NO

Liutao SUN, Yonghong YAN, Rui SUN, Zhengkang PENG, Chunli XING, Jiangquan WU

期刊论文

Stability of an annular viscous liquid jet in compressible gases with different properties inside andoutside of the jet

Chunji YAN, Maozhao XIE,

期刊论文

Combustion and emissions of RP-3 jet fuel and diesel fuel in a single-cylinder diesel engine

期刊论文

Influence of mass air flow ratio on gas-particle flow characteristics of a swirl burner in a 29 MW pulverized

Rong YAN, Zhichao CHEN, Shuo GUAN, Zhengqi LI

期刊论文

Fabrication of micro/nano-structures by electrohydrodynamic jet technique

Dazhi WANG, Xiaojun ZHAO, Yigao LIN, Tongqun REN, Junsheng LIANG, Chong LIU, Liding WANG

期刊论文

Numerical simulation of bituminous coal combustion in a full-scale tiny-oil ignition burner: influence

Zhengqi LI, Chunlong LIU, Xiang ZHANG, Lingyan ZENG, Zhichao CHEN

期刊论文

Effects of rotor and stator geometry on dissolution process and power consumption in jet-flow high shear

Lin Yang, Wenpeng Li, Junheng Guo, Wei Li, Baoguo Wang, Minqing Zhang, Jinli Zhang

期刊论文

Convective mass transfer from a horizontal rotating cylinder in a slot air jet flow

Hongting MA , Dandan MA , Na YANG ,

期刊论文

Simulation of steel beam under ceiling jet based on a wind–fire–structure coupling model

期刊论文

Numerical study on natural convection in a square enclosure containing a rectangular heated cylinder

Jianhua LU, Zhaoli GUO, Zhenhua CHAI, Baochang SHI,

期刊论文

Axial compression behavior of CFRP-confined rectangular concrete-filled stainless steel tube stub column

期刊论文

RETRACTED ARTICLE: Momentum exchange coefficient for two jet flows mixing in a tee junction

期刊论文

An experimental study on spray auto-ignition of RP-3 jet fuel and its surrogates

Yaozong DUAN, Wang LIU, Zhen HUANG, Dong HAN

期刊论文

Formation of coke in thermal cracking of jet fuel under supercritical conditions

ZHU Yuhong, YU Caixiang, LI Zimu, MI Zhentao, ZHANG Xiangwen

期刊论文

水射流技术在石油工程中的应用及前景展望

沈忠厚,李根生,王瑞和

期刊论文