The Thermal Behavior of Coal—Ash Deposits on Heat Exchangers

ＴｈｅＴｈｅｒｍａｌＢｅｈａｖｉｏｒｏｆＣｏａｌ－ＡｓｈＤｅｐｏｓｉｔｓｏｎＨｅａｔＥｘｃｈａｎｇｅｒｓ￥ＪａｍｅｓＬ．Ｓ．Ｃｈｅｎ（ＤｅｐａｒｔｍｅｎｔｏｆＭｅｃｈａｎｉｃａｌＥｎｇｉｎｅｅｒｉｎｇ，ＵｎｉｖｅｒｓｉｔｙｏｆＰｉｔｔｓｂｕｒｇｈ，Ｐ...     

A High—Resolution Hybrid Scheme for solving Three Dimensional Euler Equations of High Speed Inlet Flows

ＡＨｉｇｈ－ＲｅｓｏｌｕｔｉｏｎＨｙｂｒｉｄＳｃｈｅｍｅｆｏｒＳｏｌｖｉｎｇＴｈｒｅｅＤｉｍｅｎｓｉｏｎａｌＥｕｌｅｒＥｑｕａｔｉｏｎｓｏｆＨｉｇｈＳｐｅｅｄＩｎｌｅｔＦｌｏｗｓＷａｎｇＢａｃ－Ｇｕｏ；ＬｉｕＱｉｕ－Ｓｈｅｎｇ（ＣＦＤＢｒａｎｃｈ，Ｄ...     

Numerical Simulation of 3—D Temperature Distribution of the Flame Tube of the Combustion Chamber with Air Film COoling

ＮｕｍｅｒｉｃａｌＳｉｍｕｌａｔｉｏｎｏｆ３－ＤＴｅｍｐｅｒａｔｕｒｅＤｉｓｔｒｉｂｕｔｉｏｎｏｆｔｈｅＦｌａｍｅＴｕｂｅｏｆｔｈｅＣｏｍｂｕｓｔｉｏｎＣｈａｍｂｅｒｗｉｔｈＡｉｒＦｉｌｍＣｏｏｌｉｎｇＮｕｍｅｒｉｃａｌＳｉｍｕｌａｔｉｏｎｏｆ３－Ｄ...     

Analysis of a Coal Fired Combined Cycle with Carried—Heat Gasification

ＡｎａｌｙｓｉｓｏｆａＣｏａｌＦｉｒｅｄＣｏｍｂｉｎｅｄＣｙｃｌｅｗｉｔｈＣａｒｒｉｅｄ－ＨｅａｔＧａｓｉｆｉｃａｔｉｏｎ￥ＸｕＸｉａｎｇｄｏｎｇ；ＺｈｕＷｅｉｍｉｎＺｈａｏＬｉ（ＤｅｐｅｄｍｅｎｔｏｆＴｈｅｒｍａｌＥｎｇｉｎｅｅｒｉｎｇ，Ｔｓｉｎｇ...     

Effects of Coal—Water Mixture Properties in Atomization

ＥｆｆｅｃｔｓｏｆＣｏａｌ－ＷａｔｅｒＭｉｘｔｕｒｅＰｒｏｐｅｒｔｉｅｓｉｎＡｔｏｍｉｚａｔｉｏｎ￥ＤａｖｉｄＪ．Ｗｉｌｄｍａｎ；ＪａｍｅｓＭ．Ｅｋｍａｎｎ（ＰｉｔｔｓｂｕｒｇｈＥｎｅｒｇｙＴｅｃｈｎｏｌｏｇｙＣｅｎｔｅｒ，Ｕ．Ｓ．Ｄｅｐａｒｔｍｅｎ...     

Three Dimensional Transient Coupled Radiative—Conductive Heat Transfer in Cylinders Filled with Semi—Transparent Media with Complicated Surface Characteristics

ＴｈｒｅｅＤｉｍｅｎｓｉｏｎａｌＴｒａｎｓｉｅｎｔＣｏｕｐｌｅｄＲａｄｉａｔｉｖｅＣｏｎｄｕｃｔｉｖｅＨｅａｔＴｒａｎｓｆｅｒｉｎＣｙｌｉｎｄｅｒｓＦｉｌｌｅｄｗｉｔｈＳｅｍｉ－ＴｒａｎｓｐａｒｅｎｔＭｅｄｉａｗｉｔｈＣｏｍｐｌｉｃａｔｅｄＳｕｒｆａ...     

Recent Advances in Precombustion Coal Cleaning Processes

ＲｅｃｅｎｔＡｄｖａｎｃｅｓｉｎＰｒｅｃｏｍｂｕｓｔｉｏｎＣｏａｌＣｌｅａｎｉｎｇＰｒｏｃｅｓｓｅｓ￥Ｓｈｉａｏ－ＨｕｎｇＣｈｉａｎｇ；ＤａｘｉｎＨｅ（ＤｅｐａｒｔｍｅｎｔｏｆＣｈｅｍｉｃａｌａｎｄＰｅｔｒｏｌｅｕｍＥｎｇｉｎｅｅｒｉｎｇ，Ｕｎｉｖｅ...     

Research and Development on PFBC—CC in China and Jiawnag Pilot plant Project

ＲｅｓｅａｒｃｈａｎｄＤｅｖｅｌｏｐｍｅｎｔｏｎＰＦＢＣ－ＣＣｉｎＣｈｉｎａａｎｄＪｉａｗａｎｇＰｉｌｏｔＰｌａｎｔＰｒｏｊｅｃｔＮｉｎｇｓｈｅｎｇＣａｉ；ＭｉｎｇｙａｏＺｈａｎｇ；ＤａｎＬｉ；ＷｅｎｔｉｎｇＦｕ（ＴｈｅｒｍａｌＥｎｅｒｇｙＥｎｇｉｎ...     

Experimental Research on Heat Transfer and Pressure Drop of Two Configurations of Pin Finned—Tubes in an In—line Array

ＥｘｐｅｒｉｍｅｎｔａｌＲｅｓｅａｒｃｈｏｎＨｅａｔＴｒａｎｓｆｅｒａｎｄＰｒｅｓｓｕｒｅＤｒｏｐｏｆＴｗｏＣｏｎｆｉｇｕｒａｔｉｏｎｓｏｆＰｉｎＦｉｎｎｅｄ－ＴｕｂｅｓｉｎＩｎ－ｌｉｎｅＡｒｒａｙＳｈｏｕＧｕａｎｇＹａｏ；ＤｅＳｈｕＺｈｕ（Ｄｅｐａ...     

Numerical Calculation of 3—D TUrbulent Flow in Curvilinear Coordinate Systems with Nostaggered Grids

ＮｕｍｅｒｉｃａｌＣａｌｃｕｌａｔｉｏｎｏｆ３－ＤＴｕｒｂｕｌｅｎｔＦｌｏｗｉｎＣｕｒｖｉｌｉｎｅａｒＣｏｏｒｄｉｎａｔｅＳｙｓｔｅｍｓｗｉｔｈＮｏｎｓｔａｇｇｅｒｅｄＧｒｉｄｓＺｈａｎｇＪｉｎｇｚｈｏｕ；ＬｉＬｉｇｕｏ；ＷｕＧｕｏｃｈｕａｎ（Ｎａｍ...     

旋风炉内气相燃烧及两相流动的数值模拟

在有反应两相流动及煤粉燃烧的全双流体模型（ＰＴＦ模型,ｐｕｒｅ ｔｗｏ－ｆｌｕｉｄ ｍｏｄｅｌ）基础上,采用修正的ｋ－ε－ｋｐ两相湍流模型,对旋风炉内的湍流气相燃烧（甲烷和一氧化碳的燃烧）及在气相燃烧条件下的两相流动进行了数值模拟研究,模拟结果表明,在有燃烧的情况下,在旋风炉的底部存在近壁回流区,该回流区有利于火焰稳定,气粒两相切向速度分布具有类似的Ｒａｎｋｉｎｅ涡结构,该研究为煤粉燃烧的数值模拟     

Experimental Studieson Gas－Particle Flows and Coal Combustion in New Generation Spouting－Cyclone Combustor

ＥｘｐｅｒｉｍｅｎｔａｌＳｔｕｄｉｅｓｏｎＧａｓ－ＰａｒｔｉｃｌｅＦｌｏｗｓａｎｄＣｏａｌＣｏｍｂｕｓｔｉｏｎｉｎＮｅｗＧｅｎｅｒａｔｉｏｎＳｐｏｕｔｉｎｇ－ＣｙｃｌｏｎｅＣｏｍｂｕｓｔｏｒＤ．Ｘ．Ｗａｎｇ；Ｚ．Ｈ．Ｍａ；Ｘ．Ｌ．Ｗａｎｇ；Ｌ．Ｘ．Ｚ...     

Experimental studies on Gas—Particle Flows and Coal Combustion in New Generation Spouting—Cyclone COmbustor

Based on previous studies, an improved non-slagging spouting-cyclone combustor with two-stage combustion, organized in perpendicularly vortexing flows, is developed for clean coal combustion applied in small-size industrial furnaces and domestic furnaces. The isothermal model test and the combustion test give some encouraging results. In this study, further improvement of the geometrical configuration was made, a visualization method and a LDA system were used to study the gas-particle flow behavior, and the temperature and gas composition in combustion experiments were measured by using thermocouples and a COSA-6000-CD Portable Stack Analyzer. Stronger recirculation in the spouting zone and the strongly swirling effect in the cyclone zone were obtained in the improved combustor. The combustion temperature distribution is uniform. These results indicate that the improved geometrical configuration of the combustor is favorable to the stabilization of coal flame and the intensification of coal combustion, and it provides a basis for the practical application of this technique.     

Correlation analysis on the SGS velocity between phases in an isotropic gas-particle two-phase flow with FDF model

Correlation of the SGS (sub-grid scale) velocity between the two phases in an isotropic gas-particle two-phase flow was numerically investigated with FDF model. The results show the SGS gas velocity seen by the particles varies with the relative velocities between particle phase and gas phase. The relative velocity between the two phases produces the effect of the anisotropic turbulence on the particles. The variation of Stokes number influences the magnitude of the interaction between the two phases.     

Numerical simulation of sudden-expansion two-phase flows with two-scale second-order moment particle turbulence model

A two-scale second-order moment particle turbulence model is developed, based on the concept of particle large-scale fluctuation due to turbulence and particle small-scale fluctuation due to collision. The model is employed to simulate gas-particle flows in a sudden-expansion chamber. Simulation results are compared with the experimental results and with those obtained by the single-scale second-order moment two-phase turbulence model. It is shown that the two-scale model is with higher calculating accuracy than the single-scale model. Translated from Journal of Xi’an Jiaotong University, 2006, 40(1): 97–100, 110 [译自: 西安交通大学学报]     

ANALYSIS OF TWO-PHASE RADIATION IN THERMALLY DEVELOPING POISEUILLE FLOW

Combined conductive and radiative heat transfer in a thermally developing two-phase Poiseuille flow in a cylindrical duct is studied here. A two-phase radiative transfer equation (RTE) considering radiation by both gas and particles is taken into account. A complexform of nonlinear integrodifferential RTE is solved by the discrete ordinates method (DOM, or so called SN method) in axisymmetric geometry. After such validation, namely, the solution in a two-dimensional channel flow between two flat plates is compared with that solved by the zone method, the program is then applied to fully developed gas-particle two-phase flow in a cylindrical duct. A parametric study is performed for gas and particle absorption coefficients, particle number density, particle emissivity, and wall emissivity. The results show a significant effect of two-phase radiation on the thermal characteristics. However, in all cases, it was found that conduction is predominant near the wall.     

Experimental Studies on Swirling Gas—Particle Flows in a Spouting —Cyclone Combustor

The gas and particle time-averaged velocity rand RMS fluctuation velocity of swirling gas-particle flows in a spouting-cyclone combustor were measured by a hot-ball probe and a conventional LDV system. The results show large velocity slip between the two phases both in tangential and axial directions and high nonisotropic turbulence of the two phases were also observed which is favorable to coal combustion. The particle RMS fluctuation velocity is higher than the gas RMS fluctuation velocity only in some regions of the flow field.     

Theory of two-phase detonation—Part II: Structure

The structure of a two-phase steady detonation in a granulated solid propellant studied, and existence conditions for a one-dimensional, steady two-phase detonation are given. Ordinary differential equations from continuum mixture theory are solved numerically to determine steady wave structure. In the limiting case where heat transfer and compaction effects are negligible, the model reduces to two ordinary differential equations that have a clear geometrical interpretation in a two-dimensional phase plane. This two-equation model predicts results that are quite similar to those of the full model. This suggests that in the limited parameter space studied heat transfer and compaction are not important mechanisms in determining the detonation structure. It is found that strong and Chapman-Jouguet (CJ) detonation solutions with a leading gas phase shock and unshocked solid can be admitted, as can weak and CJ solutions with an unshocked gas and solid. As for one-phase materials, the CJ wave speed is the speed of propagation predicted for an unsupported, one-dimensional, two-phase detonation. It is predicted that there is no admissible CJ structure with a single leading gas phase shock and unshocked solid below a critical value of initial bulk density. This result cannot be predicted from equilibrium end state analysis. Thus it is concluded that it is essential to consider reaction zone structure when assissing potential solutions.     

Three-dimension simulation of two-phase flows in a thin gas flow channel of PEM fuel cell using a volume of fluid method

This study investigates the two-phase flow in a thin gas flow channel of PEM fuel cells and wall contact angle's impact using the volume of fluid (VOF) method with tracked two-phase interface. The VOF results are compared with experimental data, theoretical solution and analytical data in terms of flow pattern, pressure drop and water fraction. Stable film flow is predicted, as observed experimentally, for the contact angle ranging from 5° to 40° including varying contact angles at different walls of a channel. The contact angle is found to have small impact on the gas pressure drop for the stratified flow regime, but it determines the meniscus of the two-phase interface, which affects the optical detection of the liquid thickness in experiment. The work is important to study of two-phase flow dynamics, multichannel design, experimental design and control of two-phase flows in thin gas flow channels for PEM fuel cells.     

Studies of the effect of a coal concentrator on NO formation in swirling coal combustion

To develop low-pollution burners, the effect of a coal concentrator on NO formation in swirling coal combustion is studied using both numerical simulation and experiments. The isothermal gas–particle two-phase velocities and particle concentration in a cold model of swirl burners with and without coal concentrators were measured using the phase Doppler particle anemometer (PDPA). A full two-fluid model of reacting gas–particle flows and coal combustion with an algebraic unified second-order moment (AUSM) turbulence-chemistry model for the turbulent reaction rate of NO formation are used to simulate swirling coal combustion and NO formation with different coal concentrators. The results give the turbulent kinetic energy, particle concentration, temperature and NO concentration in cases of with and without coal concentrators. The predicted results for cold two-phase flows are in good agreement with the PDPA measurement results, showing that the coal concentrator increases the turbulence and particle concentration in the recirculation zone. The combustion modeling results indicate that although the coal concentrator increases the turbulence and combustion temperature, but still can remarkably reduce the NO formation due to creating high coal concentration in the recirculation zone.