Recent Advances in Precombustion Coal Cleaning Processes

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

Influence of Heating Rate on the Onset of Oscillation in Liquid Bridge of Half Floating Zone

ＩｎｆｌｕｅｎｃｅｏｆＨｅａｔｉｎｇＲａｔｅｏｎｔｈｅＯｎｓｅｔｏｆＯｓｃｉｌｌａｔｉｏｎｉｎＬｉｑｕｉｄＢｒｉｄｇｅｏｆＨａｌｆＦｌｏａｔｉｎｇＺｏｎｅ￥Ｊｉｎｇ－ＣｈｅｎｇＸｉｅ；Ｗｅｎ－ＲｕｉＨｕ（ＩｎｓｔｉｔｕｔｅｏｆＭｅｃｈａｎｉｃｓ，Ｃｈ...     

Heat Transfer Characteristics of Laminar Flow in Internally Finned Tubes under Various Boundary Conditions

ＨｅａｔＴｒａｎｓｆｅｒＣｈａｒａｃｔｅｒｉｓｔｉｃｓｏｆＬａｍｉｎａｒＦｌｏｗｉｎＩｎｔｅｒｎａｌｌｙＦｉｎｎｅｄＴｕｂｅｓｕｎｄｅｒＶａｒｉｏｕｓＢｏｕｎｄａｒｙＣｏｎｄｉｔｉｏｎｓ￥Ｚｅ－ＮｉｎｇＷａｎｇ；Ｑｉａｎｇ－ＴａｉＺｈｏｕ（Ｄｅｐａｒ...     

Simulating Experimental Investigation on the Safety of Nuclear Heating Reactor in Loss—of —Coolant Accidents

ＳｉｍｕｌａｔｉｎｇＥｘｐｅｒｉｍｅｎｔａｌＩｎｖｅｓｔｉｇａｔｉｏｎｏｎｔｈｅＳａｆｅｔｙｏｆＮｕｃｌｅａｒＨｅａｔｉｎｇＲｅａｃｔｏｒｉｎＬｏｓｓ－ｏｆ－ＣｏｏｌａｎｔＡｃｃｉｄｅｎｔｓＳｉｍｕｌａｔｉｎｇＥｘｐｅｒｉｍｅｎｔａｌＩｎｖｅｓｔｉｇ...     

Acoustic Wave Prediction in Flowing Steam-Water Two-Phase Mixture

ＡｃｏｕｓｔｉｃＷａｖｅＰｒｅｄｉｃｔｉｏｎｉｎＦｌｏｗｉｎｇＳｔｅａｍ－ＷａｔｅｒＴｗｏ－ＰｈａｓｅＭｉｘｔｕｒｅＸｕＪｉｎｌｉａｎｇ；ＣｈｅｎＴｉｎｇｋｕａｎ（ＳｔａｔｅＫｅｙＬａｂｏｒａｔｏｒｙｏｆＭｕｌｔｉｐｈａｓｅＦｌｏｗｉｎＰｏｗｅｒＥｎ...     

A Thermal Analysis of Characteristic Parameters in the Electrode—Region for Tubular Plasma Generators

ＡＴｈｅｒｍａｌＡｎａｌｙｓｉｓｏｆＣｈａｒａｃｔｅｒｉｓｔｉｃＰａｒａｍｅｔｅｒｓｉｎｔｈｅＥｌｅｃｔｒｏｄｅ－ＲｅｇｉｏｎｆｏｒＴｕｂｕｌａｒＰｌａｓｍａＧｅｎｅｒａｔｏｒｓＬｉｎＬｉｅ；ＷｕＣｈｅｎｇｋａｎｇ（ＩｎｓｔｉｔｕｔｅｏｆＭｅｃｈａｎ...     

Study on Characteristics of Steady Flow Condensation Heat Transfer in a Fube Under Zero—Gravitation

ＳｔｕｄｙｏｎＣｈａｒａｃｔｅｒｉｓｔｉｃｓｏｆＳｔｅａｄｙＦｌｏｗＣｏｎｄｅｎｓａｔｉｏｎＨｅａｔＴｒａｎｓｆｅｒｉｎａＴｕｂｅｕｎｄｅｒＺｅｒｏ－ＧｒａｖｉｔａｔｉｏｎＱｎＷｅｉ（ＨａｒｂｉｎＩｎｓｔｉｔｕｔｅｏｆＴｅｃｈｎｏｌｏｇｙ，Ｈａｒｂｉ...     

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

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

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

ＴｈｒｅｅＤｉｍｅｎｓｉｏｎａｌＴｒａｎｓｉｅｎｔＣｏｕｐｌｅｄＲａｄｉａｔｉｖｅＣｏｎｄｕｃｔｉｖｅＨｅａｔＴｒａｎｓｆｅｒｉｎＣｙｌｉｎｄｅｒｓＦｉｌｌｅｄｗｉｔｈＳｅｍｉ－ＴｒａｎｓｐａｒｅｎｔＭｅｄｉａｗｉｔｈＣｏｍｐｌｉｃａｔｅｄＳｕｒｆａ...     

Three－Dimensional Numerical Simulation of Natural Convection Heat Transfer in an Inclined Cylindrical Annulus

Ｔｈｒｅｅ－ＤｉｍｅｎｓｉｏｎａｌＮｕｍｅｒｉｃａｌＳｉｍｕｌａｔｉｏｎｏｆＮａｔｕｒａｌＣｏｎｖｅｃｔｉｏｎＨｅａｔＴｒａｎｓｆｅｒｉｎａｎＩｎｃｌｉｎｅｄＣｙｌｉｎｄｒｉｃａｌＡｎｎｕｌｕｓＪ．Ｇ．ｗｅｉ；Ｗ．Ｑ．Ｔａｏ（ＳｃｈｏｏｌｏｆＥｎｅｒ...     

Natural Convective Heat and Mass Transfer of Water with Corrosion Products at Super—Critical Pressures under Cooling COnditions

A numerical study is reported of laminar natural convective heat and mass transfer on a vertical cooled plate for water containing metal corrosion products at super-critical pressures. The influence of variable properties at super-critical pressures on natural convection has been analyzed. The difference between heat and mass transfer under cooling or heating conditions is also discussed and some correlations for heat and mass transfer under cooling conditions are recommended.     

Experimental and numerical study of convection heat transfer of CO2 at super-critical pressures during cooling in small vertical tube

Convection heat transfer of CO₂ at super-critical pressures during cooling in a vertical small tube with inner diameter of 2.00 mm was investigated experimentally and numerically. The local heat transfer coefficients were determined through a combination of experimental measurements and numerical simulations. This study investigated the effects of pressure, cooling water mass flow rate, CO₂ mass flow rate, CO₂ inlet temperature, flow direction, properties variation and buoyancy on convection heat transfer in small tube. The results show that the local heat transfer coefficients vary significantly along the tube when the CO₂ bulk temperatures are in the near-critical region. The increase of specific heat and turbulence kinetic energy due to the density variation leads to the increase of the local heat transfer coefficients for upward flow. The buoyancy effect induced by density variation leads to a different variation trend of the local heat transfer coefficients along the tube for upward and downward flows. The numerical simulations were conducted using several k–ε turbulence models including the RNG k–ε model with a two-layer near wall treatment and three low-Reynolds number eddy viscosity turbulence models. The simulations using the low-Reynolds number k–ε model due to Yang–Shih has been found to be able to reproduce the general features exhibited in the experiments, although with a relatively large overestimation of measured wall temperatures. A better understanding of the mechanism of properties variation and buoyancy effects on convection heat transfer of CO₂ at super-critical pressures in a vertical small tube during cooling has been developed based on the information generated by the simulation on the detailed flow and turbulence fields.     

Coupled heat and mass transfer in mixed convection over a wedge with variable wall temperature and concentration in porous media: The entire regime

A boundary layer analysis is used to investigate both heat and mass transfer characteristics of mixed convection about a wedge in saturated porous media under the coupled effects of thermal and mass diffusion. The surface of the wedge is maintained at a variable wall temperature (VWT) and variable wall concentration (VWC). The nonsimilar governing equations are obtained by using a suitable transformation and solved by Keller box method. Numerical results are presented for the local Nusselt number and the local Sherwood number. Increasing the buoyancy ratio N, the exponent of wall temperature/concentration n and the wedge angle parameter λ increases the local Nusselt number and the local Sherwood number. As mixed convection parameter χ varies from 0 to 1, the local Nusselt number and the local Sherwood number decrease initially, reach a minimum in the intermediate value of χ and then increase gradually. It is apparent that the Lewis number has a pronounced effect on the local Sherwood number than it does on the local Nusselt number. Furthermore, increasing the Lewis number decreases (increases) the local heat (mass) transfer rate.     

The skin friction in the MHD mixed convection stagnation point with mass transfer

Numerical results are presented for the effects of mass transfer on steady two-dimensional laminar MHD mixed convection owing to the stagnation flow against a heated vertical semi-infinite permeable surface. These results are obtained by solving the coupled nonlinear partial differential equations describing the conservation of mass, momentum and energy by a perturbation technique. These results are presented to illustrate the influence of the Hartmann number, wall mass transfer coefficient, heat absorption coefficient, Prandtl number and the mixed convection or buoyancy parameter. Numerical results for the dimensionless velocity profiles, the temperature profiles, the local friction coefficient and the local Nusselt number are presented for various parameters. These effects of the different parameters on the velocity and temperature as well as the skin friction and wall heat transfer are presented graphically.     

FREE CONVECTION IN OPEN-TOP ENCLOSURES FILLED WITH A POROUS MEDIUM HEATED FROM BELOW

Free convection is studied for porous medium-filled enclosures that are open for fluid flow at the top. For such setups a mixed boundary condition for the transport variable at the top is examined, which is different from the classical approach (Lapwood problem) in systems where flow is governed by Darcy's law. While the latter led to open and to closed paths within each convection cell, the mixed boundary condition induces open convection cells only. By numerical means, the onset of convection, total heat and mass transfer, and the transition from the first to the second mode are examined. At 16.5, the critical Rayleigh number for the onset of convection in the system with mixed boundary condition is much lower than the classical value.     

Darcian mixed convection along slender vertical cylinders with variable surface heat flux embedded in a porous medium

The problem of mixed convection flow along a vertical slender circular cylinder with variable surface heat flux embedded ina fluid-porous medium has been studied. The effects of mixed convection, surface curvature and buoyancy parameters are analyzed for the case of power-law variation in surface heat flux. The numerical solution of the transformed governing equations has been obtained using the Keller box method to demonstrate the important influence of these parameters on the flow and heat transfer characteristics     

节流型微通道换热特性研究

为研究节流型微通道换热特性,设计并加工制作了突缩突扩结构的微通道实验件。采用控制变量法控制改变加热电压、质量流量、入口温度,通过实验数据对比分析研究了影响节流型微通道对流换热的规律。研究结果表明:随着质量流量的增加,微通道蒸发器的对流传热系数不断减小;随着雷诺数的增大努谢尔数不断增大,对流换热效果比较明显。     

Marangoni convection in the LiCaAIF6 crystal growth by the Czochralski technique

Numerical simulation of the mixed convection induced by buoyancy, crystal rotation, and also unbalanced surface tension at the melt-gas interface is conducted by means of the finite volume method in the model of the Czochralski crystal growth. The role of Marangoni convection in the heat and mass transfer is investigated by the comparison of the models with and without surface tension included, and our results indicate that Marangoni convection plays an important role in the heat and mass transfer near the interface of melt and crystal, and also the convection structure.     

Marangoni Convection in the LiCaAIF_6 Crystal Growth by the Czochralski Technique

Numerical simulation of the mixed convection induced by buoyancy, crystal rotation, and also unbalanced surface tension at the melt-gas interface is conducted by means of the finite volume method in the model of the Czochralski crystal growth. The role of Marangoni convection in the heat and mass transfer is investigated by the comparison of the models with and without surface tension included, and our results indicate that Marangoni convection plays an important role in the heat and mass transfer near the interface of melt and crystal, and also the convection structure.     

Optimum geometry of fixed volume plate fin for maximizing heat transfer

A method is presented for finding the plate fin geometry for maximizing total heat transfer when cooled by forced or natural convection. The method is based on an approximate treatment of conjugated heat transfer in which analytical results are utilized. As a result of this type of approach, non-dimensional variables have been found that contain the geometrical and thermal properties of a fin and the flow. An essential fact is that there is no need to evaluate convection heat transfer coefficients. Only one variable with a fixed value is needed to determine the geometry of a fixed volume fin that gives the maximum heat transfer.