升温速率及热解温度对煤热解过程的影响

为了研究煤热解过程中升温速率及热解温度对热解产物分布及热解过程吸热量的影响,采用热重和热红联用技术对煤热解过程进行了分析.研究了不同升温速率和热解温度对煤热解过程的气态产物分布的影响,并对所产生的焦炭性质进行了分析.结果表明:煤的整个热解过程的吸热量随升温速率的增加而减小;煤热解产生的焦油组分含量包括芳香族、脂环族和脂肪族含量达到最大值所对应的热解温度随升温速率的增加产生滞后现象,但是煤热解产生的煤气成分随着升温速率增加而急剧释放;随着热解温度的升高,焦炭结构逐渐致密,裂纹及裂缝产生,芳香晶核增大,同时焦炭中的氧和氮含量由于含氮和含氧化合物的继续分解而降低.     

EFFECTS OF SURFACTANT ADSORPTION—DESORPTION KINETICS AND INTERFACIALRHEOLOGICAL PROPERTIES ON THE RATE OFDRAINAGE OF FOAM AND EMULSION FILMS

An analysis has been developed to describe the rate of drainage of an axi-symmetric plane-parallel foam and emulsion films associated with bubble-bubble and drop-drop coalescence phenomena. The present analysis extends the earlier work of Zapryanov et al(1983) and of others which was limited to the diffusion controlled case of the surfactant transport from the bulk phase onto the interface. Here the surfactant transport from the bulk phase to the interface is accounted for by a two step mechanism: (i) diffusion of the surfactant from the bulk to the sublayer, followed by (ii) the adsorption of the surfactant from the sublayer onto the interface. The results of a parametric study indicate that the rate of drainage of surfactant stabilized films is strongly dependent upon the surfactant adsorption-desorption kinetics, selective surfactant solubility, and interfacial Theological properties such as elasticity and interfacial viscosity. Predictions of the film drainage time are compared with our experimental data to establish the range of the applicability of the present model with respect to film radius.     

EFFECTS OF COMBINED TEMPERATURE- AND DEPTH-DEPENDENT VISCOSITY AND HALL CURRENT ON AN UNSTEADY MHD LAMINAR CONVECTIVE FLOW DUE TO A ROTATING DISK

The present study investigates the effects of mixed temperature- and depth-dependent viscosity and Hall current on an unsteady flow of an incompressible electrically conducting fluid on a rotating disk in the presence of a uniform magnetic field. We assume that the fluid viscosity strongly depends on temperature and depth, which may be directly applicable to the earth's mantle and a uniform mid-ocean ridge basalt reservoir in whole mantle flow. The system of axial symmetric nonlinear partial differential equations governing the unsteady flow and heat transfer is written in cylindrical polar coordinates and reduced to nonlinear ordinary differential equations by introducing suitable similarity parameters. Solutions for the flow and temperature fields are obtained numerically assuming large Prandtl number by using Runge-Kutta and shooting methods. The nature of radial, tangential, and axial velocities and temperature in the presence of a uniform magnetic field is presented for changing various nondimensional parameters at different layers of the medium. The coefficients of skin frictions and the rate of heat transfer are calculated at different parameters. Comparison has been made for steady flow (C = 0) and shows excellent agreement with Sparrow and Gregg (1959 Sparrow , E. M. , and Gregg , J. L. ( 1959 ). Heat transfer from a rotating disk to fluids of any Prandtl number , J. Heat Transfer C , 81 , 249 – 251 . [Google Scholar]), hence encouragement for the use of the present numerical computations.     

ON THE EFFECTIVNESS OF ION SLIP AND UNIFORM SUCTION OR INJECTION ON STEADY MHD FLOW DUE TO A ROTATING DISK WITH HEAT TRANSFER AND OHMIC HEATING

The steady flow and heat transfer of a conducting fluid due to the rotation of an infinite nonconducting porous disk in the presence of an axial uniform steady magnetic field are studied considering ion slip and ohmic heating. A uniform injection or suction is applied through the surface of the disk. The relevant equations are solved numerically using finite differences, and the solution shows that the inclusion of ion slip and the injection or suction through the surface of the disk gives some interesting results. It is found that the influence of the Hall and ion slip parameters on the velocity components is more pronounced in the injection than in the suction case. Also, ohmic heating has a marked effect on the heat transfer rate and it is of interest to see the reversal of the sign of the heat transfer rate for some values of the ion slip and suction parameters.     

ON THE EFFECTIVNESS OF ION SLIP AND UNIFORM SUCTION OR INJECTION ON STEADY MHD FLOW DUE TO A ROTATING DISK WITH HEAT TRANSFER AND OHMIC HEATING

The steady flow and heat transfer of a conducting fluid due to the rotation of an infinite nonconducting porous disk in the presence of an axial uniform steady magnetic field are studied considering ion slip and ohmic heating. A uniform injection or suction is applied through the surface of the disk. The relevant equations are solved numerically using finite differences, and the solution shows that the inclusion of ion slip and the injection or suction through the surface of the disk gives some interesting results. It is found that the influence of the Hall and ion slip parameters on the velocity components is more pronounced in the injection than in the suction case. Also, ohmic heating has a marked effect on the heat transfer rate and it is of interest to see the reversal of the sign of the heat transfer rate for some values of the ion slip and suction parameters.