ISSN:0001-1541    

DOI:10.1002/aic.690140103

出版商:American Institute of Chemical Engineers    

年代:1968

数据来源: WILEY

摘要:

AbstractLiapunov's direct method is used to obtain regions of asymptotic stability for nonlinear systems with natural boundaries. In some cases this leads to larger stable regions of interest than if the bounds had been neglected. With account taken of the natural boundaries, a design method is formulated to find controller gains that give stable responses for anticipated disturbances. To compare the stability effects of different controllers and their gains, the change in the shape of the Liapunov function must be considered as well as the change in size of the region in which its time derivative is negative definite. Neglect of changes in the shape of the Liapunov function has led to misleading conclusions in previous work.

ISSN:0001-1541    

DOI:10.1002/aic.690140104

出版商:American Institute of Chemical Engineers    

年代:1968

数据来源: WILEY

摘要:

AbstractA correlation is presented for predicting the drop volume for injection at low velocities of one Newtonian liquid into a second stationary immiscible Newtonian liquid in the absence of surface active agents. The analysis, which is based on a two‐stage process of drop formation, predicts drop volumes within an average error of 11% for fifteen liquid‐liquid systems covering a wider range of variables than any previous study. Although the equation was tested primarily with mutually saturated liquids, if correctly predicted drop size for two systems where mass transfer was occurr

ISSN:0001-1541    

DOI:10.1002/aic.690140105

出版商:American Institute of Chemical Engineers    

年代:1968

数据来源: WILEY

摘要:

AbstractEquations are derived for predicting the velocity above which a jet forms when one Newtonian liquid is injected into a second stationary immiscible liquid. Comparison of the theory with experimental data obtained for fifteen liquid‐liquid systems and five nozzle diameters shows a mean error of 6.6%. The equation also predicts the jetting velocity for injection of liquids into gases and the critical velocity at which bubble formation changes from a constant volume to a constant frequency mechanism for gas injection into liquid

ISSN:0001-1541    

DOI:10.1002/aic.690140106

出版商:American Institute of Chemical Engineers    

年代:1968

数据来源: WILEY

摘要:

AbstractThe kinetics of physical adsorption of propane from helium on fixed beds of activated alumina at 30°C. and at atmospheric pressure was studied. Two grades of activated alumina with the same average pore size distribution but different pore size distributions were used. Gas concentration, flow rate, and adsorbent particle size were also varied. The rate of internal diffusion controlled the adsorption process and was best described by Ficks' equation for unsteady state diffusion into a sphere. The internal diffusion appeared to be by a pore diffusion rather than by a surface diffusion mechanism

ISSN:0001-1541    

DOI:10.1002/aic.690140107

出版商:American Institute of Chemical Engineers    

年代:1968

数据来源: WILEY

ISSN:0001-1541    

DOI:10.1002/aic.690140108

出版商:American Institute of Chemical Engineers    

年代:1968

数据来源: WILEY

摘要:

AbstractInequalities are derived for a general class of convex‐functional means which may contain negative weights. Specific cases include the arithmetic‐mean–geometric‐mean inequality and other power‐mean inequalities. These inequalities make possible the solution of a wider class of extremum problems than are susceptible to the classical means with positive weights. In particular, it is shown that the geometric programming algorithm may in some cases be extended to functions with negative coefficients. A weaker result is derived for application without restrictions on the signs of the coefficients or variables. This leads to a computational scheme which is useful in the solution of certain classes of nonlinear programming and inequality‐constrained multistage optimizati

ISSN:0001-1541    

DOI:10.1002/aic.690140109

出版商:American Institute of Chemical Engineers    

年代:1968

数据来源: WILEY

摘要:

AbstractThis paper illustrates the synthesis of nonlinear feedforward controllers for chemical reactors. In most of the theoretical development and application of feedforward control only linear systems have been considered. There are, however, no inherent linear limitations in feedforward control. Since chemical reactors are usually nonlinear, the effectiveness of control should be improved by including nonlinearities in the design of feedforward controllers. This is particularly true for batch reactors because of the large changes in variables during a batch cycle. Continuous stirred‐tank reactors are studied with single and consecutive reactions of first and higher order. Effectiveness of linear and nonlinear feedforward controllers is compared for disturbances of various magnitude and direction. Feedforward control of batch and tubular reactors is also discusse

ISSN:0001-1541    

DOI:10.1002/aic.690140110

出版商:American Institute of Chemical Engineers    

年代:1968

数据来源: WILEY

摘要:

AbstractIn chemical engineering and process control, the numerical solution of large systems of linear, time‐invariant, differential equations must often be considered. Standard numerical techniques such as the Runge‐Kutta method usually require excessive computational time. Since often the time solution of only a few variables is desired in such large systems, a method has been developed to take advantage of this and allows the solution of large systems of differential equations to be obtained in an extremely fast and efficient manner. The basis of the method is to solve for the poles and zeros of the system and then to find the time solution in terms of these poles and ze

ISSN:0001-1541    

DOI:10.1002/aic.690140111

出版商:American Institute of Chemical Engineers    

年代:1968

数据来源: WILEY

摘要:

AbstractLocal volume averaging of the equations of continuity and of motion over each phase in a porous medium is discussed. For a Noll simple material, inertial effects may be neglected with respect to viscous effects as the product of a Reynolds number with a Weissenberg number goes to zero (in the limit of a Newtonian fluid, inertial effects may be neglected as the Reynolds number goes to zero). When inertial effects can be neglected, a resistance transformation for each phase is introduced which in part maps the local volume‐averaged velocity vector into the local force per unit volume which that phase exerts on the pore walls and the moving phase interfaces. Capillary pressure is defined through a local surface average of the jump balance for momentum. The shape of the curve denoting capillary pressure as a function of saturation in a two‐phase flow may vary with the contact angle. For an isotropic multiphase flow of incompressible materials, the functional dependence of the resistance coefficient for a Noll simple material and for a Newtonian fluid is discussed by means of the Buckingham‐Pi th

ISSN:0001-1541    

DOI:10.1002/aic.690140112

出版商:American Institute of Chemical Engineers    

年代:1968

数据来源: WILEY