ISSN:0001-1541    

DOI:10.1002/aic.690160202

出版商:American Institute of Chemical Engineers    

年代:1970

数据来源: WILEY

摘要:

AbstractFrom studies of turbulence in round jets of Newtonian and non‐Newtonian fluids, it has been found that the response of wedge shaped, hot‐film probes can be influenced by the structure of the flow. In water and in weakly viscoelastic fluids the probe is little affected by turbulence, but for more highly viscoelastic fluids the rate of heat transfer from the hot film is markedly increased. Increases as great as 37% were found in this work; this corresponds to a 250% increase in apparent velocity. For this reason, care must be taken in interpreting measurements obtained with hot‐film wedges (and probably cylinders and cones also) in flows with both laminar and turbulent re

ISSN:0001-1541    

DOI:10.1002/aic.690160203

出版商:American Institute of Chemical Engineers    

年代:1970

数据来源: WILEY

摘要:

AbstractThe differential equation for diffusion of a solute in a quasi‐homogeneous, spherical, ion exchange particle, previously solved for time‐dependent boundary conditions, is applied to an activated carbon adsorption system. This solution differs from the infinite volume solution which assumes constant boundary conditions. The result is applied to experimental data and yields effective adsorbent‐phase diffusion coefficients. Equilibrium and rate studies were performed by using the aqueous phenol solution—activated carbon system. The rigorous solution to the diffusion equation is compared with a recently published frequency domain solution. Excellent agreement is obtained for values of the effective diffusion coefficient computed from the two rate equations.It is recommended that the rigorous model be used for mechanism and diffusion coefficient determination. After the mass transfer parameters have been obtained, the simplified rate equation may be used for either lumped parameter or distributed parameter models for prediction of fixed‐bed adsorber response. Further studies are required to determine if the simplified model adequately describes fixed‐b

ISSN:0001-1541    

DOI:10.1002/aic.690160204

出版商:American Institute of Chemical Engineers    

年代:1970

数据来源: WILEY

摘要:

AbstractA general means is proposed for predicting transitional velocity patterns in concentric annuli and between parallel plates from behavior in tubes. As in laminar and turbulent flow, transformations of space coordinates yield identical profiles under specific conditions of comparison. Predictions are confirmed by published data and can be related to recent theoretical proposals.

ISSN:0001-1541    

DOI:10.1002/aic.690160205

出版商:American Institute of Chemical Engineers    

年代:1970

数据来源: WILEY

摘要:

AbstractThe efficiency of process optimization by mathematical programming can be increased by tearing, that is, rearranging the design equations so as to reduce the number of equality constraints. The structure of a system of equations may be depicted as an undirected bipartite graph; algorithm I‐T utilizes this graph to determine an order of solution for the equations which requires no tears. If this is impossible, then algorithm II‐T uses indexing in conjunction with algorithm I‐T to produce an order which minimizes the number of torn equations. This procedure is extended to the problem of minimum recycle parameters, and the two‐way interaction between tearing and algebraic simplification is illu

ISSN:0001-1541    

DOI:10.1002/aic.690160206

出版商:American Institute of Chemical Engineers    

年代:1970

数据来源: WILEY

摘要:

AbstractThe effect of various soluble and insoluble surface active agents on the absorption of ammonia into a static aqueous system was studied. Saturated straight‐chain hydrocarbons with four to twenty‐two carbon atoms and polar end groups were selected as the surface active agents to be studied. Alcohol, amine, and amide end groups were investigated. Most of the insoluble surface active agents, which were studied as films, were found to decrease the ammonia absorption rate. There was a definite correlation between the amount of mass transfer reduction and the hydrocarbon chain length, while the effect of the various end groups appeared to depend on the chain length. Surface mass transfer coefficients were computed for each surface active agent that retarded mass transfer. Most of the soluble surface active agents were found to increase the ammonia absorption rates. For all cases of enhanced mass transfer, movements in the interface could be observed. It was concluded that the interfacial movements were caused by the Marangoni effect. In general, as the chain length of the surface active agent decreased, the mass transfer enhancement increased. A mathematical model based on a surface renewal theory was fitted to the experimental d

ISSN:0001-1541    

DOI:10.1002/aic.690160207

出版商:American Institute of Chemical Engineers    

年代:1970

数据来源: WILEY

摘要:

AbstractAn investigation of the mass and heat transfer equations describing radial and axial profiles for tubular reactors in laminar and plug flow is reported. Reactor conditions evaluated were isothermal, constant wall temperature, and adiabatic. Both diffusion and nondiffusion were considered. The reaction investigated was the demethylation of toluene in the presence of hydrogen.It was found that diffusion plays only a minor role in laminar flow for the conditions investigated. It was also found that isothermal and constant wall temperature reactor operation affected the temperature and concentration profiles very little whenr/Rwas less than 0.6.

ISSN:0001-1541    

DOI:10.1002/aic.690160208

出版商:American Institute of Chemical Engineers    

年代:1970

数据来源: WILEY

摘要:

AbstractThis paper presents a quantitative study of two types of decoupling elements to achieve non‐interacting feedback control of overhead and bottoms compositions in binary distillation. Ideal decoupling, where the closed loop response of each loop is the same as it would be if the other loop were on manual control, and simplified decoupling, where two interaction compensators are used to isolate each loop, are investigated.The decoupling elements themselves are physically realizable in both cases, but unstable loops develop with ideal decoupling in higher purity columns because of increased positive feedback. Simplified decoupling gave effective, stable, noninteracting loops for all the cases studied.The decoupling elements are designed in the frequency domain from a linear model of the column, and their effectiveness is tested by digital simulation of the nonlinear column mode

ISSN:0001-1541    

DOI:10.1002/aic.690160209

出版商:American Institute of Chemical Engineers    

年代:1970

数据来源: WILEY

摘要:

AbstractThe laminar boundary‐layer equations are solved asymptotically for simultaneous mass and energy transfer in a variable property binary gas mixture when one component is rapidly transferred toward the surface. Flow is past a surface of arbitrary geometry, and both forced and free convection are studied. Advantage is taken of a mole fraction formulation of the boundary‐layer equations, which considerably simplifies the final results. General results are obtained for energy and mass transfer rates when physical properties are arbitrary functions of both temperature and composition. By considering two sets of property variations, representing extremes between which many actual variations lie, it is shown that in many forced convection problems the rates of energy and mass transfer can be expressed in a particularly simple form. The results also show that property variations are generally more important for free convection than for forced convect

ISSN:0001-1541    

DOI:10.1002/aic.690160210

出版商:American Institute of Chemical Engineers    

年代:1970

数据来源: WILEY

摘要:

AbstractThe stability of a continuous flow stirred tank reactor with consecutive chemical reactions A→B→C was investigated here for the first time. The system equations were integrated numerically, and parts of the three‐dimensional phase space were generated for systems having one and three steady states, respectively.The surface separatrix was determined by trajectory plotting after extensive computation. The system was also analyzed by Liapunov's second method. Krasovskii's form was used to generate Liapunov functions which proved to be satisfactory but extremely conservative in the estimation of the largest possible regions of asymptotic stab

ISSN:0001-1541    

DOI:10.1002/aic.690160211

出版商:American Institute of Chemical Engineers    

年代:1970

数据来源: WILEY