摘要:

AbstractA sensitivity matrix is defined as a measure of trajectory deviations to small parameter variations of both open and closed loop controlled nonlinear parabolic and first‐order hyperbolic systems. In general the parameters may enter through the system equations or the boundary conditions and may be time or spatially dependent. The introduction of a positive measure of the sensitivity, the norm of the sensitivity matrix, into the performance index is shown to be effective in limiting the trajectory deviations due to the parameter variations. The open and closed loop control of a double pipe heat exchanger is analyzed with the open loop problem solved by an approximate procedure. The sensitivity reformulation is successful in reducing trajectory sensitivity, however at the cost of decreased overall performanc

ISSN:0001-1541    

DOI:10.1002/aic.690150116

出版商:American Institute of Chemical Engineers    

年代:1969

数据来源: WILEY

摘要:

AbstractThe permeation of carbon dioxide through polyethylene membranes has been studied at pressures up to 54.4 atm. and at temperatures above and below the critical temperature of the gas (31.0°C.). The permeability coefficient is independent of pressure at the highest experimental temperature (61.0°C.), but becomes increasingly pressure‐dependent as the temperature is lowered. The principle of corresponding states can be used to correlate the solubility of both gases and vapors in polyethylene over a wide range of temperatures. This principle can also be invoked to obtain an upper limit for the penetrant pressure above which the permeability coefficient becomes pressure‐dependent. The effect of pressure on the permeability, solubility, and diffusivity of gases and vapors in polyethylene is discussed in some d

ISSN:0001-1541    

DOI:10.1002/aic.690150117

出版商:American Institute of Chemical Engineers    

年代:1969

数据来源: WILEY

摘要:

AbstractData are presented on the solubility in and permeation through polyolefin films of a number of gases and liquids. The permeation rates are found to be dependent on the type of film, the concentration and the temperature. A classical diffusion model explains the permeation mechanism and other relations serve to correlate the data.

ISSN:0001-1541    

DOI:10.1002/aic.690150118

出版商:American Institute of Chemical Engineers    

年代:1969

数据来源: WILEY

摘要:

AbstractAxial dispersion was studied experimentally for turbulent flow through a 1 1/4‐in. piping system containing 90 deg. elbows. The Reynolds number range was 15,400 to 96,555. The imperfect pulse tracer technique was used with the axial dispersion numbers being obtained from the difference in variances of concentration‐time curves observed at two points in the system.Elbows interconnected by short lengths of pipe with each succeeding one reversed so as to cause a change in the direction of flow, increased axial dispersion by 35 to 61% over that expected for straight pipe, while the same elbows turned so as to form a helix decreased the dispersion substantially; however, the amount of axial dispersion was still 8 to 22% greater than that observed for straight pipe.The equivalent lengths of the elbows depend upon both their arrangement and the Reynolds number. Closely placed, helically arranged elbows required equivalent lengths of from 2.9 to 5.1 diam., while a reversed arrangement required 6.9 to 11.6 diam. Elbows separated by a developing length and randomly arranged yielded an equivalent length range of 3.6 to 10.6 diam. The geometicall/dratio of the elbows used was 2

ISSN:0001-1541    

DOI:10.1002/aic.690150119

出版商:American Institute of Chemical Engineers    

年代:1969

数据来源: WILEY

摘要:

AbstractA generalized drying program that can simulate any drying conditions has been solved on a computer. The program includes the variation of humidity, temperature, and wind velocity over drying material. These three variables can be treated as functions of time. The correlations require knowledge of several basic properties of the material to be dried and were solved for the case of one directional heat and mass flow.The computer calculated results are checked with experimental data. The effective diffusivity and the solid surface resistance to mass transfer were evaluated by data obtained in three experiments.Solutions for constant drying conditions are presented in graphical form. Variations of such variables as humidity in a drier can be estimated from these curves but the computer program is more reliable.

ISSN:0001-1541    

DOI:10.1002/aic.690150120

出版商:American Institute of Chemical Engineers    

年代:1969

数据来源: WILEY

摘要:

AbstractThe rheological properties of foam stabilizers have been measured with an improved canal viscometer that provides absolute values of surface shear viscosity and yield strength. Studies conducted in room air confirmed previous reports of complex non‐Newtonian film properties for oil soluble surfactants at the air‐oil interface. Both shear and time dependent behavior were observed in which the apparent surface viscosity increased with decreasing rotational speed. Surface viscosities were low at all fresh interfaces but generally increased with the age of the surface over a period of several hours to several days. Experiments conducted in a controlled humidity environment have established that the phenomenon of aging in room air is due to adsorption of moisture from the gas by the surfactant film. Preliminary results indicate that the shear dependency of films in a high humidity environment can be approximated by a Bingham Plastic model which characterize their rheological behavior in terms of a Newtonian surface viscosity and yield va

ISSN:0001-1541    

DOI:10.1002/aic.690150121

出版商:American Institute of Chemical Engineers    

年代:1969

数据来源: WILEY

摘要:

AbstractProcess design computations are represented by directed graphs whose edges correspond to streams of information flow between computational units. Algorithm I‐R extends existing algorithms for finding the minimal sized blocks of units between which no recycle exists. Algorithm II‐R orders the sequence of unit computations within a block to minimize the number of recycle parameters. Algorithm III‐R uses the concept of indexing to order computations which evade algorithm II‐R. This work is directed toward the evolution of efficient programs for computer‐aided proce

ISSN:0001-1541    

DOI:10.1002/aic.690150122

出版商:American Institute of Chemical Engineers    

年代:1969

数据来源: WILEY

摘要:

AbstractA region into which particles arrive in a random manner, remain a random amount of time, and then leave is considered. This model is used in penetration theories of heat and mass transfer. From observations of the number of particles present at any time, it is desired to estimate arrival and exit statistics, residence time statistics, and average rates of transfer across the region. Assuming arrival is a Poisson process, equations governing the above statistics are derived. Some problems in spectral analysis arising from the use of nondifferentiable stochastic processes are solved. Estimators for important parameters are discussed, and it is shown that generally they are biased. A derivation linking the rate of transfer across the region with the rates of transfer of particles is obtained and compared with other such results.

ISSN:0001-1541    

DOI:10.1002/aic.690150123

出版商:American Institute of Chemical Engineers    

年代:1969

数据来源: WILEY

摘要:

AbstractSolubilities and diffusivities of various gases (helium, nitrogen, carbon dioxide, argon, neon, krypton, and monochlorodifluoromethane) in molten or thermally softened polymers (polyethylene, polypropylene, polyisobutylene, polystyrene, and polymethylmethacrylate) have been correlated with structural characteristics, temperature, and pressure. Temperature dependence of both Henry's Law constants and diffusivities were of the Arrhenius equation form. No appreciable effect of pressure was found for either Henry's Law constants or diffusivities up to 300 atm. Earlier correlations for Henry's Law constants in solid polymer systems were found to be inapplicable for molten and thermally softened polymers. New correlations were developed individually for the latter systems. The correlating factor used was the gas Lennard‐Jones force constant. Existing correlations for diffusivities were also found not to apply to molten and thermally softened systems. New correlations were again developed on an individual polymer basis. These related diffusivity to gas Lennard‐Jones collision diameter or molecular diameter. Generalized correlations were also developed that held for a number of polymers. These were for both Henry's Law constants and diffusivit

ISSN:0001-1541    

DOI:10.1002/aic.690150124

出版商:American Institute of Chemical Engineers    

年代:1969

数据来源: WILEY

摘要:

AbstractA new throttling flow calorimeter has been incorporated into the recycle facility of the Thermal Properties Laboratory. Energy is added to the expanding gas while it flows through a stainless steel capillary tubing from an insulated resistance wire located inside the entire length of the capillary. The calorimeter is designed to operate at pressures up to 2,000 lb./sq.in.abs. in the temperature range from −240 to +250°F.Data on the isothermal effect of pressure on enthalpy for a mixture containing 5 mole % propane in methane are presented and compared with data from the literatu

ISSN:0001-1541    

DOI:10.1002/aic.690150125

出版商:American Institute of Chemical Engineers    

年代:1969

数据来源: WILEY