摘要:

The dynamic behavior of process models consisting of higher order sets of linear coupled hyperbolic partial differential equations is considered. The formalism of the Riemann representation of the solution to second order hyperbolic equations is extended to problems of any order. The general time domain solution can then be written in terms of integrals of disturbance functions weighted with generalized Riemann matrices. If the solution for the Riemann matrix is approximated, a common approximation method serves to obtain the complete solution for all state variables subject to all disturbances. The approach is demonstrated on two examples, a double pipe heat exchanger and a nonisothermal packed bed reactor.

ISSN:0098-6445    

DOI:10.1080/00986448308940296

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

摘要:

The second law of thermodynamics for irreversible processes is briefly reviewed and extended to a system moving at a relative velocity. The concept of minimum entropy production is applied to a thermodynamic system which is in relative motion. The relativistic form of the second law for irreversible processes and the criterion for stability are presented.

ISSN:0098-6445    

DOI:10.1080/00986448308940297

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

摘要:

The influence of solvent chemistry on steady shear viscosity and first normal stress difference for aqueous polyacrylamide solutions (Separan AP-273) was investigated in the Weissenberg rheogoniometer and capillary tube viscometer. It was found that these rheological properties are particularly sensitive to the chemistry of the solvent. For example, the zero shear rate viscosity of a 1000 wppm Separan solution with distilled water as the solvent was greater than that with Chicago tap water as the solvent by a factor of 25, while the first normal force difference varied by a factor of two. The addition of an acid or a base to the Chicago tap water-Separan solution also influenced the zero shear rate viscosity and first normal force difference. It was found that there is an optimum pH of approximately 10 which yields a maximum value of the zero shear rate viscosity for the Separan-tap water solution.

ISSN:0098-6445    

DOI:10.1080/00986448308940298

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor