Browsing by Author "SPINNER, IH"

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APPROXIMATE SOLUTIONS FOR TRANSIENT-RESPONSE OF A SHELL AND TUBE HEAT-EXCHANGER
(1991-07-01)
TAN, KS
;
SPINNER, IH
;
應用化學系
;
Department of Applied Chemistry
Approximate solutions for the transient response of a shell and tube heat exchanger to step change in shell fluid temperature and tube fluid velocity are derived. It has been shown that other previously published limited or approximate solutions are derivable from the exact solutions. The limiting asymptotic "no wall" solutions for both response to shell fluid temperature and tube fluid velocity change are also deducible from a limiting tube wall time constant solution. Some of the approximate solutions presented include the use of simple exponential forms of equations that enable the quick estimation of the time required to reach a given degree of approach to the final steady state. The error between the exact and the approximate exponential form of solutions are in most cases less than 2%. All the previous derived exact and approximate solutions presented here are applicable to crosscurrent, cocurrent, or countercurrent flow heat exchangers with one infinite thermal capacitance rate fluid.
MULTICOMPONENT ION-EXCHANGE COLUMN DYNAMICS
(1994-04-01)
TAN, HKS
;
SPINNER, IH
;
應用化學系
;
Department of Applied Chemistry
Simple model equations which consider different rate control mechanisms are formulated for fixed bed multicomponent ion exchange processes. Efficient and accurate numerical methods are developed for solving these equations for liquid phase, solid phase or combined phase control. The algorithms are applicable to both ion exchange and liquid adsorption and are shown to be extendable to a general form of isotherms. The accuracy of the numerical algorithm is evidenced by the fact that the asymptotic limiting equilibrium solutions are closely approached as the dimensionless length parameter is increased, regardless of the rate control mechanism. Numerical examples for ion exchange applications are presented. These examples included multicomponent elution and purification problems. The effect of mass transfer resistance was also examined. Other examples examine the validity of a model reduction assumption and the comparison of equilibrium theory with the results obtained using the present finite mass transfer rate model.