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Teaching Computational Design for Biomedical and Food Process Engineering Status Report - 2nd Quarter

Several simulation runs have been conducted by Mr. Hung-Ju Liao with the licensed FIDAP program on the PENTIUM(R) II PROCESSOR W/ MMX(TM) TECHNOLOGY AL440LX 300MHz WORKSTATION. The results will be used in the Ph.D. thesis of Hung-Ju.

The specific problem being studied is the continuous thermal sterilization of a fluid food containing starch that is flowing in a tube. In general, continuous sterilization leads to better quality foods while inactivating harmful microorganisms. Because starch under goes a phase transition (gelatinizes) when heated in the presence of water, the heat transfer problem to a starch dispersion poses special challenges and hitherto was not resolved.

Earlier, experimental data on the rheological behavior of starch dispersions were obtained and models were developed that describe the rheological data as a function of temperature and shear rates. The design problem being examined is to determine the effect of different variables: e.g., different wall temperatures, different tube diameters, on the velocity and temperature profiles, sterilizer length, microbial lethality and nutrient retention.

Much effort was spent in choosing the finite-element grid and time steps necessary to solve satisfactorily the applicable partial differential equations with the appropriate boundary and initial conditions. Simulation results for laminar isothermal flow of a power law fluid (n=0.5) with constant physical properties was compared with the results reported in the literature by Lyche and Bird, 1956; the results obtained were in excellent agreement with those from of and Bird (1956) (Lyche, B. C. and Bird, R. B. 1956. The Graetz-Nusselt problem for a power-law non-Newtonian fluid. Chemical Eng. Sci. v. 6:35-41).

Specific results of the simulation will be incorporated in the Ph.D. thesis of Hung-Ju Liao that is in preparation and in future progress reports.

Teaching Computational Design for Biomedical and Food Process Engineering Status Report - 1st Quarter

	We have installed one PENTIUM(R) II PROCESSOR W/ MMX(TM) TECHNOLOGY AL440LX 300MHz WORKSTATION and also loaded a licensed copy of FIDAP. This unit is being used by one graduate student, Hung-Ju. Liao, for his Ph.D. thesis research on: continuous sterilization of food containing starch.
	Hung-Ju first conducted extensive experiments to obtain data on rheological behavior of starch dispersions as a function of shear and temperature. Currently, he is conducting computer simulations of thermal sterilization of the starch dispersions.
	Because the machine was installed only recently in March 1998, few results can be reported. However, it can be said that with the Intel-Grant Workstation, computational times have decreased substantially.
	We plan to continue to computer simulations to examine a broad range of realistic food processing conditions.

Last modified on: 10/08/99