Determination of the time-dependent reaction coefficient and the heat flux in a nonlinear inverse heat conduction problem

Diffusion processes with reaction generated by a nonlinear source are commonly encountered in practical applications related to ignition, pyrolysis and polymerization. In such processes, determining the intensity of reaction in time is of crucial importance for control and monitoring purposes. Therefore, this paper is devoted to such an identification problem of determining the time-dependent coefficient of a nonlinear heat source together with the unknown heat flux at an inaccessible boundary of a one-dimensional slab from temperature measurements at two sensor locations in the context of nonlinear transient heat conduction. Local existence and uniqueness results for the inverse coefficient problem are proved when the first three derivatives of the nonlinear source term are Lipschitz continuous functions. Furthermore, the conjugate gradient method (CGM) for separately reconstructing the reaction coefficient and the heat flux is developed. The ill-posedness is overcome by using the discrepancy principle to stop the iteration procedure of CGM when the input data is contaminated with noise. Numerical results show that the inverse solutions are accurate and stable

EFFECTS OF TEMPERATURE ON FISSION PRODUCT DEPOSITION

An analytical model developed for steady state deposition of fission products from gas streams onto conduit surfaces is extended to include the effects of axial and radial temperature variations. A computer code which evaluates the equations is described and sample results are presented that compare the calculated values with experimental data. (auth

STEAM GENERATORS FOR HIGH-TEMPERATURE GAS-COOLED REACTORS

An analytical approach and an IBM machine code were prepared for the design of gas-cooled reactor once-through steam generators for both axial-flow and cross-flow tube matrices. The codes were applied to investigate the effects of steam generator configuration, tube diameter, extended surface, type of cooling gas, steam and gas temperature and pressure conditions, and the pumping power-to-heat removal ratio on the size, weight, and cost of steam generators. The results indicate that the least expensive and most promising unit for high- temperature high-pressure gascooled reactor plants employs axial-gas flow over 0.5-in.dia bare U-tubes arranged with their axes parallel to that of the shell. The proposed design is readily adaptable to the installation of a reheater and is suited to conventional fabrication techniques. Charts are presented to facilitate tlie design of both axial-flow and cross-flow steam generators for gas- cooled reactor applications. (auth