Ken Amano

Calibration of model constants in a biological reaction model for sewage treatment plants

Various biological reaction models have been proposed which estimate concentrations of soluble and insoluble components in effluent of sewage treatment plants. These models should be effective to develop a better operation system and plant design, but their formulas consist of nonlinear equations, and there are many model constants, which are not easy to calibrate. A technique has been proposed to decide the model constants by precise experiments, but it is not practical for design engineers or process operators to perform these experiments regularly. Other approaches which calibrate the model constants by mathematical techniques should be used. In this paper, the optimal regulator method of modern control theory is applied as a mathematical technique to calibrate the model constants. This method is applied in a small sewage treatment testing facility. Calibration of the model constants is examined to decrease the deviations between calculated and measured concentrations. Results show that calculated values of component concentrations approach measured values and the method is useful for actual plants.

Three-dimensional analysis method for sloshing behavior and its application to FBRs

Abstract A three-dimensional analysis method for the sloshing behavior of sodium in FBRs is developed. The method treats the coolant in a reactor vessel as a potential flow with moving liquid surfaces. The Laplace equation of the velocity potential is solved by a boundary element method of which the boundary condition is described by the Bernoulli equation. Vibration test results of water in a rectangular pool are calculated to verify the present method. The calculated water amplitude agreed to the test result within 15%. Then the method is applied to the analysis of the sloshing behavior in tank type and loop type FBRs.

Expressions of mass transfer coefficients of bubbles and free surface of culture tanks using the k–ɛ turbulence model

For mammalian cell culture, getting a continuous supply of oxygen and extracting carbon dioxide are primary challenges even in the most modern biopharmaceutical manufacturing plants, due to the low oxygen solubility and excessive carbon dioxide accumulation. In addition, various independent flow and mass transfer characteristics in the culture tanks vessel make scale-up extremely difficult. One method for overcoming these and providing rational optimization is solving the fluid and mass transport equations by numerical simulation. To develop a simulation program, it is decisively important to know mass transfer coefficients of gaseous species in the culture tank. In this study, oxygen mass transfer coefficients are measured using a beaker with a sparger and impellers. In order to investigate the formulation of the mass transfer coefficients, the turbulent flow statistics is calculated by a CFD code for all cases, and the expressions of the mass transfer coefficients are established as functions of the statistics. Until now, the expression by Kawase is known in this field. This expression becomes a function only of energy dissipation rate ɛ. It does not coincide with the conventional experimental fact that mass transfer coefficient is proportional power 0.5 of impeller rotation speed. The new mass transfer coefficient is dependent on both of energy dissipation rate ɛ and turbulent flow energy k. It satisfies the relation of power of 0.5 of impeller rotation speed.

Three-Dimensional Analysis Method for Sloshing Behavior of FBR and Its Application to Uni- and Multi-Vessel Type FBRs

Abstract A three-dimensional analysis method for sloshing behavior of FBR is developed. The method treats the coolant in a reactor vessel as a potential flow with moving liquid surfaces. The Laplace equation of velocity potential is solved by a boundary element method with its boundary conditions described by a Bernoulli equation. The method is applied to analysis of sloshing behavior of uni- and multi-vessel type FBRs and results are presented. The latter consists of vessels for the core, heat exchangers and pumps, all of which are connected by piping. In the uni-vessel type, heat exchangers and pumps are placed in the reactor vessel.

Application of the vortex method to analysis of coolant temperature fluctuation

The two-dimensional vortex method is applied to the analysis of coolant temperature fluctuations caused by turbulent mixing to examine its applicability to the analysis of thermal striping in liquid-metal fast breeder reactors (LMFBRs). A coaxial jet flow having different temperatures streaming into a stagnant pool is simulated with the method. The calculated velocities are compared with the measurements of an air jet flow. Large scale eddy structures in the mixing region, which cause dynamic large temperature fluctuations, are observed in the numerical simulations. This vortex method can analyze temperature fluctuations caused by large eddies, and is shown to be a useful method for analyzing thermal striping phenomena in LMFBRs.