(34e) Channel Structural Design of Microdevices by Superstructure-Based Approach

The features of microdevices make it possible to handle highly exothermic and rapid reactions and to produce fine particles with narrow size distribution. The foregoing active research and development demonstrated the capabilities of microdevices in the chemical and pharmaceutical industries. So far, a variety of microdevices have been developed and analyzed rigorously by computational fluid dynamics (CFD) simulation. In addition, CFD-based design methods have been investigated in the previous works. Most design of microdevices is accomplished under the predefined channel structures. In other words, only the channel size is determined so as to maximize/minimize an objective function although the channel structure is the key design variable. In this research, a superstructure-based approach to channel structural synthesis in design of microdevices is proposed. The proposed approach is further explained here. Various passive micromixers have been reported in the literatures, and their mixing concepts are classified into contacting, multi-lamellae, flow compression, collision, and chaotic mixing. Each mixing concept is embodied in channel units such as T-, Y-, U-, split-and-recombination, interdigital, and grooved channels. In addition, the heating, cooling, and reaction operation can be embedded in each channel unit. Every channel unit is modeled by using chemical engineering knowledge and simplified advection-diffusion equations. When the channel size (width, depth, and length), flow velocity, and physical properties are given, the mixing degree, reaction yield, temperature change, and pressure drop are estimated. A superstructure model for microdevices is expressed by combining the channel units, and the best channel structure is derived by mathematical programming solvers in CPLEX®. The proposed approach is applied to a design problem of microdevices, in which consecutive parallel reactions occur. The design result is confirmed by CFD simulation.