Abstract
Computational Fluid Dynamics (CFD) plays an important roll in the research on micro chemical plants, but it requires much computational effort. Therefore, simplified models are indispensable for effectively investigating the optimal design or operation of micro chemical plants. Although models used in existent process simulators seem to be available as the simplified models of micro chemical plants, the existent models ignore the important phenomena in microdevices such as pressure drop in laminar flow through rectangular ducts and heat conduction and accumulation in device walls. These phenomena affect the performance of the microdevices significantly, and thus they cannot be ignored. Therefore, the authors are currently developing a dynamic process simulator for micro chemical plants by using Visual Modeler®.
To model the micro chemical plants, four types of basic units were developed. The first is a channel unit having a pressure drop model in laminar flow through a rectangular duct. The second is a wall unit having not only heat transfer models between fluids and walls but also heat conduction models inside walls. The others are a junction unit and a distributor unit, which give connection relations of the channel units. A dynamic model of a plate-fin microdevice with several parallel channels was developed by connecting the basic units.
By using the plate-fin microdevice model, effect of the wall unit on heat transfer and operation problems were investigated. The results show the importance of taking into account heat accumulation and heat conduction in device walls, the superiority of pressure drop control to flow control, and the influence of measuring point on the performance of pressure drop control.
