Reactor Design at Meso-, Micro-, and Nanoscales

Traditional chemical reaction engineering deals with smaller sizes, typically with tubing and pipe sizes ranging from about 1 mm to 10 m. This will be termed the macroscale. Table 16.1 provides definitions of three smaller scales meso, micro, and nano. These terms have been used in a variety of ways in the literature. The term mi-croreactor is sometimes used for systems defined here as mesoscale. The definitions in Table 16.1 are rational if somewhat arbitrary. They are based on the characteristic size of flow channels. 

The new Tunnel 3 of the water supply system for New York City has a maximum diameter of 24 ft and at full capacity would have a Reynolds number above 10 million. 

Chemical Reactor Design, Optimization, and Scaleup, Second Edition. By E. B. Nauman Copyright 2008 John Wiley Sons, Inc. 

The numerics in Table 16.2 make two points. One is that turbulence is difficult to achieve at the mesoscale and nearly impossible to achieve in micro- and nanoscale devices. The other point is that diffusion becomes so fast at the microscale that cross-channel (e.g., radial) mixing is essentially instantaneous for all but the very fastest reactions. Thus composition and temperature will be approximately uniform in the cross-channel direction. The solutions to the convective diffusion equations in 

Scale Size Range, m Typical Flow Regime Molecular Diffusion in Laminar Flow Heat Transfer in Laminar Flow 

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Chapter 16 Reactor Design at Meso-, Micro-, and Nanoscales... 

Nauman, E. Bruce. Chemical Reactor Design, Optimization, and Scaleup. 2d ed. Hoboken, N.J. John Wiley Sons, 2008. Advanced-level work that also covers many contemporary applications and looks at meso-, micro-, and nanoscales. Useful for readers familiar with basics desiring specialized knowledge in the field. 

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