Regular polygonal ducts

Fully developed flow and heat transfer in a regular polygonal duct with n equal sides, each subtending an angle of 360°/n at the duct center, have been reviewed by Shah and London [1]. The /Re and Nu are given in Table 5.56. 

TABLE 5.56 Fully Developed Laminar Flow Characteristics of Regular Polygonal Ducts [1]... 

For practical calculations, Schenkel [279] proposed the following formula to compute the /Re in regular polygonal ducts ... 

Regular Polygonal Ducts With Centered Circular Cores... 

FIGURE 5.65 Fully developed friction factors for regular polygonal ducts with centered circular cores and circular ducts with centered rectangular polygonal cores [2]. 

K. C. Cheng, Laminar Forced Convection in Regular Polygonal Ducts with Uniform Peripheral Heat Flux, /. Heat Transfer, (91) 156-157,1969. 

D. A. Ratkowsky, and N. Epstein, Laminar Flow in Regular Polygonal Ducts with Circular Centered Cores, Can. J. Chem. Eng., (46) 22-26,1968. 

Assumptions of the Convective Diffusion Model in Regular Polygon Ducts... 

FULLY DEVELOPED FLUID VELOCITY PROFILES IN REGULAR POLYGON DUCTS... 

Unlike porous pellets, it is mathematically feasible to account for chemical reaction on the well-defined catalytic surfaces that bound the flow regime in regular polygon duct reactors. A qualitative description of the boundary conditions is based on a steady-state mass balance over a differential surface element. Since convective transport vanishes on the stationary catalytic surface, the following contributions from diffusion and chemical reaction are equated, with units of moI/(areatime) ... 

Asako, Y., H. Nakamura and M. Fagri. Developing laminar flow and heat transfer in the entrance region of regular polygonal ducts. International Journal of Heat and Mass Transfer 31 2590-2593,1988. 

The structures of interest for this paper are regular polygons (of which the square and the equilateral triangle are two members) triangles (of which the equilateral triangle is an end member) and sine ducts (of which the wrapped ceramic and metal structures are members). 

Circular Ducts With Centered Regular Polygonal Cores... 

Heterogeneous catalytic reactor models for ducts with regular polygon cross sections are described within the framework of the following assumptions ... 

Reactor performance is established by calculating the molar density of reactant A from a steady-state mass balance that accounts for axial convection and transverse diffusion. Chemical reaction only occurs on the well-defined catalytic surface which bounds fluid flow in the regular polygon channel. Hence, depletion of reactant A due to chemical reaction appears in the boundary conditions, but not in the mass balance which applies volumetrically throughout the homogeneous flow channel. The mass transfer equation for duct reactors is written in vector form ... 

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