Turbulent flow tube annulus

The situation is often encountered in which a fluid flows through a conduit having a noncircular cross section, such as an annulus. The heat-transfer coefficients for turbulent flow can be determined by using the same equations that apply to pipes and tubes if the pipe diameter D appearing in these equations is replaced by an equivalent diameter De. Best results are obtained if... 

Developing Turbulent Flov/ in the Entrance Region 4/6 Turbulent Flo. v in N oncircular Tubes 476 Flow through Tube Annulus 477 Heat Transler Enhancement 477... 

For fully developed turbulent flow, the inner and outer convection coefficients are approximately equal to each other, and the tube annulus can be treated as a noncircular duct with a hydrauLc diameter of - 77, . The Nusselt num-... 

In the case of pipe flow (tubular flow, also tubular or tube electrode), the electrolyte solution is pumped through a circular tube at a rate (flow rate V"f) low enough to secure laminar flow (for the distinction from turbulent flow, see below). The working electrode is embedded as a ring (annulus) in the wall of the pipe a double ring can be mounted also to enable mechanistic studies like with a ring-disc electrode (see above). 

Heat transfer experiments have been performed with CO2 using the test facility, SPHINX [88-93]. The test sections of tubes, a concentric aimulus, and an eccentric annulus have been used. Steady-state conditions have been mainly investigated. The flow direction is both vertically upward and downward. In addition to the experiments without turbulence promoters, influence of the turbulence promoter on the heat transfer has been investigated using a tube type text section where a helical wire is inserted [93]. 

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