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Rectangular duct

The solution flow is nomially maintained under laminar conditions and the velocity profile across the chaimel is therefore parabolic with a maximum velocity occurring at the chaimel centre. Thanks to the well defined hydrodynamic flow regime and to the accurately detemiinable dimensions of the cell, the system lends itself well to theoretical modelling. The convective-diffiision equation for mass transport within the rectangular duct may be described by... [Pg.1937]

A significant heat-transfer enhancement can be obtained when a nonckcular tube is used together with a non-Newtonian fluid. This heat-transfer enhancement is attributed to both the secondary flow at the corner of the nonckcular tube (23,24) and to the temperature-dependent non-Newtonian viscosity (25). Using an aqueous solution of polyacrjiamide the laminar heat transfer can be increased by about 300% in a rectangular duct over the value of water (23). [Pg.495]

Parallel Plates and Rectangular Ducts The limidng Nusselt number for parallel plates and flat rectangular ducts is given in Table 5-4. Norris and Streid [Tran.s. Am. Soe. Meeh. Eng., 62, 525 (1940)] report for constant wall temperature... [Pg.561]

For rectangular ducts Kays and Clark (Stanford Univ, Dept. Mech. Eng. Tech. Rep. 14, Aug. 6, 1953) published relationships for headng and cooling of air in rectangular ducts of various aspect rados. For most noncircular ducts Eqs. (5-39) and (5-40) may be used if the equivalent diameter (= 4 X free area/wetted perimeter) is used as the characteristic length. See also Kays and London, Compact Heat Exchangers, 3d ed., McGraw-Hill, New York, 1984. [Pg.561]

The critical Reynolds number for transition from laminar to turbulent flow in noncirciilar channels varies with channel shape. In rectangular ducts, 1,900 < Re < 2,800 (Hanks and Ruo, Ind. Eng. Chem. Fundam., 5, 558-561 [1966]). In triangular ducts, 1,600 < Re < 1,800 (Cope and Hanks, Ind. Eng. Chem. Fundam., II, 106-117 [1972] Bandopadhayay and Hinwood, j. Fluid Mech., 59, 775-783 [1973]). [Pg.638]

For rectangular ducts, the area is evenly divided into the necessary number of measurement points. For circular ducts. Table 32-3 can be used to... [Pg.538]

For circular ducts, at least 10% of the total surface shall be tested, and for rectangular ducts, at least 20% shall be tested. In either case the area to be tested shall normally be at least 10 ra. Note that there is no specific information regarding the determination of the duct surface area. [Pg.790]

This also applies to circular pipes or ducts and oval and rectangular ducts not flowing full. The equivalent diameter is used in determining the Reynolds number for these cases, but does not apply to very narrow or slotted or annular flow cross-sections. [Pg.67]

Huebscher, R. G., Friction Equivalents for Round, Square and Rectangular Ducts, AS.H.VE. Journal Section, Heating, Piping and Air Gonditioning, Dec. (1947). [Pg.578]

A method commonly used is that of equal surface friction per unit run. If rectangular ducts are being considered their equivalent circular diameter must be found. This may be obtained by... [Pg.445]

The loss can be substantially reduced if a tapering enlarging section is used. For a circular pipe, the optimum angle of taper is about 7° and for a rectangular duct it is about 11°. [Pg.88]

The data for heating and cooling water in turbulent flow in rectangular ducts are reasonably well correlated by the use of equation 9.59 in the form ... [Pg.433]

Reciprocity relationship, radiation 448 Rectangular duct 87 Redman, J. 550, 566 Reduced coordinates 35... [Pg.889]

Jones OC (1976) An improvement in the calculation of turbulent friction factor in rectangular ducts. Trans ASME J Eluid Eng 98 173-181... [Pg.141]

Zhou, B., Sobiesiak, A., and Quan, P, Flame behavior and flame-induced flow in a closed rectangular duct with a 90 degrees bend. International Journal of Thermal Sciences, 45, 457-474, 2006. [Pg.100]

Hartnett, ). P., Kostic, M., Heat tranfer to Newtonian and non-Newtonian fluids in rectangular ducts, Adv. Heat Transfer 19 (1989) 247-356. [Pg.252]

Return air for the HVAC system should not be supplied from the crawlspace. It is best to avoid routing return air ductwork through the crawlspace, but if it must be, then it should be thoroughly sealed with duct tape at a minimum. It should be understood, however, that duct tape may dry out and fall off. A better approach would be to use seamless ductwork in these areas. The use of floor joists and subflooring as three sides of a return air plenum should be avoided because of the difficulties encountered in sealing. If the space between the joists must be used, an alternative to ducts is to use a rectangular duct to fit the space. [Pg.1281]

For a rectangular duct of width W and length L, Qv is determined using the equation... [Pg.100]

The volumetric flow rate Q (leakage rate) of a fluid in laminar flow through a high aspect ratio (h/w 1) rectangular duct (i.e., the seal volume) of width, w, height, h, and path length, z, in the flow direction is given by ... [Pg.220]

Channel techniques employ rectangular ducts through which the electrolyte flows. The electrode is embedded into the wall [33]. Under suitable geometrical conditions [2] a parabolic velocity profile develops. Potential-controlled steady state (diffusion limiting conditions) and transient experiments are possible [34]. Similar to the Levich equation at the RDE, the diffusion limiting current is... [Pg.13]

Middleman, S., Flow of Power Law Fluids in Rectangular Ducts, Trans. Soc. Rheol., 9, 83 (1965)... [Pg.326]


See other pages where Rectangular duct is mentioned: [Pg.1937]    [Pg.81]    [Pg.483]    [Pg.299]    [Pg.638]    [Pg.642]    [Pg.246]    [Pg.528]    [Pg.548]    [Pg.787]    [Pg.1392]    [Pg.1435]    [Pg.140]    [Pg.140]    [Pg.433]    [Pg.877]    [Pg.880]    [Pg.894]    [Pg.111]    [Pg.282]    [Pg.362]    [Pg.386]    [Pg.781]    [Pg.326]    [Pg.327]    [Pg.327]    [Pg.250]    [Pg.255]   


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