Forced convection in tubes

Values of B 0.021-0.027 have been reported and a mean value of 0.023 may be taken, which means that equation 12.24 very similar to the general heat transfer equation for forced convection in tubes (Volume 1, Chapter 9). The data shown in Figure 12.4 are... 

For a straight tube immersed in a well-stirred fluid, the inside film coefficient, h, may be calculated from the Nusselt number given by the general relationship applying to forced convection in tubes when Re > 10 and0.7[Pg.30]

H. A. Hasanein, M. S. Kazimi, and M. W. Golay, Forced Convection In-Tube Steam Condensation in the Presence of Noncondensable Gases, Int. J. Heat Mass Transfer, 39, pp. 2625-2639,1996. 

Correlations for forced convection over tubes in crossflow are complicated by the effect of the tube bank arrangement. For the range of Reynolds numbers likely to be encountered in industrial boilers the following equations may be used ... 

Jackson, T.W., Harrison, W.B., and Boteler, W.C., Combined Free and Forced Convection in a Constant-Temperature Vertical Tube , Trans. ASME, Vol. 80, pp. 739-745, 1958. 

Depew, C.A. and August, S.E., Heat Transfer Due to Combined Free and Forced Convection in a Horizontal and Isothermal Tube , J. Heat Transfer Vol. 93, pp. 380-384, 1971. 

Churchill, S. W., and H. Ozoe Correlations for Laminar Forced Convection in Flow over an Isothermal Flat Plate and in Developing and Fully Developed Flow in an Isothermal Tube, J. Heat Transfer, vol. 95, p. 46, 1973. 

Flfl. 5-2 Typical data correlation for forced convection in smooth tubes, turbulent flow. 

Depew, C. A., J. L. Franklin, and C. H. Ito Combined Free and Forced Convection in Horizontal, Uniformly Heated Tubes, ASME Pap. 75-HT-19, August 1975. 

Flow In Round Tubes In addition to the Nusselt (NuD = hD/k) and Prandtl (Pr = v/a) numbers introduced above, the key dimensionless parameter for forced convection in round tubes of diameter D is the Reynolds number Re = (.7 ) u where G is the mass velocity G = m/Ac and Ac is the cross-sectional area Ac = kD2I4. For internal flow in a tube or duct, the heat-transfer coefficient is defined as... 

McCabe and Stevens applied this equation successfully to data on the growth of copper sulfate crystals suspended in a forced-convection U-tube apparatus. Their calculation method is useful in designing and operating crystallizers, within the limitations of its rather simplified empirical basis. 

No. 68007 (1968) Forced convection in circular tubes. Part III, further data for turbulent flow. 

C Consider laminar forced convection in a circular tube. Will the heal flux be higher near the inlet of the tube or near the... 

Ameel, T.A., Wang, X., Barron, R.F. and Warrington, R.O., Laminar Forced Convection in a Circular Tube with Constant Heat Flux and Slip Flow, Mieroseale Ther-mophys. Eng, 1(4), 1997, 303-320. 

Micro heat pipe effect -l- two-phase forced convection in the coaxial gap (porous tube inside the glass tube) increase the heat transfer 2-2.5 times as higher as in liquid pool at low and moderate heat fluxes. 

T.A. Ameel, R.F. Barron, X.M. Wang, and R.O. Warrington, Lantinar forced convection in a circular tube with constant heat flux and shp flow. Microscale Thermophysical Engineering 1, 303-320 (1997). 

The local heat transfer coefficient for forced convection inside tubes is determined from experiments conducted with electrically heated tubes. This coefficient requires that the inner temperature of the tube walls Tt be known. However, T turns out to be more difficult to measure than the outer temperature of the tube walls, To. The usual practice is to measure To and relate it to 7i by an analytical expression. We wish to obtain this expression in terms of a tube with an inner radius J i, an outer radius f 2> and internal energy generation u ". 

HEATING AND COOLING OF FLUIDS IN FORCED CONVECTION OUTSIDE TUBES... 

The mechanism of heat flow in forced convection outside tubes differs from that of flow inside tubes, because of differences in the fluid-flow mechanism. As has been shown on pages 59 and 106 no form drag exists inside tubes except perhaps for a short distance at the entrance end, and all friction is wall friction. Because of the lack of form friction, there is no variation in the local heat transfer at different points in a given circumference, and a close analogy exists between friction and heat transfer. An increase in heat transfer is obtainable at the expense of added friction simply by increasing the fluid velocity. Also, a sharp distinction exists between laminar and turbulent flow, which calls for different treatment of heat-transfer relations for the two flow regimes. 

Heating and Cooling of Fluids in Forced Convection outside Tubes 359... 

J. A. Sabbagh, A. Aziz, A. S. El-Ariny, and G. Hamad, Combined Free and Forced Convection in Inclined Circular Tubes, J. Heat Transfer (98) 322-324,1976. 

When vapor is moving at a large approaching velocity, the shear stress between the vapor and the condensate surface must be taken into account (i.e., shear forces are large compared to gravity force). A good review of the work devoted to this problem is found in Rose [85], who provided a detailed discussion of film condensation under forced convection. In Table 17.24, a correlation derived by Fuji et al. [86] and suggested by Butterworth [81] is included for the vapor shear effect. The same equation can be applied for a tube bundle. In such a situation, the approach velocity u should be calculated at the maximum free-flow area cross section within the bundle. 

T. A. Ameel, et at. Laminar forced convection in a circular tube with constant heat... 

Sensible heat transfer in most applications involves forced convection inside tubes or ducts or forced convection over exterior surfaces. 

Churchill SW, Ozoe H. Correlations for laminar forced convection in flow over an isothermal flat plate and in developing and fully developed flow in an isothermal tube. Journal of Heat Transfer 1973 95 Ser C 416-419. 

Kuznetsov, AV, Nield, DA., 2009. Thermally developing forced convection in a porous medium occupied by a rarefied gas parallel plate channel or circular tube with walls at constant heat flux. Transp. Porous Media 76, 345-362. 

Nield, D.A., Kuznetsov, A.V., Xiong, M., 2004a. Thennally developing forced convection in a porous medium parallel plate channel or circular tube with isothermal walls. J. Porous Media 7, 19 27. 

Tube-side Rates. The film coefficient for fluids flowing in forced convection inside tubes has been studied thoroughly by Sieder and Tate, and they found that three regions exist, each of which exhibits different film characteristics. Between Reynolds numbers of 100 to 2,100, viscous... 

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