Heat transfer forced convection

In the forced convection heat transfer, the heat-transfer coefficient, mainly depends on the fluid velocity because the contribution from natural convection is negligibly small. The dependence of the heat-transfer coefficient, on fluid velocity, which has been observed empirically (1—3), for laminar flow inside tubes, is h for turbulent flow inside tubes, h and for flow outside tubes, h. Flow may be classified as laminar or... 

The mathematical formulation of forced convection heat transfer from fuel rods is well described in the Hterature. Notable are the Dittus-Boelter correlation (26,31) for pressurized water reactors (PWRs) and gases, and the Jens-Lottes correlation (32) for boiling water reactors (BWRs) in nucleate boiling. 

An important mixing operation involves bringing different molecular species together to obtain a chemical reaction. The components may be miscible liquids, immiscible liquids, solid particles and a liquid, a gas and a liquid, a gas and solid particles, or two gases. In some cases, temperature differences exist between an equipment surface and the bulk fluid, or between the suspended particles and the continuous phase fluid. The same mechanisms that enhance mass transfer by reducing the film thickness are used to promote heat transfer by increasing the temperature gradient in the film. These mechanisms are bulk flow, eddy diffusion, and molecular diffusion. The performance of equipment in which heat transfer occurs is expressed in terms of forced convective heat transfer coefficients. 

Design Procedure for Forced Convection Heat Transfer in Exchanger Design... 

Forced convection heat transfer has been measured under widely differing conditions, and using the dimensionless groups makes correlation of the experimental... 

D2. De Bortoli, R. A., Green, S. J., Le Tourneau, B. W., Troy, M., and Weiss, A., Forced convection heat transfer burnout studies for water in rectangular channels and round tubes at pressure above 500 psia, WAPD-188 (1958). 

Colburn, A.P. Trans. Am. Inst. Chem. Eng. 29 (1933) 174. A method of correlating forced convection heat transfer data and a comparison with fluid friction. 

Lin Q, Jiang F, Wang X-Q, Han Z, Tai Y-C, Lew J, Ho C-M (2000) MEMS Thermal Shear-Stress Sensors Experiments, Theory and Modehng, Technical Digest, Solid State Sensors and Actuators Workshop, Hilton Head, SC, 4—8 June 2000, pp 304-307 Lin TY, Yang CY (2007) An experimental investigation of forced convection heat transfer performance in micro-tubes by the method of hquid crystal thermography. Int. J. Heat Mass Transfer 50 4736-4742... 

Wang BX, Peng XF (1994) Experimental investigation of liquid forced-convection heat transfer through micro-channels. Int J Heat Mass Transfer 37 73-82 Wasekar VM, Manglik RM (2002) The influence of additive molecular weight and ionic nature on the pool boiling performance of aqueous surfactant solutions. Int J Heat Mass Transfer 45 483-493... 

The data presented in the previous chapters, as well as the data from investigations of single-phase forced convection heat transfer in micro-channels (e.g., Bailey et al. 1995 Guo and Li 2002, 2003 Celata et al. 2004) show that there exist a number of principal problems related to micro-channel flows. Among them there are (1) the dependence of pressure drop on Reynolds number, (2) value of the Poiseuille number and its consistency with prediction of conventional theory, and (3) the value of the critical Reynolds number and its dependence on roughness, fluid properties, etc. 

The schemes of the test sections reported in the literature are shown in Fig. 4.5. The geometrical parameters are presented in Tables 4.4 and 4.5. Peng and Peterson (1996) investigated experimentally the single-phase forced convective heat transfer... 

Bailey DK, Ameel TA, Warrington RO, Savoie TI (1995) Single-phase forced convection heat transfer in microgeometries a review ASME. lECEC paper ES-396 301-310 Bejan A (1993) Heat transfer. Wiley, New York... 

Shah, R. K., Laminar flow friction and forced convection heat transfer in ducts of arbitrary geometry, Int. ). Heat Mass Transfer 18 (1975) 849-842. 

The convective boiling coefficient lijc can be estimated using the equations for singlephase forced-convection heat transfer modified by a factor fc to account for the effects of two-phase flow ... 

The equation for forced-convective heat transfer in conduits can be used for plate heat exchangers equation 12.10. 

ESDU 78031 (2001) Internal forced convective heat transfer in coiled pipes. 

ESDU 92003 (1993) Forced convection heat transfer in straight tubes. Part 1 turbulent flow. 

ESDU 93018 (2001) Forced convection heat transfer in straight tubes. Part 2 laminar and transitional flow. ESDU 98003-98007 (1998) Design and performance evaluation of heat exchangers the effectiveness-NTU method. 

Figure 4.11 Regions of two-phase forced-convective heat transfer as a function of quality with increasing heat flux as ordinate. (From Collier and Thome, 1994. Copyright 1994 by Oxford University Press, New York. Reprinted with permission.)...

Bishop, A. A., R. O. Sandberg, and L. S. Tong, 1965, Forced Convection Heat Transfer to Water at Near-Critical Temperature and Super-Critical Pressures, USAEC Rep. WCAP-2056-Part IIIB, and also Paper 2-7, AlChE/IChE Joint Meeting, London, June, 1965. (4)... 

DeBortoli, R. A., S. J. Green, B. W. LeTourneau, M. Troy, and A. Weiss, 1958, Forced Convection Heat Transfer Burnout Studies for Water in Rectangular Channels and Round Tubes at Pressures above 500 psia, USAEC Rep. WAPD-188, Pittsburgh, PA. (5)... 

B. Correlations of Forced Convection Heat-Transfer Coefficients for... 

FORCED CONVECTIVE HEAT TRANSFER THROUGH UOUID FILM... 

The transition from nucleate boiling to forced-convection heat transfer is gradual. As fluid velocity increases, nucleation becomes more difficult, and therefore this boiling mechanism makes up a decreasing part of the total heat transfer. The transition will occur at higher velocities as pressure increases, and because the velocity at a constant quality decreases with pressure, a higher quality will also be required to suppress nucleation. 

Consider a tube heated uniformly at a heat flux q/A fed with saturated water at the base at a velocity Fo. For this velocity and heat flux, nucleate boiling will take place, and a temperature difference aTo will be established. At some distance up the tube vaporization will occur and increase the volumetric flow of material and hence the velocity to, say, Fi. The line for forced convective heat transfer meets the boiling curve below the heat flux of q/A and so nucleate boiling will still be the mode of heat transfer and the temperature difference AT, and hence the heat transfer... 

Referring to Fig. 12, it is clear that not all the three regions need necessarily be present when a liquid is boiled in a tube. For instance, the exit velocity of the two-phase mixture may never exceed that required for two-phase forced convection to take place, or the heat flux may be such that with an inlet velocity F, nucleate boiling cannot occur and only forced convective heat transfer takes place. 

In one respect Eq. (20) is satisfying. The exponents on the Reynolds and Prandtl numbers are roughly the same as those used for ordinary forced-convection heat transfer. The negative sign on the Prandtl-number exponent in Rohsenow s equation has seemed illogical to many scientists. The logical exponents found by Forster and Zuber... 

Peeples, M. L. 1962. Forced convection heat transfer characteristics of fluid milk products. A review. J. Dairy Sci. 45, 297-302. 

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