Convection correlation

Acikalin T, Wait S, Garimella S, Raman A (2004) Experimental investigation of the thermal performance of piezoelectric fans. Heat Transfer Eng 25 4-14 Adams TM, Abdel-Khalik SI, Jeter SM, Qureshi ZH (1998) An experimental investigation of single-phase forced convection in micro-channels. Int J Heat Mass Transfer 41 851-857 Adams TM, Dowling ME, Abdel-Khalik SI, Jeter SM (1999) Applicability of traditional turbulent single phase forced convection correlations to non-circular micro-channels. Int J Heat Mass Transfer 42 4411 415... 

Later measurements by Fouad and Gouda (F5), who used the ferri-ferrocyanide redox reaction, yielded a much lower coefficient in the free-convection correlation, Eq. (29a). However, uncertainty about the interfacial composition in free convection (S9a) may be responsible for the discrepancy observed in the results obtained with the redox system. Taylor and Hanratty (Tib) showed that the data of Fouad and Gouda could be... 

Fouad and Ibl (F6) have suggested that the transfer rate in free-convective turbulent flow should follow a Ra1/3 dependence. Experimentally they found a slightly lower dependence, probably due to the partly laminar regime on such plates. Because the exponent is not determined by theoretical considerations, there is considerable variation in the coefficients of turbulent, free convection correlations. Among other factors, inaccuracies in the calculation of the density-driving force may be responsible for discrepancies. This is particularly likely for the case of the ferricyanide reduction reaction. 

For Gr, < 920, mass transfer could be represented by the forced-convection correlation and for Gr, > 920, by the free-convection correlation ofFenech and Tobias (F3). Tobias and Hickman (T2) also inferred the existence of cellular vortex flow near the electrode from deposition patterns, the induction length for this behavior agreeing with Eq. (44). 

Figure 8. Comparison of data with convective correlations for vertical tube in bubbling bed of 240 pm particles. (From Chen, 1974.)...

Sleicher, C. A. and Rouse, M. W. (1975). A Convective Correlation for Heat Transfer to Constant and Variable Property Fluids in Turbulent Pipe Flow. Ini. J. Heat Mass Transfer,... 

When a system is operating at the limiting current, rather than at an appreciable fraction of the limiting current, the problem is very much simplified. Such problems can be classified as mass-transport limited. Usually, the limiting current density is correlated with dimensionless numbers. Most forced-convection correlations take the form... 

For natural convection, the Grashof number, Gr, is found instead of the Reynolds number for forced convection correlations. The Grashof number may be shown to be equivalent to a ratio of forces ... 

Clausing, A.M., Natural Convection Correlations for Vertical Surfaces Including Influences of Variable Properties", J. Heat Transfer, Vol. 105, No. 1, pp. 138-143, 1983. 

For this edition examples and problems oriented toward numerical (computer-generated) solutions have been expanded for both steady state and transient conduction in Chapters 3 and 4. New convection correlations have been added in Chapters 5, 6, and 7, and summary tables have been provided for convenience of the reader. New examples have also been provided in the radiation, convection, and heat exchanger material and over 250 new problems have been added throughout the book. Over 200 of the previous problems have been restated so that they are new for student work. In addition, all problems have been reorganized to follow the sequence of chapter topics. A total of over 850 problems is provided. 

Heat exchangers are complicated devices, and the results obtained with the simplifled approaches presented above should be used with care. For example, we assumed that the overall heat transfer coefficient V is constant throughout the heat exchanger and tliat the convection heat transfer coefficients can he predicted using the convection correlations. However, it should be kept in mind that the uncertainty in the predicted value of U can exceed 30 percent. Thus, it is natural to tend to overdesign the hear exchangers in order to avoid unpleasant surprises. 

Table 6.7 Natural convection correlations for horizontal plates...

General empirical correlations. In this approach, no attempt is made to base the correlations on nucleate pool-boiling correlations combined in some way with forced convective correlations. Rather, the data are correlated independently using a number of dimensionless groups. 

Mixed Convective Heat Transfer to Moving Materials. Buoyancy forces arising from the heating and cooling of the sheet of Fig. 18.11a modify the flow and thermal fields and thereby the heat transfer characteristics of the process. Simple empirical mixed convection correlations for local and average Nusselt numbers, based on the method of Churchill and Usagi [77], have been developed [71, 78] and are shown in Fig. 18.13. 

T. M. Adams, et cd.. Applicability of traditional turbulent single-phase forced convection correlations to non-circular microchaimels. InternationalJournal of Heat and Mass Tranfer, 1999, 42, 4411-4415. 

Men et al. (2014) have conducted experiments on the natural convection heat transfer for a PRHRS HEX in an in-containment refueling water storage tank. Several empirical correlations for the forced convection flow internal to the HEX tube and the natural convection heat transfer outside of the tube in the tank, for the vertical and horizontal portion of the tube, were compared with experimental data. The Dittus-Boelter forced convection correlation and the McAdams correlations for natural convection proved to give the better model of the data. Wenbin et al. (2014) have conducted experiments for the secondary loop of the Chinese Advance Pressurized Water Reactor for validation of the MIS AP20 models and code. These and other papers are in a special issue of the Science and Technology of Nuclear Installations journal published in 2014 as indicated by the cited references. 

The analysis which follows assumes that where the wall exchanges heat with its environment it does so either throughaheattransfer coefficient (71, or which is constant and/or with constant heat flux q/A)y, into the wall. Such an assumption produces an approximate result but permits its analytical treatment. Actually little is known of the nature of the coefficients of heat transfer on the inside of the vessel during discharge. It is a transient process which most likely also involves condensation from the gas on the wall in the region of the liquid-gas interface. One result of this present study is to indicate approximate values of these coefficients from a fit with the experimental data. Numerical values of the heat transfer coefficients used to reduce the theoretical results were taken from established free-convection correlations [3] and previous experimental measurements [1]. 

ORNL/PSU convection correlation agrees closely with empirical data... 

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