Churchill correlation

This correlation is valid for 0 < Pr < 10 and for 0 < Re < 10 , therefore, considering that inside l.C. engine exhaust systems the Prandtl number is usually lower than 1 and Re is that typical of fully turbulent flow regimes, this correlation can be applied to the study of exhaust gas flows. The friction coefficient / that appears in Eq. (17.10) is given by the Churchill correlation as well [16] ... 

Currently the standard TRACE code heat transfer (Dittus-Boelter) and fluid pressure drop (Churchill and Moody) correlations are applied to the gas cooler. Use of the Churchill correlation and Moody curves, and mathematical representations of the curves, for calculation of the single-phase friction factor in a variety of flow-channel geometries is a common engineering practice. Information on the TRACE default correlations is available in the TRACE theory manual (Reference 12-9). A surface roughness of 2E-6 m is used with the TRACE single phase friction correlations. In order to match the HB24 pressure drop prediction, additional frictional flow factors are included in the hydraulic model. The TRACE model also includes plenums to provide a location to specify form loss factors for the gas cooler. The heat transfer and pressure drop correlations would have been updated as the cooler design was determined and as test data was collected. 

Available kinetic data are seldom of sufficiently high quality to warrant the application of high precision statistical treatment. This point is made forcefully by Churchill [495] who states Our ability and inclination to postulate and construct models appear to exceed our ability and inclination to obtain good rate data. Improvement in rate correlations will come primarily from more and better measurements rather than from improvements in modelling or mathematical procedures. ... 

Zhang and Davis proposed an interpolation formula based on Churchill and Usagi s (1972) method of combining asymptotic solutions to obtain a correlation valid over the whole range of variables. Their correlation is... 

This idea was first used by Van der Hegge Zijnen (VI) and Douglas and Churchill (D4) in developing correlations for cylinders in crossflow. 

Equations (50) and (51) are in good agreement with the empirical correlations suggested by Churchill and Ozoe [17] to represent their numerical solution of the governing transport equations. Tables I and II compare the results. 

Introducing the general correlation for the friction factor suggested by Churchill (11), figure 2 shows how the choking conditions now depend on the pipe length for isothermal conditions and variable friction factor. As it is seen, the effect of the variable friction factor is negligible. 

Michenfelder J. D. (1988) The hypothermic brain. In Anesthesia and the Brain Clinical, Functional, Metabolic and Vascular Correlates (Michenfelder J. D., ed.), Churchill Livingstone, New York. 

Churchill, S.W., A Comprehensive Correlation Equation for Laminar, Assisting Forced and Free Convection , AIChE J.. Vol. 23, pp. 10-16, 1977. 

Equation (5-44) is applicable to fluids having Prandtl numbers between about 0.6 and 50. It would not apply to fluids with very low Prandtl numbers like liquid metals or to high-Prandtl-number fluids like heavy oils or silicones. For a very wide range of Prandtl numbers, Churchill and Ozoe [9] have correlated a large amount of data to give the following relation for laminar flow on an isothermal flat plate ... 

Some more comprehensive methods of correlating turbulent-boundary-layer heat transfer are given by Churchill [11]. 

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. 

Churchill, S. W. A. Comprehensive Correlating Equation for Forced Convection from Flat Plates, AlChE J., vol. 22, p. 264, 1976. 

It is desirable to have a single correlation that applies to all fluids, including liquid metals. By curve-fitting existing data, Churchill and Ozoe (1973) pro posed the following relation which is applicable for all Prandtl numbers and is claimed to be accurate tp 1%,... 

S. W, Churchill and M. Bernstein. A Correlating Equation for Forced Convection from Gases and I.iquids to a Circular Cylinder in Cross Flow." Journal of Heat Transfer 99 (1977), pp. 300 -306. 

Air (Pr = 0.7, k = 0.026 W/m K) at 200°C Oow.s across 2-cm-diameier tubes whose surface temperature is 50"C with a Reynolds number of 8000. The Churchill and Bernstein convective heat transfer correlation for the average Nusselt number in this situation is... 

S. W. Churchill and H. H. S. Chu. Correlating Equations for Laminar and Turbulent Free Convecliou from a Horizontal Cylinder. huenialional Journal of Heat Mass Transfer l 8(1975),p. 1049. 

Churchill, S.W. Chu, H.H.S. Correlating equations for laminar and turbulent free convection from a horizontal cylinder. Int. J. Heat Mass Transfer 18 (1975) 1049-1053... 

Equations (10.27) and (10.28) can be accurately combined using a method suggested by ChurchilE to yield an overall correlation ... 

S. W. Churchill and M. Berstein, A correlating equation for forced convection from gases and liquids to a circular cylinder in crossflow, J. Heat Transfer, 99,300-306,1977. 

The mean heat transfer in the mixed convection regime for assisting flows has been correlated by Churchill [55] using the equation... 

S. W. Churchill, A Comprehensive Correlating Equation for Laminar Assisting Forced and Free Convection, AIChE J. (23) 10-16,1977. 

S. W. Churchill and H. Ozoe, A Correlation of Laminar Free Convection From a Vertical Plate, ]. Heat Transfer (95) 540-541,1973. 

However, after reviewing the available experimental data and theoretical predications, Manlapaz and Churchill [194] recommended the following correlations, which contain both the Dean number De and radius ratio of Rla ... 

The fully developed Nusselt numbers for laminar flow in helicoidal pipes subjected to the uniform wall temperature have been obtained theoretically and experimentally by Mori and Nakayama [196], Tarbell and Samuels [197], Dravid et al. [198], Akiyama and Cheng [199], and Kalb and Seader [200]. A comparison of these results has been made using the Manlapaz-Churchill [201] correlation. 

In Fig. 5.36, experimental and theoretical results [196-200] are compared with the following Manlapaz-Churchill [201] correlation based on a regression analysis of the available data ... 

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