Heat transfer to liquid metals

All properties for use in Eq. (6-45) are evaluated at the bulk temperature. Equation (6-45) is valid for 102 < Pe < 104 and for Lid > 60. Seban and Shi. mazaki [16] propose the following relation for calculation of heat transfer to liquid metals in tubes with constant wall temperature ... 

Hyman, S. C., C. F. Bonilla, and S. W. Ehrlich Heat Transfer to Liquid Metals from Horizontal Cylinders, AiChE Symp. Heat Transfer. Atlantic City. 1953. p. 21. 

The relationship between the thicknesses of the two boundary layers at a given point along the plate depends on the dimensionless Prandtl number, defined as Cpfijk. When the Prandtl number is greater than unity, which is true for most liquids, the thermal layer is thinner than the hydrodynamic layer, as shown in Fig. 12.1a. The Prandtl number of a gas is usually close to 1.0 (0.69 for air, 1.06 for steam), and the two layers are about the same thickness. Only in heat transfer to liquid metals, which have very low Prandtl numbers, is the thermal layer much thicker than the hydrodynamic layer. 

Hsu [Int. J. Heat Mass Transfer, 7, 431 (1964)] and Kalish and Dwyer [Int. J. Heat Mass Transfer, 10, 1533 (1967)] discuss heat transfer to liquid metals flowing across banks of tubes. Hsu recommends the equations... 

P.L. KIRILLOV, Thesis Heat Transfer to Liquid Metals (single and two-phase flow) , Moscow Power Institute, 1968 (in Russian). 

Borishanskii, V.M., M.A. Gotorsky, and E.V. Firsova. 1969. Heat transfer to liquid metal flowing longitudinally in wetted bundles of rods. Atom. Energy 27 549-568. 

Graber, H. and M. Rieger. 1973. Experimental study of heat transfer to liquid metals flowing in line through tube bundles. Prog. Heat Mass Transfer 7 151-166. 

Film Heat Transfer Coefficient Value Most of the experimental data for liquid metals in forced convection have been obtained for round tubes. Since a large fraction of heat transfer to liquid metals in forced convection is by molecular and electronic conduction, the velocity and temperature distribution of the fluid in the channel is expected to have a noticeable effect. Until data are obtained for the reference channel, however, the data for round tubes is used with the equivalent diameter of the channel replacing the diameter of the tube. Most of the round tube data fall below the L.yon-Martinelli theoretical prediction, and therefore 85% of the Lyon-Martinelli Nusselt Number is used as the best average value in the range of Peclet Number of interest (500-1000). The factor shown in Table X represents the expected accuracy of experimental data. 

Eurther information on liquid-metal heat transfer in tube banks is given by Hsu for spheres and elliptical rod bundles [Inf. J. Heat Mass Transfer, 8, 303 (1965)] and by Kalish and Dwyer for oblique flow across tube banks [Inf. J. Heat Mass Transfer, 10, 1533 (1967)]. For additional details of heat transfer with liquid metals for various systems see Dwyer (1968 ed., Na and Nak supplement to Liquid Metals Handbook) and Stein ( Liquid Metal Heat Transfer, in Advances in Heat Transfer, vol. 3, Academic, New York, 1966). 

Heat Transfer in Transition Region between Laminar and Turbulent Flow 353 Transfer to Liquid Metals 355... 

Summary of experimental data Film boiling correlations have been quite successfully developed with ordinary liquids. Since the thermal properties of metal vapors are not markedly different from those of ordinary liquids, it can be expected that the accepted correlations are applicable to liquid metals with a possible change of proportionality constants. In addition, film boiling data for liquid metals generally show considerably higher heat transfer coefficients than is predicted by the available theoretical correlations for hc. Radiant heat contribution obviously contributes to some of the difference (Fig. 2.40). There is a third mode of heat transfer that does not exist with ordinary liquids, namely, heat transport by the combined process of chemical dimerization and mass diffusion (Eq. 2-162). 

Dean, R A., R. S. Dougall, and L. S. Tong, 1971, Effect of Vapor Injection on Critical Heat Flux in a Subcooled R-l 13 (Freon) Flow, Proc. Int. Symp. on Two-Phase Flow Systems, Haifa, Israel. (6) Deane, C. W., and W. M. Rohsenow, 1969, Mechanism and Behavior of Nucleate Boiling Heat Transfer to the Alkali Liquid Metals, USAEC Rep. DSR 76303-65, Massachusetts Institute of Technology, Cambridge, MA Also in 1970, Liquid Metal Heat Transfer and Fluid Dynamics J. C. Chen and A. A. Bishop, Eds., ASME Winter Annual Meeting, New York. (4)... 

Tippets, F. E., J. A. Bond, and J. R. Peterson, 1965, Heat Transfer and Pressure Drop Measurements for High Temperature Boiling Potassium in Forced Convection, Proc. Conf. on Applied Heat Transfer Instrumentation to Liquid Metal Experiments, ANL-7100, p. 53-95, Argonne National Lab., Argonne, IL. (3)... 

Whalley, P. B., P. Hutchinson, and G. F. Hewitt, 1973, The Calculation of Critical Heat Flux in Forced Convective Boiling, Rep. AERE-R-7520, European Two Phase Flow Group Meeting, Brussels. (5) Whalley, P. B., P. Hutchinson, and G. F. Hewitt, 1974, The Calculation of Critical Heat Flux in Forced Convection Boiling, Heat Transfer 1974, vol. IV, pp. 290-294, Int. Heat Transfer Conf., Tokyo. (5) Wichner, R. P, and H. W. Hoffman, 1965, Pressure Drop with Forced Convection Boiling of Potassium, Proc. Conf. on Applications of Heat Transfer Instrumentation to Liquid Metals Experiments, ANL-7100, p. 535, Argonne National Lab., Argonne, IL. (3)... 

Liquid metal bums are known as projections from blast furnace tap or the situation of loading with delivery of bulk into liquid metal. Metal is normally of low viscosity like water and spreads on skin and eye. Thus projections of liquid metal do not behave like viscous materials but like water and spread their enormous heat onto wide areas. When eventually cooling down, liquid metal is trapped in the conjunctival sac. When this happens, there is a maximum heat transfer with high thermoconductivity from metallic surfaces to the conjunctiva with immediate water evaporation and consecutive heat transfer from the metal to the eye up to carbonization of the tissues [16,17],... 

Conduction furnaces utilize a liquid at the operating temperature to transfer the heat from the heating elements to the work being processed. Some furnaces have a pot filled with a low melting metal, eg, lead, or a salt mixture, eg, sodium chloride and potassium chloride, with a radiation-type furnace surrounding the pot. Although final heat transfer to the work is by conduction from the hot lead or salt to the work, the initial transfer of heat from the resistors to the pot is by radiation. 

Recently, several new processes for methane thermal decomposition were reported in the literature. In one report, the authors proposed a methane decomposition reactor consisting of a molten metal bath.8 Methane bubbles through molten tin or copper bath at high temperatures (900°C and higher). The advantages of this system are efficient heat transfer to a methane gas stream and ease of carbon separation from the liquid metal surface by density difference. In... 

Why does a slug-flow model yield reasonable results when applied to liquid-metal heat transfer ... 

Heat transfer from horizontal cylinders to liquid metals may be calculated from Ref. 46 ... 

Some efforts have been made to design nuclear reactors in which liquid metals are used as heat transfer agents. Liquid sodium is the metal most often suggested. Liquid sodium has many attractive properties as a heat transfer agent, but it has one serious drawback. It reacts violently with water and great care must be taken, therefore, to make sure that the two materials do not come into contact with each other. 

Much study has been given to liquid-metal heat transfer in recent years, primarily in connection with its use in nuclear reactors. Design equations, all based on heat-momentum analogies, are available for flow in tubes, in annuli, between plates, and outside bundles of tubes. The equations so obtained are of the form... 

G. M. Harpole and I. Catton, Laminar Natural Convection About Downward Facing Heated Blunt Bodies to Liquid Metals, J. Heat Transfer (98) 208-212,1976. 

A. J. Sellers, G. M. Thur, and M. K. Wong, Recent Developments in Heat Transfer and Development of the Mercury Boiler for the SNAP-8 System, Proc. Conf. Application of High Temperature Instrumentation to Liquid-Metal Experiments, Argonne National Laboratory 7100, pp. 573-632, ANL, Argonne, IL, 1965. 

This type of load encompasses a wide range of materials including granular solids like limestone and liquids like molten metal. For this type of load, the heat transfers to the surface of the load and must conduct down into the material. This process can be enhanced by proper... 

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