Heat transfer in liquid metals

This article is a survey of basic work on heat transfer between solid surfaces and flowing liquefied metal that has been reported by both Soviet and foreign authors. The results of experiments on heat transfer to liquid metals are analyzed for cases where flow took place in both long and short tubes, flat channels, over bundles of rods and over a plate along their longitudinal directions, across cylinders, with free convection and condensation of liquid metal vapors. The effect of additives on the rate of heat transfer is examined. Questions that arise in connection with boiling of liquid metals are discussed, as are problems of wetting effects on fluid friction and on heat transfer rate. Equations for calculation of heat transfer rates are given.     

Flow measurement techniques in heavy liquid metals

This paper summarizes several flow measurement systems qualified in the operation of different lead-bismuth loops in the KArslruhe Liquid Metal LAboratory (KALLA) during the last 5 years. There are several experimental techniques which were well proven in air and water and thus could be transferred similarly to liquid metals: these techniques are split into measuring local quantities as temperature, pressure e.g. by means of pressure taps or velocities using Pitot and Prandtl tubes or the Ultrasound Doppler velocimetry (UDV) for local flow velocities, as well as an integral quantity like the flow rate. Since the knowledge of the flow rate acts in terms of the operational safety of nuclear liquid metal systems as one of the most crucial parameters, this aspect is discussed widely herein. Unfortunately, as liquid metals are opaque, an optical access is not possible. Instead, one can take advantage of the high electric conductivity of liquid metals to measure integral and local quantities, like electromagnetic flow meters and miniaturised permanent magnetic probes for local velocity measurements. In this context especially the electromagnetic frequency flow meter (EMFM) is discussed as a prospective and reliable option to measure the flow rate without demanding extensive precognitions with respect to the fluid-wall interface behaviour.This article describes some of the techniques used in KALLA for different liquid metals, explains the measurement principle and shows some of the typical results obtained using these techniques. Also the measurement accuracy as well as the temporal and spatial resolution of each device is discussed and typical error sources to be expected are illuminated. Moreover, some hints for a correct placement of the individual sensor in the liquid metal environment are given.     

Electron ionization cross-section calculations for liquid water at high impact energies

Cross-sections for the ionization of liquid water is perhaps the most essential set of data needed for modeling electron transport in biological matter. The complexity of ab initio calculations for any multi-electron target has led to largely heuristic semi-empirical models which take advantage elements of the Bethe, dielectric and binary collision theories. In this work we present various theoretical models for calculating total ionization cross-sections (TICSs) for liquid water over the 10 keV-1 MeV electron energy range. In particular, we extend our recent dielectric model calculations for liquid water to relativistic energies using both the appropriate kinematic corrections and the transverse part. Comparisons are made with widely used atomic and molecular TICS models such as those of Khare and co-workers, Kim-Rudd, Deutsch-Märk, Vriens and Gryzinski. The required dipole oscillator strength was provided by our recent optical-data model which is based on the latest experimental data for liquid water. The TICSs computed by the above models differ by up to 40% from the dielectric results. The best agreement (to within ∼10%) was obtained by Khare’s original model and an approximate form of Gryzinski’s model. In contrast, the binary-encounter-dipole (BED) models of both Kim-Rudd and Khare and co-workers resulted in ∼10-20% higher TICS values, while discrepancies increased to ∼30-40% when their simpler binary-encounter-Bethe (BEB) versions were used. Finally, we discuss to what extent the accuracy of the TICS is indicative of the reliability of the underlying differential cross-sections.     

Interfacial wave patterns and their transitions in gas-liquid two-phase flow through horizontal ducts

The interfacial wave patterns and their transition characteristics in gas-liquid two-phase flow through rectangular and circular horizontal conduits are investigated.The interfacial waves were traced and recorded by using conductance probes.With the experimental observation and the analysis,some kinds of different interfacial waves were distinguished and dfined,and then the interfacial wave patterns were given,which were compared with previous results.The interfacial wave transition mechanism between each interfacial wave pattern was discussed and a set of transition equations were presented to predict the interfacial wave pattern transitions.The repdictive results are in good agreement with the experimental data.     

Heat-transfer from the turbulent flow of liquid metals in tubes

In this article, the results are given of investigations of heat-transfer for turbulent flow of alkali and heavy liquid metals in tubes. The heat-transfer coefficients were obtained by using two different methods: by the measurement of the temperature field in the flow of the liquid metal and calculating the coefficients, and by the measurement of the wall temperature and the mean liquid-metal temperature. A comparison of the results obtained by these methods leads to certain results concerning the magnitude of the thermal-contact resistance.In the construction of the experimental section of the tube and the small-scale thermocouples, Engineer Yu. N. Pokrovskii and Laboratory Assistant A. P. Aleksandrov took part.Translated from Atomnaya Énergiya, Vol. 11, No. 2, pp. 133–139, August, 1961     

Reactions between reactive metals and iodine in aqueous solutions

Volatile I₂ is likely to be released from the core and primary system to the reactor containment in the event of a severe nuclear reactor accident. Within the containment, I₂ will be distributed between the aqueous and gas phases which makes it very important to study how I₂ will interact with containment surfaces in order to determine which processes might reduce the concentration of volatile I₂. This study focused on the reactions of I₂ with some reactive metals available in the aqueous phase of the containment. The experiments were done under conditions similar to those in the containment of a boiling water reactor in a severe accident situation. Copper, zinc and aluminium are all capable of reducing the concentration of I₂ in the aqueous phase either by adsorption or by conversion of I₂ to I⁻. Copper binds I₂ on the surface as CuI, while zinc and aluminium converts I₂ to I⁻. Rate constants were determined for the adsorption of I₂ on Cu in the temperature range of 25–85 °C and for the conversion of I₂ to I⁻ on Zn and Al in the temperature range of 25–140 °C. The rates of adsorption and conversion increased with temperature.     

Oxygen potentials in alkali metals and oxygen distribution coefficients between alkali and structural metals — an assessment

A survey of literature on the available data on plots of log P_O2 versus $\text{1}\text{T}$ for oxygen dissolved in liquid Li, Na and K, and those of oxygen distribution coefficients between the alkali metals and construction metals was carried out. It was found that the data for liquid potassium are meagre and that the existing plots for liquid sodium are not based on well-stablished solubility and free energy data. An analysis of all the available data was carried out and the best possible data were chosen. The justification for such a choice has also been outlined.     

Direct heat transfer using liquid metals — Problems and technical realization

This paper discusses the possibilities of using metal baths as heat-transfer systems for gas cooled high-temperature reactors under special consideration of the gasification of solid combustibles.     

Mechanical properties of martensitic steels after exposure to flowing liquid metals

This paper describes the tensile test results of martensitic steels EUROFER 97 and T91 after exposure to flowing Pb-17Li and Pb-55.5Bi alloy, respectively. The corrosion tests were performed in LIFUS II loop (Pb-17Li) and LECOR loop (Pb-55.5Bi) located in the ENEA Brasimone Center. Tensile test were carried in SYNTECH test machine under Ar atmosphere with an extension rate of 2 mm/min, and test temperature for EUROFER and T91 steels were at 480 and 400 °C respectively. The exposure of EUROFER steel to the liquid Pb-17Li did not affect its mechanical properties, while the ductility of T91 steel was deteriorated after exposed to flowing liquid Pb-55.5Bi.     

Analysis of data and recommendations on heat transfer by liquid metals in rod bundles

Translated from Atomnaya Énergiya, Vol. 65, No. 6, pp. 423–426, December, 1988.