Convection Loop Research Articles

金属材料の液体金属蒼鉛-鉛共晶合金による質量移行の研究

A study of corrosion and mass-transfer of 18-8 stainless steel, mild steel, 5%Al-Fe, croloy 5Si, monel and Nickel in liquid Bi-Pb eutectic alloy by the thermal convection loop was conducted. The change of structure in corroded samples and the precipitates of the cold part of loop were examined by a microscope and the crystal structures of precipitates were studied by the X-ray analysis. The results obtained were as follows: (1) Nickel and monel were completely mass-transfered. The corrosion loss was most remarkable in mild steel; in 18-8 stainless steel and 5%Al-Fe it was moderate and in 18-8 Mo stainless steel and croloy 5Si it was comparatively light. (2) Nickel and nickel-component in monel were mass-transfered and precipitated in the form of the hexagonal or pentagonal γ intermetallic compound in the loop, and a bamboo-leaf-like β intermetallic compund was observed on the surface of the liquid Bi-Pb eutectic alloy. (3) Nickel-rich intermetallic β has Ni-As-type lattice and is expressed by Ni (Bi, Nb) in which the ratio of Bi to Pb is 2 to 1. (4) In 18-8 and 18-8 Mo stainless steel, the phase changes from γ to α, but in the latter the layer depth of phase change is smaller than 10 μ and a regular array of etch pits at 1 μ intervals in the grain was observed near the surface of sample.

Properties of Uranium Dioxide-Sodium-Potassium Alloy Slurry Fuels

>In an investigation of U0/sub 2/ suspended in NaK, a forced convection loop was constructed to determine the pressure drop vs. velocity curves at various temperatures. These pseudoconsistency curves were used to establish the effects of prolonged pumping, heating, and the addition of other metals. lnterpretations of the results are given. (J.R.D.)

Heat Transfer Studies on a Forced Convection Loop with Biphenyl and Biphenyl Polymers

The pumped loop at NRL is designed to study heat transfer characteristics of organic fiuids and the effect of pyrolytic decomposition products on heat transfer surfaces. The studies are based on the direct determination of film coefficients, over-all heat transfer coefficients, or both, on an electrically heated horizontal tube. Reliable film coefficients in the high turbulent region for biphenyl and two polymer-biphenyl mixtures (25% and 40% polymer) are presented and effectively correlated with an equation of the Dittus- Boelter type. Data showing a lack of fouling at surface temperatures of 850 deg F are presented for short term experiments with biphenyl and a low-polymer mixture (25% polymer). Plugging in gage and drain lines during loop operation, resulting from low solubility of paraquaterphenyl and/or higher parapolyphenyls, is discussed. Associated with the loop studies, physical properties for a number of phenyl compounds and mixtures were determined. Density and viscosity values are reported for biphenyl, metaterphenyl, paraterphenyl, monoisopropylbiphenyl, and two polymer-biphenyl mixtures. Equations are presented for extrapolation of the data to higher temperatures. Also, solubility values are reported for a number of phenyl compounds in biphenyl and other aromatic solvents. (auth)

The Mass Transfer Properties of Various Metals and Alloys in Liquid Lead

Abstract The relative resistance to mass transfer in liquid lead of 24 metals and alloys were measured. Tests were performed in small quartz thermal convection loops. The test temperature was about 800 C with a thermal gradient of 300 C existing across the loops. Of the metals and alloys studied, only columbium and molybdenum exhibited a high resistance to mass transfer. Nickel and nickel-rich alloys were highly susceptible to mass transfer. Evidence is presented to show that alloys in which a tendency toward intermetallic compound formation exists show a higher resistance to mass transfer in liquid lead than do their pure metal components.

A Technique for Corrosion Testing in Liquid Lead

Abstract A new testing technique has been devised which was found to be satisfactory for comparing the dynamic corrosion characteristics of a series of metals in liquid lead. The tests were conducted in small quartz thermal convection loops. The necessary apparatus was simple, easy to construct and relatively inexpensive. In addition the method afforded a means of studying metals such as chromium and molybdenum which, because of difficulties in fabrication or lack of oxidation resistance, could not be tested by more conventional techniques.