R. Michael Banish

Reference Data for the Density and Viscosity of Liquid Aluminum and Liquid Iron

The available experimental data for the density and viscosity of liquid aluminum and iron have been critically examined with the intention of establishing a density and a viscosity standard. All experimental data have been categorized into primary and secondary data according to the quality of measurement specified by a series of criteria. The proposed standard reference correlations for the density of the aluminum and iron are characterized by standard deviations of 0.65% and 0.77% at the 95% confidence level, respectively. The overall uncertainty in the absolute values of the density is estimated to be one of ±0.7% for aluminum and 0.8% for iron, which is worse than that of the most optimistic claims but recognizes the unexplained discrepancies between different methods. The standard reference correlations for the viscosity of aluminum and iron are characterized by standard deviations of 13.7% and 5.7% at the 95% confidence level, respectively. The uncertainty in the absolute values of the viscosity of the two metals is thought to be no larger than the scatter between measurements made with different techniques and so can be said to be ±14% in the case of aluminum and ±6% in the case of iron.

Reference Data for the Density and Viscosity of Liquid Copper and Liquid Tin

The available experimental data for the density and viscosity of liquid copper and tin have been critically examined with the intention of establishing a density and a viscosity standard. All experimental data have been categorized into primary and secondary data according to the quality of measurement specified by a series of criteria. The proposed standard reference correlations for the density of copper and tin are characterized by standard deviations of 1.3% and 1.0% at the 95% confidence level, respectively. The standard reference correlations for the viscosity of copper and tin are characterized by standard deviations of 6.3% and 20% at the 95% confidence level, respectively.

Miniaturized Scintillation Technique for Protein Solubility Determinations

We have developed a miniaturized (volume of crystallizing solution ∼100 μl) technique for the determination of protein solubility as a function of temperature. After nucleation, crystals are detected by the light they scatter. Then the temperature at which a solution with the initial concentration is in equilibrium with the crystals is sought by stepwise, equilibrium dissolution of the crystals. The approach to solubility from the side of dissolution provides for higher accuracy of the determinations. The method was used to determine the temperature dependence of the solubility of human hemoglobin (Hb) C, for which high-resolution x-ray crystallography data are needed to understand the structural basis for the drastically different in vivo aggregation/crystallization behavior of β6 Hb mutants.

Experimental confirmation of the insensitivity of mass diffusion measurements to blockages and voids along the diffusion path

Using the real-time diffusion methodology first developed by Codastefano et al. [Rev. Sci. Instrum. 48, 1650 (1977)] we show that deviations from strictly one-dimensional transport (i.e., blockages and voids) widely cited in the literature as leading to erroneous results, have little effect on the measured diffusivity. In this methodology, radiotracer, initially located at one end of a cylindrical diffusion sample, is used as the diffusant. The sample is positioned in a concentric isothermal radiation shield with collimation bores located at defined positions along its axis. The intensity of the radiation emitted through the collimators is measured as a function of time using solid state detectors. Diffusivities are calculated from the signal difference between the detectors. These results were obtained using 114mIn radiotracer in benign indium. A 60% blockage was simulated by using a 2 mm source disk diffusing into 3 mm diameter host section. A void/bubble was simulated by inserting a 1 mm diameter by 1 ...

In-situ diffusivity measurement technique

Abstract We have developed a technique for the measurement of diffusivities in liquids over a wide temperature range. A radiotracer, initially located at one end of the cylindrical diffusion sample, is used as the diffusant. The sample is positioned in a concentric isothermal radiation shield with collimation bores located at defined positions along its axis. The intensity of the radiation emitted through the collimators is measured vs. time with solid state detectors and associated energy discrimination electronics. Diffusivities are calculated from the signal difference between pairs of collimation bores. Self-diffusivities obtained with In/In 114m in space and on Earth illustrate the high precision obtainable with this technique. The In/In 114m space data were close to the ground results, however, the data scatter was much less. By employing a tracer that emits photons of different energy, and thus, different self-absorption, transport in the bulk of the sample can be distinguished from that in the proximity of the wall. No difference was found. In support of this work 2-D numerical modelling of the effect of various blockages on the concentration profile and the resulting apparent diffusivity were conducted. For the methodology that we use very little effect was seen except in the case of extreme blockages.

Determination of thermal diffusivity in a disk shaped sample using edge heating applications to Stainless Steel

We describe a methodology for determining thermal diffusivities in real time by using temperature measurements at only two locations in a cylindrical sample. The technique is based on an analytical solution of heat transfer in a circular cylinder. This methodology does not require knowing the initial temperature increase or any timing between the applied and measured response. Starting with a cylinder heated on the outer surface and unique temperature measurement locations, the analytical solution for temperature at two specific radii can be approximated, after an initial transient, by a constant plus a single term that decreases exponentially with time. There are two special radii that fulfill the required condition. The data are analyzed by taking logarithms of the differences of the temperature versus time at these two radii, resulting in lines having slopes that are proportional to the thermal diffusivity. Surprisingly, other choices of the measurement locations lead to similar results, except with lo...

Phase transition thermal expansion measurement technique using a modified Michelson interferometer

A methodology for measuring the expansion of materials at the solid to liquid phase transition is presented. Using methods common to interferometry, a continuous experimental procedure is used in both the solid and liquid states. Previous methods have dealt with the expansion of the material within a single phase in separate experiments. A modified Michelson interferometer is used to detect the change in volume of a sample through the phase transition. The sample is placed in a closed system with an inert, high index of refraction gas such as xenon (Xe). The sample is heated to a temperature just below melting. Measurements are taken of the index of refraction of the gas via a fringe count. The sample is then heated to a liquid and maintained at a temperature just above melting. Another index of refraction measurement is then made. The change in volume of the sample from solid to liquid results in a density change of the enclosed gas. This change in density causes a change in the index of refraction. The recorded fringe counts are then used to determine the volume change of the sample using equations derived from first principles and do not rely on the choice of an equation of state. This procedure lends itself to a variety of applications including, but not limited to, the determination of other thermophysical properties of materials (not necessarily near phase transitions) and optical properties of gases, such as index of refraction.

Real-time determination of thermal diffusivity in a disk-shaped sample: Applications to graphite and boron nitride

We describe a methodology for determining thermal diffusivities in real time by using temperature measurements at only two locations in a cylindrical sample. The technique is based on an analytical solution of heat transfer in a circular cylinder. This methodology does not require knowing the initial temperature increase or any timing between the applied and measured response. Starting with a heated cylindrical region having a unique fraction of the sample radius, and unique temperature measurement locations, the analytical solution for temperature at three specific radii can be approximated, after an initial transient, by a constant plus a single term that decreases exponentially with time. There are three special radii that fulfill the required condition. The data are analyzed by taking logarithms of the differences of the temperature versus time at these three radii, resulting in lines having slopes at large times that are proportional to the thermal diffusivity. Surprisingly, other choices of the size of the heated region and the measurement locations lead to similar results, except with longer transients. Experimental results for graphite and boron nitride agree with our numerical simulations and with the manufacturer’s data. This technique is applicable to solids and to liquids if heat transport due to convection is negligible.

Vapor concentration measurement with photothermal deflectometry

Theoretical and experimental results for using the photothermal deflection technique to measure vapor species concentration, while minimizing the disturbance of the transport (material) parameters due to vapor heating, are developed and described. In contrast to common practice, the above constraints require using a pump‐beam duty cycle of less than 50%. The theoretical description of the shortened heating time is based on a step‐function formulation of the pumping cycle. The results are obtained as closed‐form solutions of the energy equation for many chopping cycles until steady state is reached, by use of a Green’s‐function method. The Euler formulation of the Fermat principle is used to calculate the deflection angle. The equations are expanded to include the effects of vapor velocity on both the temperature and temperature gradient profiles. The effects of finite (unfocused) pump and probe beams and thermal (Soret) diffusion are also accounted for. Excellent agreement between theory and experiment is obtained.

CHAPTER 5. Thermal Conductivity and Diffusivity

The chapter is concerned with new developments over the last two decades of familiar experimental techniques for the measurment of thermal conductivity and related transport properties, as well as a variety of diffusion coefficients. It begins with an historical review of the transient hot-wire instrument for accurate thermal conductivity measurement; it has widespread applicability over a wide range of thermodynamic states and a variety of materials. The second section explores a family of measurement techniques that exploit the disturbance of materials caused by absorbtion of light in photoacoustic and photothermal techniques to study thermal transport processes. In Section 5.3, solutions of the diffusive transport equations in simple geometries are derived and simplified to offer new methods for the study of thermal and mass transport in materials of industrial importance. Finally, in Section 5.4, recent work to develop established experimental techniques for the study of both mutual and self-diffusion coefficients in extremes circumstances, such as high pressures and/or high temperatures and special thermodynamic states, are considered.