Helium Transport Properties

W.J. Koros, M.W. Heliums, Transport properties, Encyclopedia of Polymer Science, second ed., Wiley-Interscience Publishers, New York, 1989. 

Another example of thin films showing metallic transport properties down to liquid helium temperature is 0-(BET-TTF)2Br.3H2O, where bilayers are grown on transparent polycarbonate substrates (Mas-Torrent et al, 2001). The bilayers are... 

Preliminary results on low temperature transport properties in YbPdSb system with MgAgAs type structure are presented by Aliev et al. (1988). Resistivity shows a maximum at T = 50-100 K and the Fermi-liquid decrease of q go + AT2 at helium temperatures. The high value of the A coefficient 5 p 2 cm/K2 indicates the possibility of the heavy fermion behavior with y about 300MOO mJ/molK2. The Seebeck coefficient S is positive and shows a maximum Smax 22 pV/K at T 200 K. 

For gas separation membranes, for example, He, O2, and N2 gas transport properties of CA/poly(methyl methacrylate) (PMMA) blends have been measured [108]. This article reported that CA/PMMA blends exhibited phase separation with limited intermiscibility between the components, but they were possibly useful as membrane materials to produce high-purity helium gas streams combined with high helium recovery. 

Superfluid. Liquid helium (more precisely the 2He4 isotope) has a "lambda point" transition temperature of 2.17 K, below which it becomes a superfluid ("Helium-II"). This superfluid, or "quantum liquid," stays liquid down to 0 K, has zero viscosity, and has transport properties that are dominated by quantized vortices thus 2He4 never freezes at lbar. Above 25.2 bar the superfluid state ceases, and 2He4 can then freeze at 1K. The other natural helium isotope, 2He3, boils at 3.19 K and becomes a superfluid only below 0.002491 K. 

Koros WJ and Heliums MW, "Transport Properties", in Mark HF, Bikales NM, Overberger CG and Menges G (Eds) "Encyclopaedia of Polymer Science and Engineering", Wiley, New York, Supplement Vol., 2nd Ed, 1986, pp 724-802. 

Source From Table of units, J. Membr. Sci., 2, 237, 2004 Koros W.J., Heliums M.W., Transport properties. In Kroschwitz, ... 

Koros WJ and Heliums MW. Transport properties. In Kroschwitz, JI, ed. Encyclopedia of Polymer Science. 2nd ed. New York Wiley-Interscience Publishers, 1989 Supplement vol. pp. 724—802. 

The values in these tables were generated from the NIST REFPROP software (Lemmon, E.W., McLinden, M.O., and Huber, M.L., NIST Standard Reference Database 23 Reference Fluid Thermodynamic and Transport Properties—REFPROP, National Institute of Standards and Technology, Standard Reference Data Program, Gaithersburg, Md., 2002, Version 7.1). The primary source for the thermodynamic properties is McCarty, R.D., and Arp, V D., A New Wide Range Equation of State for Helium, Ado. Cryo. Eng. 35 1465-1475,1990. The source for viscosity is Arp, V. D., McCarty, R. D., and Friend, D. G., Thermophysical Properties of Helium-4 from 0.8 to 1500 K with Pressures to 2000 MPa, NIST Technical Note 1334, Boulder, Colo., 1998. The source for thermal conductivity is Hands, B. A., and Arp, V. D., A Correlation of Thermal Conductivity Data for Helium, Cryogenics, 21(12) 697-703,1981. 

In the work of Bixler and Sweeting5 it was assumed that chain restriction effects are negligible for the compact helium molecule, so dial only tortuosity (edded path length) contributes to the rednclion of the di (fusion coefficient for this penetrant. Furthermore, for the 30% ciystalliue polyethylene sample studied, these authors suggest thet the tortuosity effect is essentially nondiscriminating and causes about a 65% reduction in mobility compared to the hypothetical totally amorphous case. The transport properties of a hypothetical totally amorphous branched polyethylene were assumed by these authors co be equivalam io those of unvulcanized natural rubber. 

Both approaches are likely to lead to errors. On the one hand, it has been shown that there are continental regions where the mantle heat flux into the crust is lower than that of the oceans (Torgersen et al. 1992b, 1995). On the other, it is clear that the different transport properties of helium and heat through both mantle and crust will result in transfer of volatiles and heat to the crust with He/heat ratios different from those of the mantle. 

Aziz, R.A., Janzen, A.R., Moldover, M.R. Ab initio calculations for helium a standard for transport property measurements. Phys. Rev. Lett. 74, 1586-1589 (1995)... 

It is anticipated that the superior heat capacity and transport properties of molten salts relative to helium should yield significantly better plant performance, ineluding increased total power output, reduced temperature gradients, lower pumping powers, and eooler fuel temperatures. Initial thermal-hydraulics analyses of the AHTR support these expeetations. 

Transport Properties in EPSE 2nd ed., Suppl. Vol., pp. 724-802, by William J. Koros and Mark W. Heliums, University of Texas at Austin. 

As a consequence of the better heat transfer and heat transport properties of liquids compared with gases, the normal peak operating fuel temperature in an AHTR is expected to be lower than in helium-cooled reactors for heat delivered at the same temperatures to the power cycle or thermochemical hydrogen production plant. There are four effects. 

Agosta, C. C., Wang, S., Cohen, L. H., Meyer, H. (1987). Transport properties of helium near the liquid-vapour critical point IV. The shear viscosity of He and He. J. Low Temp. Phys., 67,237-289. 

Fig. 8.6 Gas transport properties of CNT nanocomposite membrane. Gas transport properties of CNT/PS/PDMS membrane (triangle). CNTs/PS membranes (square), and Knudsen diffusion model (solid line), (a) Effeet of the pressure drop on the permeance of helium through CNTs/PS membrane, (b) Single-gas permeability as a funetion of the inverse square root of the molecular weight of the penetrant, (c) Single gas seleetivity with respect to He calculated from singe-gas permeability data, (d) Mixed-gas selectivity (CO /CH ) of CNTs/PS membrane. The composition of gas mixture was COjiCH =1 1. The feed pressure was 50 psi, and the pressure differential across the membrane was maintained by drawing a vaeuum on the permeate side. Operating temperature was maintained at 308 K. (From [8])...

Review of Helium and Xenon Pure Component and Mixture Transport Properties and Recommendation of Estimating Approach for Project Prometheus Melissa Haire David Vargo... 

The National Institute of Standards and Technology has created an on-line database to provide pure component thermodynamic and transport properties. The on-line database returns transport properties based on input temperature and pressure. The on-line database extends to 1500 K for helium and 800 K for xenon. Tabular pure component viscosity and thermal conductivity data obtained from the on-line database were used directly in the mixture property correlations. Tabular data from NIST can be accessed from http /AVebBook.nist.gov or a more advanced version can be purchased. 

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