Viscosity thermal instability effects

The increase in the molar conductivity, corrected for viscosity effects, with increasing I2 content of MI (M = Me4N, Et4N, BU4N, or Na) in I2-DMF solutions and of Nal in I2-DMSO solutions has been attributed to the so-called relay conduction mechanism of 1 ions in I2 solutions."" These results support the proposal made earlier that the lower, but normal conductivities of Nal in liquid I2 are due to the thermal instability of Na I(l2)n- The formation of I3 has been studied spectrophotometrically in MeOH, Pr OH, Bu OH, MeCN, and DMSO" and in mixtures of these solvents both with and without water. 

Other factors do intervene. Significant solar heating of the soil surface, so that the soil becomes warmer than the air, causes vertical thermal convection currents to develop within the boundary layers. This introduces turbulence or instability that acts to move the chemical signature up into the free air. When the molecules are moved into the free flow of the air, the effect is to reduce the concentration by dilution. Conversely, when the soil surface is cooler than the air, thermal convection is inhibited, with the result that the molecules are effectively trapped in the boundary layer. This effect is strengthened by the cooling of the air adjacent to the surface, which increases its viscosity. Higher viscosity lowers the Reynold s number, thus decreasing boundary layer thickness. 

The operation of polymerization reactors is subject to different sorts of instabilities, which may be caused by thermal, viscous, hydrodynamic and kinetic effects, among other reasons. For instance, the increase of the system viscosity (or polymer build-up on heat transfer surfaces) leads to significant reduction of heat transfer coefficients and... 

Mechanical face seal operation is greatly affected by thermal phenomena that provoke fluid viscosity variation, friction face distortions, and, eventually vaporisation in the interfacial fluid film. These effects also interfere with the seal dynamic behaviour. More particularly, during transient periods such as start-up, these phenomena can lead to irreversible instabilities. 

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