Viscosity, liquids

Within a series of non-haloaluminate ionic hquids containing the same cation, changing the anion dearly impacts the viscosity (Tables 3.2-1 and 3.2-3). The general order of increasing viscosity with respect to the anion is bis(trifluoromethylsulfo-nyl)amide, tetrafluoroborate, trifiuoromethyl acetate, triflate, heptafluoroethylsul-fonate, heptafluoroprop)4 acetate, methyl acetate, mesylate, nonafluorobutylsul-fonate. Obviously, this trend does not exactiy correlate with anion size. This may be 

Cation Anion Temperature, K Viscosity (t ). cP Density, gem- Reference 

Cation Temperature, Anion K Viscosity h). cP Density, gcm Reference 

---

Liquid viscosity is one of the most difficult properties to calculate with accuracy, yet it has an important role in the calculation of heat transfer coefficients and pressure drop. No single method is satisfactory for all temperature and viscosity ranges. We will distinguish three cases for pure hydrocarbons and petroleum fractions ... 

Normal boiling point K Standard specific gravity Molecular weight kg/lunol Liquid viscosity at 100°F mm /s Liquid viscosity at 2iO F mm /s Critical temperature K Critical pressure bar... 

Kouzel, B. (1965), How pressure affects liquid viscosity . Hydrocarbon Process. Petrol. Refiner, Vol. 44, No. 3, p. 120. 

Unlike gases, liquid viscosity decreases as temperature increases, as the molecules move further apart and decrease their internal friction. Like gases, oil viscosity increases as the pressure increases, at least above the bubble point. Below the bubble point, when the solution gas is liberated, oil viscosity increases because the lighter oil components of the oil (which lower the viscosity of oil) are the ones which transfer to the gas phase. 

The ease with which small gas bubbles can escape from the liquid phase is determined by the liquid viscosity higher viscosities imply longer residence times. Typical residence times vary from, some 3 minutes for a light crude to up to 20 minutes for very heavy crudes. 

This definition is in terms of a pool of liquid of depth h, where z is distance normal to the surface and ti and k are the liquid viscosity and thermal diffusivity, respectively [58]. (Thermal diffusivity is defined as the coefficient of thermal conductivity divided by density and by heat capacity per unit mass.) The critical Ma value for a system to show Marangoni instability is around 50-100. 

It was commented that surface viscosities seem to correspond to anomalously high bulk liquid viscosities. Discuss whether the same comment applies to surface diffusion coefficients. 

Fig. 23. Pressure drop and flooding correlation for various random packings (95). ip = p- o IP-l (standard acceleration of free fall) = 9.81 m/s, p, = liquid viscosity ia mPa-s numbers on lines represent pressure drop, mm H2O /m of packed height to convert to ia. H2O /ft multiply by 0.012. Packing...

Equations for vapor pressure, liquid volume, saturated liquid density, liquid viscosity, heat capacity, and saturated Hquid surface tension are described in Refs. 13, 15, and 16. 

Fig. 9. Flow patterns with different impeller types, sizes, and liquid viscosity (a) FBT (b) hydrofoil (c) PBT (d) PBT, large diameter (e) PBT, high...

Liquid viscosity generally produces adverse effects on drop size. It increases the initial film thickness and hinders the growth of unstable waves. 

Fig. 2. Liquid viscosity of butyl alcohols A, 1-butanol B, isobutyl alcohol C, 2-butanol D, /-butyl alcohol.

Liquid viscosity is accurately correlated as a function of temperature by the modified Riedel equation previously discussed for correlation of vapor pressure and shown by Eq. (2-96). 

Liquid Viscosity The viscosity of both pure hydrocarbon and pure nonhydrocarbon hquids are most accurately predicted by the method of van Velzen et al. The basic equation (2-112) depends on group contributions which are dependent on stnic tiire for the calculation of compound-specific constants B and To-... 

TABLE 2-398 Group Contribution Values for Liquid Viscosity Prediction... 

A mixing rule developed by Kendall and Monroe" is useful for determining the liquid viscosity of defined Iiydi ocai bon mixtiai es. Equation (2-119) depends only on the pure component viscosities at the given temperature and pressure and the mixture composition. 

For estimating the liquid viscosity of defined nonliydi ocai bon mixtui"es, a mixing rule shown hy Eq. (2-120) was recommended hy the Technical Data Manual. 

For predicting the liquid viscosity of pm e hydi ocai bon mixtiu es at high temperatiu es, the method of Letsoii and StieP is available. Error analyses with only a small amount of data shows errors averaging 34 percent in the reduced temperature range of 0.76 to 0.98. Equation (2-121) deBnes the method with inputs of Eqs. (2-122) and (2-123). 

Eo = Eotvos number = gA dVc Re = Reynolds number = du /[L Ap = density difference between the phases p = density of continuous liquid phase d = drop diameter [L = continuous liquid viscosity surface tension u = relative velocity... 

The physical properties of spray-dried materials are subject to considerable variation, depending on the direction of flow of the inlet gas and its temperature, the degree and uniformity of atomization, the solids content of the feed, the temperature of the feed, and the degree of aeration of the feed. The properties of the product usually of greatest interest are (1) particle size, (2) bulk density, and (3) dustiness. The particle size is a function of atomizer-operating conditions and also of the solids content, liquid viscosity, liquid density, and feed rate. In general, particle size increases with solids content, viscosity, density, and feed rate. 

Forveiy thin hquids, Eqs. (14-206) and (14-207) are expected to be vahd up to a gas-flow Reynolds number of 200 (Valentin, op. cit., p. 8). For liquid viscosities up to 100 cP, Datta, Napier, and Newitt [Trans. In.st. Chem. Eng., 28, 14 (1950)] and Siems and Kauffman [Chem. Eng. Sci, 5, 127 (1956)] have shown that liquid viscosity has veiy little effec t on the bubble volume, but Davidson and Schuler [Trans. Instn. Chem. Eng., 38, 144 (I960)] and Krishnamiirthi et al. [Ind. Eng. Chem. Fundam., 7, 549 (1968)] have shown that bubble size increases considerably over that predic ted by Eq. (14-206) for hquid viscosities above 1000 cP. In fac t, Davidson et al. (op. cit.) found that their data agreed veiy well with a theoretical equation obtained by equating the buoyant force to drag based on Stokes law and the velocity of the bubble equator at break-off ... 

---