Vapor viscosity

Fp is a correction factor for the influence of the polarity, which is characterized by the reduced dipole moment 

For some substances, the dipole moment itself can be taken from Table 3.6. The relationships for Fp are 

The expected mean error of this method is considered to be low, so that measurements of this quantity are rarely carried out. 

For process calculations, the dynamic viscosity of gases can be correlated with a simple polynomial 

1 + CT- + DT- which shows a more reliable extrapolation behavior. 

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Many of the common properties of isoprene have been presented graphically (9). These include vapor pressure, heat of vaporization, Hquid heat capacity, vapor heat capacity, Hquid density, vapor viscosity, Hquid viscosity, surface tension, and vapor thermal conductivity. 

Vinyl acetate is a colorless, flammable Hquid having an initially pleasant odor which quickly becomes sharp and irritating. Table 1 Hsts the physical properties of the monomer. Information on properties, safety, and handling of vinyl acetate has been pubUshed (5—9). The vapor pressure, heat of vaporization, vapor heat capacity, Hquid heat capacity, Hquid density, vapor viscosity, Hquid viscosity, surface tension, vapor thermal conductivity, and Hquid thermal conductivity profile over temperature ranges have also been pubHshed (10). Table 2 (11) Hsts the solubiHty information for vinyl acetate. Unlike monomers such as styrene, vinyl acetate has a significant level of solubiHty in water which contributes to unique polymerization behavior. Vinyl acetate forms azeotropic mixtures (Table 3) (12). 

Values of the viscosity of gaseous carbon monoxide have been reported (5,8,15,16). Vapor viscosity values and their relationship to density have been tabulated over a wide range of conditions (15). Values for Hquid carbon monoxide may be obtained (7). 

Example 24 Estimate the Vapor Viscosity of Isopropyl Alcohol... 

Vapor viscosity is accurately correlated as a function of temperature byEq. (2-95). 

Vapor Viscosity Methods for prediction of vapor viscosity abound such that only the most accurate and generally used methods are included. 

For prediction of the vapor viscosity of pure hydrocarbons at low pressure (below Tr of 0., the method of Stiel and Thodos is the most accurate. Only the molecular weight, the critical temperature, and the critical pressure are required. Equation (2-97) with values of N from Eqs. (2-98) and (2-99) is used. 

For prediction of the vapor viscosity of gaseous mixtures of hydi ocai bons and nonhydixjcai bon gases at low pressures below a 7, of 0.6, the method of Bromley and Wilke is recommended. 

For prediction of the vapor viscosity of gaseous bydi ocarbons and mixtures of bydi ocarbons at nigb pressui es (not applicable to nonhydrocarbon gases) above a 7, of 0.6, low pressure values are calculated from Eq. (2-97) and/or (2-100) and then corrected for pressure by the method of Dean and StieF given by Eq. (2-102). 

Example 23 Estimate the vapor viscosity of a mixture of propane and methane. Assume 60 mole percent methane and 40 mole percent propane at 125 C and 10.34 MPa total pressure. The low pressure viscosity is 0.0123 op. Use Eq. (2-102) ... 

Example 24 Estimate the vapor viscosity of isopropyl alcohol at 25UC and atmospheric pressure. 

Instead of the Martinelli parameter, Xlt, a convection number, Co, was used for the F factor neglecting the vapor viscosity effects ... 

Figure 4.18 Family of curves of Nusselt number ratio versus quality for constant bulk wall vapor viscosity ratios. (From Varone and Rohsenow, 1990. Reprinted with permission of Massachusetts Institute of Technology, Cambridge, MA.)...

Because Dpg is usually unavailable, the subscript-altered form of Eq. (2b) cannot be used directly in design. Wire-mesh manufacturers generally recommend a K (i.e., Kg) value of 0.35 fl/s This corresponds to a disengagement droplet size. Dm, of roughly 1,000 pm for a vapor viscosity, p,. of 0.03 cP, and a PiXPp—pJl value of 3.2 lbm /fl (sec Fig. 2). However, Kg should be related to physical properties at drum operating conditions, as in Fig. 3. 

Fig. 3—Relationships ot disengagement velocity "constant" at vapor viscosity of 0.03 cP...

Viscosity of the vapor. The lower the vapor viscosity, the faster the settling rate. 

All these ideas have been put into one equation, called Stokes law. Nothing against Sir Frederick Stokes, but vapor viscosities are almost always so small that they do not affect settling rates. Also, we never know the particle size distribution of the droplets. There is a more fruitful way to look at the settling tendency of droplets of liquid in an upflowing vapor stream, as shown in Fig. 26.1. The method states... 

For organic vapors only give latent heat of evaporation/specific volume/vapor viscosity. 

Tin vapor viscosities ol all l( jr compound were extt mated by (hr method of Reichcnhcrg a ... 

Figure 2S-7. Vapor viscosity ol miscellaneous aldehydes from (7 C to 500 C...

The vapor viscosities of all four compounds have been estimated hy the method of Reichcnherg.Jf>... 

The vapor viscosity has been measured from tf C to )25stV2751 The method of Rcichenhcrg was used to calculate the vapor viscosity of nil lour c mpi ttiKls N> over the range of 0 51K1T Hie average error tor acetone was less than I ... 

Golubev has determined the vapor viscosity of methyl ether and ethyl ether from 0°C to 400iC.5,t The method of Rciehcnbergwwas used to calculate the vapor viscosities of... 

The vapor viscosity has been meuxured from Wire lo 20CPC for methyl acetate1 and from OT lo 325FC for ethyl acetate. n Golubev presents experimental data for methyl and ethyl acetate from O C to 5WX The vapor viscosity of vinyl acetate and butyl acetate wetc calculated by the method of Reichenbcrg. The average error for the experimental points of methyl and ethyl acetate was about 2%... 

Figure 31-0, Vapor viscosity lor cyclic el hors from 0T to SOOT.

The vapor viscosities were calculated by the method of Roy and Ihodrn.2 ... 

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