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The Review of Physical Chemistry of Japan Vol. 38 No. 2 (1968)

M. Srichand and M. A. Tirunarayanan

square method. The values of $B$ and $C$ , so obtained, are given in Table 2 with the standard deviation, $\sigma$ , and the probable error, P. E., calculated by the equation

$\text{P. E.} = 0.6745\sigma. \quad (5)$

In Fig. 3, the excess viscosity of Freon-12 and Freon-22 vapours is plotted versus density.

Zero-density viscosity of Freon-12 and Freon-22 vapours

It is important to realize that the determination of viscosity at any temperature and density requires information regarding the temperature dependence of zero-density viscosity. The temperature dependence of zero-density viscosity may be represented by an equation of the form

$\mu_0 = B_0 \sqrt{T} - C_0, \quad (6)$

where the constants, $B_0$ and $C_0$ , depend on the nature of the vapour.

The constants, $B_0$ and $C_0$ , for Freon-12 and Freon-22 vapours are evaluated by matching equation (6) to the zero-density viscosity-temperature data presented in Table 1 using the method of least squares. The values of $B_0$ and $C_0$ , so obtained, are given in Table 3. The standard deviation is calculated by equation (4) and the probable error by equation (5).

Table 3. Constants, $B_0$ , $C_0$ and reliability information for Freon-12 and Freon-22 vapours based on zero-density viscosity data given in Table 1

Refrigerant	Constant	Constant	Standard deviation	Probable error
Refrigerant	$B_0 \times 10^6$ Poise/ $\text{K}^{1/2}$	$C_0 \times 10^6$ Poise	$\sigma \times 10^6$ Poise	P. E. $\times 10^6$ Poise
Freon-12	10.57	59.77	1.6643	1.1226
Freon-22	13.25	102.65	0.5334	0.3598

$Figure 3: Graph showing the variation of excess viscosity, (\mu - \mu_0) \times 10^5 poise, versus Density, \rho, g/cm^3. Two curves are plotted: Freon-22 (higher curve) and Freon-12 (lower curve).$

Figure 3: Graph showing the variation of excess viscosity, (\mu - \mu_0) \times 10^5 poise, versus Density, \rho, g/cm^3. Two curves are plotted: Freon-22 (higher curve) and Freon-12 (lower curve).

Fig. 3 Variation of excess viscosity of Freon-12 and Freon-22 vapours with density

$Figure 4: Graph showing the zero-density viscosity, \mu_0 \times 10^5 poise, versus \sqrt{T}, \text{K}^{1/2}. Two curves are plotted: Freon-22 (higher curve) and Freon-12 (lower curve).$

Figure 4: Graph showing the zero-density viscosity, \mu_0 \times 10^5 poise, versus \sqrt{T}, \text{K}^{1/2}. Two curves are plotted: Freon-22 (higher curve) and Freon-12 (lower curve).

Fig. 4 Zero-density viscosity of Freon-12 and Freon-22 vapours