Question

The thermo-physical properties of air at 60${}^o$C are:
Density = 1.06 kg/m${}^3$; Cp = 1.008 kJ/kgK;
Thermal conductivity = 0.028 W/mK and Dynamic viscosity = 18.97 x 10${}^{-6}$ Ns/m${}^2$ .
The Prandtl number of air at 60${}^o$C is

• A. 6.83
• B. 0.683
• C. 7.23
• D. 0.723

Answer 1

The correct option is B 0.683

Given
$\rho =1.06kg/m^3$

$K=0.028W/mK$

$C_p=1.008kJ/kg.K$

$\mu =18.97\times {10}^{-6}Ns/m^2$

$P_r=\frac{\mu C_p}{K}=\frac{18.97\times {10}^{-6}\times 1.008\times {10}^3}{\mathrm{0..028}}=0.683$