Question

The Prandtl number, Pr, is a dimensionless group important in heat transfer. It is defined as Pr - Cp*mu/k where Cp is the heat capacity of a fluid, mu is the fluid viscosity, and k is the fluid thermal conductivity. For a given fluid, Cp 0.66 J/(g * deg C), k 0.36 W/(m * deg C), and mu 1896 lbm (ft * h}. Determine the value of the Prandtl number for this fluid

Answer 1

Answer:

The Prandtl number for this example is 14,553.

Explanation:

The Prandlt number is defined as:

$Pr=\frac{C_{p}*\mu}{k}$

To compute the Prandlt number for this case, is best if we use the same units in every term of the formula.

$\mu=1896 \frac{lbm}{ft*h}*\frac{1000 g}{2.205 lbm}*\frac{3.281 ft}{1 m}*\frac{1h}{3600s} =7938 \frac{g}{m*s}$

Now that we have coherent units, we can calculate Pr

$Pr=\frac{C_{p}*\mu}{k}=0.66*7938/0.36=14553$