Question$5(8$ Marks$)$

Air at atmospheric pressure and at $200C$ is heated as it flows through a tube with a diameter of $2\mathrm{.}54$ cm at a velocity of $20\frac{m}{s}.$

If a constant heat flux is maintained on the outer surface of the tube, and the temperature difference between the wall surface and the fluid is maintained at $20C$ :

a$)$ What is the Reynolds Number associated with the airflow?

b$)$ Calculate the heat transfer rate per unit length of tube.

c$)$ Estimate the bulk temperature increase over a $3$ m length of the tube.