apply both Reynolds analogy, and Petukhov equation. estimate the average book temperature at 40C from an experienced engineer.

6-26 Liquid Freon 12(CCl2F2) enters a 3.5 -mm-diameter tube at 0C and with a flow rate such that the Reynolds number is 700 at entrance conditions. Calculate the length of tube necessary to raise the fluid temperature to 20C if the tube wall temperature is constant at 40C