Answer:
attached below
Step-by-step explanation:
Attached below is a detailed solution to the question above
Step 1 : determine the Reynolds number using the characteristics of Air at 45°c
Step 2 : calculate the Nusselt's number
Step 3 : determine heat transfer coefficient
Step 4 : calculate heat transfer ratio and thermal resistance
Repeat steps 1 - 4 for each value of diameter from 0.05 to 0.5 m
attached below is a detailed solution