What is the value of the fluid side heat transfer coefficient when air flows over cold pipes by natural convection?

What is the value of the fluid side heat transfer coefficient when ai

1.	What is the value of the fluid side heat transfer coefficient when air flows over cold pipes by natural convection?
A.	0.2 (Ta – Tm / D)1/4
B.	0.2 (Ta – Tm / D)
C.	0.2 (Ta – Tm / D)1/3
D.	0.2 (Ta – Tm / D)1/2
Answer» B. 0.2 (Ta – Tm / D)