Heat exchangers often utilize concentric tubes, with a hot fluid flowing through the inner tube and a coolant (which itself will heat up) in the annnulus: i.e., the space surrrounding the inner tube (see fig. 2.22) Create an Excel worskeet to determine the outer pipe diameter that will support the same volumetric flow as the inner pipe, assuming the fluid velocities will be the same in the annulus and the inner pipe. Hint: Since the mean fluid velocities are the same, the cross-sectiona flow area of the annulus must be the same as the cross-sectional flow area of the inner pipe: i.e., A2=A1. Hence, Pie/4(d2-2t2)^2 -pie/4(d1)^2= pie/4(d1-2t1)^2 or D2= 2t2+square root(d1^2+(d1-2t1)^2)) where d2= the outside diameter of the outer pipe, in d1=the outside diameter of the inner pipe, in t2= the thickness of the outer pipe, in t1= the thickness of the inner pipe, in Determine the outer pipe diameter for a pipe whose thickness is 0.25 inch, if the inner pipe has an outside diameter of 3 inches and a thickness of 1/8 inch.