**Math/Physic/Economic/Statistic Problems**

**Air heat exchanger design**

Decide the tube layout; determine the number of tubes per row and the number of tube rows (generally less than 10)

Determine the bundle area. Tube spacing is typically 50 or 60 mm on a triangular pitch

A„,„,„ = six number _ of _ tubes _ per _ rowx effective _ length _ of _ tubes

. Estimate air side flow rate. Typical approach velocity is 2.5 to 3.5 m/s. The air flow rate is the product of approach velocity and bundle area

Estimate pressure drop (sheets 41-43) and fan power consumption (sheet 44)

Carry out detailed simulation of the specified geometry to confirm that the assumed heat transfer coefficients and pressure drops are realistic. Modify design if needed.