A double-pipe heat exchanger consists of five hairpins connected in series. The hairpins are each 20-ft long with 4-in. schedule 40 outer pipes, 2-in. schedule 40 inner pipes and internal return bends. Nozzles are made of 2-in. schedule 40 pipe. 40,000 lb/h of a petroleum fraction having the properties given below will flow in the annulus. the heat-transfer coefficient, h_o,=178.41

determine the total pressure drop, P_o, for the annulus.

choices given

7.1 psi

8.9 psi

6.2 psi

5.3 psi