7. A direct-transfer intercooler for a gas turbine is to be designed using either surface 8.0-1T or surface 929-0.737-SR. The requirements are:

Air side Water side m= 150,000 Ibm/lir m= 300,000 tbm/hr Tin= 725 R Tin= 65o F Texit = 575R Pin = 40.0psia The heat exchanger can be the necessary width, but the air inlet side must be 1.5 ft x 4 ft. Water flows through the tubes. Select the better surface based on economy of operation by calculating (a) the heat-exchanger width required for both surfaces and (b) the pressure drop (air side) for both designs. If electricity is 74/kWh and the fan is 53 percent efficient, what are the operating costs for 2,000 hr/year operation?