If the overall heat-transfer coefficient, initial fluid temperature, and total heat-transfer area determined in Problem 22.4 remain the same, find the exit oil temperature if the configuration is...

If the overall heat-transfer coefficient, initial fluid temperature, and total heat-transfer area determined in Problem 22.4 remain the same, find the exit oil temperature if the configuration is changed to

a. crossflow, both fluids unmixed;

b. shell-and-tube with two tube passes and one shell pass.

Problem 22.4

Air at 203 kPa and 290 K flows in a long rectangular duct with dimensions 10 cm by 20 cm. A 2.5-m length of this duct is maintained at 395 K, and the average exit air temperature from this section is 300 K. Calculate the air flow rate and the total heat transfer.