An oil plant is using a double pipe heat exchanger to cool oil. Water in the tube side is flowing at 0.5 kg/s, and its temperature changes from 35 to 80 oC. Oil (Cp = 1.5 kJ/kg. ^oC) is cooled from 150 to 85 oC in the shell side. An engineer suggests to replace the single heat exchanger by two heat exchangers in sires. It is desired to compare the performance of the single counterflow heat exchanger with two smaller counterflow heat exchangers connected in series on the water side and in parallel on the oil side. The oil flow is split equally between the two exchangers, and it may be assumed that the overall heat-transfer coefficient for the smaller exchangers is the same as for the large exchanger (180 Btu/h . ft²).

1. Sketch the old heat exchanger showing all parameters

2. Sketch the ne suggested two smaller counterflow heat exchangers shwing all paprmeters and flow directions

3. Compare the surface areas of the old and new heat exchangers

4. If the smaller exchangers cost 5 percent more per unit surface area, which would be the most economical arrangementthe one large exchanger or two equal-sized small exchangers? You need to show calculations and write a full discussion

I need part 2 and 4 only.