ENG A heat exchanger has been designed and insulation is being considered for the unit. The insulation can be obtained in thickness of 25,50,75, or 100cm. The following data have been determined for different insulation thicknesses. a) What thickness of insulation should be used? The value of heat is $1.50/GJ. An annual return of 15% on fixed capital investment is required for any capital utilized in this type of investment. The income tax is 35%/ year. The exchanger operates 300 days per year. (20 pts) b) For the most profitable exchanger, if DCFROR is 15% and CCF is 1/3, what is the lifetime? (5 pts)