To recover the waste heat from the processed fluid, a chemical industry planned to invest in a heat exchanger. Company has 4 investment options namely HE1, HE2, HE3 & HE4. Company expected at least 22 % annual return before taxes based on the purchased cost.

	HE 1	HE 2	HE 3	HE 4
Purchased Cost (OMR)	19000	22000	32000	38000
Maintenance Cost (as % of purchased cost)	18	20	25	22
Operation Cost (OMR)	4500	6000	8000	9000
Energy Saving (OMR)	12000	15000	18000	25000

Suggest the suitable heat exchanger to the company based on the following methods. Justify the statement.

a) Incremental investment returns method

b) Minimum return as a cost method