Figure shows a heat exchanger network designed with the minimum number of units and to satisfy the energy target at $T_{\text{m}\text{i}\text{n}}=20C.$ On the basis of the following utilities and cost data,

it has a total annual cost of $14\mathrm{.}835106($$$*y^{-1}).$

Cost of saturated steam $(200C)=70$$$*k{W}^{-1}*y^{-1}$

Cost of cooling water to $($:$40C$