Figure P7.141 provides steady-state operating data for an air compressor-intercooler system. The numbers given for each of the six streams, in MW, represent rates of exergy flow. The unit cost of the power input is $\mathrm{c}_{2}=3.6$ cents per $\mathrm{kW} \cdot \mathrm{h} . \mathrm{On}$ the advice of a cost engineer, the unit costs based on exergy of the compressed air (stream 3) and cooled compressed air (stream 4) are assumed to be equal, and no costs are associated with the incoming air (stream 1) and feedwater (stream 5). The costs of owning and operating the air compressor and intercooler are $\$ 36 / \mathrm{h}$ and $\$ 72 / \mathrm{h}$, respectively. Determine the (a) rate of exergy destruction for the air compressor and intercooler, each in MW.
(b) exergetic efficiency for the air compressor, the intercooler, and an overall system formed from the two components
(c) unit cost based on exergy, in cents/kW - h, for each of streams 3,4 , and 6 .
(d) cost rate, in $\$ / h$, associated with each of streams $2,3,4$, and 6 , and comment.