Reconsider Prob. 2–56E. Using appropriate software, study the effects of the unit cost of energy, the new combustion efficiency on the annual energy, and cost savings. Let the efficiency vary from 0.7 to 0.9, and let the unit cost vary from $12 to $14 per million Btu. Plot the annual energy and cost savings against the efficiency for unit costs of $12, $13, and $14 per million Btu, and discuss the results.

Data from Prob. 2-56E

The steam requirements of a manufacturing facility are being met by a boiler whose rated heat input is 5.5 × 10⁶ Btu/h. The combustion efficiency of the boiler is measured to be 0.7 by a handheld flue gas analyzer. After tuning up the boiler, the combustion efficiency rises to 0.8. The boiler operates 4200 h a year intermittently. Taking the unit cost of energy to be $13/10⁶ Btu.