Propane (C3H8) gas at 258C, 1 atm and a mass flow rate of

Chapter 13, Problem 13.102

(choose chapter or problem)

Propane (\(\mathrm{C}_{3} \mathrm{H}_{8}\)) gas at \(25^{\circ} \mathrm{C}\), 1 atm and a mass flow rate of 0.67 kg/min enters an internal combustion engine operating at steady state. The fuel burns with air entering at \(25^{\circ} \mathrm{C}\), 1 atm according to

\(\begin{array}{l} \mathrm{C}_{3} \mathrm{H}_{8}+4.5\left[\mathrm{O}_{2}+3.76 \mathrm{~N}_{2}\right] \rightarrow 2.7 \mathrm{CO}_{2}+0.3 \mathrm{CO}+3.3 \mathrm{H}_{2} \mathrm{O} \\ +0.7 \mathrm{H}_{2}+16.92 \mathrm{~N}_{2} \end{array}\)

The combustion products exit at 1000 K, 1 atm and the rate of energy transfer by heat from the engine is 100 kW. For the hydrogen, cp  29.5 kJ/kmol  K. The effects of motion and gravity can be ignored. Using the environment of Table A-26 (Model II), evaluate an exergetic efficiency for the engine.