Thursday, September 29, 2011

Automotive Chemical Engineering Problem

I have a 93' camaro Z28. Initially, I have 2 U.S. gallons of extremely high octane fuel (essentially pure octane) in the fuel tank. I burn 0.75 U.S. gallons of the fuel in the 275 hp motor. High octane fuel has an average specific gravity equal to 0.740. According to the U.S. EPA high octane fuel has an energy content equal to 35MJ/L. If the car produces 11,000 ft·lbf of torque, what is the cars efficiency of turning the energy of combustion into useable torque measured at the wheel? Assume the combustion reaction proceeds to completion because almost all of the undesired products will be converted to desired products by the catalytic converter. It is a reasonable approximation to average the enthalpys of the 300 °F gases exiting the dual 3 in. diameter exhaust pipes.

a.) What is the initial and final internal energies of the octane in the fuel tank?
b.) Write the balanced chemical equation for the motor
c.) What is the mass of the combined exhaust gases?
d.) How much energy leaves the system in the form of heat? 
e.) What is the thermal efficiency of the motor?

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