Repeat Problem 1, but consider the combustion to be occurring at a mass-based air–fuel rat...

Repeat Problem 1, but consider the combustion to be occurring at a mass-based air–fuel ratio of 12.5. Solve for the requested quantities.

Problem 1

Consider the Brayton cycle described in Problem. The heat is to be supplied by the combustion of octane (C8H18) with air, with 10% excess air being used in the combustion and the combustion proceeding to completion. The air enters the process at the exit temperature from the compressor, the fuel enters at 77°F, and the products exit at 2200°F. For both parts (a) and (b) of Problem 2, determine the mass flow rate of octane needed for the combustion process.

Problem 2

A Rankine cycle power plant has a thermal efficiency of 40% and produces 750 MW of power. The heat is to be supplied to the water in the steam generator through the combustion of methane (CH4) with 10% excess air. The methane and air both enter the steam generator at 298 K and burn to completion, and the products exit the steam generator at 650 K. The combustion process takes place at 101 kPa. Determine the required mass flow rate of the methane, and the corresponding volumetric flow rate of the fuel and the volumetric flow rate of the air entering the steam generator.