# Consider problem 5.16(a). Determine the amount of fuel required per mole of air if the fuel is modeled as isooctane

## Question:

Consider problem 5.16(a). Determine the amount of fuel required per mole of air if the fuel is modeled as isooctane and combustion is complete.

Data from problem 5.16(a)

A Brayton gas turbine typically operates with only a small amount of fuel added so that theinlet temperatures of the turbine are kept relatively low because of material degradation athigher temperatures, thus the flowing streams can be modeled as only air. Refer to the onlinesupplement for stream labels. Consider a Brayton cycle modeled with air under the followingconditions: TA = 298 K, PA = PD = 0.1 MPa, PB = 0.6 MPa, and TC = 973 K. The efficienciesof the turbine and compressor are to be 85%. Consider air as an ideal gas streamwith CP = 0.79·CP,N2 = 0.21·CP,O2. Determine the thermal efficiency, heat required, and network output per mole of air assuming

(a) The heat capacities are temperature-independent at the values at 298 K.

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