Explanation:
The key to this analysis is understanding what constitutes the air standard cycle analysis. There are really two key features: air is the working fluid (that is, we ignore the presence of fuel or combustion products except as an energy source) and all expansions or compressions are adiabatic and reversible (isentropic). For this latter case, we may write TV(k-1) = constant, where k = Cp/Cvis 1.4 for air. By memorizing these two factors, you will be able to perform air standard analyses. For this question, we first perform an isentropic compression by a factor of 12, and then we add the heat of combustion at constant volume. The final temperature is then T = (293)12 0.4 + (70,000/14) (1/0.7) = 7934°K.
