Heat engine cycle limitations imposed by fuel properties

The heat energy of fuels used in a heat engine cycle is the source of the cycle's useful effect. The maximum fuel efficiency is particularly desirable in rocket and aircraft engines due their carrying the fuel (and the oxidant, in rocket engines) during the entire mission. In vehicle engines and power plants fuels are selected based on their cost and availability. Using the most prevalent Brayton cycle as an example, the article considers parameters that determine the maximum available heat factor introduced by a fuel into the cycle. Two parameters limiting the Brayton cycle's efficiency are considered, the maximum efficiency imposed by strength properties of materials and the maximum level of combustion products. The values of excess air factors for fuel combustion processes and limiting characteristics of heat engine cycles are determined for the case of Brayton cycles.