In order to evaluate the performance of a new power generation system in which the generator is driven by the fuel vapor turbine, the pyrolysis characteristics and the compositions of pyrolyzed fuel mixture are experimentally studied. An algorithm is developed for the calculation of isentropic enthalpy drop of fuel vapor using a real gas model based on the SRK (Soave-Redlich-Kwong) equation of state. Fuel vapor is a variable mixture of fuel and its cracking products at different temperatures and pressures, making its physical properties variable. The working capacity of fuel vapor is dramatically enhanced in the pyrolysis reaction process. Benefiting from the high enough working capacity, the fuel vapor turbine still has enough power to drive a generator in addition to a fuel pump. The low-grade heat energy absorbed by fuel is transformed into high-grade mechanical/electrical energy by this System to achieve better energy utilization. Evaluation results indicate that this thermodynamic power generation system can be operated in a wide range of temperature to support the off-design operation of a scramjet. (C) 2014 Elsevier Ltd. All rights reserved.