Publication Date


Document Type


Committee Members

Mitch Wolff, Ph.D. (Advisor); Abdeel Roman, Ph.D. (Committee Member); Jose Camberos, Ph.D., P.E. (Committee Member)

Degree Name

Master of Science in Mechanical Engineering (MSME)


This work is investigating a dual mode Rankine cycle for aircraft applications, specifically meeting vehicle thermal and power requirements. This multiconfigurational approach allows the Thermal Management System (TMS) to be controlled based on aircraft needs. In this design, waste heat is removed from critical areas of the aircraft (e.g., propulsion, structure, subsystems) using the fuel as a heat sink. Hot fuel is then forced through a heat exchanger actively boiling water. The vapor byproduct is fed to a turbine coupled to a generator, providing power. The low-pressure steam is then condensed using cold fuel drawn from its tank; however, when additional cooling is needed, this steam is exhausted instead. Methods used are a blend of empirical and theoretical studies where a small-scale experimental rig is used to validate component models. MATLAB/Simulink software is used to capture their individual performance within the steady state and transient reschemes. With model fidelity established, scaling is used to assess the feasibility of the dual mode Rankine cycle. Using steady state results accuracy of modeled components was assessed based on root-mean-squared-error (RMSE). The single-phase heat exchanger showed the least error at 0.8%. Tube-in-tube and corrugated plate evaporators resulted in an RMSE of 14.2% and 1.0%, respectively. Evaporator transients were also analyzed, and predicted time constants led the experimental results showing a mean error of 13.8%, for the tube-in-tube evaporator and 82% for the corrugated plate evaporator. The scroll expanders performance represented the power capabilities of the system. Model results showed a RMSE of 10.1% and second law efficiency RMSE of 0.15%. With increased confidence in component models, a vehicle scaling was performed predicting system performance during two operating modes . During high-heat mode, thermal efficiency was 6.51% and second law efficiencies was 63.7%. During reduced-heat mode, thermal efficiency was 8.92% and second law efficiencies was 68.8%.

Page Count


Department or Program

Department of Mechanical and Materials Engineering

Year Degree Awarded