Design and simulation of turbogenerators for series hybrid electric vehicles

Abstract

To reduce emissions and fuel consumption in the automotive world, researchers are looking for alternative energy converters in the series hybrid electric vehicle and previous studies demonstrate that turbogenerator technologies are promising candidates. This study presents a methodology for the design, modelization, and dynamic simulation of different turbogenerator thermodynamic architectures to compare their performances, compute their efficiencies and select the best candidate to replace the internal combustion engine in the series hybrid electric vehicle taking into account the startup phase, where the inertia of the components affect the performance of the machine. Therefore, four types of turbogenerator configurations were thermodynamically investigated. Then an extensive work was conducted to design the turbomachines components with high efficiencies, followed by a design procedure of the recuperators. Dynamic models of the turbogenerators were developed and simulated with a constant power start-up strategy where the data of the designed components were integrated into the models. Results show that the turbogenerators that contain a recuperator have a startup phase characterized by high fuel consumption for 70 s mainly caused by the thermal inertia of the recuperator that causes a reduction in turbogenerators efficiencies by about 3%. Moreover, the intercooled regenerative reheated turbogenerator presented a better performance than the other turbogenerators with the highest rate of temperature increase at the inlet of the combustion chamber resulting in the lowest fuel consumption. Consequently, the intercooled regenerative reheated turbogenerator was selected as the best candidate as it had the best dynamic performance, the highest efficiency 37.9%, and net specific work 205 kJ/kg for a turbine inlet temperature of 950 °C. The developed methodology in this paper could be applied to reproduce new turbogenerator energy architectures, compare their performances, and select the best designs.