Gas turbine as range extender for future electric automobiles

Abstract

The propulsion of automobiles by motors, especially by hub motors, integrated into the wheels, offers remarkable advantages in terms of vehicle dynamics, stability and freedom of movement. But the most important benefit is the operation in conditions of local zero emission of pollutants and noise, which strongly recommend the utilization of such vehicles in urban areas. However, a major problem of the electric propulsion is the limited speed range caused by the poor energy density of every form of batteries. For the mentioned intelligent wheel robots, a supply of on board-electric energy is imperative. A solution with basic advantages is the use of thermal engines – such as piston, Wankel or Stirling – as on-board current generators. The paper presents a very promising alternative, which is the use of thermal turbomachines. A detailed comparison of the thermodynamic cycles of piston engines with gas turbines configured for current generation shows net advantages of the new solution in terms of efficiency and pollution limitation. For the continuous combustion at unchanged operation point a multitude of renewable fuels, alcohols, ethers or hydrogen, are applicable. Solutions with axial and radial gas turbine, which were successfully tested in automobiles with electric propulsion are described in base on characteristics and specific design aspects.