Comparison of fully pneumatic and pneumatic - electric hybrid configurations for propulsion of a refrigerated vehicle

Two different configurations of using a multistage air powered engine with variable valve timing for powering a light transport vehicle were evaluated through thermodynamic simulation. The expanded cold air between the stages was used to refrigerate the cold space and thereby get reheated. However this cannot meet the refrigeration load completely. Thus in the first configuration the air engine provided the shaft power for propulsion and for additional refrigeration. In the second configuration the air engine was connected in parallel to a motor/generator and Li-ion battery. The total refrigeration load was met by the expanded cold air between stages. The additional shaft power available was used to charge the battery. After depletion of the compressed air, the battery was used to provide shaft power and refrigeration. The range of the hybrid configuration was evaluated to be slightly higher.