Potential analysis of a waste heat recovery combined system based on recuperator and organic Rankine cycle on rotorcraft powerplant

Nowadays, substantial research efforts are being devoted to technologies which could potentially increase propulsion efficiency and reduce emissions of aircrafts. For this purpose, a waste heat recovery (WHR) combined system based on recuperator and organic Rankine cycle (ORC) is proposed in this paper for rotorcraft powerplant application. The concept is systematically analyzed within an integrated multidisciplinary simulation framework targeting the implicit coupling between rotorcraft-engine system and WHR module under designated flight conditions, also taking the additional weight penalty into consideration. Obtained results through quantification of the potential benefits suggest a considerable improvement in engine fuel economy with the adoption of highly effective recuperator, and ORC can significantly increase the power output, representing more than 24% of the engine power with benzene as working fluid. Reducing the power -to -weight ratio of ORC from 4 to 0.5 kW/kg, the added weight of WHR unit grows exponentially from 80 to 450 kg, which heavily penalizes the valuable carrying capability of the rotorcraft and consequently results in an increase of approximately 3.35%-4.2% in fuel consumption for the designated cruise mode of the generic mission scenario. The overall methodology can be effectively deployed to assess the implementation of WHR technologies for rotorcraft powerplant applications under realistic flight operations.