Performance and economic analysis of an organic Rankine Cycle for hybrid electric vehicles

Car manufacturers need to develop efficient technologies to reduce emissions and save fuel in order to cater of European regulations and satisfy customers’ requirements. Internal combustion engines have a main limitation on efficiency due mainly to the heat losses. Processing an energy integration, it has been shown than an Organic Rankine Cycle (ORC) can improve the overall powertrain efficiency by recovering the heat into electricity. In parallel, hybrid electric vehicles attractiveness increases as it enables important energy saving. The contribution of this article is to design highly efficient vehicles, using both Organic Rankine Cycle and hybrid electric technologies. An adapted methodology based on energy integration techniques is required to choose the best points for the integrated system design. This study applies a methodology on hybrid electric vehicles, so as to define the powertrain configuration of the vehicle that is energy integrated. The energy recovery potential of a single stage Organic Rankine Cycle for a thermal engine in combination with a mild hybrid electric powertrain is studied. The assessment is done for different drive cycles. A study of economic feasibility and fuel consumption improvement is also done, in order to characterize the integrated energy system.