On the design of waste heat recovery organic Rankine cycle systems for engines of long-haul trucks

The reduction of CO2 emissions from anthropogenic activities is a strategic goal of the EU in which heavy duty vehicles can contribute in a relevant way. A promising solution is the recovery of the thermal energy initially wasted by the engine, which represents around 60 % of the combustion energy. Transforming this heat into mechanical or electrical energy will thus increase the engine thermal efficiency. The conversion can be performed by means of a thermodynamic cycle (e.g. organic or non-organic Rankine cycles) using the waste heat as energy source, as it has already been developed in large stationary applications. Depending on the operating conditions, fuel consumption, and hence CO2 emissions, can theoretically be reduced by 10% to 15%.
Nonetheless, the adoption of such technology in the automotive domain requires specific R&D activities to select the working fluid, the components and the most appropriate system architecture in order to achieve sustainable costs and the required level of reliability, while the transient nature of the heat sources available on the truck must be taken into account to evaluate the resulting fuel economy. In this regards, this thesis, based on experimental studies and simulation models, contributes to the characterization and the design of Waste Heat Recovery Organic Rankine Cycle Systems for engines of long haul trucks.