Engine Bottoming Cycle for Waste Heat Recovery - Second Year Poster Session - Ph.D. University of Trieste

Heavy Duty Diesel Engines (HDDE) are widely used as commercial vehicles and ship propulsion units and are also between the main contributors to CO2, Green House Gases (GHG) and pollutants emissions. Fuel cost and emissions reduction, in order to fulfil new stringent legislations, are pushing engine manufactures and developers in the direction of further increasing energy efficiency. In the last years, Organic Rankine Cycles (ORC) are constantly gaining increased interest in order to recover engine waste heat from several sources: exhaust gas, EGR (Exhaust Gas Recirculation), Jacket Cooling Water, CAC (Charge Air Cooler) or oil circuit. However, currently, ORC are mostly developed as a retrofit of existing engines, resulting in a non-optimized powertrain. For this reason, in a preliminary phase of an engine-ORC development project, it could be useful to investigate combined optimized concepts in oder to maximize energy efficiency and reduce emissions. For this purpose, first and second law of thermodynamics techniques can help in order to understand where, in the combined system, irreversibilities destroy exergy, thus increasing system entropy production and reducing overall system performance. Furthermore, an accurate assessment of typical applications duty profiles and thermo-economic techniques can help to design the most efficient and cost effective system.