Organic Rankine cycle – review and research directions in engine applications

Abstract

Abstract. Waste heat to power conversion using Organic Rankine Cycles (ORC) is expected to play an important role in CO2 reductions from diesel engines. Firstly, a review of automotive ORCs is presented focusing on the pure working fluids, thermal architectures and expanders. The discussion includes, but is not limited to: R245fa, ethanol and water as fluids; series, parallel and cascade as architectures; dry saturated, superheated and supercritical as expansion conditions; and scroll, radial turbine and piston as expansion machines. Secondly, research direction in versatile expander and holistic architecture (NOx + CO2) are proposed. Benefits of using the proposed unconventional approaches are quantified using Ricardo Wave and Aspen HYSYS for diesel engine and ORC modelling. Results indicate that, the implementation of versatile piston expander tolerant to two-phase and using cyclopentane can potentially increase the highway drive cycle power by 8%. Furthermore, holistic architecture offering complete utilisation of charge air and exhaust recirculation heat increased the performance noticeably to 5% of engine power at the design point condition.

Solar Driven Organic Rankine Cycle System and Hydrogen Fuel Production with Waste Heat Recovery

“…The working fluid was pressurized working fluid from the pump was fed to the recuperator, further, it was preheated, evaporated and superheated in the exhaust gas boiler channel. This superheated fluid was sent to the steam turbine where it was expanded thereby additional power was produced 4 . Organic Rankine Cycle (ORC) is a proven technology that can transform low to medium-grade heat into useful work 5 .…”