A novel working fluid for Organic Rankine Cycles (ORC)

The use of ORCs on long-haul Heavy Duty Diesel Engines (HDDE) is a possible way to improve the specific fuel consumption. One of the key considerations in the research and development efforts for ORCs is to investigate and identify technical paths that may improve the practicality of such a heat to power conversion concept. For this, simple solutions are vital for a timely deployment of the technology to meet the anticipated CO2 regulations. To provide a potential solution, this paper presents the simulation results of a novel organic working fluid (using Aspen HYSYS) which has been especially formulated for the HDDE sector. Due to the unique heat transfer and expansion characteristics, the primary advantage of the novel working fluid included an equivalent performance to ethanol despite a 20% reduction in the total heat transfer area and a 20% reduction in the size of the expansion machine. The secondary advantages over ethanol included a higher molecular weight (Δ 20 g/mol) and the requirement of a lower maximum system pressure (Δ 15 bar). Additionally, the novel fluid is expected to offer low global warming potential (< 20) and a high thermal stability (≈ 360°C).