Evaluation of Waste Heat Recovery technology in FCEV on different drive-cycles

Growing global warming and the associated climate change have expedited the need for adoption of carbon-neutral technologies. The transportation sector accounts for ~ 25 % of total carbon emissions. Hydrogen (H2) is widely explored as an alternative for decarbonizing the transport sector. The application of H2 through PEM Fuel Cells is one of the options available for the trucking industry, due to their relatively higher efficiency (~50%) and power density. However, at present the cost of an FCEV truck is considerably higher than its diesel equivalent. Hence, new technologies either enabling cost reduction or efficiency improvement for FCEVs are imperative for their widespread adoption. FCEVs have a system efficiency in the range of 40-60% implying that around half of the input energy is lost to the atmosphere as waste heat. However, recapturing this significant amount of low-grade waste heat into useful work is a challenge. This paper discusses the feasibility of waste heat recovery (WHR) system for a long-haul FCEV heavy duty truck with a rated power of 300 kW. Two WHR system are evaluated – widely used Organic Rankine Cycle (ORC). The working fluids considered for ORC are R1233zd(E), R245fa and n-Pentane. The 0-D model of the ORC based WHR systems is developed in Matlab-Simulink platform for analysis. The waste heat generated is quantified at different drive-cycles, namely flat, moderate hilly and hilly terrain, using a complete vehicle simulation tool developed in Simulink platform. The waste heat data from complete vehicle simulation tool is provided as an input for the developed 0-D WHR models. The results show a considerable improvement in the overall fuel consumption of FCEV trucks with WHR systems. The findings imply the importance of WHR in FCEV truck to improve the overall system efficiency.