Experimental study of an organic Rankine cycle with R1233zd(E) for waste heat recovery from the coolant of a heavy-duty truck engine

Highlights: • Experiments showed the potential to produce up to 0.7 kW of expander power. • Up to 0.7% of the engine's power could be recovered experimentally. • An empirical model was developed to evaluate the performance in a driving cycle. • Between 0.7 and 1.3% of the energy was recovered in a driving cycle simulation. Waste heat recovery is an effective method for improving engine efficiency. While most research on waste heat recovery from heavy-duty engines focuses on the high-temperature heat sources, this paper investigates the performance of a low-temperature system. The experimental setup features an organic Rankine cycle with R1233zd(E) as the working fluid recovering heat from the coolant of a heavy-duty Diesel engine. Experiments at multiple engine operating points indicated a maximum operating cycle pressure of 8 bar and temperature of 92 °C. Between 0.1 and 0.7 kW net shaft power was achieved with a thermodynamic efficiency between 1.1 and 1.8%, resulting in a maximum expander power of 0.7% relative to the engine power. A simple empirical model based on the experimental results indicated that approximately 0.7% of the engine's energy could be recovered during a driving cycle, rising to 1.3% if a high efficiency pump and expander are used. The main contribution of this paper lies in the presentation of the experimental setup and experimental results specifically dedicated to recovering the heat from the engine coolant, which permits realistic evaluation of the performance.