Optimization of organic Rankine cycle used for waste heat recovery of construction equipment engine with additional waste heat of hydraulic oil cooler

The aim of this study is to provide an optimal organic Rankine cycle (ORC) system for waste heat recovery (WHR) from a construction equipment engine. Construction equipment machines have very high annual fuel consumption, and most of the engine power is used to drive a hydraulic oil pump, thus producing additional waste heat from the hydraulic oil cooler. In order to compare the WHR of the construction equipment engine with that of a conventional engine without the heat of the hydraulic oil, four different single-loop ORC cases were considered and optimized for maximum net power. The results of this study showed that at the half-load condition as the primary operating condition, the use of additional waste heat from the hydraulic oil can increase the net power output of the ORC in the construction equipment engine by 11% despite at a low expander inlet temperature without a recuperator as compared to the system without the heat of hydraulic oil. However, the use of waste heat from the hydraulic oil increased the cost of the system owing to the preheater used by hydraulic oil and the increased condenser size.