Thermodynamic assessment and optimization of the influences of the steam-assisted turbocharging and organic Rankine cycle on the overall performance of a diesel engine-based cogeneration integrated with a reverse osmosis desalination unit

摘要

Waste heat recovery (WHR) of internal combustion engines (ICEs) is a subject of study for researchers concerned with energy conservation. For this purpose, various bottoming cycles, along with the influences of Steam-Assisted Turbocharger (SAT) on diesel engines' performances, have sufficiently been investigated. In this paper, a cogeneration system powered by a steam-assisted turbocharged marine Diesel engine and an organic Rankine cycle (ORC) is thermodynamically evaluated. Seawater is desalinated by a Reverse-Osmosis (RO) module to provide freshwater for heating units and engine's cooling jacket. Exergy analysis reveals that the condenser, the RO module, the heat exchanger 1, and the oil cooler are the devices with the lowest exergy efficiencies. Furthermore, the genetic algorithm is used to optimize the system parameters and determine the best combination of the proposed system. Results indicate that the combination of SAT with other components can negatively affect the cogeneration system's overall efficiency. On the optimal state, the system exhibits cogeneration energy and exergy efficiencies of 82.82% and 54.10%, respectively, being 2.18 and 1.54 times higher than the sole engine. The optimized system offers a net electrical power of 668 kW and a heating capacity of 646.3 kW through supplying process steam and domestic hot water (DHW).