Thermodynamic and exergoeconomic analyses and optimization of an auxiliary tri-generation system for a ship utilizing exhaust gases from its engine

Utilizing exhaust gases from engines with the goal of heat recovery is recognized as an essential solution to overcome the economic and environmental problems in the energy industry. Hence, the motivation of this study is to design an auxiliary tri-generation system for a ship based on exhaust gases from its engine and implement the smart use technique of the waste heat. Thermodynamic and exergoeconomic analyses are conducted to evaluate the proposed system considering acceptable thermodynamic assumptions. The system consists of a Kalina cycle, an ejector-booster refrigeration cycle, and a humidification dehumidification desalination unit for power, cooling, and freshwater production. A parametric analysis is conducted to illustrate the effect of some design variables on the sum unit cost of products. Also, to achieve the best design of the system, different optimized cases are evaluated based on a genetic algorithm. According to the attained results, employing exhaust gases from a ship's engine through the proposed tri-generation system enhanced the thermodynamic and cost outcomes. So, this is a cost-effective and clean production solution to improve the design of a ship. Considering the multi-objective optimization, energy and exergy efficiencies and the sum unit cost of products were 81%, 49%, and 78.6 $/GJ, correspondingly.