Comprehensive analysis of a novel cooling/electricity cogeneration system driven by waste heat of a marine diesel engine

Abstract

ABSTRACT In recent years, the increment of pollutants emissions in the environment, global warming concerns, and governmental restrictions on fossil fuel consumption have necessitated the prevention of the spread of pollution in various industries, such as waterborne transport. In this study, new electricity and cooling cogeneration system is proposed for waste heat recovery of exhaust gas from the combustion of a marine diesel engine. The proposed system encompasses a combination of an absorption power cycle and an ejector refrigeration cycle to supply the cooling and electricity required for the crew. The performance of the proposed system is evaluated from the perspective of the first and second laws of thermodynamics, and a parametric study is conducted to predict the behavior of the system under the influence of the input parameters. Later, due to the existing conflicting trend between energy efficiency and exergy efficiency, multi-objective optimization is used to merge several optimal design points into a final optimal point. The results indicate that the proposed cogeneration system has a capacity of 49.72 kW and 23.56 kW of electricity and cooling production in the optimal mode. In addition, in this case, the energy and exergy efficiencies of the system are obtained at 17.25% and 28.82%, respectively, which the former has improved by about 9.32% and the latter by 6.9%. Based on the obtained results, the total fuel exergy through exhaust gas is about 174.8 kW, of which 100.3 kW, 24.11 kW, and 50.38 kW are associated with exergy destruction, loss, and product rates.