Analyzing the dual-loop organic rankine cycle for waste heat recovery of container vessel

Abstract

Increasing the efficiency of ships via waste heat recovery systems is one of the most effective methods to minimize emissions from ships, especially carbon dioxide emissions. The organic rankine cycle is a promising system. The purpose of this study is to analyze the dual-loop organic rankine cycle system using jacket cooling water, exhaust gas and scavenge air. Two model is designed to analyze the waste heat recovery system for the different main engine load. In the first model, while the exhaust gas is used as the heat source in the high temperature cycle, jacket cooling water and high temperature loop waste heat are used as heat sources in low temperature cycle. Scavenge air and exhaust gas and jacket cooling water are used as heat sources in the second model. Different working fluid combinations that have been familiar from literature and their alternatives are analyzed in two models and the net power output by using thermodynamics, reduction in carbon dioxide and fuel consumption are calculated. In low engine load, since the temperature range of scavenge air is low the second model is suitable for high main engine load. Results show that with the second model when benzene-R245fa(1,1,1,3,3-pentafluoropropane) combination is used as working fluid, 3373 kW net power can be produced, 13588,3 tonnes/year Carbon dioxide emissions can be reduced. However, since benzene is a flammable fluid, it is not recommended for use in the ship. Instead of benzene, R1233zd(E) (trans-1-chloro-3,3,3-trifluoro-1-propene) is more suitable for high temperature source.